Abstract
A limited number of studies have demonstrated the role of Lactococcus lactis (L. lactis) in human colorectal cancers (CRCs). The association of L. lactis abundance with the density of natural killer (NK) cells has not been investigated before. In this study, the L. lactis abundance in 60 CRC specimens, 20 adenoma (AD) specimens, and 29 normal colorectal tissues (NCs) specimens was investigated using the fluorescence in situ hybridization of 16S ribosomal RNA. The density of NK cells was detected using immunofluorescence in 28 CRC specimens, 12 AD specimens, and 22 NC specimens. The presence of L. lactis in NCs (48.28%) was detected significantly higher than that in the AD (20.00%, P = .044) and CRC (23.33%, P = .018) specimens. The abundance of L. lactis in NCs (32.73 ± 7.24) was also found to be significantly higher than that in AD (8.91 ± 5.89, P = .029) and CRC (5.63 ± 1.67, P = .003) specimens. In addition, the density of NKp30+ NK cells in NCs (51.14 ± 4.84) was significantly higher than that in the AD (6.10 ± 1.31) and CRC (1.72 ± 0.40) specimens (P < .001). Moreover, a positive association of L. lactis abundance with NKp30+ NK cells density in the colorectal samples (P < .001) was observed. The low abundance of L. lactis in the CRC tissues was associated with the decreased NK cells, which suggested that this might contribute to the progression of CRC by decreasing the number of NK cells.
Supplemental data for this article is available online at https://doi.org/10.1080/01635581.2021.1944649
Disclosure Statement
The authors declare that they have no competing interests.
Authors’ Contributions
HL and XD conducted the experiments. HL, XD, LY, ZT, LZ, QZ, XZ, GC, HY analyzed the data. XF performed the endoscopy and sampling. HL wrote the paper. XF conceived and designed the study.
Availability of Data and Materials
The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.
Ethics Approval and Consent to Participate
All patients who participated in the present study had signed an informed consent form. All procedures performed in studies involving human participants were supported by the Affiliated Hospital of Southwest Medical University Research Ethics Committee.
Patient Consent for Publication
Written informed consent was obtained from each patient.