Therapeutic potential of regulatory cytokines that target B cells

B-cells Drive Response to PD-1 Blockade in Glioblastoma Upon Neutralization of TGFβ-mediated Immunosuppression

Immunotherapy has revolutionized cancer treatment but has yet to be translated into brain tumors. Studies in other solid tumors suggest a central role of B-cell immunity in driving immune-checkpoint-blockade efficacy. Using single-cell and single-nuclei transcriptomics of human glioblastoma and melanoma brain metastasis, we found that tumor-associated B-cells have high expression of checkpoint molecules, known to block B-cell-receptor downstream effector function such as plasmablast differentiation and antigen-presentation. We also identified TGFβ-1/TGFβ receptor-2 interaction as a crucial modulator of B-cell suppression. Treatment of glioblastoma patients with pembrolizumab induced expression of B-cell checkpoint molecules and TGFβ-receptor-2. Abrogation of TGFβ using different conditional knockouts expanded germinal-center-like intratumoral B-cells, enhancing immune-checkpoint-blockade efficacy. Finally, blocking αVβ8 integrin (which controls the release of active TGFβ) and PD-1 significantly increased B-cell-dependent animal survival and immunological memory. Our study highlights the importance of intratumoral B-cell immunity and a remodeled approach to boost the effects of immunotherapy against brain tumors.

Peripheral blood B cell subset ratios and expression levels of B cell-associated genes are altered in benign multiple sclerosis

The interplay between the immune system, sleep dysfunction and cognitive impairment participates in the progression of disability in multiple sclerosis (MS). Our aim was to identify molecular pathways and B cell associated with separate components of MS disability. Benign MS, non-benign MS patients and healthy controls were recruited. Patients underwent polysomnography and cognitive studies. Microarray and bioinformatics analysis performed using peripheral blood mononuclear cell samples identified B cell-associated genes with the most significantly altered expression. Expression levels of these genes were validated by real-time PCR and peripheral blood cell subsets were examined by flow cytometry. Putative correlations among clinical and laboratory parameters were investigated by correlation network analysis. Sleep and cognitive functions were equally impaired in BMS and NBMS. BMS patients showed significantly reduced memory B cell and increased regulatory B cell percentages than NBMS patients. Among genes that were selected by bioinformatics, levels of BLK, BLNK, BANK1, FCRL2, TGFB1 and KCNS3 genes were significantly different among study subgroups. Correlation network analysis showed associations among physical-cognitive disability and sleep dysfunction measures of MS versus expression levels of selected genes. BMS and NBMS differ by physical disability but not cognitive and sleep dysfunction. Different components of disability in MS are associated with peripheral blood B cell ratios and B cell related gene expression levels. Thus, it is likely that altered B cell functions participate in the progression of disability in MS.

How severe RNA virus infections such as SARS-CoV-2 disrupt tissue and organ barriers—Reconstitution by mesenchymal stem cell-derived exosomes

The host tissue barriers arrange numerous lines of resistance to influx and cell-to-cell spread of pathogenic viruses. However, the highly virulent pathogens are equipped with diverse molecular mechanisms that can subvert the host countermeasures and/or exaggerate the host cell responses to toxic levels leading to severe illnesses. In his review, we discuss the immune-mediated pathogenesis of COVID-19 disease induced by the SARS-Cov-2 coronavirus. SARS-Cov-2 primarily infects type II alveolar epithelial cells. These cells are highly abundant with the ACE2 receptor protein, which occurs to be counterpart of the viral Spike protein and thus facilitates internalization of the virus. Following infection onset, the rapid clinical deterioration occurs about in a week suggesting that the respiratory failure in COVID-19 could result from a unique pattern of immune impairment characterized by severe Cytokine Release Syndrome (known as cytokine storm) leading to macrophage activation syndrome. In addition, the SARS-Cov-2 infection can induce a profound depletion of CD4 lymphocytes, CD19 lymphocytes, and natural killer cells, i.e., all major guardians cell components of the host immune barrier. However, while the numbers of that cells decline in the sequelae of the disease, the presence of persistent hyper-inflammation driving progressive tissue injury, suggests that the deteriorating impact of the systemic reactive responses can be more significant than the virus-induced cytopathic effects on the immunocompetent cells. In this respect, the authors discuss the emerging evidence of beneficial effects of administration of exosomes derived from mesenchymal stem cells—another sentinel-type cells—in management of the hyper-inflammatory response to SARS-CoV-2. Moreover, they also discuss the exosomes-originated mechanisms, which sustain regeneration of the damaged pulmonary lining cells and the vascular endothelial cells in various organs, including the brain.

