Gut region-specific TNFR expression: TNFR2 is more affected than TNFR1 in duodenal myenteric ganglia of diabetic rats

Abstract

BACKGROUND Cytokines are essential in autoimmune inflammatory processes that accompany type 1 diabetes. Tumor necrosis factor alpha plays a key role among others in modulating enteric neuroinflammation, however, it has a dual role in cell degeneration or survival depending on different TNFRs. In general, TNFR1 is believed to trigger apoptosis, while TNFR2 promotes cell regeneration. The importance of the neuronal microenvironment has been recently highlighted in gut region-specific diabetic enteric neuropathy, however, the expression and alterations of different TNFRs in the gastrointestinal tract has not been reported. AIM To investigate the TNFR1 and TNFR2 expression in myenteric ganglia and their environment in different intestinal segments of diabetic rats. METHODS Ten weeks after the onset of hyperglycemia, gut segments were taken from the duodenum, ileum and colon of streptozotocin-induced (60 mg/body weight kg i.p.) diabetic ( n = 17), insulin-treated diabetic ( n = 15) and sex- and age-matched control ( n = 15) rats. Myenteric plexus whole-mount preparations were prepared from different gut regions for TNFR1/HuCD or TNFR2/HuCD double-labeling fluorescent immunohistochemistry. TNFR1 and TNFR2 expression was evaluated by post-embedding immunogold electron microscopy on ultrathin sections of myenteric ganglia. TNFRs levels were measured by enzyme-linked immun-osorbent assay in muscle/myenteric plexus-containing (MUSCLE-MP) tissue homogenates from different gut segments and experimental conditions. RESULTS A distinct region-dependent TNFRs expression was detected in controls. The density of TNFR1-labeling gold particles was lowest, while TNFR2 density was highest in duodenal ganglia and a decreased TNFRs expression from proximal to distal segments was observed in MUSCLE-MP homogenates. In diabetics, the TNFR2 density was only significantly altered in the duodenum with decrease in the ganglia (0.32 ± 0.02 vs 0.45 ± 0.04, P < 0.05), while no significant changes in TNFR1 density was observed. In diabetic MUSCLE-MP homogenates, both TNFRs levels significantly decreased in the duodenum (TNFR1: 4.06 ± 0.65 vs 20.32 ± 3.1, P < 0.001; TNFR2: 11.72 ± 0.39 vs 15.91 ± 1.04, P < 0.01), which markedly influenced the TNFR2/TNFR1 proportion in both the ganglia and their muscular environment. Insulin treatment had controversial effects on TNFR expression. CONCLUSION Our findings show diabetes-related region-dependent changes in TNFR expression and suggest that TNFR2 is more affected than TNFR1 in myenteric ganglia in the duodenum of type 1 diabetic rats.

Oxidative-Stress-Related Alterations in Metabolic Panel, Red Blood Cell Indices, and Erythrocyte Morphology in a Type 1 Diabetic Rat Model

“…The highest occurrence of other RBC morphologies, namely acanthocytes, ovalocytes, dacrocytes, and schistocytes, was found in smears of insulin-treated diabetic rats compared to the controls and/or diabetics. This result is in line with earlier findings that exogenously administered insulin may be ineffective in some aspects of diabetes-related alterations [43][44][45]. Insulin is a drug that can induce immune-mediated hemolysis, which may explain the increased proportion of schistocytes in insulin-treated diabetic rats [46].…”

Intestinal Region-Dependent Alterations of Toll-Like Receptor 4 Expression in Myenteric Neurons of Type 1 Diabetic Rats

“…TNFα levels were increased in the small intestine and decreased in colonic ganglia in response to diabetes similarly to TLR4 expression [5]. Based on our recent study [35] TNFα causes the diabetes-related effects primarily through TNFR2.…”

The role of gut microbiota in diabetic peripheral neuropathy rats with cognitive dysfunction

“…In this study, there was no significant difference in the alphadiversity (composed of Shannon and Simpson indices) among the Previous studies have confirmed that the most predominant microbial taxa in this population are Firmicutes, Bacteroidetes, Aspergillus, Actinomycetes, and Clostridium. These bacteria are associated with diabetes, obesity (Jayapala and Lim, 2023), and AD (Patterson et al, 2015;Liu et al, 2020;Barta et al, 2023). A significant reduction in the abundance of thick-walled bacteria and actinomycetes at the phylum level was found in AD patients, in addition to an enrichment of allergic bacteria, which were highly correlated with biomarkers of AD pathology, suggesting that alterations in the AD microbiome may be associated with neuropathological changes in AD (Cenit et al, 2017).…”