Use of Ophiocordyceps sinensis (syn. Cordyceps sinensis) combined with angiotensin-converting enzyme inhibitors (ACEI)/angiotensin receptor blockers (ARB) versus ACEI/ARB alone in the treatment of diabetic kidney disease: a meta-analysis

Abstract

Ophiocordyceps sinensis (O. sinensis; syn. Cordyceps sinensis) has been used in clinical therapy for diabetic kidney disease (DKD) for more than 15 years. O. sinensis is a household name in china and it is available even in supermarket. However, the precise role of O. sinensis has not been fully elucidated with meta-analysis. The aim of this study was to review existing evidence on the effectiveness of O. sinensis for the treatment of DKD. We identified 60 trials involving 4288 participants. Overall, O. sinensis combined with ACEI/ARB had a better effect when compared to ACEI/ARB alone on 24 h UP (MD = −0.23 g/d, 95% CI: − 0.28 to −0.19, p < 0.00001), UAER (MD = −19.71 μg/min, 95% CI: −22.76 to −16.66, p < 0.00001), MAU (MD = −45.09 mg/d, 95% CI: −55.68 to −34.50, p < 0.00001), BUN (MD = −0.70 mmol/L, 95% CI: −1.02 to −0.39, p < 0.0001), SCr (MD = −8.37 μmol/L, 95% CI: −12.41 to −4.32, p < 0.0001), CRP (MD = −1.32 mg/L; 95% CI: −1.78 to −0.86; p < 0.00001), TG (MD = −0.51 mmol/L; 95% CI: −0.69 to −0.34, p < 0.00001), TC (MD = −0.64 mmol/L; 95% CI: −0.91 to −0.37, p < 0.00001), and SBP (MD = −2.01 mmHg; 95% CI: −3.45 to −0.58, p = 0.006). However, no effects were found for DBP, FBG, and HbA1C. This meta-analysis suggested that use of O. sinensis combined with ACEI/ARB may have a more beneficial effect on the proteinuria, inflammatory, dyslipidemia status as compared to ACEI/ARB alone in DKD III–IV stage patients, while there is no evidence that O. sinensis could improve the hyperglycemia status. However, with regard to low-quality and significant heterogeneity of included trials, to further verify the current results from this meta-analysis, long-term and well-designed RCTs with high-quality study are warranted to ascertain the long-term efficacy of O. sinensis.

• Diabetic kidney disease
• meta-analysis
• Ophiocordyceps sinensis
• therapy

Introduction

Diabetic kidney disease (DKD), a common microvascular complication of diabetes, is a leading cause of end-stage renal disease (ESRD) worldwide.1 The successive manifestations of DKD were high glomerular filtration rate (GFR), microalbuminuria, albuminuria, and ESRD. If left untreated, the resulting uremia is fatal. DKD is reversible in both microalbuminuria and albuminuria. However, once the disease reaches azotemia, the progression of DKD becomes irreversible.2 Therefore, it is imperative to find early and effective ways to treat this disease.

The inhibition of the renin–angiotensin system (RAS), including angiotensin-converting enzyme inhibitors (ACEI) and angiotensin receptor blockers (ARB), has been shown to reduce albuminuria and delay the progression of DKD, and has become the standard treatment for albuminuric patients.3^,4 However, in spite of the renoprotective effects of ACEI and ARB, DKD still progresses to ESRD in a large proportion of patients.5 This indicates that, in addition to RAS, other pathways are involved in the pathogenesis of ESRD. Several recent studies have demonstrated that traditional Chinese medicine (TCM) combined with ACEI/ARB treatment can safely and effectively treat DKD.6^,7

The caterpillar fungus Ophiocordyceps sinensis (syn. Cordyceps sinensis), one of the most famous TCMs and an ingredient in Chinese herbs is an enteropathogenic fungus that belongs to the family Clavicipitaceae, division Ascomycotina. O. sinensis is also called “Dong Chong Xia Cao” or “winter worm summer grass”. Several active components have been extracted and purified from O. sinensis, such as cordycepin and its derivatives, polysaccharides, trace elements, mycelium, and melanin.8^,9 These components have various physiological properties, such as anti-oxidative, anti-fibrogenic, anti-tumor, anti-thrombotic, anti-viral, anti-fungal, and anti-inflammatory activities.10–13 In recent decades, artificial cultivated fungus and curative products derived from the so-called “Cordyceps” in various forms such as capsules (e.g. jin shui bao capsule, bai ling capsule, zhi ling capsule) has been applied in clinical therapy for DKD. However, its efficacy has not been fully identified. In this meta-analysis, we aimed to systematically review the evidence regarding the benefits of O. sinensis in the treatment of DKD.

Methods

Data sources and search strategies

A systematic review of the published literature was performed according to the approach recommended by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for conducting meta-analyses.14 MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials (CCRCT), the Chinese Biomedical Literature (CBM), China National Knowledge Infrastructure (CNKI), Wang Fang, and VIP databases were searched to identify eligible studies (all to September 2014). The following search terms were used: Ophiocordyceps sinensis, Cordyceps sinensis, O. sinensis, C. sinensis, cordycepin, Cordyceps militaris, winter worm summer herb, dong chong xia cao, bai ling capsule, jin shui bao capsule, ACEI or angiotensin-converting enzyme inhibitors or ACE inhibitors, ARB or angiotensin receptor blockers, DKD or diabetic kidney disease, diabetic nephropathy, and kidney disease (Figure 1 shows details of the search method used in this meta-analysis). The search was limited to randomized controlled trials (RCTs) comparing O. sinensis combined with ACEI/ARB with ACEI/ARB alone without language limitation.

Figure 1. Flow chart of study selection process.

Inclusion criteria

Types of studies

Published reports of randomized controlled trials (RCTs) comparing O. sinensis + ACEI/ARB and with ACEI/ARB alone in patients diagnosed with DKD stage III or IV15^,16 with available data for our prescribed outcomes, while without language limitation.

Type of participants

The studies were restricted to any patients who were diagnosed with DKD stage III or IV according to Mogensen staging.16

Type of interventions

Studies comparing O. sinensis + ACEI/ARB and with ACEI/ARB alone for DKD patients. The form of O. sinensis was artificial cultivated fungus, while these studies with the form of O.sinensis were a decoction or formula were excluded.

Type of outcome measures

Proteinuria parameters: 24-h proteinuria (24hUP), urinary albumin excretion rate (UAER), microalbuminuria (MAU); Renal Function parameters: serum creatinine (SCr), blood urea nitrogen (BUN); Inflammatory parameters: C-reactive protein (CRP); Lipid parameters: serum triglycerides (TG), total cholesterol (TC) levels; Blood pressure parameters: systolic blood pressure (SBP), diastolic blood pressure (DBP); Blood glucose parameters: fasting blood glucose (FBG), and glycated hemoglobin A1C (HbA1c).

Data extraction and management and assessment of study quality

Data on participants were extracted from all referenced studies to retrieve the characteristics of the study sample, baseline of the study, and intervention characteristics for each group. Two reviewers (Y. L. and S. K. Y.) extracted data independently. Disagreements were resolved after discussion with a third reviewer (L. X.). Outcomes included the level of 24hUP, UAER, and MAU; BUN and SCr; CRP; TC and TG; SBP and DBP; and FBG and HbA1c. The validated Jadad scale was used to evaluate the quality of data from each study.17 The Jadad score included the following components: randomization (0–2 points), double-blinding (0–2 points), and description of withdrawals and dropouts (0–1 point). Allocation concealment was estimated by the criteria adopted from Schulz et al.18 Studies with Jadad scores of ≥3 were regarded as being of high quality.

Data analysis

Meta-analysis was performed using Review Manager version 5.2 (The Cochrane Collaboration, Oxford, UK). The mean change in each study from baseline to end point was considered a continuous variable. Continuous data using the same unit were presented as the mean difference (MD) with 95% CI. The chi-squared test for heterogeneity (defined as significant when I² is >50% or p < 0.1) was performed. The random effect model was used for the meta-analysis when there was significant heterogeneity. If there was not significant heterogeneity, the fixed effect model was used for the analysis.

