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The treatment of ischemic stroke (IS) remains a big challenge in clinics, and it is urgently needed to develop novel, safe, and effective medicines against IS. Here, we report the design, synthesis, and biological evaluation of organic NO 2 - donors as potential agents for the treatment of IS. The representative compound 4a was able to slowly generate low concentrations of NO 2 - by reaction with a thiol-containing nucleophile, and the NO 2 - was selectively converted into NO under ischemic/hypoxia conditions to protect primary rat neurons from oxygen-glucose deprivation and recovery (OGD/R)-induced cytotoxicity by enhancing the Nrf2 signaling and activating the NO/cGMP/PKG pathway. Treatment with 4a at 2 h before or after ischemia mitigated the ischemia/reperfusion-induced brain injury in middle cerebral artery occlusion (MCAO) rats by producing NO and enhancing Nrf2 signaling. Furthermore, 4a significantly promoted endothelial cell proliferation and angiogenesis within the ischemic penumbra. Our findings suggest that this type of NO 2 - donors, like 4a , may be valuable to fight IS and other ischemic diseases.

There is an urgent need for new treatments to prevent and ameliorate severe illness and death induced by SARS-CoV-2 infection in COVID-19 patients. The coronavirus mouse hepatitis virus (MHV)-1 causes pneumonitis in mice which shares many pathological characteristics with human SARS-CoV infection. Previous studies have shown that the amino acid gamma-aminobutyric acid (GABA) has anti-inflammatory effects. We tested whether oral treatment with GABA could modulate the MHV-1 induced pneumonitis in susceptible A/J mice. As expected, MHV-1-inoculated control mice became severely ill (as measured by weight loss, clinical score, and the ratio of lung weight to body weight) and >60% of them succumbed to the infection. In contrast, mice that received GABA immediately after MHV-1 inoculation became only mildly ill and all of them recovered. When GABA treatment was initiated after the appearance of illness (3 days post-MHV-1 infection), we again observed that GABA treatment significantly reduced the severity of illness and greatly increased the frequency of recovery. Therefore, the engagement of GABA receptors (GABA-Rs) prevented the MHV-1 infection-induced severe pneumonitis and death in mice. Given that GABA-R agonists, like GABA and homotaurine, are safe for human consumption, stable, inexpensive, and available worldwide, they are promising candidates to help prevent severe illness stemming from SARS-CoV-2 infection and other coronavirus strains.

Immune cells express γ-aminobutyric acid receptors (GABA-R), and GABA administration can inhibit effector T cell responses in models of autoimmune disease. The pharmacokinetic properties of GABA, however, may be suboptimal for clinical applications. The amino acid homotaurine is a type A GABA-R (GABA A -R) agonist with good pharmacokinetics and appears safe for human consumption. In this study, we show that homotaurine inhibits in vitro T cell proliferation to a similar degree as GABA but at lower concentrations. In vivo, oral homotaurine treatment had a modest ability to reverse hyperglycemia in newly hyperglycemic NOD mice but was ineffective after the onset of severe hyperglycemia. In severely diabetic NOD mice, the combination of homotaurine and low-dose anti-CD3 treatment significantly increased 1) disease remission, 2) the percentages of splenic CD4 + and CD8 + regulatory T cells compared with anti-CD3 alone, and 3) the frequencies of CD4 + and CD8 + regulatory T cells in the pancreatic lymph nodes compared with homotaurine monotherapy. Histological examination of their pancreata provided no evidence of the large-scale GABA A -R agonist-mediated replenishment of islet β-cells that has been reported by others. However, we did observe a few functional islets in mice that received combined therapy. Thus, GABA A -R activation enhanced CD4 + and CD8 + regulatory T cell responses following the depletion of effector T cells, which was associated with the preservation of some functional islets. Finally, we observed that homotaurine treatment enhanced β-cell replication and survival in a human islet xenograft model. Hence, GABA A -R agonists, such as homotaurine, are attractive candidates for testing in combination with other therapeutic agents in type 1 diabetes clinical trials., (Copyright © 2019 The Authors.)

A series of nitric oxide (NO)-releasing glycosyl derivatives () of oleanolic acid were synthesized to improve the aqueous solubility and cytotoxicity of the parent compound . Derivative exhibited better solubility and strong cytotoxicity against human hepatocellular carcinoma (HCC) in vitro. Furthermore, displayed low acute toxicity to mice and significantly inhibited the growth of HCC tumors in vivo, indicating that may be a promising candidate for the treatment of human HCC.

