Siddharth Jhunjhunwala

Aims: To characterise the type 2 diabetes (T2D) cascade of care in an urban Indian academic-employer cohort, and to compare biochemical, lifestyle, and dietary phenotypes between individuals with previously diagnosed (aware) and newly identified (unaware) T2D.Methods: PREDIICT is a single-centre, prospective cohort of urban adults aged 35–65 years (n=227) recruited between November 2023 and July 2025 at the Indian Institute of Science, Bengaluru, India. Participants underwent biochemical profiling (35 parameters), anthropometry, blood-pressure measurement, and a structured lifestyle questionnaire including a validated food-frequency module. Diabetes was defined as HbA1c ≥6.5% (≥48 mmol/mol) and/or glucose-lowering medication use.Results: At baseline, 27.8% (63/227; 95% CI 22.3–33.9%) had T2D and 30.8% (70/227; 95% CI 25.2–37.1%) had prediabetes. Notably, 34.9% (22/63; 95% CI 24.3–47.2%) of those with T2D were unaware of their diagnosis prior to screening. Despite high treatment uptake among aware individuals (87.8%; 36/41; 95% CI 74.5–94.7%), only 38.9% (14/36; 95% CI 24.8–55.1%) of treated individuals achieved HbA1c <7.0% (<53 mmol/mol). Unaware individuals had significantly higher total cholesterol, LDL cholesterol, and added-sugar consumption compared with aware individuals, while aware individuals had elevated NT-proBNP (1.54-fold; p=0.009), consistent with longer recognised disease duration. Exploratory follow-up analyses suggested a subset of newly diagnosed participants initiated physical activity (4 of 8 previously inactive) and reduced added-sugar intake.Conclusion: One in three individuals with T2D was undiagnosed at screening, and fewer than four in ten treated individuals achieved glycaemic control. The divergent biochemical and dietary profile of unaware individuals identifies a high-risk, reachable population for targeted early intervention

Uptake of large (~3 µm) sized particles affects efferocytosis capacity of macrophages.

Alpha-hemolysin (α-HL) is a small pore-forming toxin secreted by pathogenic Staphylococcus aureus, inducing cell death process by forming pores in membrane. So far, detergents or artificial lipid environments have been utilized to characterize the toxin structure. The toxin-induced changes in the membrane, membrane remodeling after toxin treatment, and the role of the toxin during pore formation process remain ambiguous. Thus, understanding pore formation in the cellular environment, including the roles of the plasma membrane and lipid composition, is crucial for drug development. In this study, we captured step-by-step oligomerization of α-HL and membrane rupture of erythrocyte cells using confocal microscopy, cryo-EM imaging, and single-particle analysis. We resolved 3.1–3.8 Å resolution structures of pore, prepore, and immature pore conformations in cellular environment. Furthermore, mass spectrometry analysis demonstrated key erythrocyte lipid components interacting with α-HL. Our findings indicate that shorter or unsaturated lipid chains facilitate pore formation and the role of phosphatidylcholine with varying physical properties in modulating the toxin’s activity.

It is generally assumed that without active escape mechanisms, all cargo phagocytosed by macrophages eventually reaches lysosomes. Yet, the influence of specific ligands present on the cargo, like lipopolysaccharide (LPS), on phagosome maturation is unclear. Using sterile, non‐immunogenic particles as model cargo phagocytosed by macrophages, this study showed that in the absence of a specific ligand on the cargo, less than half the cargo‐loaded phagosomes fuse with lysosomes. Quantification of phagosome maturation revealed that early events triggered by LPS‐induced signaling enhance both cargo delivery to lysosomes and phagosome acidification rates. Specifically, it is demonstrated that stress‐activated p38 alpha mitogen‐activated protein kinase (p38 MAPK) enhances phagosome maturation under LPS‐triggered signaling. Other signals known to activate p38 MAPK such as flagellin, IgG, and albumin, also enhance lysosomal delivery of phagocytosed cargo. The work indicates that phagosome maturation in macrophages is enhanced by specific ligands on the cargo, which activate cell surface receptors that signal via p38 MAPK.

Community-associated methicillin-resistant Staphylococcus aureus strains often demonstrate enhanced virulence, with different strains eliciting varied immune responses in humans. The factors that enable some S. aureus strains to evade killing by immune cells remain unclear. Here, we describe studies designed to understand ex vivo intracellular survival assays that revealed that while a well-characterized MRSA ST8 strain (USA300) was susceptible to phagocytic clearance, a genotypically similar MRSA ST88 strain (LVP-7) effectively evaded neutrophil killing. A pronounced enhancement in neutrophil lysis upon ST88 infection suggests that ST88 can infect polymorphonuclear human neutrophils yet circumvent phagocytosis-associated killing. Both ST8 and ST88 strains show a similar response to extracellular stress elicited by H₂O₂, HOCl, or NO. Host bactericidal mechanisms, such as the release of reactive oxygen species, myeloperoxidases, and elastases, were similar when infected with either strain. The transcriptome profile of ST88 upon phagocytosis at different stages of infection alongside a comparison of the phenotypic traits of ST8 and ST88 revealed factors that could potentially rationalize ST88's evasion of killing by neutrophils. Upon phagocytosis, the ST88 transcriptome showed distinct changes in the levels of the quorum sensing accessory gene regulator (Agr). Confocal imaging revealed that the ST88 strain clusters more with higher bacteria per infected neutrophil than the ST8 strain. A pronounced reduction in ST88 clumping was seen upon the addition of the cognate autoinducing peptide AIP-III, consistent with the premise that the Agr mechanism plays a role in the evasion of neutrophil-mediated killing by the ST88 strain. It thus appears likely that clumping, modulated by quorum sensing, provides a route for this S. aureus strain to evade the human innate immune response.

In macrophages, it is generally assumed that without active escape mechanisms, all phagocytosed cargo eventually reaches lysosomes. Yet, the influence of specific ligands, like lipopolysaccharide (LPS), on phagosome maturation is unclear. Here, using sterile, non-immunogenic particles as model cargo phagocytosed by macrophages, we show that in the absence of an external signal, less than half the phagosomes fuse with lysosomes. By quantifying phagosome maturation in terms of lysosomal localization and mapping lumenal pH dynamics, we find that early events triggered by LPS-induced signaling enhance both cargo delivery to lysosomes and phagosome acidification rates. We demonstrate that stress-activated p38 alpha mitogen-activated protein kinase (p38 MAPK) is important for this signaling event. Other signals known to activate p38 MAPK such as flagellin, IgG and albumin also enhance lysosomal delivery of phagocytosed cargo. Our work indicates that the maturation of phagosomes in macrophages is enhanced by the presence of specific ligands on the cargo, which activate cell surface receptors that signal via p38 MAPK.

Individuals with underlying chronic inflammatory conditions are prone to increased morbidity when posed with an additional inflammatory challenge such as an injury or infection, but why this occurs remains unclear. Herein, we address this question in mouse models by demonstrating that chronic inflammation results in a pronounced expansion of circulating immature neutrophils that exhibit dysregulated effector functions as determined by single cell RNA sequencing and ex vivo functional assays. We show that these immature neutrophils are associated with and contribute to increased immunopathology in response to a new inflammatory challenge. Blocking the migration or function of these immature neutrophils through the administration of therapeutic antibodies or small molecules, profoundly lowers the immunopathology caused by the inflammatory challenge. Together, these studies establish a causal link between immature neutrophils and increased immunopathology, while also providing insights into new therapeutic strategies for treating individuals with chronic inflammatory ailments.