Results

Search results

Of the 794 studies identified through online searches, 236 were ruled out because duplicates were found. The full text of the remaining 558 studies was retrieved, of which 385 were removed on review of the titles and abstracts. Among these, non-RCTs, reviews, comments, and animal studies were excluded. After further reading, 85 studies did not compare O. sinensis + ACEI/ARB with ACEI/ARB alone, 11 studies lacked clear information on dosage and outcomes of treatments, 9 studies contained unauthenticated data, 4 studies contained no outcomes of interest, the form of O. sinensis is decoction or formula in three studies, and the follow up was too short in one studies. At the end of the review process, 60 studies were included in the meta-analysis, 42 studies compared O. sinensis + ARB with ARB alone, and 18 compared O. sinensis + ACEI with ACEI alone. Figure 1 shows a chart of the study selection process.

Study characteristics and quality assessment

The main characteristics of the selected studies are summarized in Table 1. The 60 articles comprising 4288 participants (2163 in the experimental group and 2125 in the control group) were published in Chinese between 2005 and 2013. The median sample size was 72 (range, 36–205). Three kinds of O. sinensis were analyzed in this study: 25 articles discussed jin shui bao capsule (JSB), 32 discussed bai ling capsule (BL), and 3 discussed zhi ling capsule (ZL). The Jadad score of included study were listed in Table 1 and most trials were of low quality. Only 7 of 60 studies with Jadad score = 3 were regarded as being of high quality.19–25 Five articles were described as having used random number tables.19–23 None of the articles reviewed contained clear methods used for allocation concealment. Blinding was not confirmed. However, the outcomes were not likely to be influenced from any lack of blinding. In all studies, the characteristics of the participants in the different groups were similar at baseline (age, sex, disease course, etc.).

Table 1. Characteristics of included studies.

