Expression and function of VISTA on myeloid cells

VISTA as a context-dependent immune checkpoint: Implications for tumor immunity and autoimmune pathogenesis

V-domain Ig suppressor of T cell activation (VISTA) is a recently characterized as immune checkpoint regulator with critical roles in modulating immune responses across pathological contexts. In cancer, VISTA contributes to immune evasion by sustaining an immunosuppressive tumor microenvironment, emerging as a promising target for immunotherapeutic intervention. In contrast, in autoimmune diseases, VISTA preserves peripheral immune tolerance and suppresses aberrant immune activation, thereby preventing tissue destruction. This functional dichotomy reflects the complexity of VISTA-mediated signaling, which is modulated by cellular context, microenvironmental cues, and disease stage. Recent studies have elucidated key aspects of VISTA biology, including its structural features, ligand interactions, and context-dependent expression patterns. VISTA operates as a co-inhibitory molecule in cancer, while exerting co-stimulatory or regulatory effects in autoimmunity. This review provides a comprehensive overview of VISTA's discovery, molecular mechanisms, and dual roles in cancer and autoimmune pathogenesis. Furthermore, the current status of VISTA-targeted therapeutic strategies is critically examined, highlighting the translational challenges posed by discrepancies between preclinical models and clinical trial outcomes. Finally, the potential of targeting VISTA within the broader paradigm of immune checkpoint plasticity is discussed, with emphasis on overcoming compensatory immune resistance to enhance therapeutic efficacy. A deeper mechanistic understanding of VISTA is essential for the rational design of future immunomodulatory therapies tailored to specific disease contexts.

Immune Checkpoint VISTA Negatively Regulates Microglia Glycolysis and Activation via TRIM28-Mediated Ubiquitination of HK2 in Sepsis-Associated Encephalopathy

V-domain immunoglobulin suppressor of T cell activation (VISTA) has emerged as a crucial player in the pathogenesis of neurological disorders. However, the specific mechanism by which VISTA regulates microglial activation remains unclear. Septic mice were intracerebroventricularly injected with an agonistic anti-VISTA antibody or isotype control. To investigate the differential gene expression profiles, RNA sequencing was conducted on brain tissues from these mice. In vitro, VISTA was silenced in BV2 microglial cells using shRNA. Co-immunoprecipitation assays were performed to identify protein-protein interactions involving hexokinase 2 (HK2), and ubiquitination assays were used to examine the ubiquitination status of HK2. Additionally, BV2 cells were transfected with either tripartite motif-containing 28 overexpression plasmids (TRIM28-PcDNA3.1( +)) or TRIM28-specific siRNA to assess the impact of TRIM28 on VISTA-mediated microglial activation. The cellular glycolytic activity was measured using extracellular acidification rate assays, and proinflammatory cytokine and chemokines were quantified. Treatment with VISTA antibodies significantly alleviated microglial activation and prevented cognitive impairment in septic mice. In contrast, VISTA silencing in BV2 microglia led to the overexpression of proinflammatory cytokines and enhanced glycolysis in an HK2-dependent manner. Mechanistically, HK2 expression was regulated by the E3 ubiquitin ligase TRIM28 through K63-linked ubiquitination, which targeted HK2 for proteasomal degradation. Furthermore, knockdown of TRIM28 reduced the elevated glycolysis and proinflammatory response observed in VISTA-silenced microglia. VISTA modulates microglial activation in sepsis-associated encephalopathy by regulating HK2 expression through TRIM28-mediated K63-linked ubiquitination. These findings highlight VISTA as a potential therapeutic target for modulating microglial activation in sepsis.

VISTA in hematological malignancies: a review of the literature

In recent years, tumor immunotherapy has become an active research area, with the emergence of immune checkpoint inhibitors (ICIs) revolutionizing immunotherapy. Clinical evidence indicates that programmed cell death protein 1 (PD-1) monoclonal antibodies and other drugs have remarkable therapeutic effects. V-domain Ig suppressor of T-cell activation (VISTA) is a new type of immune checkpoint receptor that is highly expressed in various tumors. It is co-expressed with PD-1, T-cell immunoglobulin domain, mucin domain-3 (Tim-3), T-cell immunoglobulin, and immunoreceptor tyrosine-based inhibitory motif domain (TIGIT) and is associated with prognosis, which suggests that it may be a target for immunotherapy. As an immune checkpoint receptor with no mature drugs, VISTA is highly expressed in acute myeloid leukemia (AML), multiple myeloma (MM), and other hematological malignancies; however, its pathogenic mechanism should be defined to better guide treatment.

Baker's yeast beta glucan supplementation was associated with an improved innate immune mRNA expression response after exercise

Beta glucans are found in many natural sources, however, only Baker's Yeast Beta Glucan (BYBG) has been well documented to have structure-function effects that are associated with improved innate immune response to stressors (e.g., exercise, infection, etc.). The purpose was to identify a BYBG-associated mRNA expression pattern following exercise. Participants gave IRB-approved consent and were randomized to BYBG (Wellmune®; N=9) or Placebo (maltodextrin; N=10) for 6-weeks prior to performing 90 min of whole-body exercise. Paxgene blood samples were collected prior to exercise (PRE), after exercise (POST), two hours after exercise (2H), and four hours after exercise (4H). Total RNA was isolated and analyzed for the expression of 770 innate immune response mRNA (730 mRNA targets; 40 housekeepers/controls; Nanostring nCounter). The raw data were normalized against housekeeping controls and expressed as Log2 fold change from PRE for a given condition. Significance was set at p < 0.05 with adjustments for multiple comparisons and false discovery rate. We identified 47 mRNA whose expression was changed after exercise with BYBG and classified them to four functional pathways: 1) Immune Cell Maturation (8 mRNA), 2) Immune Response and Function (5 mRNA), 3) Pattern Recognition Receptors and DAMP or PAMP Detection (25 mRNA), and 4) Detection and Resolution of Tissue Damage (9 mRNA). The identified mRNA whose expression was altered after exercise with BYBG may represent an innate immune response pattern and supports previous conclusions that BYBG improves immune response to a future sterile inflammation or infection.