Impact of vaccine type on HIV-1 vaccine elicited antibody durability and B cell gene signature

Efficacious HIV-1 vaccination requires elicitation of long-lived antibody responses. However, our understanding of how different vaccine types elicit durable antibody responses is lacking. To assess the impact of vaccine type on antibody responses, we measured IgG isotypes against four consensus HIV antigens from 2 weeks to 10 years post HIV-1 vaccination and used mixed effects models to estimate half-life of responses in four human clinical trials. Compared to protein-boosted regimens, half-lives of gp120-specific antibodies were longer but peak magnitudes were lower in Modified Vaccinia Ankara (MVA)-boosted regimens. Furthermore, gp120-specific B cell transcriptomics from MVA-boosted and protein-boosted vaccines revealed a distinct signature at a peak (2 weeks after last vaccination) including CD19, CD40, and FCRL2-5 activation along with increased B cell receptor signaling. Additional analysis revealed contributions of RIG-I-like receptor pathway and genes such as SMAD5 and IL-32 to antibody durability. Thus, this study provides novel insights into vaccine induced antibody durability and B-cell receptor signaling.

Cytokine Milieu in Infectious Disease: A Sword or a Boon?

Cytokines have a myriad role in an infectious disease, whether being pathogenic, bacterial, or viral. All proinflammatory and anti-inflammatory cytokine biological function are dependent on its concentration, followed by combination with the other cytokines and the stage of the disease. Plasticity in switching off from one phenotype to the other of these regulatory mediators in congruence with the traditional concept of inhibitory and stimulatory effects on immune system is dealt with. This review highlights the dual functionality of some of these cytokines and cytokine-based immunotherapy.

B lymphocytes confer immune tolerance via cell surface GARP-TGF-β complex

GARP, a cell surface docking receptor for binding and activating latent TGF-β, is highly expressed by platelets and activated Tregs. While GARP is implicated in immune invasion in cancer, the roles of the GARP-TGF-β axis in systemic autoimmune diseases are unknown. Although B cells do not express GARP at baseline, we found that the GARP-TGF-β complex is induced on activated human and mouse B cells by ligands for multiple TLRs, including TLR4, TLR7, and TLR9. GARP overexpression on B cells inhibited their proliferation, induced IgA class-switching, and dampened T cell-independent antibody production. In contrast, B cell-specific deletion of GARP-encoding gene Lrrc32 in mice led to development of systemic autoimmune diseases spontaneously as well as worsening of pristane-induced lupus-like disease. Canonical TGF-β signaling more readily upregulates GARP in Peyer patch B cells than in splenic B cells. Furthermore, we demonstrated that B cells are required for the induction of oral tolerance of T cell-dependent antigens via GARP. Our studies reveal for the first time to our knowledge that cell surface GARP-TGF-β is an important checkpoint for regulating B cell peripheral tolerance, highlighting a mechanism of autoimmune disease pathogenesis.

Hepatitis C virus-induced tumor-initiating cancer stem-like cells activate stromal fibroblasts in a xenograft tumor model

Hepatitis C virus (HCV) often causes persistent infection and is an increasingly important factor in the etiology of fibrosis/cirrhosis and hepatocellular carcinoma, although the mechanisms for the disease processes remain unclear. We have shown previously that HCV infection generates an epithelial-mesenchymal transition state and tumor-initiating cancer stem-like cells in human hepatocytes. In this study, we investigated whether HCV-induced tumor-initiating cancer stem-like cells when implanted into mice activate stromal fibroblasts. A number of fibroblast activation markers, including matrix metalloproteinase 2, were significantly increased at the mRNA or protein level in the xenograft tumors, suggesting the presence of tumor-associated fibroblasts. Fibroblast activation markers of murine origin were specifically increased in tumor, suggesting that fibroblasts migrate to form stroma. Next, we demonstrated that conditioned medium from HCV-infected human hepatocytes activates fibrosis-related markers in hepatic stellate cells. We further observed that these HCV-infected hepatocytes express transforming growth factor beta, which activates stromal fibroblast markers. Subsequent analysis suggested that anti-transforming growth factor beta neutralizing antibody, when incubated with conditioned medium from HCV-infected hepatocytes, inhibits fibrosis marker activation in primary human hepatic stellate cells.

CONCLUSION

HCV-infected hepatocytes induce local fibroblast activation by secretion of transforming growth factor beta, and a preneoplastic or tumor state of the hepatocytes influences the network for the tumor-associated fibroblast environment. (Hepatology 2017;66:1766-1778).