Targeting Dectin-1 and or VISTA enhances anti-tumor immunity in melanoma but not colorectal cancer model.

PURPOSE: Acquired resistance to immune checkpoint blockers (ICBs) is a major barrier in cancer treatment, emphasizing the need for innovative strategies. Dectin-1 (gene Clec7a) is a C-type lectin receptor best known for its ability to recognize ß-glucan-rich structures in fungal cell walls. While Dectin-1 is expressed in myeloid cells and tumor cells, its significance in cancer remains the subject of controversy. METHODS: Using Celc7a-/- mice and curdlan administration to stimulate Dectin-1 signaling, we explored its impact. VISTA KO mice were employed to assess VISTA's role, and bulk RNAseq analyzed curdlan effects on neutrophils. RESULTS: Our findings reveal myeloid cells as primary Dectin-1 expressing cells in the tumor microenvironment (TME), displaying an activated phenotype. Strong Dectin-1 co-expression/co-localization with VISTA and PD-L1 in TME myeloid cells was observed. While Dectin-1 deletion lacked protective effects, curdlan stimulation significantly curtailed B16-F10 tumor progression. RNAseq and pathway analyses supported curdlan's role in triggering a cascade of events leading to increased production of pro-inflammatory mediators, potentially resulting in the recruitment and activation of immune cells. Moreover, we identified a heterogeneous subset of Dectin-1+ effector T cells in the TME. Similar to mice, human myeloid cells are the prominent cells expressing Dectin-1 in cancer patients. CONCLUSION: Our study proposes Dectin-1 as a potential adjunctive target with ICBs, orchestrating a comprehensive engagement of innate and adaptive immune responses in melanoma. This innovative approach holds promise for overcoming acquired resistance to ICBs in cancer treatment, offering avenues for further exploration and development.

A Retrospective Analysis of Leadership, Awardees, and Member Gender Representation of the Canadian Society for Immunology.

The Canadian Society for Immunology (CSI) established a formal Equity, Diversity, and Inclusion (EDI) Committee with the goal of providing EDI advocacy and leadership within the CSI, as well as in the broader scientific community. A first task of this committee was to review the publicly available historical data on gender representation within the CSI's membership, leadership, award recipients, and conference chairs/presenters as a step in establishing a baseline reference point and monitoring the trajectory of future success in achieving true inclusion. We found that, except for overall membership and a specific subset of awards, all categories showed a historical bias toward men, particularly prior to 2010. Bias persists in various categories, evident even in recent years. However, we note an encouraging trend toward greater gender parity, particularly in the roles of President, symposium presenters, and workshop chairs, especially from 2017 onward. We present these findings as well as our recommendations to enhance inclusivity. These include a more comprehensive collection and secure storage of self-identification data, emphasis on EDI as an essential component of all annual meeting activities, and innovative measures of outreach, collaboration, and leadership with the aim of making the CSI a model for improving EDI in other professional research societies.

Transcriptomic profiling of peripheral blood cells in HPV-associated carcinoma patients receiving combined valproic acid and avelumab.

Human papillomavirus (HPV)-associated cancer continues to evade the immune system by promoting a suppressive tumor microenvironment. Therefore, immunotherapy appears to be a promising approach for targeting HPV-associated tumors. We hypothesized that valproic acid (VA) as an epigenetic agent combined with avelumab may enhance the antitumor immunity in HPV-associated solid tumors. We performed bulk RNA-sequencing (RNA-Seq) on total peripheral blood mononuclear cells (PBMCs) of seven nonresponders (NRs) and four responders (Rs). A total of 39 samples (e.g., pretreatment, post-VA, postavelumab, and endpoint) were analyzed. Also, we quantified plasma analytes and performed flow cytometry. We observed a differential pattern in immune response following treatment with VA and/or avelumab in NRs vs. Rs. A significant upregulation of transcripts associated with NETosis [the formation of neutrophil extracellular traps (NETs)] and neutrophil degranulation pathways was linked to the presence of a myeloid-derived suppressor cell signature in NRs. We noted the elevation of IL-8/IL-18 cytokines and a distinct transcriptome signature at the baseline and endpoint in NRs. By using the receiver operator characteristics, we identified a cutoff value for the plasma IL-8/IL-18 to discriminate NRs from Rs. We found differential therapeutic effects for VA and avelumab in NRs vs. Rs. Thus, our results imply that measuring the plasma IL-8/IL-18 and bulk RNA-Seq of PBMCs may serve as valuable biomarkers to predict immunotherapy outcomes.

