Stress‐induced Effects on Endometriosis and Tight Junction Protein Expression are Counteracted by VSL#3 Administration in an Animal Model

Introduction Endometriosis is a gynecological disorder in which tissue that normally lines the endometrium grows outside the uterus and commonly results in peritoneal inflammation and infertility. Our previous studies show that stress exacerbates the development of endometriosis symptoms with worsening of colonic damage, and probiotic administration can decrease lesion size. Tight junction proteins are important to maintain the integrity of the intestinal barrier, and their disturbance can contribute to a variety of pathological conditions. It is possible that in our model stress contributes to the intestinal effects via modulation of tight junction proteins, but it is unclear whether probiotic use could counteract any of these effects. In this project we focused on tight junction protein expression intensity using the specific integral membrane proteins occludin and claudin‐2 to investigate how probiotics might alleviate endometriotic damage in the colon. Downregulation of occludin can enhance paracellular permeability, while claudin‐2 overexpression has been linked to intestinal pathophysiology by decreasing barrier function of other claudins. Hypothesis Probiotic administration will reverse the effects of stress on colonic tight junction protein expression in an animal model of endometriosis. Methods Endometriosis was induced by suturing uterine horn tissue next to the intestinal mesenteries in female Sprague‐Dawley rats (11–12/group) on day 0. One week later, rats were given the probiotic mixture VSL#3 or placebo in their drinking water before subjecting to 7 days of water avoidance stress (60 mins/day; days 14–20). Non‐stressed controls also received VSL#3 or placebo. On day 60 the rats were sacrificed, the vesicles were retrieved and measured, and the tissues collected before paraffin embedding. Colonic damage was measured and immunofluorescence for occludin and claudin‐2 was performed. Results The vesicle area from rats exposed to stress were significantly larger in size than non‐stressed controls (p<0.05), while after probiotic administration the size was reduced (p<0.01). Colonic macroscopic damage had a trend to increase in endometriosis animals and was reduced after probiotic administration (p<0.05). Colonic occludin expression showed a trend to increase when probiotic was administered after stress, while claudin‐2 expression was downregulated after stress (p<0.01) and probiotic administration (p<0.01). Conclusion Stress aggravates endometriosis symptoms causing larger vesicles and increased colonic damage. After probiotic administration, these symptoms are reversed and integrity of the tight junctions in colonic tissue is increased. This tendency provides further support for the potential use of probiotics as a complementary treatment to reduce the effects of inflammation in this condition. Support or Funding Information Supported in part by P20 GM103475‐15, R25GM096955 & R25GM082406 This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .