Biology subjects

Reynolds, M. B.

Publications and source records attributed to Reynolds, M. B..

6 recordsLinked to original sources

bioRxiv2026

IL-10/ACOD1 axis regulates catabolism of phagocytosed lipids in trained macrophages

Macrophages clear excess host and microbial debris to restore homeostasis in inflamed tissues, yet the regulation and molecular fate of phagocytosed lipids during innate immune training remains largely unexplored. Leveraging stable isotope tracing of 13C-labeled bacteria, we establish an experimental framework to track microbe-to-host lipid transfer and define the fates of microbial lipids in macrophages in vitro and in vivo. While naive macrophages scavenge phagocytosed bacterial fatty acids into the host lipidome, TLR4-trained macrophages direct flux to mitochondria for {beta}-oxidation or lipid droplets in the context of mitochondrial dysfunction. While TLR4 signaling increases ACOD1 expression to produce itaconate that throttles TCA flux, trained macrophages produce IL-10 that reduces ACOD1 to sustain bacterial lipid disposal and promote resolution. These findings reveal an IL-10/ACOD1 regulatory axis in trained macrophages that reprograms lipid metabolism to optimally reestablish tissue homeostasis post-inflammation.

immunology↗

bioRxiv2025

Multi-site phosphorylation of BCL2L13 in a TBK1- and AMPK-dependent manner reveals new modes of mitophagy regulation

Mitophagy is a selective autophagic process that eliminates damaged mitochondria via lysosomal degradation, playing a crucial role in maintaining cellular metabolic balance. Mitophagy can occur through two pathways: ubiquitin-dependent and ubiquitin-independent. Recently, we and others have shown that, upon mitochondrial stress, AMP-activated protein kinase (AMPK) contributes to Parkin-mediated, ubiquitin-dependent mitophagy. The ubiquitin-independent pathway involves multiple outer mitochondrial membrane (OMM) "mitophagy receptors" that contain LC3-interacting region (LIR) motifs, including BNIP3, NIX/ BNIP3L, FUNDC1, and BCL2L13. LIR motifs bind Atg8/LC3 family proteins, facilitating the recruitment of the autophagosome membrane to target damaged mitochondria for degradation. The kinase Unc-51 Like autophagy activating kinase 1 (ULK1) phosphorylates the serine preceding the LIR motif in BNIP3, NIX, and FUNDC1, enhancing their binding to LC3 and promoting mitophagy. However, while BCL2L13 has been identified as a ULK1 binding partner, its regulation by phosphorylation remains unclear. We utilized mass spectrometry (MS) to map phosphorylation sites in BCL2L13 following mitochondrial stress and developed phospho-specific antibodies against two sites, Ser261 and Ser275, which were induced after exposure to the mitochondrial uncoupler, CCCP. Endogenous BCL2L13 Ser261 and Ser275 were both phosphorylated in an AMPK-dependent manner in cells and tissues. As neither site matches the established AMPK substrate consensus motif, we sought to identify which kinases directly mediate their phosphorylation downstream of AMPK. Surprisingly, genetic studies revealed that ULK1 is not regulating either site, but instead, TBK1 is controlling Ser275. This work reveals that BCL2L13 is unique amongst mitophagy receptors in being activated by mitochondrial stress and innate immune stimuli in an AMPK- and TBK1-dependent manner.

cell biology↗

bioRxiv2024

Epidermal ZBP1 stabilizes mitochondrial Z-DNA to drive UV-induced IFN signaling in autoimmune photosensitivity

Photosensitivity is observed in numerous autoimmune diseases and drives poor quality of life and disease flares. Elevated epidermal type I interferon (IFN) production primes for photosensitivity and enhanced inflammation, but the substrates that sustain and amplify this cycle remain undefined. Here, we show that IFN-induced Z-DNA binding protein 1 (ZBP1) stabilizes ultraviolet (UV)B-induced cytosolic Z-DNA derived from oxidized mitochondrial DNA. ZBP1 is significantly upregulated in the epidermis of adult and pediatric patients with autoimmune photosensitivity. Strikingly, lupus keratinocytes accumulate extensive cytosolic Z-DNA after UVB, and transfection of keratinocytes with Z-DNA results in stronger IFN production through cGAS-STING activation compared to B-DNA. ZBP1 knockdown abrogates UV-induced IFN responses, whereas overexpression results in a lupus-like phenotype with spontaneous Z-DNA accumulation and IFN production. Our results highlight Z-DNA and ZBP1 as critical mediators for UVB-induced inflammation and uncover how type I IFNs prime for cutaneous inflammation in photosensitivity. One Sentence Summary: ZBP1 and mitochondrial Z-DNA drive autoimmune photosensitivity via cGAS-STING activation.