Studies of mice lacking MHC class I (MHC I)-associated proteins have demonstrated a role for MHC I in neurodevelopment. A central question arising from these observations is whether neuronal recognition of MHC I has specificity for the MHC I allele product and the peptide presented. Using a well-established embryonic retina explant system, we observed that picomolar levels of a recombinant self-MHC I molecule inhibited neurite outgrowth. We then assessed the neurobiological activity of a panel of recombinant soluble MHC Is, consisting of different MHC I heavy chains with a defined self- or nonself-peptide presented, on cultured embryonic retinas from mice with different MHC I haplotypes. We observed that self-MHC I allele products had greater inhibitory neuroactivity than nonself-MHC I molecules, regardless of the nature of the peptide presented, a pattern akin to MHC I recognition by some innate immune system receptors. However, self-MHC I molecules had no effect on retinas from MHC I-deficient mice. These observations suggest that neuronal recognition of MHC I may be coordinated with the inherited MHC I alleles, as occurs in the innate immune system. Consistent with this notion, we show that MHC I and MHC I receptors are coexpressed by precursor cells at the earliest stages of retina development, which could enable such coordination.

The determinant spreading of T cell autoimmunity plays an important role in the pathogenesis of type 1 diabetes and in the protective mechanism of Ag-based immunotherapy in NOD mice. However, little is known about the role of APCs, particularly B cells, in the spreading of T cell autoimmunity. We studied determinant spreading in NOD/scid or Igmu(-/-) NOD mice reconstituted with NOD T and/or B cells and found that mice with mature B cells (TB NOD/scid and BMB Igmu(-/-) NOD), but not mice that lacked mature B cells (T NOD/scid and BM Igmu(-/-) NOD), spontaneously developed Th1 autoimmunity, which spread sequentially among different beta cell Ags. Immunization of T NOD/scid and BM Igmu(-/-) NOD mice with a beta cell Ag could prime Ag-specific Th1 or Th2 responses, but those T cell responses did not spread to other beta cell Ags. In contrast, immunization of TB NOD/scid and BMB Igmu(-/-) NOD mice with a beta cell Ag in IFA induced Th2 responses, which spread to other beta cell Ags. Furthermore, we found that while macrophages and dendritic cells could evoke memory and effector T cell responses in vitro, B cells significantly enhanced the detection of spontaneously primed and induced Th1 responses to beta cell Ags. Our data suggest that B cells, but not other APCs, mediate the spreading of T cell responses during the type 1 diabetes process and following Ag-based immunotherapy. Conceivably, the modulation of the capacity of B cells to present Ag may provide new interventions for enhancing Ag-based immunotherapy and controlling autoimmune diseases.

As organ-specific autoimmune diseases do not become manifest until well-advanced, interventive therapies must inhibit late-stage disease processes. Using a panel of immunogenic peptides from various beta cell Ags, we evaluated the factors influencing the efficacy of Ag-based therapies in diabetes-prone NOD mice with advanced disease. The ability of the major beta cell autoantigen target determinants (TDs) to prime Th2 responses declined sharply between 6 and 12 wk of age, whereas the ability of immunogenic ignored determinants (IDs) of beta cell Ags to prime Th2 responses was unaffected by the disease process. The different patterns of TD and ID immunogenicity (even from the same beta cell Ag) may be due to the exhaustion of uncommitted TD-reactive, but not ID-reactive, T cell pools by recruitment into the autoimmune cascade. Therapeutic efficacy was associated with a peptide's immunogenicity and ability to promote Th2 spreading late in the disease process but not its affinity for I-Ag7 or its expression pattern (beta cell specific/nonspecific or rare/abundant). Characterization of some IDs revealed them to be "absolute" cryptic determinants. Such determinants have little impact on T cell selection, leaving large precursor T cell pools available for priming by synthetic peptides. Traditional Ag-based therapeutics using whole autoantigens or their TDs cannot prime responses to such determinants. These findings suggest a new strategy for designing more efficacious Ag-based therapeutics for late-stage autoimmune diseases.

Gamma-aminobutyric acid (GABA) is both a major inhibitory neurotransmitter in the CNS and a product of beta cells of the peripheral islets. Our previous studies, and those of others, have shown that T cells express functional GABAA receptors. However, their subunit composition and physiological relevance are unknown. In this study, we show that a subset of GABAA receptor subunits are expressed by CD4+ T cells, including the delta subunit that confers high affinity for GABA and sensitivity to alcohol. GABA at relatively low concentrations down-regulated effector T cell responses to beta cell Ags ex vivo, and administration of GABA retarded the adoptive transfer of type 1 diabetes (T1D) in NOD/scid mice. Furthermore, treatment with low dose of GABA (600 microg daily) dramatically inhibited the development of proinflammatory T cell responses and disease progression in T1D-prone NOD mice that already had established autoimmunity. Finally, GABA inhibited TCR-mediated T cell cycle progression in vitro, which may underlie GABA's therapeutic effects. The immunoinhibitory effects of GABA on T cells may contribute to the long prodomal period preceding the development of T1D, the immunological privilege of the CNS, and the regulatory effects of alcohol on immune responses. Potentially, pharmacological modulation of GABAA receptors on T cells may provide a new class of therapies for human T1D as well as other inflammatory diseases.