Equity, Diversity and Inclusion in Canadian immunology: communication and complexity.

The Canadian Society for Immunology (CSI) organized an Equity, Diversity and Inclusion (EDI) training workshop during its 2022 Scientific Meeting to improve understanding of EDI and explore strategies to achieve EDI goals in the scientific environment. The workshop focused on identifying Specific, Measurable, Achievable, Realistic and Timely (SMART) goals related to EDI in academia through small group discussions and learning exercises. Attendees highlighted several equity considerations within the field of academic immunology, including financial barriers, lack of diversity in research teams and gender bias; they emphasized the importance of creating an inclusive and accessible research environment. The collection and use of data relevant to EDI goals within the CSI were also identified as challenges. Fostering a culture of active and nonjudgmental listening within the CSI community is another aspirational goal to address EDI. The workshop received positive feedback from attendees, who noted that more diverse voices and specific actions for local research environments are needed.

CD71+ erythroid cells suppress T-cell effector functions and predict immunotherapy outcomes in patients with virus-associated solid tumors.

BACKGROUND: Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of cancer. However, only a portion of patients respond to such treatments. Therefore, it remains a prevailing clinical need to identify factors associated with acquired resistance or lack of response to ICIs. We hypothesized that the immunosuppressive CD71+ erythroid cells (CECs) within the tumor and/or distant 'out-of-field' may impair antitumor response. METHODS: We studied 38 patients with cancer through a phase II clinical trial investigating the effects of oral valproate combined with avelumab (anti-programmed death-ligand 1 (PD-L1)) in virus-associated solid tumors (VASTs). We quantified the frequency/functionality of CECs in blood and biopsies of patients. Also, we established an animal model of melanoma (B16-F10) to investigate the possible effects of erythropoietin (EPO) treatment on anti-PD-L1 therapy. RESULTS: We found a substantial expansion of CECs in the blood of patients with VAST compared with healthy controls. We noted that the frequency of CECs in circulation was significantly higher at the baseline and throughout the study in non-responders versus responders to PD-L1 therapy. Moreover, we observed that CECs in a dose-dependent manner suppress effector functions of autologous T cells in vitro. The subpopulation of CD45+CECs appears to have a more robust immunosuppressive property compared with their CD45- counterparts. This was illustrated by a stronger expression of reactive oxygen species, PD-L1/PD-L2, and V-domain Ig suppressor of T-cell activation in this subpopulation. Lastly, we found a higher frequency of CECs in the blood circulation at the later cancer stage and their abundance was associated with anemia, and a poor response to immunotherapy. Finally, we report the expansion of CECs in the spleen and tumor microenvironment of mice with melanoma. We found that although CECs in tumor-bearing mice secret artemin, this was not the case for VAST-derived CECs in humans. Notably, our results imply that EPO, a frequently used drug for anemia treatment in patients with cancer, may promote the generation of CECs and subsequently abrogates the therapeutic effects of ICIs (eg, anti-PD-L1). CONCLUSIONS: Our results demonstrate that anemia by the expansion of CECs may enhance cancer progression. Notably, measuring the frequency of CECs may serve as a valuable biomarker to predict immunotherapy outcomes.

Sex Matters: Physiological Abundance of Immuno-Regulatory CD71+ Erythroid Cells Impair Immunity in Females.

