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1.
Immunity ; 52(4): 575-577, 2020 04 14.
Artículo en Inglés | MEDLINE | ID: mdl-32294402

RESUMEN

Myeloid-derived suppressor cells (MDSCs) can promote tumor progression. In this issue of Immunity, Mohamed et al. show that the unfolded protein response sensor, PERK, enhances MDSC-mediated immunosuppression through the NRF2 transcription factor, preventing oxidative damage, mitochondrial DNA release, and DNA sensor-STING-dependent type I interferon production.


Asunto(s)
Células Mieloides , Células Supresoras de Origen Mieloide , Tolerancia Inmunológica , Terapia de Inmunosupresión , Células Mieloides/inmunología , Células Supresoras de Origen Mieloide/inmunología , Respuesta de Proteína Desplegada
2.
J Cell Sci ; 135(4)2022 02 15.
Artículo en Inglés | MEDLINE | ID: mdl-35107133

RESUMEN

The internalization of solutes by macropinocytosis provides an essential route for nutrient uptake in many cells. Macrophages increase macropinocytosis in response to growth factors and other stimuli. To test the hypothesis that nutrient environments modulate solute uptake by macropinocytosis, this study analyzed the effects of extracellular amino acids on the accumulation of fluorescent fluid-phase probes in murine macrophages. Nine amino acids, added individually or together, were capable of suppressing macropinocytosis in murine bone marrow-derived macrophages stimulated with the growth factors colony stimulating factor 1 (CSF1) or interleukin 34, both ligands of the CSF1 receptor (CSF1R). The suppressive amino acids did not inhibit macropinocytosis in response to lipopolysaccharide, the chemokine CXCL12, or the tumor promoter phorbol myristate acetate. Suppressive amino acids promoted release of CSF1R from cells and resulted in the formation of smaller macropinosomes in response to CSF1. This suppression of growth factor-stimulated macropinocytosis indicates that different nutrient environments modulate CSF1R levels and bulk ingestion by macropinocytosis, with likely consequences for macrophage growth and function.


Asunto(s)
Aminoácidos , Factor Estimulante de Colonias de Macrófagos , Animales , Endosomas/metabolismo , Macrófagos/metabolismo , Ratones , Pinocitosis/efectos de los fármacos , Proteínas Tirosina Quinasas Receptoras/metabolismo
3.
PLoS Pathog ; 18(10): e1010855, 2022 10.
Artículo en Inglés | MEDLINE | ID: mdl-36191054

RESUMEN

Infection of the human gut by Salmonella enterica Typhimurium (STM) results in a localized inflammatory disease that is not mimicked in murine infections. To determine mechanisms by which neutrophils, as early responders to bacterial challenge, direct inflammatory programming of human intestinal epithelium, we established a multi-component human intestinal organoid (HIO) model of STM infection. HIOs were micro-injected with STM and seeded with primary human polymorphonuclear leukocytes (PMN-HIOs). PMNs did not significantly alter luminal colonization of Salmonella, but their presence reduced intraepithelial bacterial burden. Adding PMNs to infected HIOs resulted in substantial accumulation of shed TUNEL+ epithelial cells that was driven by PMN Caspase-1 activity. Inhibition of Caspases-1, -3 or -4 abrogated epithelial cell death and extrusion in the infected PMN-HIOs but only Caspase-1 inhibition significantly increased bacterial burden in the PMN-HIO epithelium. Thus, PMNs promote cell death in human intestinal epithelial cells through multiple caspases as a protective response to infection. IL-1ß was necessary and sufficient to induce cell shedding in the infected HIOs. These data support a critical innate immune function for human neutrophils in amplifying cell death and extrusion of human epithelial cells from the Salmonella-infected intestinal monolayer.


