Suppression of PTRF Alleviates Post-Infectious Irritable Bowel Syndrome via Downregulation of the TLR4 Pathway in Rats

Abstract

Background: Accumulating evidence suggests that the polymerase I and transcript release factor (PTRF), a key component of the caveolae structure on the plasma membrane, plays a pivotal role in suppressing the progression of colorectal cancers. However, the role of PTRF in the development of functional gastrointestinal (GI) disorders remains unclear. Post-infectious irritable bowel syndrome (PI-IBS) is a common functional GI disorder that occurs after an acute GI infection. Here, we focused on the role of PTRF in the occurrence of PI-IBS and investigated the underlying mechanisms.Methods: Lipopolysaccharide (LPS) (5 μg/ml) was used to induce inflammatory injury in human primary colonic epithelial cells (HCoEpiCs). Furthermore, a rat model of PI-IBS was used to study the role of PTRF. Intestinal sensitivity was assessed based on the fecal water content. A two-bottle sucrose intake test was used to evaluate behavioral changes. Furthermore, shRNA-mediated knockdown of PTRF was performed both in vitro and in vivo. We detected the expression of PTRF in colonic mucosal tissues through immunohistochemistry (IHC), western blotting (WB), and immunofluorescence (IF) analysis. Luciferase activity was quantified using a luciferase assay. Co-localization of PTRF and Toll-like receptor 4 (TLR4) was detected using IF analysis. The activation of the signaling pathways downstream of TLR4, including the iNOs, p38, extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK) pathways, was detected via WB. The levels of NO, IL-1β, IL-6, and TNF-α were measured using enzyme-linked immunosorbent assays.Results: LPS significantly induced PTRF expression and signaling downstream of TLR4, including p38, ERK, and JNK pathways, in HCoEpiCs. Moreover, shRNA-mediated knockdown of PTRF in HCoEpiCs significantly decreased the phosphorylation of JNK, ERK, and p38 and iNOS expression. In PI-IBS rats, the lack of PTRF not only reduced fecal water content and suppressed depressive behavior but also increased the body weight. Furthermore, we found a strong co-localization pattern for PTRF and TLR4. Consistently, the lack of PTRF impaired TLR4 signaling, as shown by the decreased levels of p-JNK, p-ERK, and p-p38, which are upstream factors involved in iNOS expression.Conclusion: PTRF promoted PI-IBS and stimulated TLR4 signaling both in vitro and in vivo. The results of this study not only enlighten the pathogenesis of PI-IBS but also help us understand the biological activity of PTRF and provide an important basis for the clinical treatment of PI-IBS by targeting PTRF.

Poria cocos Attenuated DSS-Induced Ulcerative Colitis via NF-κB Signaling Pathway and Regulating Gut Microbiota

“…These harmful cellular stimuli can activate the NF-κB pathway in intestinal epithelial cells, leading to transcription and the production of proinflammatory cytokines TNF-α, IL-1β, and IL-6. In addition, these cytokines can directly exacerbate TJ protein expression and distribution [10,35]. For instance, elevated levels of TNF-α can disrupt the structure and function of the TJs [36], while IL-1β could increase TJ permeability in human intestinal epithelial cells [37].…”

Non-alcoholic fatty liver disease combined with rheumatoid arthritis exacerbates liver fibrosis by stimulating co-localization of PTRF and TLR4 in rats

“…Our previous study demonstrated that the TLR4 signaling pathway is stimulated by PTRF ( Zhou et al, 2021 ). In this study, we performed high resolution liver tissue imaging to show that PTRF and TLR4 have a strong co-localization pattern.…”

“…Our group previously showed that the TLR4 signaling pathway is stimulated by polymerase 1 and transcript release factor (PTRF), also known as cavin-1, a conserved structural protein involved in the formation of caveolae ( Zhou et al, 2021 ). TLR4 physically binds to PTRF in caveolae of the plasma membrane at the basal level, and PTRF is required for TLR4 signaling assembly, which is especially stimulated by LPS ( Zheng et al, 2013 ).…”

Zn(II)–curcumin prevents cadmium-aggravated diabetic nephropathy by regulating gut microbiota and zinc homeostasis

“…Briefly, renal tissues were fixed in 4% paraformaldehyde and embedded in paraffin. A measure of 3-μm sections were stained with hematoxylin and eosin (H&E), Alcian blue-periodic acid–schiff (AB-PAS), or Masson’s trichrome staining by using standard methods ( Zhou et al, 2021 ; Tao et al, 2022 ; Zhang et al, 2023 ). Images were captured under a Leica DM6B microscope (Leica, Weltzar, Germany).…”