Author, Year	The stage of DKD	No. of patients	Mean age (years)	Course of DM (years)	Intervention	Study duration (weeks)	Results	Jaded score
Cui et al. [26] 2010	IV	E:49 C:49	(55–70)^a	NR	E: JSB (1.65 g Tid) + Benazepril (20 mg Qd) C: Benazepril (40 mg Qd)	8	Decrease 24hUP, BUN, and Scr, No effect on SBP and DBP	2
Gao et al. [19] 2013	III	E:100 C:105	E 57.3 ± 5.7 C 59.3 ± 5.2	E13.9 ± 4.5 C14.5 ± 5.1	E: JSB (0.99 g Tid) + Valsartan (80 mg Qd) C: Valsartan (80 mg Qd)	12	Decrease 24hUP, BUN, and Scr	3
Huang et al. [27] 2010	III	E:32 C:32	E 71.1 ± 10.7 C 71.3 ± 11.6	E10.4 ± 5.2 C10.9 ± 5.7	E: JSB (1.98 g Tid) + Perindopril (4 mg Qd) C: Perindopril (4 mg Qd)	12	Decrease 24hUP and UAER, No effect on FBG and HbA1C	2
Li et al. [28] 2011	IV	E:23 C:23	E 50 (38–66) C 54 (42–69)^a	NR	E: BL (1.0 g Tid) + Irbesartan (300 mg Qd) C: Irbesartan (300 mg Qd)	12	Decrease 24hUP and Scr, No effect on SBP and DBP	2
Li [29] 2012	III–IV	E:27 C:27	57.5 ± 8.3	8.4 ± 2.7	E: JSB (1.65 g Tid) + Benazepril (20 mg Qd) C: Benazepril (20 mg Qd)	8	Decrease 24hUP	2
Lin [30] 2009	IV	E 18 C 18	E 48.9 ± 17.5 C 50.7 ± 16.4	E 8.9 ± 3.9 C 9.6 ± 2.5	E: JSB (0.99 g Tid) + Valsartan (80 mg Qd) C: Valsartan (80 mg Qd)	8	Decrease 24hUP, BUN, Scr, TG, TC, SBP, and DBP	2
Liu et al. [31] 2011	III	E 42 C 38	E 49.7 ± 5.83 C 48.6 ± 5.27	E 5.0 ± 0.32 C 5.1 ± 0.38	E: BL (1.0 g Tid) + Irbesartan (150 mg Qd) C: Irbesartan (150 mg Qd)	12	Decrease 24hUP and UAER, No effect on Scr and BUN	2
Qian et al. [32] 2012	III–IVIV	E 40 C 40	61.74 ± 7.21	16.54 ± 7.56	E: JSB (0.99 g Tid) + Enalapril (10 mg Qd) C: Enalapril (10 mg Qd)	12	Decrease 24hUP, BUN, and Scr,	2
Shen et al. [33] 2011	III–IV	E 40 C 40	NR	NR	E: BL (1.0 g Tid) + Valsartan (80–160 mg Qd) C: Valsartan (80–160 mg Qd)	12	Decrease 24hUP	2
Sun et al. [34] 2012	III	E 45 C 45	E 75.6 ± 4.6 C 72.0 ± 1.5	E 13.2 ± 3.2 C 12.5 ± 3.5	E: BL (1.0 g Tid) + Enalapril (5 mg Bid) C: Enalapril (5 mg Bid)	12	Decrease 24hUP, Scr, BUN, SBP, and DBP	2
Wang et al. [35] 2010	III	E 30 C 30	E 64.9 ± 4.6 C 66.0 ± 3.5	E 16.1 ± 4.6 C 15.1 ± 4.5	E: BL (1.0 g Tid) + Benazeperil (10 mg Qd) C: Benazeperil (10 mg Qd)	12	Decrease 24hUP, No effect on BUN, Scr, SBP, and DBP	2
Wei [36] 2010	III	E 30 C 30	51 (37–70)^a	(10–18)^a	E: JSB (1.65 g Tid) + Benazepril (10 mg Qd) C: Benazepril (10 mg Qd)	8	Decrease 24hUP, No effect on BUN and Scr	2
Yang et al. [37] 2011	III	E 30 C 30	E 66.1 ± 4.5 C 65 ± 3.5	E 16.9 ± 4.5 C 15.3 ± 4.6	E: JSB (1.65 g Tid) + Benazepril (10 mg Qd) C: Benazepril (10 mg Qd)	12	Decrease 24hUP, No effect on BUN, Scr, SBP, and DBP	2
Ye et al. [38] 2012	III	E 26 C 26	E 54 ± 5 C 55 ± 5	NR	E: BL (1.0 g Tid) + Candesartan (8 mg Qd) C: Candesartan (8 mg Qd)	4	Decrease 24hUP and UAER, No effect on Scr	2
Yi et al. [39] 2009	III–IV	E 20 C 20	E 67.0 ± 4.8 C 66.2 ± 5.4	E 16.4 ± 4.1 C 16.3 ± 4.6	E: JSB (0.99 g Tid) + Irbesartan (150 mg Qd) C: Irbesartan (150 mg Qd)	12	Decrease 24hUP, BUN, Scr, TC, and TG, No effect on SBP and DBP	2
Yu et al. [40] 2013	III	E 40 C 40	47.6 ± 3.2	11.5 ± 2.9	E: JSB (0.99 g Tid) + Olmesartan (20 mg Qd) C: Olmesartan (20 mg Qd)	12	Decrease 24hUP	2
Zhang [23] 2011	III	E 42 C 42	68.4 ± 5.1	6.4 ± 2.5	E: JSB (1.98 g Tid) + Irbesartan (150 mg Qd) C: Irbesartan (150 mg Qd)	6	Decrease 24hUP, Scr, and FBG	3
Hong [41] 2010	III–IV	E 30 C 30	E 66.2 ± 5.4 C 65.8 ± 5.0	E 11.2 ± 6.7 C 15.1 ± 5.5	E: BL (1.0 g Tid) + Irbesartan (150 mg Qd) C: Irbesartan (150 mg Qd)	16	Decrease 24 h UP, BUN, and Scr, No effect on SBP and DBP	2
Liu [43] 2010	III–IV	E 40 C 40	E 41.2 ± 5.4 C 43.8 ± 5.0	E16.3 ± 4.6 C16.1 ± 4.5	E: JSB (0.99 g Tid) + Telmisartan (80 mg Qd) C: Telmisartan (80 mg Qd)	16	Decrease 24hUP, BUN, Scr, TG, and TC	2
Shan [44] 2012	IV	E 30 C 30	E 52 ± 15 C 52 ± 14	E (5–22) C (5–20)^a	E: BL (1.0 g Tid) + Valsartan (80 mg Qd) C: Valsartan (80 mg Qd)	14	Decrease 24hUP, BUN, and Scr, No effect on SBP and DBP	2
Song et al. [20] 2009	III	E 30 C 30	E 51.2 ± 17.2 C 50.3 ± 16.7	E11.8 ± 5.2 C10.7 ± 5.5	E: BL (2.0 g Tid) + Benazepril (10 mg Qd) C: Benazepril (10 mg Qd)	16	Decrease 24hUP, UAER, and CRP, No effect on Scr and FBG, HbA1C	3
Li [42] 2012	III–IV	E 50 C 50	NR	NR	E: BL (1.0 g Tid) + Irbesartan (150 mg Qd) C: Irbesartan (150 mg Qd)	24	Decrease 24hUP, Scr, TG, and TC	2
Tao et al. [45] 2009	III	E 43 C 42	E 50.6 ± 6.7 C 51.2 ± 6.9	E14.9 ± 8.6 C14.7 ± 8.9	E: JSB (0.99 g Tid) + Enalapril (10 mg Qd) C: Enalapril (10 mg Qd)	24	Decrease 24hUP, Scr and CRP, No effect on BUN	2
Cao [46] 2012	III	E 18 C 18	E65.10 (51–79) C 63.21 (51–77) ^a	NR	E: BL (1.0 g Tid) + Valsartan (80 mg Qd) C: Valsartan (80 mg Qd)	12	Decrease UAER and CRP, No effect on BUN and Scr	2
Chen et al. [47] 2010	III	E 28 C 26	(36–73)^a	8.42 ± 3.56	E: BL (1.0 g Tid) + Valsartan (80 mg Bid) C: Valsartan (80 mg Bid)	8	Decrease UAER, MAU, SBP, and DBP	2
Hong [48] 2008	III	E 20 C 20	NR	NR	E: ZL (0.75 g Tid) + Irbesartan (150 mg Qd) C: Irbesartan (150 mg Qd)	12	Decrease UAER, No effect on Scr and FBG	2
Li [24] 2010	III	E 42 C 36	55.7 ± 9.6	7.8 ± 4.2	E: BL (1.0 g Tid) + Losartan (100 mg Qd) C: Losartan (100 mg Qd)	4	Decrease UAER, MAU, TG, and TC, No effect on BUN, Scr, FBG, SBP, and DBP	3
Liu et al. [49] 2011	III	E 32 C 32	E 54 ± 17 C 52 ± 14	E (5–22) C (5–20)^a	E: BL (1.0 g Tid) + Irbesartan (150 mg Qd) C: Irbesartan (150 mg Qd)	12	Decrease UAER and CRP, No effect on Scr and FBG	2
Liu [50] 2011	III	E 79 C 79	E 57.7 ± 5.3 C NR	E 6.4 ± 0.9 C NR	E: BL (1.2 g Tid) + Benazepril (10 mg Qd) C: Benazepril (10 mg Qd)	8	Decrease UAER, MAU, BUN, and Scr	2
Luo et al. [51] 2011	III	E 40 C 40	NR	NR	E: BL (1.0 g Tid) + Irbesartan (150 mg Qd) C: Irbesartan (150 mg Qd)	12	Decrease UAER, Scr and CRP	2
Lv [52] 2012	III	E 31 C 30	E 63.8 ± 3.6 C 64.6 ± 4.1	E (6–17) C (7–18)^a	E: ZL (0.5 g Tid) + Losartan (50 mg Qd) C: Losartan (50 mg Qd)	8	Decrease UAER and CRP, No effect on BUN and Scr	2
Ma et al. [53] 2011	III	E 25 C 25	E 48.1 ± 9.3 C 46.2 ± 7.9	E 6.5 ± 1.2 C 6.8 ± 1.5	E: BL (1.0 g Tid) + Irbesartan (150 mg Qd) C: Irbesartan (150 mg Qd)	12	Decrease UAER, No effect on Scr, FBG, and HbA1c	2
Shen [55] 2012	III	E 46 C 40	65.2 ± 15.8	(5–15)^a	E: BL (1.0 g Tid) + Valsartan (80 mg Qd) C: Valsartan (80 mg Qd)	12	Decrease UAER, MAU, SBP, and DBP, No effect on FBG	2
Wang et al. [56] 2009	III	E 25 C 25	NR	NR	E: BL (1.0 g Tid) + Benazeperil (10 mg Qd) C: Benazeperil (10 mg Qd)	12	Decrease UAER, Scr, and CRP	2
Wang et al. [57] 2008	III	E 30 C 30	NR	NR	E: BL (1.0 g Tid) + Telmisartan (40 mg Qd) C: Telmisartan (40 mg Qd)	12	Decrease UAER, Scr, and CRP	2
Xiong [21] 2011	III	E 30 C 30	E 49.7 (36–60) C48.3 (35–60)^a	E 7.2 (1.2–16) C 7.6 (1.4–17)^a	E: BL (1.0 g Tid) + Irbesartan (150 mg Qd) C: Irbesartan (150 mg Qd)	12	Decrease UAER	3
Yang et al. [59] 2012	III	E 30 C 30	E 57 ± 7 C 56 ± 7	E 5.5 ± 2.2 C 6.1 ± 2.0	E: JSB (0.99 g Tid) + Enalapril (10 mg Bid) C: Enalapril (10 mg Bid)	8	Decrease UAER	2
Yu [60] 2012	III	E 42 C 42	E 64.3 ± 4.2 C 63.8 ± 4.4	E (8–21) C (9–19)^a	E: BL (1.0 g Tid) + Losartan (50 mg Qd) C: Losartan (50 mg Qd)	8	Decrease UAER, No effect on BUN and Scr	2
Zhang et al. [61] 2012	III	E 30 C 30	NR	NR	E: JSB (1.65 g Tid) + Valsartan (80 mg Qd) C: Valsartan (80 mg Qd)	20	Decrease UAER, TG, and TC, No effect on SBP, DBP, and HbA1C	2
Zhen [62] 2011	III	E 32 C 32	E (47–63) C (45–71)^a	NR	E: BL (1.0 g Tid) + Irbesartan (150 mg Qd) C: Irbesartan (150 mg Qd)	12	Decrease UAER and CRP, No effect on BUN, Scr, and SBP	2
Lei et al. [64] 2009	III	E 47 C 45	59.8 ± 7.1	8.3 ± 3.03	E: JSB (1.98 g Tid) + Irbesartan (150 mg Qd) C: Irbesartan (150 mg Qd)	24	Decrease UAER, No effect on Scr, SBP, DBP, FBG, and HbA1C	2
Lu [65] 2010	IV	E 33 C 33	NR	NR	E: BL (1.0 g Tid) + Telmisartan (80 mg Qd) C: Telmisartan (80 mg Qd)	4	Decrease MAU and Scr	2
Shi [66] 2010	III	E 37 C 35	E 58.1 ± 3.5 C 57.8 ± 3.7	E 6.8 ± 2.9 C 7.1 ± 3.2	E: JSB (0.99 g Tid) + Perindopril (4 mg Qd) C: Perindopril (4 mg Qd)	8	Decrease MAU	2
Wang [67] 2007	III	E 35 C 33	E 58.3 ± 3.6 C 57.6 ± 3.8	E 6.9 ± 2.8 C 7.2 ± 3.2	E: JSB (0.99 g Tid) + Fosinopril (10 mg Qd) C: Fosinopril (10 mg Qd)	6	Decrease MAU	2
Xue [68] 2009	III–IV	E 31 C 33	E 63 ± 5 C 62 ± 6	E 7.9 ± 3.4 C 7.9 ± 2.9	E: BL (1.0 g Tid) + Irbesartan (150 mg Qd) C: Irbesartan (150 mg Qd)	12	Decrease MAU, No effect on Scr, SBP, DBP, and FBG	2
Yang [69] 2013	III	E 20 C 20	E 50.8 ± 7.3 C 49.1 ± 7.9	E 11.2 ± 5.3 C10.7 ± 5.5	E: JSB (0.99 g Tid) + Losartan (50 mg Qd) C: Losartan (50 mg Qd)	12	Decrease MAU and Scr, No effect on BUN, TG, TC, FBG, and HbA1C	2
Zeng et al. [22] 2010	III	E 39 C 39	E 68.4 ± 5.1 C 67.5 ± 4.7	E 6.4 ± 2.5 C 6.2 ± 2.1	E: JSB (1.98 g Tid) + Irbesartan (150 mg Qd) C: Irbesartan (150 mg Qd)	6	Decrease MAU, TG, TC, and FBG	3
Zhang et al. [70] 2009	III	E 41 C 44	NR	NR	E: BL (1.0 g Tid) + Benazeperil (10 mg Qd) C: Benazeperil (10 mg Qd)	12	Decrease MAU, No effect on BUN, Scr, and HbA1C	2
Zhou [71] 2012	III	E 29 C 29	NR	NR	E: JSB (0.99 g Tid) + Losartan (50 mg Qd) C: Losartan (50 mg Qd)	4	Decrease MAU and Scr	2
Guo et al. [73] 2012	III	E 30 C 30	NR	NR	E: JSB (0.99 g Tid) + Irbesartan (150 mg Qd) C: Irbesartan (150 mg Qd)	20	Decrease MAU, SBP, and DBP	2
Liu [74] 2011	III	E 20 C 20	(35–72)^a	NR	E: BL (9 g/d) + Losartan (50 mg Qd) C: Losartan (50 mg Qd)	16	Decrease MAU, No effect on Scr	2
Wang et al. [75] 2007	III	E 50 C 48	E 65.6 ± 1.6 C 64.6 ± 2.4	E 7.3 ± 2.5 C 6.5 ± 3.3	E: BL (9 g/d) + Losartan (100 mg Qd) C: Losartan (100 mg Qd)	16	Decrease MAU, No effect on Scr	2
Chen [72] 2011	III	E 50 C 50	48.0 ± 14.8	(8–22)^a	E: ZL (0.75 g Tid) + Irbesartan (150 mg Qd) C: Irbesartan (150 mg Qd)	6 months	Decrease MAU, BUN, Scr, TG, TC, FBG, and HbA1C	2
Wu [76] 2012	III	E 40 C 40	E 61.2 ± 13.5 C59.6 ± 15.8	NR	E: JSB (1.98 g Tid) + Valsartan (80 mg Qd) C: Valsartan (80 mg Qd)	1 year	Decrease MAU, No effect on BUN, Scr, SBP, and DBP	2
Fang [77] 2010	IV	E 30 C 30	51.7 ± 2.1	11.4 ± 3.2	E: JSB (0.99 g Tid) + Telmisartan (80 mg Qd) C: Telmisartan (80 mg Qd)	12 months	Decrease BUN and Scr, No effect on SBP and DBP	2
Guan et al. [78] 2010	III	E 31 C 31	E 53.3 ± 5.7 C 52.2 ± 6.5	E 10.9 ± 3.4 C 9.9 ± 2.9	E: BL (1.0 g Tid) + Irbesartan (150 mg Qd) C: Irbesartan (150 mg Qd)	24	Decrease Scr and CRP, No effect on FBG and HbA1C	2
Yan et al. [58] 2005	III	E 40 C 20	E 49.7 ± 8.9 C 50.2 ± 9.1	E 12.3 ± 7.3 C 14.2 ± 6.7	E: BL (1.0 g Tid) + Enalapril (10 mg Qd) C: Enalapril (10 mg Qd)	8	Decrease UAER, BUN, and CRP	2
Cao et al. [63] 2007	III	E 30 C 30	E 59.4 ± 14.1 C 58.9 ± 11.2	E8.36 ± 5.3 C8.86 ± 5.0	E: JSB (1.98 g Tid) + Valsartan (80 mg Qd) C: Valsartan (80 mg Qd)	6 months	Decrease UAER, No effect on SBP, DBP, and HbA1C	2
Qiao [54] 2013	III	E 62 C 62	E 55.9 ± 11.8 C 54.6 ± 12.4	E11.9 ± 3.9 C11.5 ± 3.7	E: BL (1.0 g Tid) + Telmisartan (80 mg Qd) C: Telmisartan (80 mg Qd)	12	Decrease UAER	2
Lou et al. [25] 2010	III	E 31 C 31	E 61 ± 10 C 60 ± 8	E 10 ± 2.6 C 9 ± 2.8	E: BL (1.0 g Tid) + Valsartan (80 mg Qd) C: Valsartan (80 mg Qd)	4	Decrease MAU, No effect on BUN and Scr	3

