Biology subjects

Yennemadi, A. S.

Publications and source records attributed to Yennemadi, A. S..

7 recordsLinked to original sources

bioRxiv2026

SLE Monocyte Subsets Are Pro-Inflammatory and Display Dysregulated Metabolism in Response to Bacterial Stimuli

Systemic lupus erythematosus (SLE) is associated with infection susceptibility and altered innate immune function. Monocyte metabolism is linked to appropriate cytokine release and bacterial containment. We investigated cytokine production and metabolic programming in the monocyte population from SLE patients and healthy controls following lipopolysaccharide (LPS) stimulation. SLE monocytes displayed increased IL-10, TNF, and IL-8 production, with impaired IL-1{beta} induction. Metabolic profiling revealed altered substrate use, with increased glucose dependence and reduced fatty acid and amino acid oxidation after LPS stimulation. SLE patients exhibited reduced numbers of classical monocytes, expansion of intermediate monocytes, and dysregulated subset-specific metabolic reprogramming in response to LPS. This descriptive study provides a cornerstone for (i) understanding infection susceptibility in SLE, (ii) subset-resolved immunometabolic profiling as a tool in autoimmunity, and (iii) developing future metabolic-targeted therapeutic strategies HighlightsO_LIDescriptive mapping shows SLE monocytes are proinflammatory with glucose dependence after LPS C_LIO_LIClassical and intermediate SLE subsets show divergent baseline metabolic preferences versus healthy C_LIO_LISLE subsets display aberrant LPS responses, i.e.. increased glucose and reduced fatty acid oxidation C_LIO_LIThis study provides a cornerstone for subset-resolved immunometabolism in infection susceptibility. C_LI

immunology↗

bioRxiv2026

Neutrophil subsets in SLE exhibit increased glycolysis that correlates with disease activity

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterised by sustained type I interferon signalling and widespread immune dysregulation. Low-density neutrophils (LDNs) are expanded in SLE and display pro-inflammatory and tissue-damaging properties. However, their metabolic phenotype remains poorly defined. Here, we performed a comprehensive metabolic characterisation of circulating LDNs and normal-density neutrophils (NDNs) from patients with SLE and matched healthy individuals (HC). Neutrophil subsets were isolated from peripheral blood of SLE patients and HC donors using a two-step protocol of negative selection and Percoll density centrifugation. Immunophenotyping phenotype was carried out by flow cytometry to assess phenotypic expression of common neutrophil markers CD15, CD16, CD10, CD66b, CD62L, MPO, and IL-1{beta}. Bioenergetic profiling of LDNs and NDNs was performed in situ using the Seahorse MitoStress test to measure oxygen consumption rate (OCR) and extracellular acidification rate (ECAR). Metabolic flexibility and phenotypic alterations were assessed in LDNs and NDNs following inhibiting mitochondrial metabolism with oligomycin and glycolysis with 2DG. We found that SLE LDNs exhibit an immature phenotype compared with autologous and healthy NDNs, as determined transcriptionally by C/EBP{varepsilon} and by surface protein expression levels of CD10. Both LDNs and NDNs from SLEDAI[≥]4 patients demonstrated significantly elevated ECAR relative to HC neutrophils. Further, SLE LDNs displayed enhanced metabolic flexibility, with the capacity to switch towards a glycolytic phenotype under metabolic stress conditions. Inhibition of glycolysis altered the inflammatory and maturation-associated phenotype of both SLE neutrophil subsets, indicating a direct link between cellular metabolism and pathogenic neutrophil function. Collectively, these findings identify fundamental metabolic alterations in SLE neutrophil subsets and support neutrophil immunometabolism as a potential therapeutic target in SLE.