Mature erythrocytes are the major metabolic regulators by transporting oxygen throughout the body. However, their precursors and progenitors defined as CD71+ Erythroid Cells (CECs) exhibit a wide range of immunomodulatory properties. Here, we uncover pronounced sexual dimorphism in CECs. We found female but not male mice, both BALB/c and C57BL/6, and human females were enriched with CECs. CECs, mainly their progenitors defined as CD45+CECs expressed higher levels of reactive oxygen species (ROS), PDL-1, VISTA, Arginase II and Arginase I compared to their CD45- counterparts. Consequently, CECs by the depletion of L-arginine suppress T cell activation and proliferation. Expansion of CECs in anemic mice and also post-menstrual cycle in women can result in L-arginine depletion in different microenvironments in vivo (e.g. spleen) resulting in T cell suppression. As proof of concept, we found that anemic female mice and mice adoptively transferred with CECs from anemic mice became more susceptible to Bordetella pertussis infection. These observations highlight the role of sex and anemia-mediated immune suppression in females. Notably, enriched CD45+CECs may explain their higher immunosuppressive properties in female BALB/c mice. Finally, we observed significantly more splenic central macrophages in female mice, which can explain greater extramedullary erythropoiesis and subsequently abundance of CECs in the periphery. Thus, sex-specific differences frequency in the frequency of CECs might be imprinted by differential erythropoiesis niches and hormone-dependent manner.

The Quality of SARS-CoV-2-Specific T Cell Functions Differs in Patients with Mild/Moderate versus Severe Disease, and T Cells Expressing Coinhibitory Receptors Are Highly Activated.

Understanding the function of SARS-CoV-2 Ag-specific T cells is crucial for the monitoring of antiviral immunity and vaccine design. Currently, both impaired and robust T cell immunity is described in COVID-19 patients. In this study, we explored and compared the effector functions of SARS-CoV-2-reactive T cells expressing coinhibitory receptors and examine the immunogenicity of SARS-CoV-2 S, M, and N peptide pools in regard to specific effector T cell responses, Th1/Th2/Th17, in COVID-19 patients. Analyzing a cohort of 108 COVID-19 patients with mild, moderate, and severe disease, we observed that coinhibitory receptors (e.g., PD-1, CTLA-4, TIM-3, VISTA, CD39, CD160, 2B4, TIGIT, Gal-9, and NKG2A) were upregulated on both CD4+ and CD8+ T cells. Importantly, the expression of coinhibitory receptors on T cells recognizing SARS-CoV-2 peptide pools (M/N/S) was associated with increased frequencies of cytokine-producing T cells. Thus, our data refute the concept of pathological T cell exhaustion in COVID-19 patients. Despite interindividual variations in the T cell response to viral peptide pools, a Th2 phenotype was associated with asymptomatic and milder disease, whereas a robust Th17 was associated with severe disease, which may potentiate the hyperinflammatory response in patients admitted to the Intensive Care Unit. Our data demonstrate that T cells may either play a protective or detrimental role in COVID-19 patients. This finding could have important implications for immune correlates of protection, diagnostic, and prophylaxis with respect to COVID-19 management.

Galectin-9, a Player in Cytokine Release Syndrome and a Surrogate Diagnostic Biomarker in SARS-CoV-2 Infection.

