Damage-induced NAD release activates intestinal CD4+ and CD8+ T cell via P2X7R signaling

BACKGROUND

Postoperative ileus (POI) is characterized by the activation of inflammation triggered by tissue damage. Damage-associated molecular patterns (DAMPs) reportedly induce local inflammation after injury. However, the impact of DAMPs on intestinal resident lymphocytes during POI remains poorly elucidated.

METHODS

POI in mice was induced via intestinal manipulation (IM). The concentration of nicotinamide adenine dinucleotide (NAD) was detected after IM. The gastrointestinal motility of the mice was assessed after IM or NAD injection. Cytokine production and calcium influx in T cells were investigated after NAD stimulation using flow cytometry.

RESULTS

The concentration of extracellular NAD significantly increased after IM administration, and NAD directly impaired gastrointestinal motility. Intraperitoneal injection of NAD promoted the expression of TNF-α in intestinal CD8+ and CD4+ T cells, but only IFN-γ production by CD8+ T cells was significantly promoted by NAD injection. Granzyme B production in CD8+ and CD4+ T cells decreased after administration. Concordantly, the same results were observed in NAD stimulation of intestinal CD3+ T cells in vitro. Blocking the P2X7R-related membrane enzyme ART2.2 significantly diminished the pro-inflammatory effect of NAD.

CONCLUSION

IM includes the release of NAD derived from damaged tissues, consequently promoting pro-inflammatory cytokine production in intestinal CD4+ and CD8+ T lymphocytes. NAD-induced intestinal T cells activation may be associated with POI progression in the mouse.

Human intestinal myofibroblasts deposited collagen VI enhances adhesiveness for T cells - A novel mechanism for maintenance of intestinal inflammation

OBJECTIVE

Inflammatory bowel diseases (IBD) cause chronic intestinal damage and extracellular matrix (ECM) remodeling. The ECM may play an active role in inflammation by modulating immune cell functions, including cell adhesion, but this hypothesis has not been tested in IBD.

DESIGN

Primary human intestinal myofibroblast (HIMF)-derived ECM from IBD and controls, 3D decellularized colon or ECM molecule-coated scaffolds were tested for their adhesiveness for T cells. Matrisome was analysed via proteomics. Functional integrin blockade was used to investigate the underlying mechanism. Analysis of the pediatric Crohn's disease (CD) RISK inception cohort was used to explore an altered ECM gene expression as a potential predictor for a future complicated disease course.

RESULTS

HIMF-derived ECM and 3D decellularized colonic ECM from IBD bound more T cells compared to control. Control HIMFs exposed to the pro-inflammatory cytokines Iinterleukin-1β (IL-1β) and tumor necrosis factor (TNF) increased, and to transforming growth factor-β1 (TGF-β1) decreased ECM adhesiveness to T cells. Matrisome analysis of the HIMF-derived ECM revealed collagen VI as a major culprit for differences in T cell adhesion. Collagen VI knockdown in HIMF reduced adhesion T cell as did the blockage of integrin αvβ1. Elevated gene expression of collagen VI in biopsies of pediatric CD patients was linked to risk for future stricturing disease.

CONCLUSION

HIMF-derived ECM in IBD binds a remarkably enhanced number of T cells, which is dependent on Collagen VI and integrin αvβ1. Collagen VI expression is a risk factor for a future complicated CD course. Blocking immune cells retention may represent a novel approach to treatment in IBD.

T lymphocytes in the intestinal mucosa: defense and tolerance

Although lymphocytes are known to circulate throughout lymphoid tissues and blood, they also establish residency in nonlymphoid organs, most prominently in barrier tissues, such as the intestines. The adaptation of T lymphocytes to intestinal environments requires constant discrimination between natural stimulation from commensal flora and food and pathogens that need to be cleared. Genetic variations that cause a defective defense or a break in tolerance along with environmental cues, such as infection or imbalances in the gut microbiota known as dysbiosis, can trigger several immune disorders via the activation of T lymphocytes in the intestines. Elucidation of the immune mechanisms that distinguish between commensal flora and pathogenic organisms may reveal therapeutic targets for the prevention or modulation of inflammatory diseases and boost the efficacy of cancer immunotherapy. In this review, we discuss the development and adaptation of T lymphocytes in the intestine, how these cells protect the host against pathogenic infections while tolerating food antigens and commensal microbiota, and the potential implications of targeting these cells for disease management and therapeutics.