Biology subjects

Lenardo, M. J.

Publications and source records attributed to Lenardo, M. J..

5 recordsLinked to original sources

bioRxiv2026

Immunoregulatory gene GIMAP6 suppresses lethal atherosclerotic vasculopathy and ischemic heart failure

Controlling hyperlipidemia has reduced but not eliminated atherosclerotic cardiovascular disease as a predominant cause of human mortality. Here, we report that loss of the immunoregulatory gene GTPase of immunity-associated protein 6 (GIMAP6), causes an inflammatory vasculopathy and accelerated atherosclerosis in the absence of hyperlipidemia. These pathologic changes in turn result in progressive cardiac ischemia, myocardial infarction, and heart failure, culminating in early death. In humans, rare deleterious GIMAP6 variants are associated with premature severe cardiovascular disease. These findings reveal GIMAP6 to play an important protective role against atherosclerotic cardiovascular disease whose identification offers opportunities for improved risk management and a target for new therapies.

immunology↗

bioRxiv2021

Human immunodeficiency reveals GIMAP5 as lymphocyte-specific regulator of senescence

Elucidating the molecular basis of immunodeficiency diseases is a powerful approach to discovering new immunoregulatory pathways in humans. Here we report 10 affected individuals from 4 families with a new immunodeficiency disease comprising of severe progressive lymphopenia, autoimmunity, immunodeficiency, and liver disease due to recessive loss of function variants in "GTPase of immunity-associated proteins" protein 5 (GIMAP5). We show that the disease involves the progressive loss of naive T lymphocytes and a corresponding increase in antigen-experienced, but poorly functional and replicatively senescent T cells. In vivo treatment of Gimap5-deficient mice with rapamycin (an inhibitor of mTORC1) significantly restores the fraction of naive T lymphocytes. Furthermore, a GIMAP5-deficient human patient who was treated with rapamycin (sirolimus) showed a remarkable reduction in spleen/lymph node size. Together, these observations reveal that GIMAP5 plays a critical role in lymphocyte metabolism which is essential for senescence prevention and immune competence, suggesting that an inhibitor of mTORC1 could be a valuable clinical intervention in treating patients deficient for GIMAP5.

immunology↗

bioRxiv2019

Human plasma-like medium improves T lymphocyte activation

T lymphocytes are critical for effective immunity and the ability to study their behavior in synthetic media in vitro facilitates major discoveries in their development, function, and fate. However, the composition of human plasma differs from synthetic media and we hypothesized that these differences could have important effects on cell physiology. We therefore compared T lymphocyte activation in human plasma-like medium (HPLM) to RPMI supplemented with dialyzed FBS (RPMIdFBS) and found that it entrained markedly different transcriptional responses. We also found that the concentration of calcium in RPMIdFBS is six-fold lower than HPLM causing altered T cell activation which could be reversed by calcium addition. Thus, investigators should be cognizant of differences between commonly used media formulations and HPLM which is based on the in vivo plasma environment as these could profoundly affect their experimental results. Physiologic media may be a valuable new way to study immune cells in culture.

immunology↗

bioRxiv2019

Genetic immunodeficiency and autoimmune disease reveal distinct roles of Hem1 in the WAVE2 and mTORC2 complexes

Immunodeficiency often coincides with immune hyperresponsiveness such as autoimmunity, lymphoproliferation, or atopy, but the molecular basis of this paradox is typically unknown. We describe four families with immunodeficiency coupled with atopy, lymphoproliferation, cytokine overproduction, hemophagocytic lymphohistocytosis, and autoimmunity. We discovered loss-of-function variants in the gene NCKAP1L, encoding the hematopoietic-specific Hem1 protein. Three mutations cause Hem1 protein and WAVE regulatory complex (WRC) loss, thereby disrupting actin polymerization, synapse formation, and immune cell migration. Another mutant, M371V encodes a stable Hem1 protein but abrogates binding of the Arf1 GTPase and identifies Arf1 as a critical Hem1 regulator. All mutations reduce the cortical actin barrier to cytokine release explaining immune hyperresponsiveness. Finally, Hem1 loss blocked mTORC2-dependent AKT phosphorylation, T cell proliferation, and effector cytokine production during T cell activation. Thus, our data show that Hem1 independently governs two key regulatory complexes, the WRC and mTORC2, and how Hem1 loss causes a combined immunodeficiency and immune hyperresponsiveness disease.\n\nOne sentence summaryHem1 loss of function mutations cause a congenital immunodysregulatory disease and reveal its role regulating WAVE2 and mTORC2 signaling.

immunology↗

bioRxiv2018

Human IL-2 receptor β mutations associated with defects in immunity and peripheral tolerance

Interleukin-2, which conveys essential signals for effective immunity and immunological tolerance, operates through a heterotrimeric receptor comprised of , {beta} and {gamma} chains. Genetic deficiency of the or {gamma} chain causes debilitating disease. Here we identify human interleukin-2 receptor (IL-2R) {beta} chain (CD122) gene defects as a cause of life-threatening dysregulation of immunity and peripheral tolerance. We report homozygous mutations in the human IL-2R{beta} gene from four consanguineous families, comprising either recessive missense mutations in five children or an early stop-gain mutation in two deceased fetuses and a premature neonate. All patients surviving to childhood presented with autoantibodies, hypergammaglobulinemia, bowel inflammation, and dermatological abnormalities, as well as cytomegalovirus disease in most cases. Patient T lymphocytes lacked surface expression of IL-2R{beta} and were unable to normally respond to high-dose IL-2 stimulation. By contrast, patient natural killer (NK) cells retained partial IL-2R{beta} expression and cytotoxic function. IL-2R{beta} loss of function was recapitulated in a recombinant system, in which endoplasmic reticulum sequestration was revealed as the mechanism by which certain missense mutations cause disease. Hematopoietic stem cell transplant resulted in resolution of clinical symptoms in one patient. The hypomorphic nature of this disease highlights the significance of variable IL-2R{beta} expression in different lymphocyte subsets as a means of modulating immune function. Insights from these patients can inform the development of IL-2-based therapeutics for immunological diseases and cancer.

immunology↗