Role Of Co-inhibitory Molecules Research Articles

Sepsis-Induced Immunosuppression: The Role of Co-inhibitory Molecules

Sepsis is one of the most common cause of death among hospitalized patients in the intensive care unit (ICU), with current therapeutic options falling short of a comprehensive solution. The condition's pathophysiology is marked by a spectrum of immunological impairments, with a growing consensus that immunosuppression plays a decisive role in the condition's rising morbidity and mortality rates. Extensive preclinical and clinical research has identified the upregulation of several co-inhibitory molecules during sepsis, including Programmed Death-1 (PD-1), Programmed Death Ligand-1 (PD-L1), Cytotoxic T-Lymphocyte Antigen-4 (CTLA-4), B and T Lymphocyte Attenuator (BTLA), T Cell Membrane Protein-3 (TIM-3), and Lymphocyte Activation Gene-3 (LAG-3). These molecules, which exert a significant inhibitory effect on T cell function, are believed to contribute to the immunosuppressive state induced by sepsis. The elucidation of the intricate mechanisms by which these molecules induce immunosuppression is essential for devising the most efficacious treatment strategies for sepsis. The burgeoning field of immunotherapy, particularly the blockade of co-inhibitory molecules, represents a significant frontier in sepsis research. This approach holds substantial promise for the future of sepsis therapy, warranting further exploration and clinical investigation to harness its potential fully.

Modulation of regulatory T cell function and stability by co-inhibitory receptors.

Regulatory T (Treg) cells constitute a dynamic population that is essential for controlling immune responses in health and disease. Defects in Treg cell function and decreases in Treg cell numbers have been observed in patients with autoimmunity and the opposite effects on Treg cells occur in cancer settings. Current research on new therapies for these diseases is focused on modulating Treg cell function to increase or decrease suppressive activity in autoimmunity and cancer, respectively. In this regard, several co-inhibitory receptors that are preferentially expressed by Treg cells under homeostatic conditions have recently been shown to control Treg cell function and stability in different disease settings. These receptors could be amenable to therapeutic targeting aimed at modulating Treg cell function and plasticity. This Review summarizes recent data regarding the role of co-inhibitory molecules in the control of Treg cell function and stability, with a focus on their roles and potential therapeutic use in autoimmunity and cancer.

Modulation of Innate Immune Mechanisms to Enhance Leishmania Vaccine-Induced Immunity: Role of Coinhibitory Molecules.

No licensed human vaccines are currently available against any parasitic disease including leishmaniasis. Several antileishmanial vaccine formulations have been tested in various animal models, including genetically modified live-attenuated parasite vaccines. Experimental infection studies have shown that Leishmania parasites utilize a broad range of strategies to undermine effector properties of host phagocytic cells, i.e., dendritic cells (DCs) and macrophages (MΦ). Furthermore, Leishmania parasites have evolved strategies to actively inhibit TH1 polarizing functions of DCs and to condition the infected MΦ toward anti-inflammatory/alternative/M2 phenotype. The altered phenotype of phagocytic cells is characterized by decreased production of antimicrobial reactive oxygen, nitrogen molecules, and pro-inflammatory cytokines, such as IFN-γ, IL-12, and TNF-α. These early events limit the activation of TH1-effector cells and set the stage for pathogenesis. Furthermore, this early control of innate immunity by the virulent parasites results in substantial alteration in the adaptive immunity characterized by reduced proliferation of CD4+ and CD8+ T cells and TH2-biased immunity that results in production of anti-inflammatory cytokines, such as TGF-β, and IL-10. More recent studies have also documented the induction of coinhibitory ligands, such as CTLA-4, PD-L1, CD200, and Tim-3, that induce exhaustion and/or non-proliferation in antigen-experienced T cells. Most of these studies focus on viral infections in chronic phase, thus limiting the direct application of these results to parasitic infections and much less to parasitic vaccines. However, these studies suggest that vaccine-induced protective immunity can be modulated using strategies that enhance the costimulation that might reduce the threshold necessary for T cell activation and conversely by strategies that reduce or block inhibitory molecules, such as PD-L1 and CD200. In this review, we will focus on the polarization of antigen-presenting cells and subsequent role of costimulatory and coinhibitory molecules in mediating vaccine-induced immunity using live-attenuated Leishmania parasites as specific examples.

Autoimmune Disease Genetics

Autoimmune Disease Genetics