Biology subjects

Balaji, U.

Publications and source records attributed to Balaji, U..

4 recordsLinked to original sources

bioRxiv2025

Single-cell map of the healthy human immune system across the lifespan reveals unique infant immune signatures

The human immune system undergoes continuous remodeling from infancy through old age, yet the timing and trajectory of these changes across the lifespan remain poorly defined. To address this, we profiled peripheral blood mononuclear cells from 95 healthy individuals (ages 2 months to 88 years), including infants (n=27), children (n=23), adults (n=18), and older adults (n=27) using scRNA-seq and snATAC-seq. MAIT and {gamma}{delta} T cells showed a "Rise and fall" pattern, which rise in childhood, peak in young adulthood, and decline with age. CD8+ T cells were the most affected by aging with decreasing naive T cells and increasing GzK+ CD8+ T cells and TEMRA cells. Infants had lower myeloid/lymphoid ratio, with a distinct composition marked by increased frequencies of CD16+ monocytes and plasmacytoid dendritic cells and reduced frequencies of CD14+ monocytes and conventional DCs. Their adaptive immune compartment also displayed unique features, including constitutive interferon-stimulated gene expression in T and B cells, and an expanded SOX4+ populations in naive CD4+, naive CD8+ and {gamma}{delta} T cells, comprising [~]30% of the naive T cell pool. SOX4+ naive CD4+ T cells displayed a Th2 epigenetic signature. This map provides critical insights into human immune system dynamics across the lifespan, emphasizing unique features of the infant immune system.

immunology↗

bioRxiv2024

Khdc3 Regulates Metabolism Across Generations in a DNA-Independent Manner

Genetic variants can alter the profile of heritable molecules such as small RNAs in sperm and oocytes, and in this manner ancestral genetic variants can have a significant effect on offspring phenotypes even if they are not inherited. Here we show that wild type female mice descended from ancestors with a mutation in the mammalian germ cell gene Khdc3 have hepatic metabolic defects that persist over multiple generations. We find that genetically wild type females descended from Khdc3 mutants have transcriptional dysregulation of critical hepatic metabolic genes, which persist over multiple generations and pass through both female and male lineages. This was associated with dysregulation of hepatically-metabolized molecules in the blood of these wild type mice with mutational ancestry. The oocytes of Khdc3-null females, as well as their wild type descendants, had dysregulation of multiple small RNAs, suggesting that these epigenetic changes in the gametes transmit the phenotype between generations. Furthermore, injection of serum from wild type mice with ancestral history of Khdc3 mutation into wild type females is sufficient to cause hepatic transcriptional dysregulation in their offspring. Our results demonstrate that ancestral mutation in Khdc3 can produce transgenerational inherited phenotypes, potentially indefinitely.

genetics↗

bioRxiv2023

An unconventional mechanism of IL-1β secretion that requires Type I IFN in lupus monocytes

Systemic Lupus Erythematosus (SLE) is characterized by autoreactive B cell activation, upregulation of Type I Interferon (IFN) and widespread inflammation. Mitochondrial nucleic acids (NAs) are increasingly recognized as triggers of IFN1. Thus, defective removal of mitochondria from mature red blood cells (Mito+ RBCs), a feature of SLE, contributes to IFN production by myeloid cells2. Here we identify blood monocytes (Mo) that have internalized RBCs and co-express IFN-stimulated genes (ISGs) and interleukin-1{beta} (IL-1{beta}) in SLE patients with active disease. We show that ISG expression requires the interaction between Mito+ RBC-derived mitochondrial DNA (mtDNA) and cGAS, while IL-1{beta} production entails Mito+ RBC-derived mitochondrial RNA (mtRNA) triggering of RIG-I-like receptors (RLRs). This leads to the cytosolic release of Mo-derived mtDNA that activates the NLRP3 inflammasome. Importantly, IL-1{beta} release depends on the IFN-inducible myxovirus resistant protein 1 (MxA), which enables the translocation of this cytokine into a trans-Golgi network (TGN)-mediated unconventional secretory pathway. Our study highlights a novel and synergistic pathway involving IFN and the NLRP3 inflammasome in SLE.

immunology↗

bioRxiv2017

Sensitive and specific post-call filtering of genetic variants in xenograft and primary tumors

MotivationTumor genome sequencing offers great promise for guiding research and therapy, but spurious variant calls can arise from multiple sources. Mouse contamination can generate many spurious calls when sequencing patient-derived xenografts (PDXs). Paralogous genome sequences can also generate spurious calls when sequencing any tumor. We developed a BLAST-based algorithm, MAPEX, to identify and filter out spurious calls from both these sources.\n\nResultsWhen calling variants from xenografts, MAPEX has similar sensitivity and specificity to more complex algorithms. When applied to any tumor, MAPEX also automatically flags calls that potentially arise from paralogous sequences. Our implementation, mapexr, runs quickly and easily on a desktocomputer. MAPEX is thus a useful addition to almost any pipeline for calling genetic variants in tumors.

bioinformatics↗