Note: E, experimental group; C, control group; BL, bai ling capsule; JSB, jin shui bao capsule; ZL, zhi ling capsule; 24hUP, 24-h proteinuria; UAER, urinary albumin excretion rate; MAU, microalbuminuria; BUN, blood urea nitrogen; SCr, serum creatinine; CRP, C-reactive protein; TG, triglycerides; TC, total cholesterol; SBP, systolic blood pressure; DBP, diastolic blood pressure; FBG, fasting blood glucose; HbA1c, glycated hemoglobin A1C; DKD, diabetic kidney disease; DM, diabetes mellitus; NR, not reported.

^aValues were reported as median (range).

Efficacy assessment

Effects on proteinuria (24hUP, UAER, and MAU)

As shown in Table 2, the effects on proteinuria had three indicators containing 24hUP, UAER, and MAU. Data regarding the effects of therapy using O. sinensis + ACEI/ARB compared to that using ACEI/ARB alone on 24hUP were available from 2319^,20^,23^,26–45 of the 60 trials comprising 1714 participants. Based on the results of the meta-analysis, therapy with O. sinensis + ACEI/ARB decreased 24hUP by −0.23 g/d (95% CI: −0.28 to −0.19) compared to that in the control (p < 0.00001; Figure 2A and Table 2). There was evidence of significant heterogeneity in the magnitude of effects across these trials (I²= 88%, p for heterogeneity <0.00001, Figure 2A, Table 2); therefore, the random-effects model was used. Overall, O. sinensis + ACEI/ARB decreased 24hUP according to the present meta-analysis.

Figure 2. (A) Forest plot of studies comparing the effects of O. sinensis + ACEI/ARB with ACEI/ARB alone on 24hUP (g/d) in DKD. (B) Forest plot of studies comparing the effects of O. sinensis + ACEI/ARB with ACEI/ARB alone on UAER (μg/min) in DKD. (C) Forest plot of studies comparing the effects of O. sinensis + ACEI/ARB with ACEI/ARB alone on MAU (mg/d) in DKD.

Table 2. Summary effect of O. sinensis + ACEI/ARB on DKD patients.

