Rohit Verma
Basic Life Research Scientist, Neurosurgery
Education & Certifications
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Doctor of Philosophy, National Institute of Immunology (2016)
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Master of Science, Postgraduate Institute of Medical Education and Research (PGIMER) Chandigarh, Biochemistry (2010)
All Publications
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The CCR6-CCL20 axis promotes regulatory T cell glycolysis and immunosuppression in tumors.
Cancer immunology research
2024
Abstract
Regulatory T cells (Tregs) are important players in the tumor microenvironment. However, the mechanisms behind their immunosuppressive effects are poorly understood. We found that CCR6-CCL20 activity in tumor-infiltrating Tregs is associated with greater glycolytic activity and ablation of Ccr6 reduced glycolysis and lactic acid production while increasing compensatory glutamine metabolism. Immunosuppressive activity towards CD8+ T cells was abrogated in Ccr6-/- Tregs due to reduction in activation-induced glycolysis. Furthermore, Ccr6-/- mice exhibited improved survival across multiple tumor models compared to wildtype mice, and Treg and CD8+ T-cell depletion abrogated the improvement. In addition, Ccr6 ablation further promoted the efficacy of anti-PD-1 therapy in a preclinical glioma model. Follow-up knockdown of Ccl20 with siRNA also demonstrated improvement in antitumor efficacy. Our results unveil CCR6 as a marker and regulator of Treg-induced immunosuppression and identify approaches to target the metabolic determinants of Treg immunosuppressive activity.
View details for DOI 10.1158/2326-6066.CIR-24-0230
View details for PubMedID 39133127
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CCR2 and CCR5 co-inhibition modulates immunosuppressive myeloid milieu in glioma and synergizes with anti-PD-1 therapy.
Oncoimmunology
2024; 13 (1): 2338965
Abstract
Immunotherapy has revolutionized the treatment of cancers. Reinvigorating lymphocytes with checkpoint blockade has become a cornerstone of immunotherapy for multiple tumor types, but the treatment of glioblastoma has not yet shown clinical efficacy. A major hurdle to treat GBM with checkpoint blockade is the high degree of myeloid-mediated immunosuppression in brain tumors that limits CD8 T-cell activity. A potential strategy to improve anti-tumor efficacy against glioma is to use myeloid-modulating agents to target immunosuppressive cells, such as myeloid-derived suppressor cells (MDSCs) in the tumor microenvironment. We found that the co-inhibition of the chemokine receptors CCR2 and CCR5 in murine model of glioma improves the survival and synergizes robustly with anti-PD-1 therapy. Moreover, the treatment specifically reduced the infiltration of monocytic-MDSCs (M-MDSCs) into brain tumors and increased lymphocyte abundance and cytokine secretion by tumor-infiltrating CD8 T cells. The depletion of T-cell subsets and myeloid cells abrogated the effects of CCR2 and CCR5 blockade, indicating that while broad depletion of myeloid cells does not improve survival, specific reduction in the infiltration of immunosuppressive myeloid cells, such as M-MDSCs, can boost the anti-tumor immune response of lymphocytes. Our study highlights the potential of CCR2/CCR5 co-inhibition in reducing myeloid-mediated immunosuppression in GBM patients.
View details for DOI 10.1080/2162402X.2024.2338965
View details for PubMedID 38590799
View details for PubMedCentralID PMC11000615
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Ablation of Adar1 in myeloid cells imprints a global antiviral state in the lung and heightens early immunity against SARS-CoV-2.
Cell reports
2023; 42 (1): 112038
Abstract
Under normal homeostatic conditions, self-double-stranded RNA (self-dsRNA) is modified by adenosine deaminase acting on RNA 1 (ADAR1) to prevent the induction of a type I interferon-mediated inflammatory cascade. Antigen-presenting cells (APCs) sense pathogen-associated molecular patterns, such as dsRNA, to activate the immune response. The impact of ADAR1 on the function of APCs and the consequences to immunity are poorly understood. Here, we show that ADAR1 deletion in CD11c+ APCs leads to (1) a skewed myeloid cell compartment enriched in inflammatory cDC2-like cells, (2) enhanced numbers of activated tissue resident memory Tcells in the lung, and (3) the imprinting of a broad antiviral transcriptional signature across both immune and non-immune cells. The resulting changes can be partially reversed by blocking IFNAR1 signaling and promote early resistance against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Our study provides insight into the consequences of self-dsRNA sensing in APCs on the immune system.