Asunto(s)
Neutrófilos , Infecciones por Salmonella , Animales , Humanos , Ratones , Caspasas/metabolismo , Células Epiteliales , Mucosa Intestinal/microbiología , Infecciones por Salmonella/metabolismo , Salmonella typhimurium
4.
Immunity ; 43(3): 451-62, 2015 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-26341399

RESUMEN

Endoplasmic reticulum (ER) stress is observed in many human diseases, often associated with inflammation. ER stress can trigger inflammation through nucleotide-binding domain and leucine-rich repeat containing (NLRP3) inflammasome, which might stimulate inflammasome formation by association with damaged mitochondria. How ER stress triggers mitochondrial dysfunction and inflammasome activation is ill defined. Here we have used an infection model to show that the IRE1α ER stress sensor regulates regulated mitochondrial dysfunction through an NLRP3-mediated feed-forward loop, independently of ASC. IRE1α activation increased mitochondrial reactive oxygen species, promoting NLRP3 association with mitochondria. NLRP3 was required for ER stress-induced cleavage of caspase-2 and the pro-apoptotic factor, Bid, leading to subsequent release of mitochondrial contents. Caspase-2 and Bid were necessary for activation of the canonical inflammasome by infection-associated or general ER stress. These data identify an NLRP3-caspase-2-dependent mechanism that relays ER stress to the mitochondria to promote inflammation, integrating cellular stress and innate immunity.


Asunto(s)
Proteínas Portadoras/inmunología , Caspasa 2/inmunología , Estrés del Retículo Endoplásmico/inmunología , Inflamasomas/inmunología , Mitocondrias/inmunología , Animales , Proteína Proapoptótica que Interacciona Mediante Dominios BH3/genética , Proteína Proapoptótica que Interacciona Mediante Dominios BH3/inmunología , Proteína Proapoptótica que Interacciona Mediante Dominios BH3/metabolismo , Western Blotting , Brucella abortus/inmunología , Brucella abortus/fisiología , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , Caspasa 2/genética , Caspasa 2/metabolismo , Células Cultivadas , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/inmunología , Proteínas de Unión al ADN/metabolismo , Estrés del Retículo Endoplásmico/genética , Endorribonucleasas/inmunología , Endorribonucleasas/metabolismo , Células HEK293 , Interacciones Huésped-Patógeno/inmunología , Humanos , Inflamasomas/metabolismo , Interleucina-1beta/inmunología , Interleucina-1beta/metabolismo , Macrófagos/inmunología , Macrófagos/metabolismo , Macrófagos/microbiología , Ratones Endogámicos C57BL , Ratones Noqueados , Mitocondrias/genética , Mitocondrias/metabolismo , Proteína con Dominio Pirina 3 de la Familia NLR , Proteínas Serina-Treonina Quinasas/inmunología , Proteínas Serina-Treonina Quinasas/metabolismo , Interferencia de ARN/inmunología , Especies Reactivas de Oxígeno/inmunología , Especies Reactivas de Oxígeno/metabolismo , Factores de Transcripción del Factor Regulador X , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Factores de Transcripción/genética , Factores de Transcripción/inmunología , Factores de Transcripción/metabolismo
5.
PLoS Pathog ; 17(10): e1009987, 2021 10.
Artículo en Inglés | MEDLINE | ID: mdl-34669717

