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1.
Nat Immunol ; 22(3): 312-321, 2021 03.
Article in English | MEDLINE | ID: mdl-33510463

ABSTRACT

Mitochondrial abnormalities have been noted in lupus, but the causes and consequences remain obscure. Autophagy-related genes ATG5, ATG7 and IRGM have been previously implicated in autoimmune disease. We reasoned that failure to clear defective mitochondria via mitophagy might be a foundational driver in autoimmunity by licensing mitochondrial DNA-dependent induction of type I interferon. Here, we show that mice lacking the GTPase IRGM1 (IRGM homolog) exhibited a type I interferonopathy with autoimmune features. Irgm1 deletion impaired the execution of mitophagy with cell-specific consequences. In fibroblasts, mitochondrial DNA soiling of the cytosol induced cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING)-dependent type I interferon, whereas in macrophages, lysosomal Toll-like receptor 7 was activated. In vivo, Irgm1-/- tissues exhibited mosaic dependency upon nucleic acid receptors. Whereas salivary and lacrimal gland autoimmune pathology was abolished and lung pathology was attenuated by cGAS and STING deletion, pancreatic pathology remained unchanged. These findings reveal fundamental connections between mitochondrial quality control and tissue-selective autoimmune disease.


Subject(s)
Autoimmune Diseases/metabolism , Autoimmunity , Fibroblasts/metabolism , GTP-Binding Proteins/metabolism , Mitochondria/metabolism , Mitophagy , Animals , Autoimmune Diseases/genetics , Autoimmune Diseases/immunology , Autoimmune Diseases/pathology , Cells, Cultured , Fibroblasts/immunology , Fibroblasts/pathology , GTP-Binding Proteins/deficiency , GTP-Binding Proteins/genetics , Gene Expression Regulation , Macrophages/immunology , Macrophages/metabolism , Membrane Glycoproteins/genetics , Membrane Glycoproteins/metabolism , Membrane Proteins/genetics , Membrane Proteins/metabolism , Mice, Inbred C57BL , Mitochondria/genetics , Mitochondria/immunology , Mitochondria/pathology , Nucleotidyltransferases/genetics , Nucleotidyltransferases/metabolism , Signal Transduction , Toll-Like Receptor 7/genetics , Toll-Like Receptor 7/metabolism
2.
Mol Cell ; 73(3): 429-445.e7, 2019 02 07.
Article in English | MEDLINE | ID: mdl-30612879

ABSTRACT

Several large-scale genome-wide association studies genetically linked IRGM to Crohn's disease and other inflammatory disorders in which the IRGM appears to have a protective function. However, the mechanism by which IRGM accomplishes this anti-inflammatory role remains unclear. Here, we reveal that IRGM/Irgm1 is a negative regulator of the NLRP3 inflammasome activation. We show that IRGM expression, which is increased by PAMPs, DAMPs, and microbes, can suppress the pro-inflammatory responses provoked by the same stimuli. IRGM/Irgm1 negatively regulates IL-1ß maturation by suppressing the activation of the NLRP3 inflammasome. Mechanistically, we show that IRGM interacts with NLRP3 and ASC and hinders inflammasome assembly by blocking their oligomerization. Further, IRGM mediates selective autophagic degradation of NLRP3 and ASC. By suppressing inflammasome activation, IRGM/Irgm1 protects from pyroptosis and gut inflammation in a Crohn's disease experimental mouse model. This study for the first time identifies the mechanism by which IRGM is protective against inflammatory disorders.


Subject(s)
Autophagy , Colitis/metabolism , Colon/metabolism , Crohn Disease/metabolism , GTP-Binding Proteins/metabolism , Inflammasomes/metabolism , NLR Family, Pyrin Domain-Containing 3 Protein/metabolism , Animals , CARD Signaling Adaptor Proteins/genetics , CARD Signaling Adaptor Proteins/metabolism , Colitis/genetics , Colitis/pathology , Colitis/prevention & control , Colon/pathology , Crohn Disease/genetics , Crohn Disease/pathology , Crohn Disease/prevention & control , Cytokines/genetics , Cytokines/metabolism , Dextran Sulfate , Disease Models, Animal , GTP-Binding Proteins/deficiency , GTP-Binding Proteins/genetics , HEK293 Cells , HT29 Cells , Humans , Inflammasomes/genetics , Inflammation Mediators/metabolism , Mice, Inbred C57BL , Mice, Knockout , NLR Family, Pyrin Domain-Containing 3 Protein/genetics , Pyroptosis , Signal Transduction , THP-1 Cells
3.
PLoS Pathog ; 19(1): e1011003, 2023 01.
Article in English | MEDLINE | ID: mdl-36603017

