Biology subjects

Pampena, M. B.

Publications and source records attributed to Pampena, M. B..

8 recordsLinked to original sources

bioRxiv2025

Selective infection and loss of PRDM1+ LN Tfh cells in uncontrolled HIV infection precludes formation of Tfh reservoirs under ART

The multifaceted and long-lived nature of HIV-1 reservoirs has proven to be a formidable obstacle in the development of a therapeutic cure of HIV-1. One of the major dimensions of the HIV-1 reservoir is its prevalence and persistence in tissue environments, including in lymph nodes (LN). Within LN, T follicular helper (Tfh) cells are widely considered as the dominant sub-reservoir in viremic people with HIV (PWH). However, whether Tfh cells survive to establish a reservoir in PWH undergoing suppressive antiretroviral therapy (ART) has remained controversial. To address these issues, we deeply phenotyped over 500,000 cells and identified over 2,000 HIV-1 infected cells by employing single-cell multiomics on LN from PWH during viremia and suppressed on ART. While we detected HIV-1 infected Tfh cells, the majority of infected cells during viremia and ART had non-follicular phenotypes and were instead heterogeneously distributed between various CD4+ T-cell subsets. Within-subset comparisons of HIV+ and HIV- cells revealed heightened activation signatures and altered cell cycle states during viremia, but largely similar features during ART. Furthermore, the comparison between viremia and ART in PWH highlighted a noncanonical Tfh subset - defined by high locus accessibility and transcription of PRDM1 - that is selectively depleted during viremia, recovers after ART, and is highly susceptible to infection in vitro. Our work suggests a revised direction for the HIV-1 cure field where a mandate of any comprehensive strategy will be to address the high proportional burden of non-follicular cells within the HIV reservoir.

immunology↗

bioRxiv2025

Dysregulated lymphocyte localization in idiopathic multicentric Castleman disease

Idiopathic multicentric Castleman disease (iMCD) is a rare and life-threatening hematologic disease involving episodic flares of uncontrollable systemic inflammation by unknown causes. Hallmark features of iMCD include multiple enlarged lymph nodes with characteristic histopathological phenotypes and a potentially fatal, cytokine release syndrome. The key pathophysiologic drivers of disease are poorly understood and few effective treatment options exist. Here, we discovered an association between elevated chemokines, namely CXCL13, and lymph node size in iMCD, providing one possible explanation for the lymphadenopathy observed clinically. Instead of a concurrent increase in circulating CXCL13 and CXCR5-expressing cells that has been described in other contexts, during active disease, chemokine-responsive lymphocytes downregulated CXCR5 levels in iMCD. Despite heightened chemokine production by lymph node stromal cells, T and B cells failed to appropriately respond to their cues locally within the tissue and were particularly scarce within CXCL13-expressing germinal centers (GC). Inflammatory signals in iMCD lymph nodes appeared to restrict the production and movement of T follicular helper cells, which play an important role in facilitating appropriate GC responses. Together, these data provide a link between dysregulated chemokine production and germinal center lymphocyte trafficking, highlighting a potential mechanism and therapeutic target in iMCD lymphadenopathy. One Sentence SummaryLymphocyte chemotaxis to discrete areas of lymphoid tissue is disrupted in idiopathic multicentric Castleman disease.

immunology↗

bioRxiv2025

In vivo reprogramming of cytotoxic effector CD8+ T cells via fractalkine-conjugated mRNA-LNP

Selective in vivo reprogramming of cytotoxic effector CD8+ T (Teff) cells holds tremendous promise as a therapeutic tool but has not yet been accomplished. Here, we demonstrate that fractalkine-conjugated mRNA lipid nanoparticles (mRNA-LNP) can specifically target and deliver mRNA to CX3CR1+ Teff cells in vitro and in vivo. In mice, fractalkine-conjugated LNP target up to 90% of blood and splenic Teff cells, and delivery of IL-2-encoding mRNA to Teff cells enables robust exogenous IL-2 secretion. In rhesus macaques, fractalkine-conjugated mRNA-LNP target up to [~]100% of peripheral blood Teff cells and delivery of CD62L-mRNA enables transient CD62L expression. Collectively, these data demonstrate the potential of natural receptor ligand-based targeting of mRNA-LNP for effective and efficient transient in vivo modification of Teff cells.

immunology↗

bioRxiv2025

Therapeutic CD8+T cell tissue retention and immunomodulation during ART interruption fails to prevent SIV rebound