RESUMEN

Salmonella enterica represents over 2500 serovars associated with a wide-ranging spectrum of disease; from self-limiting gastroenteritis to invasive infections caused by non-typhoidal serovars (NTS) and typhoidal serovars, respectively. Host factors strongly influence infection outcome as malnourished or immunocompromised individuals can develop invasive infections from NTS, however, comparative analyses of serovar-specific host responses have been constrained by reliance on limited model systems. Here we used human intestinal organoids (HIOs), a three-dimensional "gut-like" in vitro system derived from human embryonic stem cells, to elucidate similarities and differences in host responses to NTS and typhoidal serovars. HIOs discriminated between the two most prevalent NTS, Salmonella enterica serovar Typhimurium (STM) and Salmonella enterica serovar Enteritidis (SE), and typhoidal serovar Salmonella enterica serovar Typhi (ST) in epithelial cell invasion, replication and transcriptional responses. Pro-inflammatory signaling and cytokine output was reduced in ST-infected HIOs compared to NTS infections, consistent with early stages of NTS and typhoidal diseases. While we predicted that ST would induce a distinct transcriptional profile from the NTS strains, more nuanced expression profiles emerged. Notably, pathways involved in cell cycle, metabolism and mitochondrial functions were downregulated in STM-infected HIOs and upregulated in SE-infected HIOs. These results correlated with suppression of cellular proliferation and induction of host cell death in STM-infected HIOs and in contrast, elevated levels of reactive oxygen species production in SE-infected HIOs. Collectively, these results suggest that the HIO model is well suited to reveal host transcriptional programming specific to infection by individual Salmonella serovars, and that individual NTS may provoke unique host epithelial responses during intestinal stages of infection.


Asunto(s)
Perfilación de la Expresión Génica , Intestinos/microbiología , Intestinos/fisiopatología , Infecciones por Salmonella/microbiología , Infecciones por Salmonella/fisiopatología , Humanos , Organoides , Salmonella enterica , Serogrupo , Transcriptoma
6.
J Immunol ; 207(1): 210-220, 2021 07 01.
Artículo en Inglés | MEDLINE | ID: mdl-34145058

RESUMEN

Activation of the endoplasmic reticulum stress sensor, IRE1α, is required for effective immune responses against bacterial infection and is associated with human inflammatory diseases in which neutrophils are a key immune component. However, the specific role of IRE1α in regulating neutrophil effector function has not been studied. In this study, we show that infection-induced IRE1α activation licenses neutrophil antimicrobial capacity, including IL-1ß production, formation of neutrophil extracellular traps (NETs), and methicillin-resistant Staphylococcus aureus (MRSA) killing. Inhibition of IRE1α diminished production of mitochondrial reactive oxygen species and decreased CASPASE-2 activation, which both contributed to neutrophil antimicrobial activity. Mice deficient in CASPASE-2 or neutrophil IRE1α were highly susceptible to MRSA infection and failed to effectively form NETs in the s.c. abscess. IRE1α activation enhanced calcium influx and citrullination of histone H3 independently of mitochondrial reactive oxygen species production, suggesting that IRE1α coordinates multiple pathways required for NET formation. Our data demonstrate that the IRE1α-CASPASE-2 axis is a major driver of neutrophil activity against MRSA infection and highlight the importance of IRE1α in neutrophil antibacterial function.


Asunto(s)
Endorribonucleasas/inmunología , Staphylococcus aureus Resistente a Meticilina/inmunología , Neutrófilos/inmunología , Proteínas Serina-Treonina Quinasas/inmunología , Animales , Voluntarios Sanos , Humanos , Interleucina-1beta/biosíntesis , Ratones , Transducción de Señal/inmunología
7.
Trends Immunol ; 40(2): 85-87, 2019 02.
Artículo en Inglés | MEDLINE | ID: mdl-30609966

RESUMEN

In Nature, Gerlach et al. (Nature 2018;563:705-709) report that methicillin-resistant Staphylococcus aureus camouflages its surface by displaying a 'stealth' wall teichoic acid (WTA) isomer. WTA can act as a cloak to limit exposure of surface antigens to the immune system, but this report indicates that even the cloak can become immunologically silent.


