Oral Antibiotics Attenuate Bowel Segment Reversal–Induced Alterations in Subpopulation and Function of Peripheral Blood Leukocytes,Thymocytes,and Splenocytes in Massive Bowel-Resected Rats

Abstract

Background: The authors previously demonstrated that oral antibiotics significantly attenuated inflammatory response, improved intestinal bacterial overgrowth, and augmented anabolic response in massive bowel-resected rats with bowel-segment reversal. Herein, the effects of oral antibiotics on immune functions were investigated. Methods: Male Wistar rats were subjected to a sham operation or a 70% small bowel resection with or without a 3-cm small bowel segment reversal. Thereafter, half numbers of animals with bowel resection and reversal were orally administered clindamycin plus amoxicillin (50 plus 50 mg/kg/day) for 3 weeks. Age-matched nonsurgical rats were included as references. Peripheral blood, spleen, and thymus were collected for analyzing immunocyte subpopulations and function.Results: Bowel resection significantly decreased weight gain, thymic weight, and splenic helper-T, suppressor-T, and mature-B cells but significantly increased splenic macrophage distribution and concanvavalin A–stimulated splenocytic proliferation and cytokine production, such as tumor-necrosis factor (TNF)-α, interferon-γ, and interleukin (IL)-2 (1-way ANOVA, P < .05). Bowel segment reversal further decreased circulating suppressor-T cells but increased circulating natural killer cells and spontaneous splenocytic TNF-α production. Segment reversal–induced elevations in bacterial numbers of gut content, circulating white blood cell, nitric oxide, IL-6, splenocytic interferon-γ and IL-2 production, reductions in T-thymocytic distribution, and alterations in thymocytic interferon-γ and IL-2 production were attenuated by oral antibiotics. Moreover, oral antibiotics significantly increased splenocytic granulocytes and spontaneous thymocytic proliferation. Conclusions: Oral antibiotics might augment the beneficial effects of bowel segment reversal on anabolism via attenuating bacterial overgrowth and inflammatory response, and restore subpopulation and function of splenocytes and thymocytes in massive bowel–resected rats.