Background: HOTAIR is a well-characterized long noncoding inflammation-associated RNAs which modulates the NF-κB inflammatory pathway and immunes signaling. The overexpression of HOTAIR is associated with an increased expression of IFN-γ, IL-6, IL-17, TNF-α, IL-1β and IL-6R in monocytes. It has been proven that the presence of hydrosalpinx increases the incidence of chronic endometritis via significant elevation of inflammatory cytokines such as IL-2, IL-6 and TNFα. The aim of this study was to investigate whether the surgical removal of hydrosalpinx would alter the endometrial HOTAIR expression levels and subsequently local endometrial inflammatory response (leukocyte population count) in the fourth post-treatment cycle. Materials and Methods: In this prospective study, 15 infertile women with moderate to severe (sonovisible, diameter > 10 mm) hydrosalpinx underwent laparoscopic salpingectomy, from January 2021 to January 2022 were recruited. All patients had normal hormonal profile, BMI and regular menstrual cycle confirmed by mid-luteal progesterone levels of >10 ng/mL. Mid–luteal-phase endometrial samplings were performed at the time of surgery and in forth-post treatment cycle by piplle. Fifteen fertile age-matched women with a history of successful pregnancy were considered as control group. RNA extraction and cDNA synthesis were done and real-time PCR technique was used for quantitative HOTAIR gene expression. For evaluation of local endometrial inflammatory response, the leukocytes population count was recorded in five representatives adjacent and nonoverlapping high-power fields (400 X) for pre and post salpingectomy endometrium. Wilcoxon signed Ranks Test and kruskal-Wallis were used for data analysis. A P value less than 0.05 was statistically significant. Results: Gene expression levels of HOTAIR significantly decreased (1.94-fold) after salpingectomy compared to before surgery (P=0.01). Moreover, evaluation of the H&E-stained slides of the endometrium showed a statistically significant decrease in the number of lymphocytes post compared to pre-surgery (P=0.017). There were no significant differences in the number of neutrophils, plasma cells, eosinophils, or macrophages in the cases before and after surgery (P>0.05). Conclusion: Salpingectomy resulted in significant down-regulation in HOTAIR expression level, which was associated with reduction of local inflammatory response of endometrium through a significant decrease in the lymphocyte population in forth-post treatment cycle.