Asunto(s)
Staphylococcus aureus Resistente a Meticilina , Pared Celular , Glicosilación , Meticilina , Ácidos Teicoicos
8.
PLoS Pathog ; 15(10): e1008057, 2019 10.
Artículo en Inglés | MEDLINE | ID: mdl-31671153

RESUMEN

Human astroviruses (HAstV) are understudied positive-strand RNA viruses that cause gastroenteritis mostly in children and the elderly. Three clades of astroviruses, classic, MLB-type and VA-type have been reported in humans. One limitation towards a better understanding of these viruses has been the lack of a physiologically relevant cell culture model that supports growth of all clades of HAstV. Herein, we demonstrate infection of HAstV strains belonging to all three clades in epithelium-only human intestinal enteroids (HIE) isolated from biopsy-derived intestinal crypts. A detailed investigation of infection of VA1, a member of the non-canonical HAstV-VA/HMO clade, showed robust replication in HIE derived from different patients and from different intestinal regions independent of the cellular differentiation status. Flow cytometry and immunofluorescence analysis revealed that VA1 infects several cell types, including intestinal progenitor cells and mature enterocytes, in HIE cultures. RNA profiling of VA1-infected HIE uncovered that the host response to infection is dominated by interferon (IFN)-mediated innate immune responses. A comparison of the antiviral host response in non-transformed HIE and transformed human colon carcinoma Caco-2 cells highlighted significant differences between these cells, including an increased magnitude of the response in HIE. Additional studies confirmed the sensitivity of VA1 to exogenous IFNs, and indicated that the endogenous IFN response of HIE to curtail the growth of strains from all three clades. Genotypic variation in the permissiveness of different HIE lines to HAstV could be overcome by pharmacologic inhibition of JAK/STAT signaling. Collectively, our data identify HIE as a universal infection model for HAstV and an improved model of the intestinal epithelium to investigate enteric virus-host interactions.


Asunto(s)
Infecciones por Astroviridae/inmunología , Infecciones por Astroviridae/veterinaria , Mucosa Intestinal/inmunología , Intestino Delgado/inmunología , Mamastrovirus/fisiología , Tropismo Viral/genética , Animales , Células CACO-2 , Línea Celular , Chlorocebus aethiops , Enterocitos/virología , Gastroenteritis/virología , Humanos , Inmunidad Innata/inmunología , Interferones/inmunología , Mucosa Intestinal/citología , Mucosa Intestinal/virología , Intestino Delgado/citología , Intestino Delgado/virología , Mamastrovirus/genética , Mamastrovirus/inmunología , Células Vero , Tropismo Viral/inmunología
9.
Antimicrob Agents Chemother ; 60(7): 4183-96, 2016 07.
Artículo en Inglés | MEDLINE | ID: mdl-27139470

RESUMEN

Due to the rise of antibiotic resistance and the small number of effective antiviral drugs, new approaches for treating infectious diseases are urgently needed. Identifying targets for host-based therapies represents an emerging strategy for drug discovery. The ubiquitin-proteasome system is a central mode of signaling in the eukaryotic cell and may be a promising target for therapies that bolster the host's ability to control infection. Deubiquitinase (DUB) enzymes are key regulators of the host inflammatory response, and we previously demonstrated that a selective DUB inhibitor and its derivative promote anti-infective activities in host cells. To find compounds with anti-infective efficacy but improved toxicity profiles, we tested a library of predominantly 2-cyano-3-acrylamide small-molecule DUB inhibitors for anti-infective activity in macrophages against two intracellular pathogens: murine norovirus (MNV) and Listeria monocytogenes We identified compound C6, which inhibited DUB activity in human and murine cells and reduced intracellular replication of both pathogens with minimal toxicity in cell culture. Treatment with C6 did not significantly affect the ability of macrophages to internalize virus, suggesting that the anti-infective activity interferes with postentry stages of the MNV life cycle. Metabolic stability and pharmacokinetic assays showed that C6 has a half-life in mouse liver microsomes of ∼20 min and has a half-life of approximately 4 h in mice when administered intravenously. Our results provide a framework for targeting the host ubiquitin system in the development of host-based therapies for infectious disease. Compound C6 represents a promising tool with which to elucidate the role of DUBs in the macrophage response to infection.