ABSTRACT

Toxoplasma gondii (T. gondii) is a zoonotic apicomplexan parasite that is an important cause of clinical disability in humans. On a global scale, one third of the human population is infected with T. gondii. Mice and other small rodents are believed to be responsible for transmission of T. gondii to the domestic cat, its definitive host. Interferon-inducible Immunity-Related GTPases (IRG proteins) are important for control of murine T. gondii infections. Virulence differences between T. gondii strains are linked to polymorphic rhoptry proteins (ROPs) that cooperate to inactivate individual IRG family members. In particular, the pseudokinase ROP5 isoform B is critically important in laboratory strains of mice. We identified T. gondii ROP39 in complex with ROP5B and demonstrate its contribution to acute T. gondii virulence. ROP39 directly targets Irgb10 and inhibits homodimer formation of the GTPase leading to an overall reduction of IRG protein loading onto the parasitophorous vacuolar membrane (PVM). Maintenance of PVM integrity rescues the parasite from IRG protein-mediated clearance in vitro and in vivo. This study identifies a novel T. gondii effector that is important for specific inactivation of the IRG resistance system. Our data reveal that yet unknown T. gondii effectors can emerge from identification of direct interaction partners of ROP5B.


Subject(s)
Parasites , Toxoplasma , Toxoplasmosis , Animals , Mice , Humans , Cats , Toxoplasma/metabolism , Parasites/metabolism , Virulence , Protozoan Proteins/genetics , Protozoan Proteins/metabolism , GTP Phosphohydrolases/metabolism
4.
AIDS Res Ther ; 21(1): 30, 2024 May 11.
Article in English | MEDLINE | ID: mdl-38734689

ABSTRACT

BACKGROUND: Angiolipomas have been well described in patients with HIV exposed to protease inhibitors with possible resolution after switching to non-nucleoside reverse transcriptase inhibitor-based regimens. Resolution of symptoms have occurred with switches to non-nucleoside reverse transcriptase inhibitor (NNRTI)-based regimens; however, little is known regarding the development of angiolipomas when switching from NNRTI- to modern, integrase strand transfer inhibitor-based regimens. We describe a patient who underwent switch therapy from tenofovir disoproxil fumarate/emtricitabine/efavirenz (TDF/FTC/EFV) to tenofovir alafenamide/FTC/bictegravir (TAF/FTC/BIC) who later developed angiolipomas. CASE PRESENTATION: A 55-year-old male had been on TDF/FTC/EFV for 8 years before switching to TAF/FTC/BIC. Nineteen months after antiretroviral switch, the patient presented with multiple lesions in the upper extremities and abdomen. Diagnostic biopsies revealed non-encapsulated angiolipomas and HHV-8 and non-alcoholic fatty liver disease was ruled out. New lesions continued to appear 29 months after ART switch, after which now lesions appeared and prior lesions remained stable with no increase in size noted. No surgical intervention or change in antiretroviral therapy was needed. CONCLUSIONS: Angiogenesis may have been suppressed with TDF/FTC/EFV treatment, however when switched to TAF/FTC/BIC, promoted the growth of angiolipomas. Clinicians should be aware of the impact of switching to modern ART therapies resulting in possible adipogenesis.


Subject(s)
Angiolipoma , HIV Infections , Tenofovir , Humans , Male , Middle Aged , HIV Infections/drug therapy , Angiolipoma/pathology , Tenofovir/therapeutic use , Anti-HIV Agents/therapeutic use , Drug Substitution , Antiretroviral Therapy, Highly Active
5.
Eur J Appl Physiol ; 2024 Apr 23.
Article in English | MEDLINE | ID: mdl-38652270

ABSTRACT

BACKGROUND: Maximal conditioning contractions (CCs) can lead to the enhancement of evoked-twitch characteristics in human skeletal muscle. This phenomenon is termed post-activation potentiation (PAP). In the knee extensors, PAP is greater in men compared with boys. In adults, the optimal CC duration for PAP is ~ 10 s. We examined child-adult differences in PAP among females and aimed to determine the optimal CC duration in girls and women. METHODS: Eleven girls (9.3 ± 1.4 years) and 13 women (23.4 ± 2.7 years) participated in this study. Maximal isometric evoked twitches were recorded in the knee extensors before and after 4 maximal CCs of different durations (5, 10, 20, and 30 s), in a random order. PAP was calculated as the percent-change in peak torque (Tpeak) and peak rate of torque development (RTDpeak) after each CC. RESULTS: There was a group-by-duration interaction (p < 0.001), reflecting greater Tpeak PAP in women compared with girls following 5 and 10 s CCs, and lower RTDpeak PAP in women following the 30 s CC. The 5 and 10 s CCs lead to the greatest Tpeak and RTDpeak PAP amongst the women while there were no differences between CC durations in girls. CONCLUSION: After both a 5 and 10 s CC, women have greater PAP compared with girls. The optimal CC duration for the knee extensors in women appears to be ~ 5-10 s, while CC durations between 5 and 30 s do not appear to affect levels of PAP in girls.

