Identification and Clinical Correlation Analysis of IFI44 in Systemic Lupus Erythematosus Combined with Bioinformatics and Immune Infiltration Analysis

Figures & data

Figure 1 Identification of DEGs between SLE and healthy controls. (A) Volcano plot illustrating 85 DEGs identified in GSE49454. (B) Volcano plot illustrating 113 DEGs identified in GSE65391. (C) Venn map showing 65 overlapping DEGs between the two datasets.

Abbreviations: DEG, Differentially Expressed Gene; SLE, systemic lupus erythematosus.

Figure 2 Functional enrichment based on DEGs. GO analysis for DEGs showing significant terms through (A) A bar plot and specific genes associated with these terms through (B) A gene-concept network. KEGG analysis for DEGs indicates enriched pathways via (C) A bubble plot and specific genes associated with these pathways through (D) A gene-concept network.

Abbreviations: GO, Gene Ontology; BP, biological processes; CC, cellular components; MF, molecular functions; KEGG, Kyoto Encyclopedia of Genes and Genomes.

Figure 3 Identification of IFI44 and RSAD2 by cross-linking genes from 11 ranking methods in the PPI network. (A) The PPI network acquired from the STRING database. (B) Upset plot representing the intersection between 11 ranking methods.

Abbreviations: PPI, protein-protein interaction; MNC, Maximum Neighborhood Component; MCC, Maximum Clique Centrality; EPC, Edge-Percolated Component; DMNC, Density of Maximum Neighborhood Component; Degree, Degree of Node Connection; Closeness, Closeness node connection closeness.

Figure 4 The relationship between diagnostic biomarkers and immune cell infiltration in SLE and healthy controls. Box plot of 22 types of immune cell infiltration in SLE and healthy controls in GSE49454 (A) and GSE65391 (B). The size of the dots represents the strength of the correlation between IFI44 expression and infiltrating immune cells in GSE49454 (C) and GSE65391 (D), with the color of the dots representing the corresponding P-values. Statistical significance was defined as P< 0.05.

Figure 5 Relative expression in SLE patients and healthy controls. (A) The expression of IFI44 was significantly increased in SLE patients compared to healthy controls, and it was significantly upregulated in male patients (*P<0.05, **P<0.01, ***P <0.001). (B) The diagnostic value of IFI44 in SLE.

Abbreviations: F, female; M, male; NC, healthy control; AUC, area under the curve.

Table 1 Correlation Between Relative Expression of IFI44 and Clinical Indicators in SLE Patients

mRNA	Laboratory Characteristics	All SLE Patients (n=24)		Male SLE Patients (n=9)		Female SLE Patients (n=15)
		rs	P	rs	P	rs	P
IFI44L	WBC (*10^9/L)	−0.145	0.498	−0.134	0.731	−0.057	0.840
	RBC (*10^12/L)	−0.505	0.012*	−0.552	0.123	−0.291	0.292
	HGB (g/L)	−0.488	0.015*	−0.544	0.130	−0.572	0.026*
	PLT (*10^9/L)	−0.012	0.955	0.176	0.651	0.123	0.661
	RDW-SD (fL)	0.196	0.358	0.151	0.699	0.243	0.382
	HCT%	−0.463	0.023*	−0.577	0.104	−0.549	0.034*
	MCV (fL)	0.131	0.543	0.076	0.847	−0.234	0.401
	MCH (pg)	−0.012	0.956	0.084	0.831	−0.487	0.066
	MCHC (g/L)	−0.234	0.272	−0.118	0.763	−0.413	0.126
	C3 (g/L)	−0.402	0.052	−0.710	0.032*	−0.209	0.454
	C4 (g/L)	−0.184	0.390	−0.732	0.025*	−0.104	0.713
	IgG (g/L)	−0.310	0.141	0.201	0.604	−0.431	0.109
	IgA (g/L)	−0.454	0.026*	−0.117	0.764	−0.210	0.052
	IgM (g/L)	−0.040	0.853	0.385	0.306	0.055	0.845
	CRP (mg/L)	0.203	0.341	−0.067	0.864	0.433	0.107
	ESR (mm/h)	0.442	0.031*	0.703	0.035*	0.361	0.205
	ACA (-/+)	−0.290	0.169	−0.494	0.213	0.017	0.510
	Anti-dsDNA (IU/mL)	0.012	0.957	0.008	0.983	0.227	0.436
	ANA	0.205	0.337	0.730	0.026*	−0.014	0.959
	Anti-Sm (-/+)	0.267	0.208	0.520	0.152	0.068	0.809
	Anti-U1RNP (-/+)	0.056	0.795	0.304	0.426	−0.246	0.377
	Anti-SSA (-/+)	0.169	0.431	0.565	0.113	−0.046	0.869
	Anti-SSB (-/+)	0.030	0.891	0.364	0.336	−0.270	0.330
	Anti-Jo-1 (-/+)	–	–	–	–	–	–
	Anti-SCL-70 (-/+)	–	–	–	–	–	–
	Anti-Rib (-/+)	0.355	0.089	0.413	0.270	0.454	0.089
	Anti-Ro (-/+)	0.155	0.468	0.624	0.073	−0.248	0.373
	UPRO (-/+)	0.556	0.005*	0.435	0.241	0.508	0.053
	CREA (mmol/L)	−0.500	0.815	0.042	0.915	−0.395	0.145
	UREA (mmol/L)	0.005	0.982	−0.452	0.222	−0.360	0.188
	SLEDAI	0.284	0.179	−0.018	0.966	0.408	0.131

Notes: P values and rs were calculated using Spearman rank correlation tests. *P<0.05.

Abbreviations: SLE, Systemic lupus erythematosus; WBC, White blood cells; RBC, Red blood cells; HGB, Hemoglobin; PLT, Platelets; RDW-SD, Red blood cell distribution width; HCT, Red blood cell specific volume; MCV, Mean corpuscular volume; MCH, Mean corpuscular hemoglobin; MCHC, Mean corpuscular hemoglobin concentration; C3, Complement component 3; C4, Complement component 4; IgG, Immunoglobulin G; IgA, Immunoglobulin A; IgM, Immunoglobulin M; CRP, C-reactive protein; ESR, Erythrocyte sedimentation rate; ACA, Anticardiolipin antibody; ANA, Antinuclear antibody; UPRO, Urine protein; CREA, Serum creatinine; UREA, Serum urea; SLEDAI, SLE disease activity index.

Figure 6 Correlation analysis of IFI44 expression level and clinical indicators in SLE patients. IFI44L had negative correlation with IgA, RBC, HCT, HGB (A–D), and had positive correlation with ESR and UPRO (E and F) in SLE patients.

Abbreviations: IgA, Immunoglobulin A; RBC, Red blood cell count; HCT, Red blood cell-specific volume; HGB, Hemoglobin level; ESR, Erythrocyte sedimentation rate; UPRO, Renal function Urine protein.

Figure 7 Correlation analysis of IFI44 expression level and clinical indicators in male (A–D) and in female (E and F) SLE patients.

Abbreviations: C3, Complement Component 3; C4, Complement Component 4; ESR, Erythrocyte sedimentation rate; ANA, Antinuclear antibody; HGB, Hemoglobin level; HCT, Red blood cell-specific volume.