A cross-sectional study on the correlation between cytokines in a pelvic environment and tubal factor infertility

Associations between cytokines and the risk of female and male infertility: A two-sample Mendelian randomization analysis

PURPOSE

Observational studies have linked cytokines to the occurrence of female and male infertility. However, it is not clear how biomarkers of inflammation are causally related to infertility. To explore whether genetic variants in circulating cytokines are associated with the pathogenesis of infertility, we performed two-sample Mendelian randomization (MR) analysis.

METHODS

A total of 31,112 individuals of European ancestry were included in a genome-wide association study (GWAS) of 47 circulating cytokines as instrumental variables (IVs). Outcome data were female infertility, including four different subtypes, and male infertility, from the FinnGen consortium. Five MR methods, including inverse-variance weighted (IVW), MR-Egger, simple mode, weighted median, and weighted mode were employed to examine the genetic association between cytokines and the risk of female infertility and male infertility. The false discovery rate (FDR) was controlled using the Benjamini-Hochberg method.

RESULTS

After FDR correction, cis-protein quantitative trait locus (cis-pQTL) instruments showed that the cytokines GROa and MCSF were positively associated with female infertility. In analyses of subtypes of female infertility, eotaxin and sICAM were inversely associated with ovulation-related infertility; MCP3 alone was positively associated with uterus-related infertility; GROa and MCSF were positively correlated with infertility of cervical, vaginal, and other or unspecified origin; and MIP1a was negatively correlated with tubal origin infertility. The cytokines HGF, IL-2ra, and RANTES were positively correlated with male infertility. Similar findings were obtained in sensitivity analyses. There was no evidence of pleiotropy or heterogeneity in the results.

CONCLUSION

These findings contribute to current understanding of the role of cytokine biomarkers in the etiology of female and male infertility. Furthermore clinical experimental validation is required to evaluate the potential of these cytokines as biomarkers.

The role of IL-6/JAK/STAT signal in female infertility caused by hydrosalpinx

INTRODUCTION

To explore the role of IL-6/JAK/STAT signaling in tubal infertility.

METHODS

The fimbriae tissues of 14 patients with a history of infertility and hydrosalpinx and 14 patients with no history of infertility and no fallopian tube disease were collected. The tissues were then divided into hydrosalpinx group and control group followed by analysis of the protein expression of key factors in the IL-6/JAK/STAT signaling by immunohistochemistry and Western blot.

RESULTS

Immunohistochemical staining showed significantly higher level of IL-6, JAK1, p-JAK1, JAK2, p-JAK2, STAT1, p-STAT1, STAT3, and p-STAT3 in hydrosalpinx group than those in control group with IL-6 being mainly located in the cytoplasm and p-JAK2, STAT1, p-STAT1, STAT3, and p-STAT3 in the cytoplasm and nucleus. JAK1 and p-JAK1 was mainly located in the cytoplasm and JAK2 is in the cytoplasm and nucleus without difference of their expression between two groups. Consistently, hydrosalpinx group presented significantly higher protein levels of IL-6, JAK1, p-JAK1, JAK2, p-JAK2, STAT1, p-STAT1, STAT3, and p-STAT3 than control group without difference of JAK1, p-JAK1, JAK2 level.

CONCLUSION

The activation of IL-6/JAK2/STAT1 and STAT3 signaling pathways are found in the hydrosalpinx in infertile patients, indicating that they might be involved in the pathogenesis of hydrosalpinx.

Novel FSIP2 Variants Induce Super-Length Mitochondrial Sheath and Asthenoteratozoospermia in Humans

Asthenoteratozoospermia is one of the major factors for male infertility, whereas the causes of large numbers of cases are still unknown. We identified compound heterozygous variants of FSIP2 in three unrelated individuals from a cohort of 105 patients with asthenoteratozoospermia by exome sequencing. Deleterious FSIP2 variations caused severe disassembly of the fibrous sheath and axonemal defects. Intriguingly, spermatozoa in our study manifested "super-length" mitochondrial sheaths, increased levels of the mitochondrial sheath outer membrane protein TOMM20 and decreased mitochondrial ATP consumption. Dislocation or deletion of the annulus and reduction or dislocation of the annulus protein SEPT4 were also observed. While the lengthened mitochondrial sheaths were not presented in men harboring SEPT4 variants. Furthermore, female partners of two of three men achieved successful pregnancies following intracytoplasmic sperm injection (ICSI). Overall, we presume that FSIP2 may not only serve as a structural protein of the fibrous sheath but also as an intra-flagellar transporter involving in the axonemal assembly, mitochondrial selection and the termination of mitochondrial sheath extension during spermatogenesis, and ICSI is an effective treatment for individuals with FSIP2-associated asthenoteratozoospermia.