immunology↗

bioRxiv2024

Type I interferon governs immunometabolic checkpoints that coordinate inflammation during Staphylococcal infection

Fine-tuned inflammation during infection enables pathogen clearance while minimizing host damage. Inflammation regulation depends on macrophage metabolic plasticity, yet coordination of metabolic and inflammatory programs is underappreciated. Here we show that type I interferon (IFN) temporally guides metabolic control of inflammation during methicillin-resistant Staphylococcus aureus (MRSA) infection. In macrophages, staggered Toll-like receptor and type I IFN signaling permitted a transient respiratory burst followed by inducible nitric oxide synthase (iNOS)-mediated OXPHOS disruption. OXPHOS disruption promoted type I IFN, suppressing other pro-inflammatory cytokines, notably IL-{beta}. iNOS expression peaked at 24h post-infection, followed by lactate-driven iNOS repression via histone lactylation. In contrast, type I IFN pre-conditioning sustained infection-induced iNOS expression and amplified type I IFN. Cutaneous MRSA infection in mice constitutively expressing epidermal type I IFN led to elevated iNOS levels, impaired wound healing, vasculopathy, and lung infection. Thus, kinetically regulated type I IFN signaling coordinates immunometabolic checkpoints that control infection-induced inflammation. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=101 SRC="FIGDIR/small/575104v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@977b1eorg.highwire.dtl.DTLVardef@1142c6corg.highwire.dtl.DTLVardef@170776borg.highwire.dtl.DTLVardef@b02c2f_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2023

Non-canonical activation of IRE1α during Candida albicans infection enhances macrophage fungicidal activity

While the canonical function of IRE1 is to detect misfolded proteins and activate the unfolded protein response (UPR) to maintain cellular homeostasis, microbial pathogens can also activate IRE1, which modulates innate immunity and infection outcomes. However, how infection activates IRE1 and its associated inflammatory functions have not been fully elucidated. Recognition of microbe-associated molecular patterns can activate IRE1, but it is unclear whether this depends on protein misfolding. Here, we report that a common and deadly fungal pathogen, Candida albicans, activates macrophage IRE1 through C-type lectin receptor signaling, reinforcing a role for IRE1 as a central regulator of host responses to infection by a broad range of pathogens. This activation did not depend on protein misfolding in response to C. albicans infection. Moreover, lipopolysaccharide treatment was also able to activate IRE1 prior to protein misfolding, suggesting that pathogen-mediated activation of IRE1 occurs through non-canonical mechanisms. During C. albicans infection, we observed that IRE1 activity promotes phagolysosomal fusion that supports the fungicidal activity of macrophages. Consequently, macrophages lacking IRE1 activity displayed inefficient phagosome maturation, enabling C. albicans to lyse the phagosome, evade fungal killing, and drive aberrant inflammatory cytokine production. Mechanistically, we show that IRE1 activity supports phagosomal calcium flux after phagocytosis of C. albicans, which is crucial for phagosome maturation. Importantly, deletion of IRE1 activity decreased the fungicidal activity of phagocytes in vivo during systemic C. albicans infection. Together, these data provide mechanistic insight for the non-canonical activation of IRE1 during infection, and reveal central roles for IRE1 in macrophage antifungal responses.

molecular biology↗

bioRxiv2022

Cardiolipin coordinates inflammatory metabolic reprogramming through regulation of Complex II assembly and stability

Macrophage metabolic plasticity enables repurposing of electron transport from energy generation to inflammation and host defense. Altered Respiratory Complex II function has been implicated in cancer, diabetes and inflammation but regulatory mechanisms are incompletely understood. Here we show that macrophage inflammatory activation triggers Complex II disassembly and succinate dehydrogenase-B subunit loss through sequestration and mitophagy. Mitochondrial fission was required for lipopolysaccharide-stimulated succinate dehydrogenase-B degradation but not sequestration. We hypothesized that this Complex II regulatory mechanism might be coordinated by the mitochondrial phospholipid cardiolipin. Cardiolipin synthase knockdown prevented lipopolysaccharide-induced metabolic remodeling and Complex II disassembly, sequestration and degradation. Cardiolipin-depleted macrophages were defective in lipopolysaccharide-induced pro-inflammatory cytokine production, a phenotype partially rescued by Complex II inhibition. Thus, cardiolipin acts as a critical organizer of inflammatory metabolic remodeling.

immunology↗