Biology subjects

Mamula, M. J.

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

3 recordsLinked to original sources

bioRxiv2025

Gut microbiota of dogs with cancer receiving anti-EGFR/HER2 immunization reveals potential biomarkers of patient survival

BackgroundCanine cancer remains a leading cause of death in dogs, yet advances in veterinary oncology lag behind human medicine, particularly in immunotherapy. While immune checkpoint inhibitors are just entering clinical trials in dogs, other immunotherapies, such as anti-EGFR/HER2 vaccines, have shown promise. In parallel, mounting evidence in human oncology links gut microbiota composition to immunotherapy response. However, this relationship remains unexplored in canine patients. In this pilot study, we analyzed the gut microbiome of dogs enrolled in a clinical trial of anti-EGFR/HER2 immunotherapy to identify microbial biomarkers associated with survival outcomes. MethodsRectal swab samples of 51 dogs were collected at the time of first vaccine administration (baseline microbiota) and underwent 16S rRNA gene sequencing according to standard protocols. ResultsMicrobiome composition showed no significant differences by cancer type, sex, or breed, suggesting no inherent microbiome bias in the cohort. However, Cox regression analysis revealed 11 bacterial taxa whose abundances were significantly associated with overall survival (FDR < 0.1), independently of cancer type. Seven taxa were linked to increased mortality risk, while four were associated with prolonged survival. These associations remained significant after adjusting for confounders such as hemangiosarcoma diagnosis and advanced age. ConclusionsTo our knowledge, this is the first study to identify gut microbial signatures associated with survival in dogs undergoing cancer immunotherapy. These findings suggest that specific bacterial taxa may serve as prognostic biomarkers for immunotherapy outcomes in canine cancer, laying the groundwork for microbiota-targeted strategies to improve therapeutic efficacy in veterinary oncology.

cancer biology↗

bioRxiv2021

A discovery-based proteomics approach identifies protein disulfide isomerase (PDIA1) as a biomarker of β cell stress in type 1 diabetes

BackgroundActivation of stress pathways intrinsic to the {beta} cell are thought to both accelerate {beta} cell death and increase {beta} cell immunogenicity in type 1 diabetes (T1D). However, information on the timing and scope of these responses is lacking. MethodsTo identify temporal and disease-related changes in islet {beta} cell protein expression, data independent acquisition-mass spectrometry was performed on islets collected longitudinally from NOD mice and NOD-SCID mice rendered diabetic through T cell adoptive transfer. FindingsIn islets collected from female NOD mice at 10, 12, and 14 weeks of age, we found a time-restricted upregulation of proteins involved in the maintenance of {beta} cell function and stress mitigation, followed by loss of expression of protective proteins that heralded diabetes onset. Pathway analysis identified EIF2 signaling and the unfolded protein response, mTOR signaling, mitochondrial function, and oxidative phosphorylation as commonly modulated pathways in both diabetic NOD mice and NOD-SCID mice rendered acutely diabetic by adoptive transfer, highlighting this core set of pathways in T1D pathogenesis. In immunofluorescence validation studies, {beta} cell expression of protein disulfide isomerase A1 (PDIA1) and 14-3-3b were found to be increased during disease progression in NOD islets, while PDIA1 plasma levels were increased in pre-diabetic NOD mice and in the serum of children with recent-onset T1D compared to age and sex-matched non-diabetic controls. InterpretationWe identified a common and core set of modulated pathways across distinct mouse models of T1D and identified PDIA1 as a potential human biomarker of {beta} cell stress in T1D.

physiology↗

bioRxiv2021

Citrullination of glucokinase linked to autoimmune diabetes

Inflammation, including reactive oxygen species and inflammatory cytokines in tissue microenvironments amplify the appearance of various post-translational modifications (PTMs) of self-proteins. Previously, a number of PTMs have been identified as autoimmune biomarkers in the initiation and progression of Type 1 diabetes (T1D). Herein, we have identified the citrullination of glucokinase (GK) as a result of inflammation, triggering autoimmunity and affecting its biological functions. Glucokinase is predominantly expressed in hepatocytes to regulate glycogen synthesis, and in pancreatic beta cells, where it acts as a glucose sensor to initiate glycolysis and insulin signaling. Herein, we demonstrate that glucokinase is citrullinated in inflamed non-obese diabetic (NOD) islets as well as in human GK. Autoantibodies against both native and citrullinated GK arise in both spontaneous human T1D and murine models. Likewise, autoreactive CD4+ T cells to both native and citrullinated glucokinase epitopes are present in the circulation of T1D patients. Finally, citrullination alters GK biologic activity and suppresses glucose-stimulated insulin secretion. Our studies define glucokinase as a T1D biomarker, providing new insights into altering glucose metabolism, creating neoautoantigens, and better define the broad impact of PTMs on the tissue pathology of T1D.

immunology↗