6.
Psychosom Med ; 85(5): 389-396, 2023 06 01.
Article in English | MEDLINE | ID: mdl-37053097

ABSTRACT

OBJECTIVE: Stress and stressful events are associated with poorer health; however, there are multiple ways to conceptualize and measure stress and stress responses. One physiological mechanism through which stress could result in poorer health is accelerated biological aging. This study tested which types of stress were associated with accelerated biological aging in adulthood. METHODS: Studying 955 participants from the Dunedin Longitudinal Study, we tested whether four types of stress assessed from ages 32 to 45 years-perceived stress, number of stressful life events, adverse childhood experiences, and posttraumatic stress disorder-were associated with accelerated biological aging. RESULTS: Higher levels of all four measures of stress were significantly associated with accelerated aging in separate models. In a combined model, more perceived stress and more stressful life events remained associated with faster aging, and the stress measures explained 6.9% of the variance in aging. The magnitudes of the associations between the four measures of stress and biological aging were comparable to associations for smoking and low education, two established risk factors for accelerated aging. People with high levels of perceived stress, numerous adverse childhood experiences (4+), high stressful life event counts, or posttraumatic stress disorder were aging an additional estimated 2.4 months, 1.1 additional months, 1.4 months, and 1.4 months per year, respectively. CONCLUSIONS: Assessing stress, particularly perceived stress, could help identify people at risk of accelerated aging. Intervening to treat stress or the health-relevant sequelae of stress could potentially slow the rate at which people are aging, improving their health as they age.


Subject(s)
Adverse Childhood Experiences , Stress Disorders, Post-Traumatic , Humans , Stress Disorders, Post-Traumatic/epidemiology , Longitudinal Studies , Aging , Stress, Psychological/epidemiology , Life Change Events
7.
Colorectal Dis ; 25(4): 738-746, 2023 04.
Article in English | MEDLINE | ID: mdl-36328985

ABSTRACT

AIM: A vertical rectus abdominis myocutaneous (VRAM) flap is commonly used to reconstruct perineal defects for low rectal and anal cancer. The incidence of midline incisional hernias after VRAM reconstruction varies from 3.6% when detected clinically to 50% when detected radiologically. The aim of this study is to accurately determine the radiological incidence of donor-site incisional and parastomal hernia following VRAM reconstruction. METHOD: This was a retrospective cohort study of patients undergoing colorectal surgery requiring VRAM reconstruction over 10 years. Data were collected on patient demographics, indication for surgery and surgical procedure, including details of any hernia repair. Images from surveillance CTs were reviewed for the presence and size of midline incisional and/or parastomal hernias. Parastomal hernias were classified based on the European Hernia Society (EHS) classification. RESULTS: One hundred and seventy three patients were included in the analysis. The median age was 67 years (range 29-88 years) and the median length of follow-up was 49 months (interquartile range 24.3-71.0 months). The cumulative incidence of donor-site incisional hernia after VRAM at 1, 2 and 5 years was 15.1%, 25.4% and 29.1%, respectively. The cumulative incidence for PSH at 1, 2 and 5 years was 33.1%, 46.6% and 53.3%, respectively (95% CI 45.4%-60.5%). CONCLUSION: Most patients who develop donor-site incisional hernia and parastomal herniation following VRAM tend to do so within the first 2 years. Although the use of CT imaging improves the diagnosis of donor-site incisional and parastomal hernias, the clinical significance of this is unknown.