immunology↗

bioRxiv2025

Sex-Specific Metabolic Programming in Human Neutrophil Subsets

BackgroundSex differences in immune responses are well-documented, with females exhibiting more robust immunity against infections but higher susceptibility to autoimmune diseases, while males often demonstrate more severe inflammatory pathology. Neutrophils which are key players in the innate immune response, display sex-based functional differences, but whether these extend to metabolic programming, particularly in low-density neutrophils (LDNs), remains unknown. MethodsWe isolated LDNs and normal-density neutrophils (NDNs) from healthy human donors using density gradient centrifugation and negative selection. Cellular metabolism was assessed via Seahorse XF analysis (measuring oxygen consumption rate, OCR, and extracellular acidification rate, ECAR), alongside flow cytometry for maturity markers (CD16hi/lo). ResultsMale LDNs exhibited significantly higher basal OCR and ATP production than female LDNs, while no sex differences were observed in NDNs. Strikingly, male LDNs had higher OCR and glycolysis than their matched NDNs, whereas female NDNs were more oxidative than their LDNs. These metabolic differences were independent of neutrophil maturity, as CD16hi frequencies did not differ between subsets or sexes. ConclusionsOur study reveals, for the first time, subset-specific sexual dimorphism in neutrophil metabolism whereby male LDNs adopt a hypermetabolic (oxidative/glycolytic) phenotype, while female NDNs retain higher oxidative capacity. This reprogramming occurs independently of developmental stage, suggesting sex hormones or epigenetic regulation may drive these differences. These findings provide a metabolic basis for sex-biased immune responses and highlight the need for sex-stratified approaches in neutrophil-targeted therapies. Plain English SummaryMen and women fight infections differently, and our study could reveal why--their immune cells produce energy in distinct ways. We examined two types of neutrophils (infection-fighting cells), normal cells (NDNs) and low-density cells (LDNs) found in inflammation. Using advanced metabolic measurements, we discovered that mens LDNs use more oxygen and generate more energy than womens. Surprisingly, while mens LDNs were more active than their normal neutrophils, women showed the opposite--their normal neutrophils were more energetic than their LDNs. These differences werent due to cell maturity, suggesting biological distinctions between sexes. This may help explain why men often have worse outcomes in diseases like sepsis (where oxygen-driven inflammation dominates), while women are more prone to autoimmune diseases like lupus. Our findings could lead to better sex-specific treatments by dampening overactive immune responses in men or adjusting metabolism in women to prevent autoimmune flares. This research highlights why medical studies must consider sex differences, as one-size-fits-all treatments may miss key biological variations. HighlightsO_LICD16hi frequencies show no sex differences, however female (but not male) NDNs contain significantly more mature CD15+ CD16hi cells than their LDNs, revealing female-specific maturation differences between subsets. C_LIO_LIFirst report of sex-specific metabolic differences in LDNs where males exhibit significantly higher basal respiration and ATP production than female LDNs. C_LIO_LIMale LDNs show higher OCR than matched NDNs, while female NDNs are more oxidative than their LDNs. C_LI

immunology↗

bioRxiv2025

Human macrophages secrete both interferon α and interferon β protein during infection with Mycobacterium tuberculosis.

Mycobacterium tuberculosis (Mtb) infection activates type I interferons (IFNs) which are crucial mediators of tuberculosis (TB) pathogenesis. Despite assumptions that IFN and IFN{beta} are secreted by macrophages, direct protein quantification in primary human monocyte-derived macrophages is surprisingly lacking. Here, we demonstrate measurable IFN and IFN{beta} secretion by MDMs infected with both virulent (H37Rv) and attenuated (H37Ra) Mtb strains as early as 48 h post-infection, with levels persisting at 120 h. These findings challenge existing assumptions about type I IFN kinetics and highlight the importance of timing in experimental designs and provides a foundation for exploring their role in host-pathogen interactions.

immunology↗

bioRxiv2025

Dexamethasone impairs glycolysis but improves mycobacterial killing in primary human macrophages

Glucocorticoids (GC) are useful adjunctive host directed therapies for sub-types of tuberculosis (TB). Macrophages play a central role in controlling Mycobacterium tuberculosis (Mtb) infection, relying on glycolytic reprogramming to support an effective host defense, yet the influence of GC on these important phagocytes is poorly understood. Here, we examined the impact of dexamethasone on metabolic and functional responses of primary human airway macrophages (AM) from bronchoalveolar lavage fluid and monocyte-derived macrophages (MDM). We found that dexamethasone significantly reduced basal and compensatory glycolysis in both AM and MDM, and decreased expression of the glycolytic enzyme PFKFB3. Oxidative metabolism was lower in dexamethasone AM but not MDM, indicating different specific metabolic sensitivity of macrophages. Dexamethasone also inhibited the glycolytic response to Mtb and reduced secretion of IL-1{beta}, TNF, IL-6, IL-8, and IL-10. Dexamethasone-treated macrophages showed enhanced survival following Mtb infection and these cells had a significant reduction in bacterial burden. This antimicrobial effect was impaired when macrophages were pre-treated with bafilomycin A1, implicating that phagosomal acidification may at least in part mediate dexamethasone-induced bacterial control. Collectively, these findings demonstrate that dexamethasone reprograms human macrophage metabolism toward a less glycolytic state while preserving their ability to limit Mtb growth. These results may offer a basis for the clinical benefit of GC in some TB presentations and support the development of targeting GC therapies to macrophages, thereby mitigating inflammation without compromising host antimicrobial defense.

immunology↗

bioRxiv2025

Mitochondrial Bioenergetic Failure in SLE Immunocytes: Targeting Fitness for Therapy