Asunto(s)
Antivirales/farmacología , Animales , Enzimas Desubicuitinizantes/metabolismo , Humanos , Listeria monocytogenes/efectos de los fármacos , Listeria monocytogenes/metabolismo , Macrófagos/virología , Ratones , Norovirus/efectos de los fármacos , Norovirus/metabolismo , Replicación Viral/efectos de los fármacos
11.
PLoS Pathog ; 8(7): e1002628, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-22807671

RESUMEN

The cysteine protease caspase-7 has an established role in the execution of apoptotic cell death, but recent findings also suggest involvement of caspase-7 during the host response to microbial infection. Caspase-7 can be cleaved by the inflammatory caspase, caspase-1, and has been implicated in processing and activation of microbial virulence factors. Thus, caspase-7 function during microbial infection may be complex, and its role in infection and immunity has yet to be fully elucidated. Here we demonstrate that caspase-7 is cleaved during cytosolic infection with the intracellular bacterial pathogen, Listeria monocytogenes. Cleavage of caspase-7 during L. monocytogenes infection did not require caspase-1 or key adaptors of the primary pathways of innate immune signaling in this infection, ASC, RIP2 and MyD88. Caspase-7 protected infected macrophages against plasma membrane damage attributable to the bacterial pore-forming toxin Listeriolysin O (LLO). LLO-mediated membrane damage could itself trigger caspase-7 cleavage, independently of infection or overt cell death. We also detected caspase-7 cleavage upon treatment with other bacterial pore-forming toxins, but not in response to detergents. Taken together, our results support a model where cleavage of caspase-7 is a consequence of toxin-mediated membrane damage, a common occurrence during infection. We propose that host activation of caspase-7 in response to pore formation represents an adaptive mechanism by which host cells can protect membrane integrity during infection.


Asunto(s)
Caspasa 7/metabolismo , Membrana Celular/microbiología , Listeria monocytogenes/patogenicidad , Listeriosis/enzimología , Listeriosis/patología , Macrófagos/metabolismo , Animales , Proteínas Reguladoras de la Apoptosis , Toxinas Bacterianas/metabolismo , Proteínas Adaptadoras de Señalización CARD , Caspasa 1/metabolismo , Células Cultivadas , Proteínas del Citoesqueleto/metabolismo , Proteínas de Choque Térmico/metabolismo , Proteínas Hemolisinas/metabolismo , Listeria monocytogenes/inmunología , Listeria monocytogenes/metabolismo , Listeriosis/inmunología , Macrófagos/microbiología , Ratones , Ratones Endogámicos C57BL , Factor 88 de Diferenciación Mieloide/metabolismo , Proteína Serina-Treonina Quinasa 2 de Interacción con Receptor , Proteína Serina-Treonina Quinasas de Interacción con Receptores/metabolismo , Factores de Virulencia/metabolismo
12.
Proc Natl Acad Sci U S A ; 108(4): 1633-8, 2011 Jan 25.
Artículo en Inglés | MEDLINE | ID: mdl-21220348

RESUMEN

Virulence of the intracellular pathogen Listeria monocytogenes (Listeria) requires escape from the phagosome into the host cytosol, where the bacteria replicate. Phagosomal escape is a multistep process characterized by perforation, which is dependent on the pore-forming toxin listeriolysin O (LLO), followed by rupture. The contribution of host factors to Listeria phagosomal escape is incompletely defined. Here we show that the cystic fibrosis transmembrane conductance regulator (CFTR) facilitates Listeria cytosolic entry. CFTR inhibition or mutation suppressed Listeria vacuolar escape in culture, and inhibition of CFTR in wild-type mice before oral inoculation of Listeria markedly decreased systemic infection. We provide evidence that high chloride concentrations may facilitate Listeria vacuolar escape by enhancing LLO oligomerization and lytic activity. We propose that CFTR transiently increases phagosomal chloride concentration after infection, potentiating LLO pore formation and vacuole lysis. Our studies suggest that Listeria exploits mechanisms of cellular ion homeostasis to escape the phagosome and emphasize host ion-channel function as a key parameter of bacterial virulence.