Subject(s)
Colorectal Surgery , Incisional Hernia , Myocutaneous Flap , Humans , Child, Preschool , Child , Incisional Hernia/diagnostic imaging , Incisional Hernia/epidemiology , Incisional Hernia/etiology , Myocutaneous Flap/transplantation , Rectus Abdominis/diagnostic imaging , Rectus Abdominis/transplantation , Incidence , Retrospective Studies , Hernia
8.
Health Expect ; 26(1): 172-182, 2023 02.
Article in English | MEDLINE | ID: mdl-36444391

ABSTRACT

BACKGROUND: Health literacy plays an essential role in how individuals process health information to make decisions about health behaviours including cancer screening. Research is scarce to address health literacy as a strategy to improve cancer screening participation among women living with human immunodeficiency virus (HIV), particularly Black women who, despite the heavy burden of cervical cancer, report consistently low screening rates. AIM: To assess the feasibility, acceptability and preliminary efficacy of a health literacy-focused intervention called CHECC-uP-Community-based, HEalth literacy focused intervention for Cervical Cancer control-among women living with HIV. METHODS: We conducted a community-based, single-blinded randomized pilot trial. A total of 123 eligible women were enrolled and randomized to one of two conditions, control (i.e., cervical cancer brochure) or intervention (cervical cancer brochure plus 30-60 min health literacy-focused education followed by monthly phone counselling and navigation assistance for 6 months). Study assessments were done at baseline, 3 and 6 months. The final analysis sample included 58 women who completed all data points and whose Papanicolaou (Pap) test status was confirmed by medical records. RESULTS: All intervention participants who completed the programme would recommend the CHECC-uP to other women living with HIV. However, adherence in the experimental conditions was low (49.6% attrition rate including 20 women who dropped out before the intervention began) due, in large part, to phone disconnection. Those who had received the intervention had a significantly higher Pap test rate compared to women in the control group at 6 months (50% vs. 21.9%, p = .025). Participation in the intervention programme was associated with improved health literacy and other psychosocial outcomes at 3 months but the trend was attenuated at 6 months. CONCLUSIONS: The CHECC-uP was highly acceptable and led to improved Pap testing rates among Black women living with HIV. Future research should consider addressing social determinants of health such as phone connectivity as part of designing a retention plan targeting low-income Black women living with HIV. IMPLICATIONS: The findings should be incorporated into a future intervention framework to fulfil the unmet needs of Black women living with HIV to facilitate their decision-making about Pap test screening. PATIENT OR PUBLIC CONTRIBUTION: Nineteen community members including women living with HIV along with HIV advocates and care providers participated in four focus groups to develop cervical cancer screening decision-relevant information and the health literacy intervention. Additionally, a community advisory board was involved to provide guidance in the general design and conduct of the study.


Subject(s)
HIV Infections , Health Literacy , Uterine Cervical Neoplasms , Female , Humans , Uterine Cervical Neoplasms/prevention & control , Uterine Cervical Neoplasms/diagnosis , HIV , Early Detection of Cancer/psychology , Pilot Projects , Papanicolaou Test , HIV Infections/prevention & control
9.
PLoS Pathog ; 16(8): e1008327, 2020 08.
Article in English | MEDLINE | ID: mdl-32853276

ABSTRACT

Host resistance to Toxoplasma gondii relies on CD8 T cell IFNγ responses, which if modulated by the host or parasite could influence chronic infection and parasite transmission between hosts. Since host-parasite interactions that govern this response are not fully elucidated, we investigated requirements for eliciting naïve CD8 T cell IFNγ responses to a vacuolar resident antigen of T. gondii, TGD057. Naïve TGD057 antigen-specific CD8 T cells (T57) were isolated from transnuclear mice and responded to parasite-infected bone marrow-derived macrophages (BMDMs) in an antigen-dependent manner, first by producing IL-2 and then IFNγ. T57 IFNγ responses to TGD057 were independent of the parasite's protein export machinery ASP5 and MYR1. Instead, host immunity pathways downstream of the regulatory Immunity-Related GTPases (IRG), including partial dependence on Guanylate-Binding Proteins, are required. Multiple T. gondii ROP5 isoforms and allele types, including 'avirulent' ROP5A from clade A and D parasite strains, were able to suppress CD8 T cell IFNγ responses to parasite-infected BMDMs. Phenotypic variance between clades B, C, D, F, and A strains suggest T57 IFNγ differentiation occurs independently of parasite virulence or any known IRG-ROP5 interaction. Consistent with this, removal of ROP5 is not enough to elicit maximal CD8 T cell IFNγ production to parasite-infected cells. Instead, macrophage expression of the pathogen sensors, NLRP3 and to a large extent NLRP1, were absolute requirements. Other members of the conventional inflammasome cascade are only partially required, as revealed by decreased but not abrogated T57 IFNγ responses to parasite-infected ASC, caspase-1/11, and gasdermin D deficient cells. Moreover, IFNγ production was only partially reduced in the absence of IL-12, IL-18 or IL-1R signaling. In summary, T. gondii effectors and host machinery that modulate parasitophorous vacuolar membranes, as well as NLR-dependent but inflammasome-independent pathways, determine the full commitment of CD8 T cells IFNγ responses to a vacuolar antigen.


