calpain and Colitis

The intracellular protein HMGB1 is released from cells and acts as a damage-associated molecular pattern molecule during many diseases, including inflammatory bowel disease (IBD); however, the intracellular function of HMGB1 during inflammation is poorly understood. Here, we demonstrated that cytosolic HMGB1 regulates apoptosis by protecting the autophagy proteins beclin 1 and ATG5 from calpain-mediated cleavage during inflammation. Colitis in mice with an intestinal epithelial cell-specific Hmgb1 deletion and patients with IBD were both characterized by increased calpain activation, beclin 1 and ATG5 cleavage, and intestinal epithelial cell (IEC) death compared with controls. In vitro cleavage assays and studies of enteroids verified that HMGB1 protects beclin 1 and ATG5 from calpain-mediated cleavage events that generate proapoptotic protein fragments. Together, our results indicate that HMGB1 is essential for mitigating the extent and severity of inflammation-associated cellular injury by controlling the switch between the proautophagic and proapoptotic functions of beclin 1 and ATG5 during inflammation. Moreover, these studies demonstrate that HMGB1 is pivotal for reducing tissue injury in IBD and other complex inflammatory disorders.

Topics: Adaptive Immunity; Animals; Apoptosis; Apoptosis Regulatory Proteins; Autophagy; Autophagy-Related Protein 5; Beclin-1; Calpain; Cell Cycle Checkpoints; Cells, Cultured; Colitis; Cytosol; Dextran Sulfate; Dipeptides; Epithelial Cells; Female; HMGB1 Protein; Humans; Intestinal Mucosa; Male; Mice, Inbred C57BL; Mice, Transgenic; Microtubule-Associated Proteins; Proteolysis

Topics: Animals; Apoptosis; Apoptosis Regulatory Proteins; Autophagy; Autophagy-Related Protein 5; Beclin-1; Calpain; Cell Differentiation; Colitis; Dextran Sulfate; Disease Models, Animal; Epithelial Cells; HMGB1 Protein; Humans; Inflammation; Inflammatory Bowel Diseases; Interleukin-10; Intestinal Mucosa; Mice; Mice, Knockout; Microtubule-Associated Proteins; Organoids

Searching for alternative therapies that are effective, safe and less expensive of those currently used for ulcerative colitis, we investigated the efficacy of a polyphenol extract from apple in rat colitis.. Rats with trinitrobenzensulphonic acid-induced colitis were treated daily with rectal administration of apple polyphenols 10(-4) M for 14 days. COX-2, TNF-α, tissue transglutaminase and calpain in colon mucosa samples were assessed by reverse transcription-polymerase chain reaction and western blot analyses. To ascertain the role of tissue transglutaminase in mucosal healing, wounded rat fibroblasts were incubated with cystamine (a tissue transglutaminase activity inhibitor).. Colitis was associated with increased COX-2, TNF-α, calpain, and tissue transglutaminase mRNA. The protein expression of COX-2, TNF-α and calpain was increased whilst tissue transglutaminase was decreased. Apple extract treatment reduced the severity of colitis (p<0.05) and restored all the considered biomarkers at the baseline level. Apple polyphenols reduced the degradation of tissue transglutaminase protein occurring through calpain action. Apple polyphenols-treated wounded fibroblast recovered within 24h showing intense immunoreactivity for tissue transglutaminase.. The efficacy of apple extract is mediated by its effects on COX-2 and TNF-α. The unbalance between calpain and tissue transglutaminase may play a role in colonic damage and future therapeutic interventions in ulcerative colitis can target this mechanisms.

Topics: Animals; Calpain; Colitis; Cyclooxygenase 2; GTP-Binding Proteins; Intestinal Mucosa; Male; Malus; Mice; NIH 3T3 Cells; Phytotherapy; Plant Extracts; Polyphenols; Protein Glutamine gamma Glutamyltransferase 2; Rabbits; Rats, Wistar; RNA, Messenger; Transglutaminases; Trinitrobenzenesulfonic Acid; Tumor Necrosis Factor-alpha

Galectin-4 is a carbohydrate-binding protein belonging to the galectin family. Here we provide novel evidence that galectin-4 is selectively expressed and secreted by intestinal epithelial cells and binds potently to activated peripheral and mucosal lamina propria T-cells at the CD3 epitope. The carbohydrate-dependent binding of galectin-4 at the CD3 epitope is fully functional and inhibited T cell activation, cycling and expansion. Galectin-4 induced apoptosis of activated peripheral and mucosal lamina propria T cells via calpain-, but not caspase-dependent, pathways. Providing further evidence for its important role in regulating T cell function, galectin-4 blockade by antisense oligonucleotides reduced TNF-alpha inhibitor induced T cell death. Furthermore, in T cells, galectin-4 reduced pro-inflammatory cytokine secretion including IL-17. In a model of experimental colitis, galectin-4 ameliorated mucosal inflammation, induced apoptosis of mucosal T-cells and decreased the secretion of pro-inflammatory cytokines. Our results show that galectin-4 plays a unique role in the intestine and assign a novel role of this protein in controlling intestinal inflammation by a selective induction of T cell apoptosis and cell cycle restriction. Conclusively, after defining its biological role, we propose Galectin-4 is a novel anti-inflammatory agent that could be therapeutically effective in diseases with a disturbed T cell expansion and apoptosis such as inflammatory bowel disease.

Topics: Animals; Antigens, CD7; Apoptosis; Calpain; CD3 Complex; Cell Cycle; Cell Proliferation; Colitis; Galectin 4; Inflammatory Bowel Diseases; Integrin beta1; Intestinal Mucosa; Mice; Mice, Inbred BALB C; T-Lymphocyte Subsets; T-Lymphocytes