Asunto(s)
Regulador de Conductancia de Transmembrana de Fibrosis Quística/metabolismo , Listeria monocytogenes/fisiología , Listeriosis/microbiología , Fagosomas/microbiología , Animales , Toxinas Bacterianas/química , Toxinas Bacterianas/metabolismo , Benzoatos/farmacología , Bloqueadores de los Canales de Calcio/farmacología , Línea Celular , Células Cultivadas , Cloruros/metabolismo , Regulador de Conductancia de Transmembrana de Fibrosis Quística/antagonistas & inhibidores , Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Citosol/microbiología , Femenino , Glicina/análogos & derivados , Glicina/farmacología , Proteínas de Choque Térmico/química , Proteínas de Choque Térmico/metabolismo , Proteínas Hemolisinas/química , Proteínas Hemolisinas/metabolismo , Interacciones Huésped-Patógeno , Hidrazinas/farmacología , Concentración de Iones de Hidrógeno , Listeria monocytogenes/metabolismo , Listeriosis/genética , Listeriosis/metabolismo , Macrófagos/efectos de los fármacos , Macrófagos/metabolismo , Macrófagos/microbiología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Multimerización de Proteína , Tiazolidinas/farmacología , Vacuolas/microbiología , ortoaminobenzoatos/farmacología
13.
bioRxiv ; 2024 Jan 26.
Artículo en Inglés | MEDLINE | ID: mdl-38328232

RESUMEN

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.

14.
Cell Rep ; 43(5): 114156, 2024 May 28.
Artículo en Inglés | MEDLINE | ID: mdl-38687642

RESUMEN

The maintenance of antigen-specific CD8+ T cells underlies the efficacy of vaccines and immunotherapies. Pathways contributing to CD8+ T cell loss are not completely understood. Uncovering the pathways underlying the limited persistence of CD8+ T cells would be of significant benefit for developing novel strategies of promoting T cell persistence. Here, we demonstrate that murine CD8+ T cells experience endoplasmic reticulum (ER) stress following activation and that the ER-associated degradation (ERAD) adapter Sel1L is induced in activated CD8+ T cells. Sel1L loss limits CD8+ T cell function and memory formation following acute viral infection. Mechanistically, Sel1L is required for optimal bioenergetics and c-Myc expression. Finally, we demonstrate that human CD8+ T cells experience ER stress upon activation and that ER stress is negatively associated with improved T cell functionality in T cell-redirecting therapies. Together, these results demonstrate that ER stress and ERAD are important regulators of T cell function and persistence.


Asunto(s)
Linfocitos T CD8-positivos , Estrés del Retículo Endoplásmico , Degradación Asociada con el Retículo Endoplásmico , Memoria Inmunológica , Animales , Humanos , Ratones , Enfermedad Aguda , Linfocitos T CD8-positivos/inmunología , Linfocitos T CD8-positivos/metabolismo , Péptidos y Proteínas de Señalización Intracelular , Coriomeningitis Linfocítica/inmunología , Coriomeningitis Linfocítica/virología , Coriomeningitis Linfocítica/patología , Ratones Endogámicos C57BL , Proteínas , Proteínas de Unión al ARN/metabolismo , Proteínas de Unión al ARN/genética , Masculino , Femenino
15.
Adv Appl Microbiol ; 85: 93-118, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23942149

RESUMEN

The human gut microbiota is inextricably linked to health and disease. One important function of the commensal organisms living in the intestine is to provide colonization resistance against invading enteric pathogens. Because of the complex nature of the interaction between the microbiota and its host, multiple mechanisms likely contribute to resistance. In this review, we dissect the biological role of short-chain fatty acids (SCFA), which are fermentation end products of the intestinal microbiota, in host-pathogen interactions. SCFA exert an extensive influence on host physiology through nutritional, regulatory, and immunomodulatory functions and can also affect bacterial fitness as a form of acid stress. Moreover, SCFA act as a signal for virulence gene regulation in common enteric pathogens. Taken together, these studies highlight the importance of the chemical environment where the biology of the host, the microbiota, and the pathogen intersects, which provides a basis for designing effective infection prevention and control.