Subject(s)
CD8-Positive T-Lymphocytes/immunology , Inflammasomes/immunology , Interferon-gamma/metabolism , NLR Family, Pyrin Domain-Containing 3 Protein/metabolism , Protozoan Proteins/metabolism , Signal Transduction , Toxoplasma/immunology , Toxoplasmosis, Animal/immunology , Animals , CD8-Positive T-Lymphocytes/parasitology , Female , Macrophages/immunology , Macrophages/parasitology , Mice , NLR Family, Pyrin Domain-Containing 3 Protein/genetics , Protozoan Proteins/genetics , Toxoplasmosis, Animal/parasitology , Vacuoles/immunology , Vacuoles/metabolism , Vacuoles/parasitology , Virulence/immunology
10.
PLoS Pathog ; 16(5): e1008553, 2020 05.
Article in English | MEDLINE | ID: mdl-32453761

ABSTRACT

IRGM and its mouse orthologue Irgm1 are dynamin-like proteins that regulate vesicular remodeling, intracellular microbial killing, and pathogen immunity. IRGM dysfunction is linked to inflammatory bowel disease (IBD), and while it is thought that defective intracellular killing of microbes underscores IBD susceptibility, studies have yet to address how IRGM/Irgm1 regulates immunity to microbes relevant to intestinal inflammation. Here we find that loss of Irgm1 confers marked susceptibility to Citrobacter rodentium, a noninvasive intestinal pathogen that models inflammatory responses to intestinal bacteria. Irgm1-deficient mice fail to control C. rodentium outgrowth in the intestine, leading to systemic pathogen spread and host mortality. Surprisingly, susceptibility due to loss of Irgm1 function was not linked to defective intracellular killing of C. rodentium or exaggerated inflammation, but was instead linked to failure to remodel specific colon lamina propria (C-LP) myeloid cells that expand in response to C. rodentium infection and are essential for C. rodentium immunity. Defective immune remodeling was most striking in C-LP monocytes, which were successfully recruited to the infected C-LP, but subsequently underwent apoptosis. Apoptotic susceptibility was induced by C. rodentium infection and was specific to this setting of pathogen infection, and was not apparent in other settings of intestinal inflammation. These studies reveal a novel role for Irgm1 in host defense and suggest that deficiencies in survival and remodeling of C-LP myeloid cells that control inflammatory intestinal bacteria may underpin IBD pathogenesis linked to IRGM dysfunction.


Subject(s)
Citrobacter rodentium/immunology , Colon/immunology , Enterobacteriaceae Infections/immunology , GTP-Binding Proteins/deficiency , Inflammatory Bowel Diseases/immunology , Monocytes/immunology , Animals , Colon/microbiology , Colon/pathology , Enterobacteriaceae Infections/genetics , Enterobacteriaceae Infections/pathology , GTP-Binding Proteins/immunology , Inflammatory Bowel Diseases/genetics , Inflammatory Bowel Diseases/microbiology , Inflammatory Bowel Diseases/pathology , Mice , Mice, Knockout , Monocytes/microbiology , Monocytes/pathology , Mucous Membrane/immunology , Mucous Membrane/microbiology , Mucous Membrane/pathology
11.
Blood ; 136(12): 1442-1455, 2020 09 17.
Article in English | MEDLINE | ID: mdl-32542357

ABSTRACT

Acute graft-versus-host disease (GVHD) is a life-threatening complication after allogeneic hematopoietic cell transplantation (allo-HCT). Although currently used GVHD treatment regimens target the donor immune system, we explored here an approach that aims at protecting and regenerating Paneth cells (PCs) and intestinal stem cells (ISCs). Glucagon-like-peptide-2 (GLP-2) is an enteroendocrine tissue hormone produced by intestinal L cells. We observed that acute GVHD reduced intestinal GLP-2 levels in mice and patients developing GVHD. Treatment with the GLP-2 agonist, teduglutide, reduced de novo acute GVHD and steroid-refractory GVHD, without compromising graft-versus-leukemia (GVL) effects in multiple mouse models. Mechanistically GLP-2 substitution promoted regeneration of PCs and ISCs, which enhanced production of antimicrobial peptides and caused microbiome changes. GLP-2 expanded intestinal organoids and reduced expression of apoptosis-related genes. Low numbers of L cells in intestinal biopsies and high serum levels of GLP-2 were associated with a higher incidence of nonrelapse mortality in patients undergoing allo-HCT. Our findings indicate that L cells are a target of GVHD and that GLP-2-based treatment of acute GVHD restores intestinal homeostasis via an increase of ISCs and PCs without impairing GVL effects. Teduglutide could become a novel combination partner for immunosuppressive GVHD therapy to be tested in clinical trials.


