The Costimulatory Pathways and T Regulatory Cells in Ischemia-Reperfusion Injury: A Strong Arm in the Inflammatory Response?

Revisiting regulatory T cells as modulators of innate immune response and inflammatory diseases

Regulatory T cells (Treg) are known to be critical for the maintenance of immune homeostasis by suppressing the activation of auto- or allo-reactive effector T cells through a diverse repertoire of molecular mechanisms. Accordingly, therapeutic strategies aimed at enhancing Treg numbers or potency in the setting of autoimmunity and allogeneic transplants have been energetically pursued and are beginning to yield some encouraging outcomes in early phase clinical trials. Less well recognized from a translational perspective, however, has been the mounting body of evidence that Treg directly modulate most aspects of innate immune response under a range of different acute and chronic disease conditions. Recognizing this aspect of Treg immune modulatory function provides a bridge for the application of Treg-based therapies to common medical conditions in which organ and tissue damage is mediated primarily by inflammation involving myeloid cells (mononuclear phagocytes, granulocytes) and innate lymphocytes (NK cells, NKT cells, γδ T cells and ILCs). In this review, we comprehensively summarize pre-clinical and human research that has revealed diverse modulatory effects of Treg and specific Treg subpopulations on the range of innate immune cell types. In each case, we emphasize the key mechanistic insights and the evidence that Treg interactions with innate immune effectors can have significant impacts on disease severity or treatment. Finally, we discuss the opportunities and challenges that exist for the application of Treg-based therapeutic interventions to three globally impactful, inflammatory conditions: type 2 diabetes and its end-organ complications, ischemia reperfusion injury and atherosclerosis.

Upregulation of B7-H4 Is Involved in and Related to the Severity of Acute Pancreatitis

The expression and clinical significance of co-stimulator B7-H4 in acute pancreatitis (AP) is still unclear. In vitro study showed that the expression of soluble B7-H4 (sB7-H4) and proportions of membrane B7-H4-positive CD14⁺ cells in the peripheral blood mononuclear cells were upregulated in response to stimulation with plasma from AP patients, lipopolysaccharides, or tumor necrosis factor α (TNF-α). sB7-H4 in the plasma of AP patients were positively correlated with interleukin (IL)-6, IL-10, IL-17A, TNF-α, and interferon-γ The areas under the curves (AUCs) of receiver operating characteristic (ROC) curves of plasma sB7-H4 to distinguish the AP patients from healthy donors, the mild AP (MAP) from the moderately severe acute pancreatitis (MSAP)+severe acute pancreatitis (SAP) or the SAP from the MAP+MSAP were 0.78 (P < 0.001) or 0.773 (P < 0.001) or 0.764 (P < 0.001). sB7-H4 in the plasma of patients were positively correlated with the RANSON scores, Bedside Index of Severity of Acute Pancreatitis scores, Marshall scores, and Acute Physiology And Chronic Health Evaluation II scores; and the AUCs of ROC curves of plasma sB7-H4 in the prediction of local complications was 0.726 (P = 0.001). In conclusion, the co-stimulator B7-H4 is involved in the immune response in AP.

Minimizing Ischemia Reperfusion Injury in Xenotransplantation

The recent dramatic advances in preventing "initial xenograft dysfunction" in pig-to-non-human primate heart transplantation achieved by minimizing ischemia suggests that ischemia reperfusion injury (IRI) plays an important role in cardiac xenotransplantation. Here we review the molecular, cellular, and immune mechanisms that characterize IRI and associated "primary graft dysfunction" in allotransplantation and consider how they correspond with "xeno-associated" injury mechanisms. Based on this analysis, we describe potential genetic modifications as well as novel technical strategies that may minimize IRI for heart and other organ xenografts and which could facilitate safe and effective clinical xenotransplantation.

Methane attenuates lung ischemia-reperfusion injury via regulating PI3K-AKT-NFκB signaling pathway

Objective: This study aims to investigate the protective effects and possible mechanism of methane-rich saline (MS) on lung ischemia-reperfusion injury (LIRI) in rats.Methods: MS (2 ml/kg and 20 ml/kg) was injected intraperitoneally in rats after LIRI. Lung injury was assayed by Hematoxylin-eosin (HE) staining and wet-to-dry weight (W/D). The cells in the bronchoalveolar lavage fluid (BALF) and blood were counted. Oxidative stress was examined by the level of malondialdehyde (MDA) and superoxide dismutase (SOD). Inflammatory factors including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-10 (IL-10) were determined by ELISA. Lung tissue apoptosis was detected by TUNEL staining and western blotting of Bcl-2, Bax, and caspase-3. The expressions of IкBα, p38, PI3K, AKT, and NF-κB were analyzed with Western blotting.Results: MS effectively decreased the lung W/D ratio as well as the lung pathological damage and reduced the localized infiltration of inflammatory cells. Methane suppressed the expression of the PI3K-AKT-NFκB signaling pathway during the lung IR injury, which inhibited the activation of NF-kB and decreased the level of inflammatory cytokines, such as TNF-α, IL-1β, and IL-10. Moreover, we found that MS treatment relieved reactive oxygen species (ROS) damage by downregulating MDA and upregulating SOD. MS treatment also regulated apoptosis-related proteins, such as Bcl-2, Bax, and caspase-3.Conclusions: MS could repair LIRI and reduce the release of oxidative stress, inflammatory cytokines, and cell apoptosis via the PI3K-AKT-NFκB signaling pathway, which may provide a novel and promising strategy for the treatment of LIRI.

Berberine protects against ischemia-reperfusion injury: A review of evidence from animal models and clinical studies

Ischemia-reperfusion (I/R) injury is accompanied with high morbidity and mortality and has seriously negative social and economic influences. Unfortunately, few effective therapeutic strategies are available to improve its outcome. Berberine is a natural medicine possessing multiple beneficial biological activities. Emerging evidence indicates that berberine has potential protective effects against I/R injury in brain, heart, kidney, liver, intestine and testis. However, up-to-date review focusing on the beneficial role of berberine against I/R injury is not yet available. In this paper, results from animal models and clinical studies are concisely presented and its mechanisms are discussed. We found that berberine ameliorates I/R injury in animal models via its anti-oxidant, anti-apoptotic and anti-inflammatory effects. Moreover, berberine also attenuates I/R injury by suppressing endoplasmic reticulum stress and promoting autophagy. Additionally, regulation of periphery immune system may also contributes to the beneficial effect of berberine against I/R injury. Although clinical evidence is limited, the current studies indicate that berberine may attenuate I/R injury via inhibiting excessive inflammatory response in patients. Collectively, berberine might be used as an alternative therapeutic strategy for the management of I/R injury.