View details for DOI 10.1016/j.celrep.2023.112038
View details for PubMedID 36732946
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A TLR7-nanoparticle adjuvant promotes a broad immune response against heterologous strains of influenza and SARS-CoV-2.
Nature materials
2023
Abstract
The ideal vaccine against viruses such as influenza and SARS-CoV-2 must provide a robust, durable and broad immune protection against multiple viral variants. However, antibody responses to current vaccines often lack robust cross-reactivity. Here we describe a polymeric Toll-like receptor 7 agonist nanoparticle (TLR7-NP) adjuvant, which enhances lymph node targeting, and leads to persistent activation of immune cells and broad immune responses. When mixed with alum-adsorbed antigens, this TLR7-NP adjuvant elicits cross-reactive antibodies for both dominant and subdominant epitopes and antigen-specific CD8+ T-cell responses in mice. This TLR7-NP-adjuvanted influenza subunit vaccine successfully protects mice against viral challenge of a different strain. This strategy also enhances the antibody response to a SARS-CoV-2 subunit vaccine against multiple viral variants that have emerged. Moreover, this TLR7-NP augments antigen-specific responses in human tonsil organoids. Overall, we describe a nanoparticle adjuvant to improve immune responses to viral antigens, with promising implications for developing broadly protective vaccines.
View details for DOI 10.1038/s41563-022-01464-2
View details for PubMedID 36717665
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SREBP signaling is essential for effective B cell responses.
Nature immunology
2022
Abstract
Our previous study using systems vaccinology identified an association between the sterol regulatory binding protein (SREBP) pathway and humoral immune response to vaccination in humans. To investigate the role of SREBP signaling in modulating immune responses, we generated mice with B cell- or CD11c+ antigen-presenting cell (APC)-specific deletion of SCAP, an essential regulator of SREBP signaling. Ablation of SCAP in CD11c+ APCs had no effect on immune responses. In contrast, SREBP signaling in B cells was critical for antibody responses, as well as the generation of germinal centers,memory B cells and bone marrow plasma cells. SREBP signaling was required for metabolic reprogramming in activated B cells. Upon mitogen stimulation, SCAP-deficient B cells could not proliferate and had decreased lipid rafts. Deletion of SCAP in germinal center B cells using AID-Cre decreased lipid raft content and cell cycle progression. These studies provide mechanistic insights coupling sterol metabolism with the quality and longevity of humoral immunity.
View details for DOI 10.1038/s41590-022-01376-y
View details for PubMedID 36577930
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Injectable Hydrogels for Sustained Codelivery of Subunit Vaccines Enhance Humoral Immunity.
ACS central science
2020; 6 (10): 1800–1812
Abstract
Vaccines aim to elicit a robust, yet targeted, immune response. Failure of a vaccine to elicit such a response arises in part from inappropriate temporal control over antigen and adjuvant presentation to the immune system. In this work, we sought to exploit the immune system's natural response to extended pathogen exposure during infection by designing an easily administered slow-delivery vaccine platform. We utilized an injectable and self-healing polymer-nanoparticle (PNP) hydrogel platform to prolong the codelivery of vaccine components to the immune system. We demonstrated that these hydrogels exhibit unique delivery characteristics, whereby physicochemically distinct compounds (such as antigen and adjuvant) could be codelivered over the course of weeks. When administered in mice, hydrogel-based sustained vaccine exposure enhanced the magnitude, duration, and quality of the humoral immune response compared to standard PBS bolus administration of the same model vaccine. We report that the creation of a local inflammatory niche within the hydrogel, coupled with sustained exposure of vaccine cargo, enhanced the magnitude and duration of germinal center responses in the lymph nodes. This strengthened germinal center response promoted greater antibody affinity maturation, resulting in a more than 1000-fold increase in antigen-specific antibody affinity in comparison to bolus immunization. In summary, this work introduces a simple and effective vaccine delivery platform that increases the potency and durability of subunit vaccines.
View details for DOI 10.1021/acscentsci.0c00732
View details for PubMedID 33145416
View details for PubMedCentralID PMC7596866
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N6-Methyladenosine Modification Controls Circular RNA Immunity.
