Biology subjects

Rathinam, C. V.

Publications and source records attributed to Rathinam, C. V..

3 recordsLinked to original sources

bioRxiv2025

Influenza virus infection in the lungs leads to pancytopenia and defective immune cell differentiation program in the thymus and bone marrow

Exaggerated inflammation and cytokine storm are hallmark features of influenza A virus (IAV)-induced respiratory diseases. While previous studies unequivocally demonstrated the pathophysiological consequences (multiorgan failure) of IAV-associated cytokine storm, it remains unknown if IAV-induced systemic inflammation impacts the "fitness" and differentiation of immune cells from hematopoietic stem cells (HSCs). Our data on lethal IAV-infected C57BL/6 wildtype mice after 10 days of infection indicated reduced monocyte- and lymphocyte-counts in the peripheral blood, and overall cellularity of spleen, thymus and lymph nodes. IAV-infection resulted in increased numbers of myeloid cells, CD8+ T cells, alveolar macrophages (AVMs), CD11b+ dendritic cells (DCs) & plasmacytoid DCs (pDCs), whereas decreased frequencies of CD103+ DCs, in the lungs of IAV-infected mice. Analysis of spleen and draining lymph nodes indicated reduced absolute numbers of B cells, T cells, monocytes and DCs after 10 days of lethal IAV infection. Thymic analysis indicated perturbed T cell differentiation and bone marrow (BM) data revealed impaired DC differentiation following IAV infection. Hematopoietic stem and progenitor cells (HSPCs) studies demonstrated an imbalanced distribution of HSCs, multipotent progenitors (MPPs), myeloid progenitors and DC progenitors within the BM niche. Mechanistic studies exhibited elevated levels of systemic inflammation and altered local pro-inflammatory milieu. Molecular analyses documented elevated levels of intracellular reactive oxygen species (ROS) at all stages of HSPC differentiation and increased mass of active mitochondria in HSPC subsets. In essence, our studies provide novel insights into mechanisms through which lethal IAV-infection induces deficiencies of the innate and adaptive immune system.

immunology↗

bioRxiv2022

Trim28 plays an indispensable role in maintaining functions and transcriptional integrity of hematopoietic stem cells

Hematopoiesis is a complex process that is regulated at multiple levels and through both intrinsic and extrinsic regulators. Trim28 is a multidomain protein that functions as a transcription factor and E3 ubiquitin ligase. Recent studies have established the pivotal roles of Trim28 in a variety of pathophysiologic processes including inflammation, autoimmune disorders, viral pathogenesis, cancer, tumor microenvironment and epithelial-to- mesenchymal transition. However, importance of Trim28 in early hematopoiesis, particularly in the maintenance and functions of hematopoietic stem and progenitor cells (HSPCs), remains largely unknown. In the present study, we identified Trim28 as a critical regulator of self-renewal, quiescence, and functions of hematopoietic stem cells (HSC). Conditional ablation of Trim28 in HSCs leads to perinatal lethality, due to pancytopenia within the hematopoietic lineage. Loss of Trim28 in HSCs affects their differentiation into myeloid-, erythroid-, and lymphoid- lineages. Trim28 deletion leads to altered frequencies and absolute numbers of HSCs, Multipotent Progenitors (MPPs) and lineage committed progenitors in the bone marrow (BM). Primary- and secondary- BM transplantation studies identified an indispensable and a cell-intrinsic role for Trim28 in HSCs. Mechanistic studies identified hyperproliferation of HSPCs and deregulated expression of cell cycle regulators in HSPCs. Strikingly, gene expression studies demonstrated that Trim28 deficiency impairs the transcriptional landscape and transcription factors signatures of HSPCs. In essence, these studies highlight a previously unknown role for Trim28 in the maintenance, functions, and multi-lineage differentiation of HSPCs.

immunology↗

bioRxiv2021

Traumatic brain injury alters dendritic cell differentiation and distribution in lymphoid and non-lymphoid organs

Pathophysiological consequences of traumatic brain injury (TBI) mediated secondary injury remain incompletely understood. In particular, the impact of TBI on the differentiation and maintenance of dendritic cells (DCs), remains completely unknown. Here, we report that DC-differentiation, maintenance and functions are altered at both early and late phases of TBI. Our studies identify that; 1. frequencies and absolute numbers of DCs in the spleen and BM are altered at both acute and late phases of TBI; 2. surface expression of key molecules involved in antigen presentation of DCs were affected both at early and late phases of TBI; 3. distribution and functions of tissue-specific DC subsets of both circulatory and lymphatic systems were imbalanced following TBI; 4. early differentiation program of DCs, especially the commitment of hematopoietic stem cells to common DC progenitors, were deregulated after TBI; and 5. intracellular ROS levels were reduced in DC progenitors and differentiated DCs at both early and late phases of TBI. Our data demonstrate, for the first time, that TBI affects the distribution pattern of DCs and induces an imbalance among DC subsets in both lymphoid and non-lymphoid organs. In addition, the current study demonstrates that TBI results in reduced levels of ROS in DCs at both early and late phases of TBI, which may explain altered DC differentiation paradigm following TBI. A deeper understanding on the molecular mechanisms that contribute to DC defects following TBI would be essential and beneficial in treating infections in patients with acute central nervous system (CNS) injuries.

immunology↗