					Assessment of heterogeneity		Publication bias
Outcome variables	No. study	No. patient	Mean net change (95% CI)	p Value	I2 index (%)	Q-statistic p Value	Funnel plots
Proteinuria markers
24hUP (total)	23	1714	−0.23 (−0.28,−0.19)	<0.00001	88	<0.00001	Asymmetric
24hUP (study duration ≤3months)	17	1269	−0.19 (−0.23, −0.15)	<0.00001	87	<0.00001	–
24hUP (study duration 3–6months)	4	260	−0.37 (−0.58, −0.15)	0.0008	86	<0.0001	–
24hUP (study duration ≥6months)	2	185	−0.41 (−0.62, −0.20)	<0.0001	0	0.97	–
24hUP (ACEI VS O. sinensis + ACEI)	10	711	−0.18 (−0.23, −0.13)	<0.00001	47	0.05	–
24hUP (ARB VS O. sinensis + ARB)	13	1003	−0.27 (−0.33, −0.21)	<0.00001	92	<0.00001	–
24hUP (ACEI/ARB VS JSB + ACEI/ARB)	13	1026	−0.23 (−0.30, −0.17)	<0.00001	87	<0.00001	–
24hUP (ACEI/ARB VS BL + ACEI/ARB)	10	688	−0.31 (−0.41, −0.22)	<0.00001	90	<0.00001	–
UAER (total)	25	1737	−19.71 (−22.76, −16.66)	<0.00001	79	<0.00001	Asymmetric
UAER (study duration ≤3months)	22	1525	−20.12 (−23.20, −17.05)	<0.00001	18	<0.00001	–
UAER (study duration 3–6months)	1	60	−13.90 (−29.65, 1.85)	0.08	/	/	–
UAER (study duration ≥6months)	2	152	−19.07 (−40.52, 2.39)	0.08	88	0.003	–
UAER (ACEI VS O. sinensis + ACEI)	6	452	−16.13 (−21.08, −11.18)	<0.00001	75	0.001	–
UAER (ARB VS O. sinensis + ARB)	19	1285	−21.00 (−24.71, −17.29)	<0.00001	78	<0.00001	–
UAER (ACEI/ARB VS JSB + ACEI/ARB)	5	336	−17.84 (−26.10, −9.57)	<0.0001	88	<0.00001	–
UAER (ACEI/ARB VS BL + ACEI/ARB)	18	1300	−20.67 (−24.06, −17.28)	<0.00001	76	<0.00001	–
UAER (ACEI/ARB VS ZL + ACEI/ARB)	2	101	−16.24 (−24.56, −7.93)	0.0001	0	0.51	–
MAU (total)	18	1347	−45.09 (−55.68, −34.50)	<0.00001	99	<0.00001	Asymmetric
MAU (study duration ≤3months)	13	969	−49.91 (−65.39, −43.42)	<0.00001	99	<0.00001	–
MAU (study duration 3–6months)	3	198	−38.00 (−75.46, −0.54)	0.05	89	<0.0001	–
MAU (study duration ≥6months)	2	180	−21.05 (−28.08, −14.02)	<0.00001	0	0.35	–
MAU (ACEI VS O. sinensis + ACEI)	4	383	−74.87 (−109.66, −40.08)	<0.0001	100	<0.00001	–
MAU (ARB VS O. sinensis + ARB)	14	964	−33.29 (−41.16, −25.43)	<0.00001	97	<0.00001	–
MAU (ACEI/ARB VS JSB + ACEI/ARB)	7	456	−33.12 (−49.84, −16.40)	0.0001	99	<0.00001	–
MAU (ACEI/ARB VS BL + ACEI/ARB)	10	791	−56.00 (−99.05, −12.96)	0.01	99	<0.00001	–
MAU (ACEI/ARB VS ZL + ACEI/ARB)	1	100	−33.00 (−58.90, −7.10)	0.01	/	/	–
Renal function markers
BUN (total)	27	2062	−0.70 (−1.02, −0.39)	<0.0001	89	<0.00001	Asymmetric
BUN (study duration ≤3months)	20	1537	−0.43 (−0.67, −0.18)	0.0005	61	0.0002	–
BUN (study duration 3–6months)	3	200	−1.85 (−2.04, −1.67)	<0.0001	0	0.55	–
BUN (study duration ≥6months)	4	325	−0.93 (−1.76, −0.11)	0.03	91	<0.00001	–
BUN (ACEI VS O. sinensis + ACEI)	10	836	−0.46 (−0.80, −0.11)	0.010	57	0.01	–
BUN (ARB VS O. sinensis + ARB)	17	1226	−0.82 (−1.22, −0.41)	<0.0001	91	<0.00001	–
BUN (ACEI/ARB VS JSB + ACEI/ARB)	12	924	−0.87 (−1.35, −0.38)	0.0005	87	<0.00001	–
BUN (ACEI/ARB VS BL + ACEI/ARB)	13	977	−0.57 (−1.09, −0.06)	0.03	91	<0.00001	–
BUN (ACEI/ARB VS ZL + ACEI/ARB)	2	161	−0.56 (−1.30, 0.19)	0.14	82	0.02	–
SCr (total)	44	3168	−8.37 (−12.41, −4.32)	<0.0001	95	<0.00001	Asymmetric
SCr (study duration ≤3months)	31	2191	−4.96 (−7.80, −2.12)	0.0006	82	<0.00001	–
SCr (study duration 3–6months)	6	398	−17.47 (−32.12, −2.81)	0.02	99	<0.00001	–
SCr (study duration ≥6months)	7	579	−13.44 (−22.72, −4.16)	0.005	79	<0.0001	–
SCr (ACEI VS O. sinensis + ACEI)	11	886	−2.95 (−5.48, −0.42)	0.02	5	0.39	–
SCr (ARB VS O. sinensis + ARB)	33	2282	−9.81 (−14.71, −4.91)	<0.0001	96	<0.00001	–
SCr (ACEI/ARB VS JSB + ACEI/ARB)	15	1158	−12.66 (−20.52, −4.81)	0.002	95	<0.00001	–
SCr (ACEI/ARB VS BL + ACEI/ARB)	26	1809	−5.99 (−10.65, −1.32)	0.01	94	<0.00001	–
SCr (ACEI/ARB VS ZL + ACEI/ARB)	3	201	−5.30 (−12.14, 1.54)	0.13	59	0.09	–
Inflammatory markers
CRP (total)	11	682	−1.32 (−1.78, −0.86)	<0.00001	94	<0.00001	Asymmetric
CRP (study duration ≤3months)	8	475	−1.48 (−2.00, −0.96)	<0.00001	94	<0.00001	–
CRP (study duration 3–6months)	1	60	−0.56 (−0.87, −0.25)	0.0004	/	/	–
CRP (study duration ≥6months)	2	147	−1.13 (−2.64, 0.38)	0.14	79	0.03	–
CRP (ACEI VS O. sinensis + ACEI)	4	255	−1.09 (−1.65, −0.53)	0.0001	75	0.008	–
CRP (ARB VS O. sinensis + ARB)	7	427	−1.36 (−1.97, −0.76)	<0.0001	96	<0.00001	–
CRP(ACEI/ARB VS JSB + ACEI/ARB)	1	85	−2.06 (−3.44, −0.68)	0.004	/	/	–
CRP (ACEI/ARB VS BL + ACEI/ARB)	9	536	−1.24 (−1.75, −0.73)	<0.00001	95	<0.00001	–
CRP (ACEI/ARB VS ZL + ACEI/ARB)	1	61	−1.63 (−2.07, −1.19)	<0.00001	/	/	–
Blood lipid markers
TG (total)	9	612	−0.51 (−0.69, −0.34)	<0.00001	71	0.0005	Asymmetric
TG (study duration ≤3months)	5	272	−0.51 (−0.77, −026)	<0.0001	52	0.08	–
TG (study duration 3–6months)	2	140	−0.39 (−0.53, −0.24)	<0.00001	0	0.83	–
TG (study duration ≥6months)	2	200	−0.80 (−1.71, 0.11)	0.08	92	0.0003	–
TG (ARB VS O. sinensis + ARB)	9	612	−0.51 (−0.69, −0.34)	<0.00001	71	0.0005	–
TG (ACEI/ARB VS JSB + ACEI/ARB)	6	334	−0.40 (−0.52, −0.28)	<0.00001	0	0.43	–
TG (ACEI/ARB VS BL + ACEI/ARB)	2	178	−0.96 (−1.52, −0.40)	0.0008	78	0.03	–
TG (ACEI/ARB VS ZL + ACEI/ARB)	1	100	−0.37 (−0.47, −0.27)	<0.00001	/	/	–
TC (total)	9	612	−0.64 (−0.91, −0.37)	<0.00001	93	<0.00001	Asymmetric
TC (study duration ≤3months)	5	272	−0.57 (−0.99, −015)	0.008	87	<0.00001	–
TC (study duration 3–6months)	2	140	−0.68 (−0.87, −0.50)	<0.00001	0	0.93	–
TC (study duration ≥6months)	2	200	−0.75 (−1.45, −0.06)	0.03	99	<0.00001	–
TC (ARB VS O. sinensis + ARB)	9	612	−0.64 (−0.91, −0.37)	<0.00001	93	<0.00001	–
TC (ACEI/ARB VS JSB + ACEI/ARB)	6	334	−0.57 (−0.91, −0.23)	0.001	84	<0.0001	–
TC (ACEI/ARB VS BL + ACEI/ARB)	2	178	−0.95 (−1.29, −0.61)	<0.00001	85	0.010	–
TC (ACEI/ARB VS ZL + ACEI/ARB)	1	100	−0.40 (−0.50, −0.30)	<0.00001	/	/	–
Blood pressure markers
SBP(total)	20	1308	−2.01 (−3.45, −0.58)	0.006	72	<0.00001	Asymmetric
SBP (study duration ≤3months)	12	776	−2.34 (−4.20, −0.48)	0.01	68	0.0003	–
SBP (study duration 3–6months)	4	240	−2.05 (−5.10, 1.01)	0.19	81	0.001	–
SBP (study duration ≥6months)	4	292	−0.77 (−3.05, 1.50)	0.51	19	0.29	–
SBP (ACEI VS O. sinensis + ACEI)	4	308	0.97 (−3.07, 5.01)	0.64	63	0.05	–
SBP (ARB VS O. sinensis + ARB)	16	1000	−2.59 (−4.11, −1.06)	0.0009	73	<0.00001	–
SBP (ACEI/ARB VS JSB + ACEI/ARB)	10	646	−0.93 (−2.94, 1.08)	0.36	57	0.01	–
SBP (ACEI/ARB VS BL + ACEI/ARB)	10	662	−2.90 (−4.90, −0.90)	0.004	79	<0.00001	–
DBP (total)	19	1244	−1.19 (−3.46, 1.07)	0.30	93	<0.00001	Asymmetric
DBP (study duration ≤3months)	11	712	−0.93 (−4.45, 2.59)	0.60	95	<0.00001	–
DBP (study duration 3–6months)	4	240	−1.65 (−4.70, 1.39)	0.29	88	<0.0001	–
DBP (study duration ≥6months)	4	292	−1.32 (−4.14, 1.51)	0.36	51	0.11	–
DBP (ACEI VS O. sinensis + ACEI)	4	308	−0.42 (−3.42, 2.59)	0.79	70	0.02	–
DBP (ARB VS O. sinensis + ARB)	15	936	−1.44 (−4.11, 1.22)	0.29	94	<0.00001	–
DBP (ACEI/ARB VS JSB + ACEI/ARB)	10	646	0.13 (−1.26, 1.53)	0.85	41	0.08	–
DBP (ACEI/ARB VS BL + ACEI/ARB)	9	598	−2.58 (−5.95, 0.80)	0.13	95	<0.00001	–
Blood glucose markers
FBG (total)	14	962	−0.11 (−0.42, 0.21)	0.50	84	<0.00001	Asymmetric
FBG (study duration ≤3months)	10	648	−0.17 (−0.49, 0.15)	0.29	72	0.0002	–
FBG (study duration 3–6months)	1	60	1.00 (0.58, 1.42)	<0.00001	/	/	–
FBG (study duration ≥6months)	3	254	−0.30 (−1.06, 0.45)	0.43	90	<0.0001	–
FBG (ACEI VS O. sinensis + ACEI)	2	124	0.48 (−0.53, 1.49)	0.35	92	0.0004	–
FBG (ARB VS O. sinensis + ARB)	12	838	−0.22 (−0.53, 0.09)	0.17	79	<0.00001	–
FBG (ACEI/ARB VS JSB + ACEI/ARB)	5	358	−0.26 (−0.76, 0.24)	0.31	88	<0.00001	–
FBG (ACEI/ARB VS BL + ACEI/ARB)	7	464	0.11 (−0.31, 0.53)	0.61	74	0.0008	–
FBG (ACEI/ARB VS ZL + ACEI/ARB)	2	140	−0.39 (−1.92, 1.14)	0.62	92	0.0003	–
HbA1C (total)	10	673	0.09 (−0.02, 0.20)	0.13	32	0.16	Asymmetric
HbA1C (study duration ≤3months)	4	239	0.11 (−0.05, 0.27)	0.18	0	0.80	–
HbA1C (study duration 3∼6months)	2	120	0.20 (0.01, 0.38)	0.04	46	0.17	–
HbA1C (study duration ≥6months)	4	314	−0.05 (−0.29, 0.18)	0.66	48	0.12	–
HbA1C (ACEI VS O. sinensis + ACEI)	3	209	0.12 (−0.03, 0.26)	0.11	0	0.79	–
HbA1C (ARB VS O. sinensis + ARB)	7	464	0.55 (−0.13, 0.22)	0.61	53	0.05	–
HbA1C(ACEI/ARB VS JSB + ACEI/ARB)	5	316	0.18 (0.08, 0.28)	0.0007	0	0.64	–
HbA1C (ACEI/ARB VS BL + ACEI/ARB)	4	257	0.03 (−0.12, 0.17)	0.73	0	0.86	–
HbA1C (ACEI/ARB VS ZL + ACEI/ARB)	1	100	−0.69 (−1.29, −0.09)	0.02	/	/	–