Molecular cell
2019
Abstract
Circular RNAs (circRNAs) are prevalent in eukaryotic cells and viral genomes. Mammalian cells possess innate immunity to detect foreign circRNAs, but the molecular basis of self versus foreign identity in circRNA immunity is unknown. Here, we show that N6-methyladenosine (m6A) RNA modification on human circRNAs inhibits innate immunity. Foreign circRNAs are potent adjuvants to induce antigen-specific Tcell activation, antibody production, and anti-tumor immunity invivo, and m6A modification abrogates immune gene activation and adjuvant activity. m6A reader YTHDF2 sequesters m6A-circRNA and is essential for suppression of innate immunity. Unmodified circRNA, but not m6A-modified circRNA, directly activates RNA pattern recognition receptor RIG-I in the presence of lysine-63-linked polyubiquitin chain to cause filamentation of the adaptor protein MAVS and activation of the downstream transcription factor IRF3. CircRNA immunity has considerable parallel to prokaryotic DNA restriction modification system that transforms nucleic acid chemical modification into organismal innate immunity.
View details for DOI 10.1016/j.molcel.2019.07.016
View details for PubMedID 31474572
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Cutting Edge: ACVRL1 Signaling Augments CD8 alpha(+) Dendritic Cell Development
JOURNAL OF IMMUNOLOGY
2016; 197 (4): 1029-1034
Abstract
Dendritic cells (DCs) are a collection of different subtypes, each of which is characterized by specific surface markers, gene-expression patterns, and distinct functions. Members of the IFN regulatory factor family play critical roles in DC development and functions. Recently, Irf8 was shown to activate TGF-β signaling, which led to exacerbated neuroinflammation in the experimental autoimmune encephalomyelitis mouse model. We analyzed the effect of Irf8 on TGF-β/bone morphogenetic protein pathway-specific genes in DCs and identified Acvrl1, a type I TGF-β superfamily receptor, as a gene strongly induced by Irf8 expression. Among various DC subtypes, Acvrl1 is differentially expressed in CD8α(+) DCs. ACVRL1 signaling augmented Irf8-directed classical CD8α(+) DC development. Irf8 expression is essential for plasmacytoid DC and CD8α(+) DC development, and this study demonstrates that ACVRL1 signaling plays a pivotal role whereby it suppresses plasmacytoid DC development while enhancing that of CD8α(+) DCs, thus contributing to DC diversity development.
View details for DOI 10.4049/jimmunol.1501849
View details for Web of Science ID 000384999100004
View details for PubMedID 27421479
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Batf3 and Id2 Have a Synergistic Effect on Irf8-Directed Classical CD8 alpha(+) Dendritic Cell Development
JOURNAL OF IMMUNOLOGY
2013; 191 (12): 5993-6001
Abstract
Dendritic cells (DCs) are heterogeneous cell populations represented by different subtypes, each varying in terms of gene expression patterns and specific functions. Recent studies identified transcription factors essential for the development of different DC subtypes, yet molecular mechanisms for the developmental program and functions remain poorly understood. In this study, we developed and characterized a mouse DC progenitor-like cell line, designated DC9, from Irf8(-/-) bone marrow cells as a model for DC development and function. Expression of Irf8 in DC9 cells led to plasmacytoid DCs and CD8α(+) DC-like cells, with a concomitant increase in plasmacytoid DC- and CD8α(+) DC-specific gene transcripts and induction of type I IFNs and IL12p40 following TLR ligand stimulation. Irf8 expression in DC9 cells led to an increase in Id2 and Batf3 transcript levels, transcription factors shown to be important for the development of CD8α(+) DCs. We show that, without Irf8, expression of Id2 and Batf3 was not sufficient for directing classical CD8α(+) DC development. When coexpressed with Irf8, Batf3 and Id2 had a synergistic effect on classical CD8α(+) DC development. We demonstrate that Irf8 is upstream of Batf3 and Id2 in the classical CD8α(+) DC developmental program and define the hierarchical relationship of transcription factors important for classical CD8α(+) DC development.
View details for DOI 10.4049/jimmunol.1203541
View details for Web of Science ID 000328483900026
View details for PubMedID 24227775
View details for PubMedCentralID PMC4805111