Subject(s)
Glucagon-Like Peptide 2/therapeutic use , Graft vs Host Disease/drug therapy , Hematopoietic Stem Cell Transplantation/adverse effects , Intestines/drug effects , Paneth Cells/drug effects , Peptides/therapeutic use , Stem Cells/drug effects , Animals , Female , Gastrointestinal Agents/therapeutic use , Graft vs Host Disease/pathology , Humans , Intestines/cytology , Intestines/pathology , Male , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Paneth Cells/pathology , Stem Cells/pathology , Transplantation, Homologous/adverse effects
12.
EMBO Rep ; 21(11): e50830, 2020 11 05.
Article in English | MEDLINE | ID: mdl-33124745

ABSTRACT

Inflammation associated with gram-negative bacterial infections is often instigated by the bacterial cell wall component lipopolysaccharide (LPS). LPS-induced inflammation and resulting life-threatening sepsis are mediated by the two distinct LPS receptors TLR4 and caspase-11 (caspase-4/-5 in humans). Whereas the regulation of TLR4 activation by extracellular and phago-endosomal LPS has been studied in great detail, auxiliary host factors that specifically modulate recognition of cytosolic LPS by caspase-11 are largely unknown. This study identifies autophagy-related and dynamin-related membrane remodeling proteins belonging to the family of Immunity-related GTPases M clade (IRGM) as negative regulators of caspase-11 activation in macrophages. Phagocytes lacking expression of mouse isoform Irgm2 aberrantly activate caspase-11-dependent inflammatory responses when exposed to extracellular LPS, bacterial outer membrane vesicles, or gram-negative bacteria. Consequently, Irgm2-deficient mice display increased susceptibility to caspase-11-mediated septic shock in vivo. This Irgm2 phenotype is partly reversed by the simultaneous genetic deletion of the two additional Irgm paralogs Irgm1 and Irgm3, indicating that dysregulated Irgm isoform expression disrupts intracellular LPS processing pathways that limit LPS availability for caspase-11 activation.


Subject(s)
Lipopolysaccharides , Shock, Septic , Animals , Caspases/genetics , Caspases, Initiator , Dynamins , Inflammasomes , Lipopolysaccharides/toxicity , Mice , Shock, Septic/chemically induced , Shock, Septic/genetics
13.
Infect Immun ; 89(11): e0020221, 2021 10 15.
Article in English | MEDLINE | ID: mdl-34338548

ABSTRACT

Gamma interferon (IFN-γ)-induced immunity-related GTPases (IRGs) confer cell-autonomous immunity to the intracellular protozoan pathogen Toxoplasma gondii. Effector IRGs are loaded onto the Toxoplasma-containing parasitophorous vacuole (PV), where they recruit ubiquitin ligases, ubiquitin-binding proteins, and IFN-γ-inducible guanylate-binding proteins (Gbps), prompting PV lysis and parasite destruction. Host cells lacking the regulatory IRGs Irgm1 and Irgm3 fail to load effector IRGs, ubiquitin, and Gbps onto the PV and are consequently defective for cell-autonomous immunity to Toxoplasma. However, the role of the third regulatory IRG, Irgm2, in cell-autonomous immunity to Toxoplasma has remained unexplored. Here, we report that Irgm2 unexpectedly plays a limited role in the targeting of effector IRGs, ubiquitin, and Gbps to the Toxoplasma PV. Instead, Irgm2 is instrumental in the decoration of PVs with γ-aminobutyric acid receptor-associated protein-like 2 (GabarapL2). Cells lacking Irgm2 are as defective for cell-autonomous host defense to Toxoplasma as pan-Irgm-/- cells lacking all three Irgm proteins, and Irgm2-/- mice succumb to Toxoplasma infections as readily as pan-Irgm-/- mice. These findings demonstrate that, relative to Irgm1 and Irgm3, Irgm2 plays a distinct but critically important role in host resistance to Toxoplasma.