Note: BL, bai ling capsule; JSB, jin shui bao capsule; ZL, zhi ling capsule; 24hUP, 24-h proteinuria; UAER, urinary albumin excretion rate; MAU, microalbuminuria; BUN, blood urea nitrogen; SCr, serum creatinine; CRP, C-reactive protein; TG, triglycerides; TC, total cholesterol; SBP, systolic blood pressure; DBP, diastolic blood pressure; FBG, fasting blood glucose; HbA1c, glycated hemoglobin A1C; DKD, diabetic kidney disease; ACEI/ARB, angiotensin-converting enzyme inhibitors/angiotensin receptor blockers; CI, confidence interval.

Data for the effects of therapy using O. sinensis + ACEI/ARB compared to using ACEI/ARB alone on UAER were available from 25 trials comprising 1737 participants.20^,21^,24^,27^,31^,38^,46–64 In general, therapy with O. sinensis + ACEI/ARB decreased UAER by 19.71 µg/min (95% CI: −22.76 to −16.66) compared with that of ACEI/ARB alone (p < 0.00001; Figure 2B and Table 2). There was evidence of significant heterogeneity in the magnitude of effects across these trials (I²= 79%, p for heterogeneity < 0.00001; Figure 2B and Table 2).

Eighteen trials22^,24^,25^,47^,50^,55^,65–76 comprising 1347 participants had outcomes for MAU. The meta-analysis showed that therapy with O. sinensis + ACEI/ARB decreased MAU by 45.09 mg/d (95% CI: −55.68 to −34.50) compared with that of the control (p < 0.00001; Figure 2C and Table 2). There was evidence of significant heterogeneity in the magnitude of effects across these trials (I²= 99%, p for heterogeneity <0.00001; Figure 2C and Table 2). In all, therapy using O. sinensis + ACEI/ARB was more effective in reducing MAU as well as 24hUP and UAER. Meanwhile, a subgroup analysis was performed that was stratified by the study duration. The results also showed that there was a significant difference on 24hUP and MAU among trials of different duration.