A primary obstacle for HIV elimination is the long-term viral reservoir in lymphoid tissues (LT) that can cause rebound viremia if therapy is stopped. Cytotoxic CD8+ T cells are critical for control of HIV and SIV viremia; however, CD8+ T cells that migrate to LT are primarily non-cytotoxic, calling into question whether these cells could reduce the viral reservoir on ART or control viral replication when therapy is halted. To determine if CD8+ T cells can inhibit viral replication when retained in lymphoid tissues, we inhibited lymphocyte egress from LTs in antiretroviral therapy (ART)-treated SIV-infected rhesus macaques (RM) during analytic treatment interruption (ATI) using the S1PR modulator FTY720 alone or in combination with anti-PD1 and the IL-15 receptor superagonist N-803 to increase cytolytic function. FTY720 retained migrating CD4+ and CD8+ T cells in LT, whereas cytotoxic CD8+ T cells remained in the vasculature. After ATI and viral rebound, activated SIV-specific CD8+ T cells increased in frequency in LT of FTY720-treated RM but failed to become cytotoxic or control plasma viremia compared to controls, even when combined with anti-PD1 and N-803. These findings indicate that LT-localized CD8+ T cells alone are insufficient to delay or prevent plasma viral rebound during ATI. Significance StatementHIV therapeutic and cure strategies have all operated under the assumption that CD8+ T cells can become cytotoxic in lymph nodes to eliminate infected cells from reservoir repositories. Using FTY720 to prevent lymphocyte egress from lymph nodes, we demonstrated that lymphoid tissue-restricted CD8+ T cells are insufficient to prevent SIV rebound during antiretroviral treatment interruption, even in the presence of immunomodulators such as IL-15 receptor superagonist and PD-1 blockade. These findings call into question the ability of lymph node CD8+ T cells to control or eliminate SIV/HIV infection from lymphoid tissues without substantial immunomodulation, a notion contrary to current efforts to engage CD8+ T cells for therapeutic elimination of HIV viral reservoirs during ART.

immunology↗

bioRxiv2024

Immune perturbations in human pancreas lymphatic tissues prior to and after type 1 diabetes onset

Autoimmune destruction of pancreatic {beta} cells results in type 1 diabetes (T1D), with pancreatic immune infiltrate representing a key feature in this process. Studies of human T1D immunobiology have predominantly focused on circulating immune cells in the blood, while mouse models suggest diabetogenic lymphocytes primarily reside in pancreas-draining lymph nodes (pLN). A comprehensive study of immune cells in human T1D was conducted using pancreas draining lymphatic tissues, including pLN and mesenteric lymph nodes, and the spleen from non-diabetic control, {beta} cell autoantibody positive non-diabetic (AAb+), and T1D organ donors using complementary approaches of high parameter flow cytometry and CITEseq. Immune perturbations suggestive of a proinflammatory environment were specific for T1D pLN and AAb+ pLN. In addition, certain immune populations correlated with high T1D genetic risk independent of disease state. These datasets form an extensive resource for profiling human lymphatic tissue immune cells in the context of autoimmunity and T1D.

immunology↗

bioRxiv2021

Immunogenicity of an AAV-based, room-temperature stable, single dose COVID-19 vaccine in mice and non-human primates

The SARS-CoV-2 pandemic has affected more than 70 million people worldwide and resulted in over 1.5 million deaths. A broad deployment of effective immunization campaigns to achieve population immunity at global scale will depend on the biological and logistical attributes of the vaccine. Here, two adeno-associated viral (AAV)-based vaccine candidates demonstrate potent immunogenicity in mouse and nonhuman primates following a single injection. Peak neutralizing antibody titers remain sustained at 5 months and are complemented by functional memory T-cells responses. The AAVrh32.33 capsid of the AAVCOVID vaccine is an engineered AAV to which no relevant pre-existing immunity exists in humans. Moreover, the vaccine is stable at room temperature for at least one month and is produced at high yields using established commercial manufacturing processes in the gene therapy industry. Thus, this methodology holds as a very promising single dose, thermostable vaccine platform well-suited to address emerging pathogens on a global scale.

immunology↗

bioRxiv2020

Deep immune profiling of COVID-19 patients reveals patient heterogeneity and distinct immunotypes with implications for therapeutic interventions

COVID-19 has become a global pandemic. Immune dysregulation has been implicated, but immune responses remain poorly understood. We analyzed 71 COVID-19 patients compared to recovered and healthy subjects using high dimensional cytometry. Integrated analysis of [~]200 immune and >30 clinical features revealed activation of T cell and B cell subsets, but only in some patients. A subgroup of patients had T cell activation characteristic of acute viral infection and plasmablast responses could reach >30% of circulating B cells. However, another subgroup had lymphocyte activation comparable to uninfected subjects. Stable versus dynamic immunological signatures were identified and linked to trajectories of disease severity change. These analyses identified three "immunotypes" associated with poor clinical trajectories versus improving health. These immunotypes may have implications for therapeutics and vaccines.

immunology↗

bioRxiv2020

Immunologic perturbations in severe COVID-19/SARS-CoV-2 infection

Although critical illness has been associated with SARS-CoV-2-induced hyperinflammation, the immune correlates of severe COVID-19 remain unclear. Here, we comprehensively analyzed peripheral blood immune perturbations in 42 SARS-CoV-2 infected and recovered individuals. We identified broad changes in neutrophils, NK cells, and monocytes during severe COVID-19, suggesting excessive mobilization of innate lineages. We found marked activation within T and B cells, highly oligoclonal B cell populations, profound plasmablast expansion, and SARS-CoV-2-specific antibodies in many, but not all, severe COVID-19 cases. Despite this heterogeneity, we found selective clustering of severe COVID-19 cases through unbiased analysis of the aggregated immunological phenotypes. Our findings demonstrate broad immune perturbations spanning both innate and adaptive leukocytes that distinguish dysregulated host responses in severe SARS-CoV-2 infection and warrant therapeutic investigation. One Sentence SummaryBroad immune perturbations in severe COVID-19

immunology↗