Subject(s)
GTP Phosphohydrolases/physiology , GTP-Binding Proteins/physiology , Toxoplasmosis/immunology , Animals , Apoptosis Regulatory Proteins/physiology , Mice , Mice, Inbred C57BL , Microtubule-Associated Proteins/physiology , Ubiquitin/physiology , Vacuoles/physiology
14.
Nature ; 514(7522): 339-42, 2014 Oct 16.
Article in English | MEDLINE | ID: mdl-25296250

ABSTRACT

Classical novae are the most common astrophysical thermonuclear explosions, occurring on the surfaces of white dwarf stars accreting gas from companions in binary star systems. Novae typically expel about 10(-4) solar masses of material at velocities exceeding 1,000 kilometres per second. However, the mechanism of mass ejection in novae is poorly understood, and could be dominated by the impulsive flash of thermonuclear energy, prolonged optically thick winds or binary interaction with the nova envelope. Classical novae are now routinely detected at gigaelectronvolt γ-ray wavelengths, suggesting that relativistic particles are accelerated by strong shocks in the ejecta. Here we report high-resolution radio imaging of the γ-ray-emitting nova V959 Mon. We find that its ejecta were shaped by the motion of the binary system: some gas was expelled rapidly along the poles as a wind from the white dwarf, while denser material drifted out along the equatorial plane, propelled by orbital motion. At the interface between the equatorial and polar regions, we observe synchrotron emission indicative of shocks and relativistic particle acceleration, thereby pinpointing the location of γ-ray production. Binary shaping of the nova ejecta and associated internal shocks are expected to be widespread among novae, explaining why many novae are γ-ray emitters.

15.
J Biol Chem ; 292(11): 4651-4662, 2017 03 17.
Article in English | MEDLINE | ID: mdl-28154172

ABSTRACT

The immunity-related GTPases (IRGs) are a family of proteins that are induced by interferon (IFN)-γ and play pivotal roles in immune and inflammatory responses. IRGs ostensibly function as dynamin-like proteins that bind to intracellular membranes and promote remodeling and trafficking of those membranes. Prior studies have shown that loss of Irgm1 in mice leads to increased lethality to bacterial infections as well as enhanced inflammation to non-infectious stimuli; however, the mechanisms underlying these phenotypes are unclear. In the studies reported here, we found that uninfected Irgm1-deficient mice displayed high levels of serum cytokines typifying profound autoinflammation. Similar increases in cytokine production were also seen in cultured, IFN-γ-primed macrophages that lacked Irgm1. A series of metabolic studies indicated that the enhanced cytokine production was associated with marked metabolic changes in the Irgm1-deficient macrophages, including increased glycolysis and an accumulation of long chain acylcarnitines. Cells were exposed to the glycolytic inhibitor, 2-deoxyglucose, or fatty acid synthase inhibitors to perturb the metabolic alterations, which resulted in dampening of the excessive cytokine production. These results suggest that Irgm1 deficiency drives metabolic dysfunction in macrophages in a manner that is cell-autonomous and independent of infectious triggers. This may be a significant contributor to excessive inflammation seen in Irgm1-deficient mice in different contexts.


Subject(s)
Cytokines/immunology , GTP-Binding Proteins/genetics , Macrophages/immunology , Animals , Autophagy , Cells, Cultured , GTP-Binding Proteins/immunology , Gene Deletion , Glycolysis , Inflammation/genetics , Inflammation/immunology , Interferon-gamma/immunology , Macrophages/cytology , Macrophages/metabolism , Mice
18.
Proc Natl Acad Sci U S A ; 111(44): 15723-8, 2014 Nov 04.
Article in English | MEDLINE | ID: mdl-25331875

ABSTRACT

Most eukaryotic cells elaborate several proteoglycans critical for transmitting biochemical signals into and between cells. However, the regulation of proteoglycan biosynthesis is not completely understood. We show that the atypical secretory kinase family with sequence similarity 20, member B (Fam20B) phosphorylates the initiating xylose residue in the proteoglycan tetrasaccharide linkage region, and that this event functions as a molecular switch to regulate subsequent glycosaminoglycan assembly. Proteoglycans from FAM20B knockout cells contain a truncated tetrasaccharide linkage region consisting of a disaccharide capped with sialic acid (Siaα2-3Galß1-4Xylß1) that cannot be further elongated. We also show that the activity of galactosyl transferase II (GalT-II, B3GalT6), a key enzyme in the biosynthesis of the tetrasaccharide linkage region, is dramatically increased by Fam20B-dependent xylose phosphorylation. Inactivating mutations in the GALT-II gene (B3GALT6) associated with Ehlers-Danlos syndrome cause proteoglycan maturation defects similar to FAM20B deletion. Collectively, our findings suggest that GalT-II function is impaired by loss of Fam20B-dependent xylose phosphorylation and reveal a previously unappreciated mechanism for regulation of proteoglycan biosynthesis.