Asunto(s)
Ácidos Grasos Volátiles , Intestinos , Bacterias , Fermentación , Tracto Gastrointestinal/microbiología , Interacciones Huésped-Patógeno , Humanos , Microbiota
16.
bioRxiv ; 2023 Oct 02.
Artículo en Inglés | MEDLINE | ID: mdl-37873171

RESUMEN

Infection by intracellular pathogens can trigger activation of the IRE1α branch of the unfolded protein response (UPR), which then modulates innate immunity and infection outcomes during bacterial or viral infection. However, the mechanisms by which infection activates IRE1α have not been fully elucidated. While recognition of microbe-associated molecular patterns can activate IRE1α, it is unclear whether this depends on the canonical role of IRE1α in detecting misfolded proteins. Here, we report that Candida albicans infection of macrophages results in IRE1α activation through C-type lectin receptor signaling, reinforcing a role for IRE1α as a central regulator of host responses to infection by a broad range of pathogens. However, IRE1α activation was not preceded by protein misfolding in response to either C. albicans infection or lipopolysaccharide treatment, implicating a non-canonical mode of IRE1α activation after recognition of microbial patterns. Investigation of the phenotypic consequences of IRE1α activation in macrophage antimicrobial responses revealed that IRE1α activity enhances the fungicidal activity of macrophages. Macrophages lacking IRE1α activity displayed inefficient phagolysosomal fusion, enabling C. albicans to evade fungal killing and escape the phagosome. Together, these data provide mechanistic insight for the non-canonical activation of IRE1α during infection, and reveal central roles for IRE1α in macrophage antifungal responses.

17.
Sci Adv ; 9(5): eade8701, 2023 02 03.
Artículo en Inglés | MEDLINE | ID: mdl-36735777

RESUMEN

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 subunit B loss through sequestration and selective mitophagy. Mitochondrial fission supported lipopolysaccharide-stimulated succinate dehydrogenase subunit 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.


Asunto(s)
Cardiolipinas , Succinato Deshidrogenasa , Humanos , Succinato Deshidrogenasa/metabolismo , Cardiolipinas/metabolismo , Lipopolisacáridos/farmacología , Mitocondrias/metabolismo , Inflamación/metabolismo
18.
mBio ; 14(1): e0306822, 2023 02 28.
Artículo en Inglés | MEDLINE | ID: mdl-36475773

RESUMEN

Immune cells must be able to adjust their metabolic programs to effectively carry out their effector functions. Here, we show that the endoplasmic reticulum (ER) stress sensor Inositol-requiring enzyme 1 alpha (IRE1α) and its downstream transcription factor X box binding protein 1 (XBP1) enhance the upregulation of glycolysis in classically activated macrophages (CAMs). The IRE1α-XBP1 signaling axis supports this glycolytic switch in macrophages when activated by lipopolysaccharide (LPS) stimulation or infection with the intracellular bacterial pathogen Brucella abortus. Importantly, these different inflammatory stimuli have distinct mechanisms of IRE1α activation; while Toll-like receptor 4 (TLR4) supports glycolysis under both conditions, TLR4 is required for activation of IRE1α in response to LPS treatment but not B. abortus infection. Though IRE1α and XBP1 are necessary for maximal induction of glycolysis in CAMs, activation of this pathway is not sufficient to increase the glycolytic rate of macrophages, indicating that the cellular context in which this pathway is activated ultimately dictates the cell's metabolic response and that IRE1α activation may be a way to fine-tune metabolic reprogramming. IMPORTANCE The immune system must be able to tailor its response to different types of pathogens in order to eliminate them and protect the host. When confronted with bacterial pathogens, macrophages, frontline defenders in the immune system, switch to a glycolysis-driven metabolism to carry out their antibacterial functions. Here, we show that IRE1α, a sensor of ER stress, and its downstream transcription factor XBP1 support glycolysis in macrophages during infection with Brucella abortus or challenge with Salmonella LPS. Interestingly, these stimuli activate IRE1α by independent mechanisms. While the IRE1α-XBP1 signaling axis promotes the glycolytic switch, activation of this pathway is not sufficient to increase glycolysis in macrophages. This study furthers our understanding of the pathways that drive macrophage immunometabolism and highlights a new role for IRE1α and XBP1 in innate immunity.