Effects on renal function (BUN, SCr)

As seen in Table 2, the effect on renal function has two parameters: BUN and SCr. Twenty-seven trials comprising 2062 participants19^,24–26^,30–32^,34–37^,39^,41^,43–46^,50^,52^,58^,60^,62^,69^,70^,72^,76^,77 reported effects on BUN. In summary, therapy with O. sinensis + ACEI/ARB decreased BUN by 0.70 mmol/L (95% CI: −1.02 to −0.39) compared with that of ACEI/ARB alone (p < 0.0001; Figure 3A and Table 2). There was evidence of significant heterogeneity in the magnitude of effects across these trials (I²= 89%, p for heterogeneity <0.00001; Figure 3A and Table 2).

Figure 3. (A) Forest plot of studies comparing the effects of O. sinensis + ACEI/ARB with ACEI/ARB alone on BUN (mmol/L) in DKD. (B) Forest plot of studies comparing the effects of O. sinensis + ACEI/ARB with ACEI/ARB alone on SCr (μmol/L) in DKD.

Forty-four trials comprising 3168 participants19^,20^,23–26^,28^,30–32^,34–39^,41–46^,48–53^,56^,57^,60^,62^,64^,65^,68–72^,74–78 showed results for SCr levels. Overall, therapy with O. sinensis + ACEI/ARB decreased SCr by 8.37 µmol/L (95% CI: −12.41 to −4.32) compared to that of ACEI/ARB alone (p < 0.0001; Figure 3B and Table 2). There was evidence of significant heterogeneity in the magnitude of effects across these trials (I²= 95%, p for heterogeneity <0.00001; Figure 3B and Table 2). It is indicated that therapy with O. sinensis + ACEI/ARB has an advantage over therapy with ACEI/ARB alone in reducing BUN and SCr. In addition, a subgroup analysis was conducted according to study duration. The results on BUN and SCr among trials of different duration were in accordance with the results of whole studies.

Effects on inflammatory biomarkers (CRP)

The changes in CRP were analyzed from 11 trials comprising 682 participants.20^,45^,46^,49^,51^,52^,56–58^,62^,78 There were significant changes in CRP (p < 0.00001, MD: −1.32 mg/L; 95% CI: −1.78 to −0.86; Figure 4 and Table 2). As there was evidence of heterogeneity (p < 0.00001, I²= 94%; Figure 4 and Table 2), the random-effects model was used for meta-analysis.

Figure 4. Forest plot of studies comparing the effects of O. sinensis + ACEI/ARB with ACEI/ARB alone on CRP (mg/L) in DKD.

Effects on blood lipids (TG, TC)

The meta-analysis on blood lipids had two parameters: TG and TC. TG and TC were compared among patients receiving O. sinensis + ACEI/ARB and those receiving ACEI/ARB alone in nine trials comprising 612 patients.22^,24^,30^,39^,42^,43^,61^,69^,72 The significant difference was identified in terms of the TG (p < 0.00001, MD: −0.51 mmol/L, 95% CI: −0.69 to −0.34; Figure 5A and Table 2) and TC (p < 0.00001, MD: −0.64 mmol/L, 95% CI: −0.91 to −0.37; Figure 5B and Table 2); therefore, it can be concluded that therapy with O. sinensis + ACEI/ARB was more effective in ameliorating blood lipids than therapy with ACEI/ARB alone.

Figure 5. (A) Forest plot of studies comparing the effects of O. sinensis + ACEI/ARB with ACEI/ARB alone on TG (mmol/L) in DKD. (B) Forest plot of studies comparing the effects of O. sinensis + ACEI/ARB with ACEI/ARB alone on TC (mmol/L) in DKD.

Effects on blood pressure (SBP, DBP)

As shown in Table 2, the effects on SBP and DBP were assessed in 20 trials comprising 1308 participants24^,26^,28^,30^,34^,35^,37^,39^,41^,44^,47^,55^,61–64^,68^,73^,76^,77 and 19 trials comprising 1244 participants,24^,26^,28^,30^,34^,35^,37^,39^,41^,44^,47^,55^,61^,63^,64^,68^,73^,76^,77 respectively. Based on the results of the meta-analysis, the groups that received therapy with O. sinensis + ACEI/ARB showed a significant decrease in SBP compared to that of the controls (P = 0.006, MD: −2.01 mmHg, 95% CI: −3.45 to −0.58; Figure 6A and Table 2); however, a non-significant decrease was found for DBP (p = 0.30, MD: −1.19 mmHg, 95% CI: −3.46 to 1.07; Figure 6B and Table 2).

Figure 6. (A) Forest plot of studies comparing the effects of O. sinensis + ACEI/ARB with ACEI/ARB alone on SBP (mmHg) in DKD. (B) Forest plot of studies comparing the effects of O. sinensis + ACEI/ARB with ACEI/ARB alone on DBP (mmHg) in DKD.

Effects on blood glucose (FBG, HbA1c)

Fourteen trials comprising 962 participants20^,22–24^,27^,48^,49^,53^,55^,64^,68^,69^,72^,78 and 10 trials comprising 673 participants20^,27^,53^,61^,63^,64^,69^,70^,72^,78 reported the effects on FBG and HbA1c, respectively. The meta-analysis indicated that therapy using O. sinensis + ACEI/ARB produced no statistically significant change in FBG compared to that of therapy using ACEI/ARB alone (p = 0.50, MD: −0.11 mmol/L, 95% CI: −0.42 to 0.21; Figure 7A and Table 2). In addition, the combined therapy did not decrease the level of HbA1C (p = 0.13, MD: 0.09%, 95% CI: −0.02 to 0.20; Figure 7B and Table 2).

Figure 7. (A) Forest plot of studies comparing the effects of O. sinensis + ACEI/ARB with ACEI/ARB alone on FBG (mmol/L) in DKD. (B) Forest plot of studies comparing the effects of O. sinensis + ACEI/ARB with ACEI/ARB alone on HbA1c (%) in DKD.

Investigations of heterogeneity

We performed subgroup analysis to exploring mean change in proteinuria, renal function, inflammatory, blood lipid, blood pressure, and blood glucose parameters; the analysis was stratified by different kinds of artificial cultivated fungus capsules, different study duration, and different character of the controlled group. As shown in Table 2, the results of subgroup analysis showed that there was no difference on 24hUP, UAER, MAU, TC, DBP, and FBG levels among trials of different kinds of artificial cultivated fungus capsules or different study duration. In addition, use of O. sinensis could both effectively improve these parameters when compared with ACEI or ARB. However, therapy with zhi ling capsule(ZL) has no effect on serum BUN and Scr. Encouragingly, Funnel plots for some key outcomes such as 24hUP, UAER, MAU, BUN, SCr, CRP, TG, TC, SBP, DBP, FBG, and HbA1C were asymmetric (Table 2 and Figure 8), which suggested there was publication bias among these studies.

Figure 8. Funnel plots with mean differences (MD) for studies included in this meta-analysis comparing O. sinensis + ACEI/ARB with ACEI/ARB alone for the treatment of HD patients.

Discussion

This systematic review and meta-analysis have consolidated data from a great deal of RCTs administering therapy with O. sinensis + ACEI/ARB to patients with DKD. In summary, O. sinensis + ACEI/ARB appears to have significantly reduced proteinuria (24hUP, UAER, MAU) and improved renal function (BUN, SCr) compared with therapy using ACEI/ARB alone. Furthermore, O. sinensis combined + ACEI/ARB decreased the level of CRP, TG, TC, and SBP; however, a non-significant decrease was found for DBP, FBG, and HbA1c. If confirmed in larger high-quality studies, these results suggest that therapy using O. sinensis + ACEI/ARB might play a role in delaying or even preventing the progression of DKD.