BackgroundSystemic Lupus Erythematosus (SLE) is characterized by dysregulated immune responses linked to immunometabolic perturbations. While mitochondrial dysfunction has been implicated in SLE, its cell-type-specific impact on immune subsets remains underexplored. MethodsWe repurposed existing RNA-seq data from SLE patient peripheral blood mononuclear cells, with a focus on nuclear-encoded mitochondrial (NEmt) genes, as well as mitochondrial genes themselves, to identify differentially expressed genes compared to healthy controls. Mitochondrial stress tests were performed on freshly isolated CD4+ T cells, CD8+ T cells, B cells, and monocytes from SLE patients and healthy donors to assess bioenergetic function. ResultsRNA-seq revealed that both NEmt genes and mitochondrial genes were downregulated in the PBMC population of SLE patients. In situ mitochondrial stress tests revealed significant reductions in oxygen consumption rate (OCR), indicating impaired oxidative phosphorylation (OXPHOS) across all immune subsets, while extracellular acidification rate (ECAR), a marker of glycolysis, remained unchanged. These findings highlight immune-cell-specific mitochondrial bioenergetic failure in SLE, without compensatory glycolytic adaptation. ConclusionOur results position mitochondrial fitness as a novel therapeutic target in SLE. We propose leveraging high-throughput screening of mitochondria-targeted compounds, including FDA-approved agents, to enhance OXPHOS, regulate mitophagy, or mitigate oxidative stress. This precision-based approach offers a paradigm shift from conventional immunosuppression to metabolic recalibration, with the potential to restore immune homeostasis in SLE. Key messagesO_LIWhat is already known on this topic: Mitochondrial dysfunction and metabolic reprogramming have been linked to SLE pathogenesis, but the cell-type-specific extent of mitochondrial impairment and its therapeutic potential remained unclear. C_LIO_LIWhat this study adds: We demonstrate reduced OXPHOS in CD4+ T cells, CD8+ T cells, B cells, and monocytes from SLE patients for the first time, highlighting cell-type-specific mitochondrial dysfunction as a possible driver of immune dysregulation and target for therapy. C_LIO_LIHow this study might affect research, practice, or policy: This study advocates for drug repurposing to restore mitochondrial fitness, offering a novel therapeutic strategy to complement existing SLE treatments and improve patient outcomes. C_LI

immunology↗

bioRxiv2025

HIV inhibits Warburg metabolism in human macrophages infected with Mycobacterium tuberculosis.

Tuberculosis (TB)-associated mortality remains disproportionately high among people living with HIV (PLWH), with macrophage dysfunction representing a key mechanism of impaired host defence against Mycobacterium tuberculosis (Mtb) infection. Using the U1 chronically HIV-infected macrophage cell line model coupled with primary human monocyte-derived macrophages (MDMs) exposed to HIV-1 gp120, we systematically characterized immunometabolic perturbations during Mtb infection. Nanostring RNA analysis revealed that Mtb monoinfection upregulated glycolytic genes while suppressing oxidative phosphorylation (OXPHOS) transcripts, consistent with a Warburg-type metabolic shift. Conversely, HIV infection downregulated glycolytic enzymes and enhanced mitochondrial respiratory chain components. Coinfection studies demonstrated HIV-mediated suppression of Mtb-induced glycolytic reprogramming. Extracellular flux analysis demonstrated that gp120 exposure increased basal oxygen consumption rate while impairing spare respiratory capacity in Mtb-infected MDMs, effectively blocking the Warburg metabolic transition. Notably, gp120 concentrations equivalent to those observed in antiretroviral therapy (ART)-treated PLWH significantly disrupted metabolic plasticity and high-dose gp120 attenuated Mtb-induced TNF- secretion. ImportanceThis study provides mechanistic insight into HIV-associated susceptibility to TB by demonstrating that HIV-1 infection fundamentally alters macrophage immunometabolic responses to Mtb. We establish that HIV-1, through gp120-mediated signaling, subverts the critical glycolytic induction required for effective antimicrobial responses against Mtb. The persistence of this metabolic dysregulation at clinically relevant gp120 concentrations, comparable to those observed in virologically suppressed PLWH, suggests ongoing immunological vulnerability despite ART. These findings identify HIV-induced metabolic reprogramming as a potential contributor to the persistently elevated TB risk in ART-treated individuals and highlight macrophage immunometabolism as a promising therapeutic target for host-directed therapies in HIV/TB coinfection. The dissociation between metabolic and cytokine responses suggests complex, multifactorial mechanisms underlying HIV-associated impairment of anti-mycobacterial immunity, warranting further investigation into the molecular pathways connecting cellular metabolism and immune effector functions.

immunology↗