Asunto(s)
Proteínas Serina-Treonina Quinasas , Receptor Toll-Like 4 , Proteínas Serina-Treonina Quinasas/genética , Receptor Toll-Like 4/metabolismo , Endorribonucleasas/metabolismo , Proteína 1 de Unión a la X-Box/genética , Proteína 1 de Unión a la X-Box/metabolismo , Lipopolisacáridos/metabolismo , Respuesta de Proteína Desplegada , Factores de Transcripción/metabolismo , Estrés del Retículo Endoplásmico
19.
J Bacteriol ; 194(19): 5274-84, 2012 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-22843841

RESUMEN

Fatty acids (FAs) are the major structural component of cellular membranes, which provide a physical and chemical barrier that insulates intracellular reactions from environmental fluctuations. The native composition of membrane FAs establishes the topological and chemical parameters for membrane-associated functions and is therefore modulated diligently by microorganisms especially in response to environmental stresses. However, the consequences of altered FA composition during host-pathogen interactions are poorly understood. The food-borne pathogen Listeria monocytogenes contains mostly saturated branched-chain FAs (BCFAs), which support growth at low pH and low temperature. In this study, we show that anteiso-BCFAs enhance bacterial resistance against phagosomal killing in macrophages. Specifically, BCFAs protect against antimicrobial peptides and peptidoglycan hydrolases, two classes of phagosome antimicrobial defense mechanisms. In addition, the production of the critical virulence factor, listeriolysin O, was compromised by FA modulation, suggesting that FAs play a key role in virulence regulation. In summary, our results emphasize the significance of FA metabolism, not only in bacterial virulence regulation but also in membrane barrier function by providing resistance against host antimicrobial stress.


Asunto(s)
Ácidos Grasos/metabolismo , Listeria monocytogenes/metabolismo , Estrés Fisiológico/fisiología , Factores de Virulencia/metabolismo , Animales , Línea Celular , Ácidos Grasos/química , Listeria monocytogenes/genética , Listeria monocytogenes/patogenicidad , Macrófagos/microbiología , Ratones , Estructura Molecular , Mutación , Virulencia , Factores de Virulencia/genética
20.
J Biol Chem ; 286(36): 31447-56, 2011 Sep 09.
Artículo en Inglés | MEDLINE | ID: mdl-21768091

RESUMEN

Although a complete pathway of lipoic acid metabolism has been established in Escherichia coli, lipoic acid metabolism in other bacteria is more complex and incompletely understood. Listeria monocytogenes has been shown to utilize two lipoate-protein ligases for lipoic acid scavenging, whereas only one of the ligases can function in utilization of host-derived lipoic acid-modified peptides. We report that lipoic acid scavenging requires not only ligation of lipoic acid but also a lipoyl relay pathway in which an amidotransferase transfers lipoyl groups to the enzyme complexes that require the cofactor for activity. In addition, we provide evidence for a new lipoamidase activity that could allow utilization of lipoyl peptides by lipoate-protein ligase. These data support a model of an expanded, three-enzyme pathway for lipoic acid scavenging that seems widespread in the Firmicutes phylum of bacteria.


Asunto(s)
Listeria monocytogenes/metabolismo , Ácido Tióctico/metabolismo , Amidohidrolasas/metabolismo , Proteínas Bacterianas , Redes y Vías Metabólicas , Péptido Sintasas/metabolismo , Transaminasas/metabolismo
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