DKD is the most devastating and costly complication in patients with diabetes worldwide. The pathogenesis of DKD is complicated and not yet fully understood. In addition to RAS, other pathways, such as oxidative stress,79 polyol,80 protein kinase C (PKC) activation,81 inflammation,82 and excessive production of advanced glycation end products (AGEPs)83 also contribute to the occurrence and development of DKD, especially oxidative stress and the production of reactive oxygen species(ROS).84^,85 It is known that treatment with ACEI/ARB can slow the progression of DKD to ESRD; however, it does not stop or reverse the process.

Ophiocordyceps sinensis (syn. C. sinensis) (Berk.) Sacc, a fungus highly valued in China as a tonic and herbal medicine, was discovered 2000 years ago86 and its use was documented formally in the Qing Dynasty and mentioned in the Bencao Congxin (New Compilation of Materia Medica) in 1757. Ophiocordyceps sinensis parasitizes the larvae of moths (Lepidoptera), particularly Hepialus armoricanus, and uses the nutrients from each larva to create mycelia and replace the larval body with sclerotium, from which the stroma and fruiting body grow. Several kinds of active components have been extracted and purified from O. sinensis, such as cordycepin and its derivatives, polysaccharides, trace elements, mycelium, and melanin.8^,9 Ophiocordyceps sinensis is now used for multiple medicinal purposes, such as anti-inflammatory, antitumor activity, immunostimulating properties, anti-microbial, anti-fibrotic, and neuroprotective effects,87^,88 due to its various physiological properties. Several experiments have proved that the chemical components, pharmacology, and toxicology of natural and cultured O. sinensis are similar; therefore, natural O. sinensis can be replaced by cultured O. sinensis.89

Oxidative stress and increased production of ROS plays an important role in the occurrence and development of DKD. Our previous study90 demonstrated that cordycepin (3′-deoxyadenosine) could ameliorate the albumin-induced epithelial–mesenchymal transition of tubular cells (HK2) by decreasing Nicotinamide Adenine Dinucleotide Phosphate (NADPH) oxidase activity and inhibiting ROS production. The trace elements in C. sinensis, which serve as coenzymes of glutathione peroxidase, can reduce mesangial cell contractility and oxidative stress.91 In vitro and in vivo studies have proved that a polysaccharide isolated from O. sinensis and containing glucose, mannose, and galactose exhibited strong antioxidant activity, acted as a direct free-radical scavenger, and might have attenuate renal failure.92^,93 The aqueous extract of the Indian species of Ophiocordyceps sinensis has spectacular antioxidant and anti-inflammatory capabilities.94 In addition, the melanin derived from O. sinensis also exhibited chelating ability and antioxidant activity.95 Superoxide dismutase (SOD) can eliminate superoxide anion and inhibit lipid peroxidation. C. sinensis can elevate SOD and decrease the biomarkers of oxidative stress (such as methylenedioxyamphetamine and advanced oxidation protein products).96

Aldose reductase (AR), the first and rate-limiting enzyme of the polyol pathway that converts glucose to fructose, plays a key role in the pathogenesis of DKD.97 Previous studies have shown that bailing capsule can inhibit AR.91 Therefore, we speculate that the nephroprotection of O. sinensis is partially a result of that. In addition, several studies have demonstrated that the extracts from C. sinensis could reduce the pressure within glomeruli and decrease the capillary hydrostatic pressure, thus lowering glomerular hyperfiltration and preventing the development of glomerulosclerosis.98

Previous study has demonstrated that nephrin loss is a main cause of proteinuria.99 Evidence from animal studies showed that DKD was ameliorated with bailing capsule, which may be related to the restoration and gene expression of nephrin.100 Transforming growth factor-β1 (TGF-β1) and connective tissue growth factor (CTGF) are indispensable during the pathogenesis of DKD.101 Cordycepin (3′-deoxyadenosine) interferes with the TGF-β1 and bone morphogenetic protein signaling through downregulation of Smads, which might be the underlying anti-fibrotic effect of this agent.102 Moreover, cordycepin markedly blocks TGF-β1-mediated activation of renal interstitial fibroblast cells through up regulating anti-fibrotic hepatocyte growth factor (HGF) at both the gene and protein levels.103 In addition, one study proved that bailing capsule can reduce the expression of TGF-β1 and CTGF in rats with DKD, which can reduce renal tissue injury.104

Hyperlipidemia, a risk factor for DKD, can stimulate cell proliferation and induce glomerulosclerosis. Recent studies showed that cordycepin prevents hyperlipidemia by activating AMP-activated protein kinase, which plays a critical role in the regulation of fat metabolism.11^,105 A polysaccharide (O. sinensis-F30) obtained from the cultured mycelium of O. sinensis lowered the plasma TG and TC levels in genetic diabetic mice after intraperitoneal administration.106 In addition, C. sinensis has anti-lipid peroxidation properties and inhibits accumulation of cholesteryl, a cholesterol ester, in macrophages by suppressing low-density lipoprotein oxidation.107

The increases of both hypoxia inducible factor-1 (HIF-1α) and vascular endothelial growth factor (VEGF) in the kidneys of rats with DKD, and the positive correlation suggests that there is chronic hypoxia in the renal tissue of those with DKD. C. sinensis might protect against chronic hypoxia injury in those with DKD by lowering the expression of HIF-1α and VEGF.108 Caspase-3 is a key enzyme of apoptosis that is closely related to kidney injuries. The protective effect of C. sinensis may be inhibiting the activation of caspase-3 during the AngII-induced apoptosis of NRK-52 E.109 Moreover, bailing capsule can protect renal tubular Na⁺–K⁺ATP enzyme, stimulate the production of epidermal growth factor from renal tubular epithelial cells, improve immunologic competence, and motivate renal tubular epithelial cell proliferation.110 In summary, O. sinensis might protect renal tissues through antioxidant activity, inhibiting AR, ameliorating glomerular hyperfiltration, elevating nephrin levels, restraining renal interstitial fibrosis, and reducing hyperlipidemia. The underlying mechanism and potential effects of O. sinensis on DKD warrant further investigation.

There are several important potential study limitations to this systematic review. The major limitation was the poor quality of the trials. Most of the trials were of very low methodological quality and the interpretation of any positive findings for the efficacy of the included O. sinensis for treating DKD should be made with caution. Second, all trials were published in Chinese, creating the possibility of publication bias. Third, adverse effects were not described in detail. Only 14 RCTs reported any adverse events, and none were serious. Fourth, most of the included studies reported short-term (<1 year) outcomes of O. sinensis supplementation treatment, the long-term efficacy of O. sinensis need to be proven by further long-term studies. Finally, there was evidence of heterogeneities of baseline clinical features in these included RCTs, such as different study duration and different types of artificial cultivated O. sinensis. We tried to control some of these differences by performing subgroup analysis according to the level of baseline characters and using random-effect models in our analysis, nevertheless, we must have to take note that the accuracy of the pooled analytical results might be influenced.

Conclusion

Taken together, use of O. sinensis combined with ACEI/ARB may have a more beneficial effect on the proteinuria, inflammatory, dyslipidemia status as compared to ACEI/ARB alone in DKD III–IV stage patients, while there is no evidence that O. sinensis could improve the hyperglycemia status. However, with regard to low-quality and significant heterogeneity of included trials, therefore, the clinical application should be concerned with more long-term high-quality and well-designed RCTs to ascertain the clinical value of O. sinensis as an additional therapeutic option for DKD patients.

Acknowledgements

Y. L., S. K. Y., X. Z., M. W., and D. T. generated the data for the manuscript and wrote the manuscript. F. Y. L. and L. S. edited the manuscript. X. L. had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Declaration of interest

The authors declare that there is no conflict of interests regarding the publication of this paper. This study was supported by grants from the National Natural Science Foundation of China (81370832 and 81100541).