The outbreak of SARS-CoV-2 infection has enormously impacted our lives. Clinical evidence has implicated the emergence of cytokine release syndrome as the prominent cause of mortality in COVID-19 patients. In this study, we observed massive elevation of plasma Galectin-9 (Gal-9) in COVID-19 patients compared to healthy controls (HCs). By using the receiver operating characteristic (ROC) curve, we found that a baseline of 2,042 pg/ml plasma Gal-9 can differentiate SARS-CoV-2-infected from noninfected individuals with high specificity/sensitivity (95%). Analysis of 30 cytokines and chemokines detected a positive correlation of the plasma Gal-9 with C-reactive protein (CRP) and proinflammatory cytokines/chemokines such as interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), IP-10, MIP-1α, and MCP-1 but an inverse correlation with transforming growth factor ß (TGF-ß) in COVID-19 patients. In agreement, we found enhanced production of IL-6 and TNF-α by monocytes and NK cells of COVID-19 patients once treated with the recombinant human Gal-9 in vitro Also, we observed that although the cell-membrane expression of Gal-9 on monocytes does not change in COVID-19 patients, those with higher Gal-9 expression exhibit an activated phenotype. Furthermore, we noted significant downregulation of surface Gal-9 in neutrophils from COVID-19 patients compared to HCs. Our further investigations indicated that immune activation following SARS-CoV-2 infection results in Gal-9 shedding from neutrophils. The strong correlation of Gal-9 with proinflammatory mediators suggests that inhibition of Gal-9 may severe as a therapeutic approach in COVID-19 infection. Besides, the plasma Gal-9 measurement may be used as a surrogate diagnostic biomarker in COVID-19 patients.IMPORTANCE The outbreak of SARS-CoV-2 infection has enormously impacted our lives. Clinical evidence has implicated the emergence of cytokine release syndrome as the prominent cause of mortality in COVID-19 patients. We observed substantial elevation of the plasma Galectin-9 (Gal-9) in COVID-19 patients compared to healthy controls. Gal-9 is an abundant protein in many immune and nonimmune cells. We found that Gal-9 detection assay can differentiate SARS-CoV-2-infected from noninfected individuals with a specificity/sensitivity of 95%. Importantly, we found a positive correlation of the plasma Gal-9 with a wide range of proinflammatory biomarkers in COVID-19 patients. In agreement, we found enhanced expression and production of such proinflammatory molecules by immune cells of COVID-19 patients once treated with Gal-9 in vitro Our results propose Gal-9 as an important contributing factor in cytokine release syndrome; therefore, Gal-9 inhibition may serve as a beneficial therapeutic approach by suppressing the hyperimmune activation in COVID-19 patients.

Non-Adherent Bone Marrow-Derived Mesenchymal Stem Cells Ameliorate Clinical Manifestations and Inflammation in an Experimental Model of Ulcerative Colitis in Rats.

BACKGROUND: Functional and developmental versatility of mesenchymal stem cells (MSCs) have generated great interest in their clinical application. Recently, it has been proposed that the non-adherent population of bone marrow cells can differentiate to MSCs in vitro. The present study aimed to compare the anti-inflammatory potentials of adherent and non-adherent MSCs in an experimental model of ulcerative colitis (UC) in rats. METHODS: The present experimental study was conducted at the School of Veterinary Medicine, Urmia University (Urmia, Iran) during March-May 2018. UC was induced using acetic acid in three groups of male Wistar rats, namely the control colitis, adherent MSCs treated, and non-adherent MSCs treated groups. Adherent and non-adherent MSCs were collected, characterized, and proliferated. The isolated cells were injected into the peritoneum of the respective groups of colitis rats. After 10 days, the animals were evaluated for gross and microscopic pathology, production of inflammatory mediators, and stress oxidative profile in the gut tissue. The statistical analysis was performed using SPSS software (version 23.0). P<0.05 was considered statistically significant. RESULTS: The non-adherent MSCs had almost similar therapeutic potency compared to the adherent MSCs (P=0.12). They significantly reduced the level of inflammatory mediators and improved the oxidative stress profile in colonic tissue compared to the control colitis group (P=0.0001). CONCLUSION: The molecular assays and histopathological assessment revealed that the non-adherent MSCs not only had anti-inflammatory and regulatory potency but also enhanced tissue regeneration in UC rats. Therefore, the non-adherent fraction of bone marrow-derived MSCs could be used as a complementary source of MSCs in stem cell therapies.