Subject(s)
Galactosyltransferases/metabolism , Proteoglycans/biosynthesis , Sialic Acids/metabolism , Xylose/metabolism , Ehlers-Danlos Syndrome/genetics , Ehlers-Danlos Syndrome/metabolism , Galactosyltransferases/genetics , Gene Knockdown Techniques , HEK293 Cells , Humans , Phosphorylation/genetics , Proteoglycans/genetics , Sialic Acids/genetics , Xylose/genetics
19.
Aging Clin Exp Res ; 28(2): 231-7, 2016 Apr.
Article in English | MEDLINE | ID: mdl-26174129

ABSTRACT

BACKGROUND AND AIMS: Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulatory technique that can affect human pain perception. The present open-label, single-arm study investigated whether primary motor cortex anodal tDCS treatment reduces chronic foot pain intensity and improves depression and pain-related anxiety symptoms in patients with chronic plantar fasciitis. METHODS: Ten patients with symptomatic treatment-resistant plantar fasciitis were enrolled in the study. The treatment consisted of anodal tDCS over the motor area of the leg contralateral to the symptomatic foot for 20 min, at 2 mA for 5 consecutive days. Pre-tDCS (T0), post-tDCS (T1), 1 week (T2), and 4 weeks (T3) post-treatment assessments were conducted consisting of the Visual Analog Scale for pain intensity, the Foot Function Index (FFI), the Pain Anxiety Symptom Scale (PASS-20), and the Hamilton Rating Scale for Depression (HDRS-17 items). RESULTS: Anodal tDCS treatment induced a significant improvement in pain intensity; FFI and PASS scores that were maintained up to 4 weeks post-treatment. In addition, patients reported taking fewer pain medication tablets following the treatments. DISCUSSION AND CONCLUSIONS: Our results indicate that anodal tDCS may be a viable treatment to control pain and psychological comorbidity in elderly patients with treatment-resistant foot pain.


Subject(s)
Anxiety/therapy , Chronic Pain , Depression/therapy , Fasciitis, Plantar , Transcranial Direct Current Stimulation/methods , Aged , Anxiety/etiology , Anxiety/physiopathology , Chronic Pain/diagnosis , Chronic Pain/physiopathology , Chronic Pain/psychology , Chronic Pain/therapy , Depression/etiology , Depression/physiopathology , Fasciitis, Plantar/complications , Fasciitis, Plantar/therapy , Female , Humans , Male , Middle Aged , Motor Cortex , Pain Management/methods , Pain Measurement/methods , Pilot Projects , Psychiatric Status Rating Scales , Treatment Outcome
20.
Infect Immun ; 83(4): 1406-17, 2015 Apr.
Article in English | MEDLINE | ID: mdl-25644000

ABSTRACT

Gamma interferon (IFN-γ) drives antiparasite responses and immunopathology during infection with Plasmodium species. Immunity-related GTPases (IRGs) are a class of IFN-γ-dependent proteins that are essential for cell autonomous immunity to numerous intracellular pathogens. However, it is currently unknown whether IRGs modulate responses during malaria. We have used the Plasmodium berghei ANKA (PbA) model in which mice develop experimental cerebral malaria (ECM) to study the roles of IRGM1 and IRGM3 in immunopathology. Induction of mRNA for Irgm1 and Irgm3 was found in the brains and spleens of infected mice at times of peak IFN-γ production. Irgm3-/- but not Irgm1-/- mice were completely protected from the development of ECM, and this protection was associated with the decreased induction of inflammatory cytokines, as well as decreased recruitment and activation of CD8+ T cells within the brain. Although antigen-specific proliferation of transferred CD8+ T cells was not diminished compared to that of wild-type recipients following PbA infection, T cells transferred into Irgm3-/- recipients showed a striking impairment of effector differentiation. Decreased induction of several inflammatory cytokines and chemokines (interleukin-6, CCL2, CCL3, and CCL4), as well as enhanced mRNA expression of type-I IFNs, was found in the spleens of Irgm3-/- mice at day 4 postinfection. Together, these data suggest that protection from ECM pathology in Irgm3-/- mice occurs due to impaired generation of CD8+ effector function. This defect is nonintrinsic to CD8+ T cells. Instead, diminished T cell responses most likely result from defective initiation of inflammatory responses in myeloid cells.


Subject(s)
CD8-Positive T-Lymphocytes/immunology , Cell Differentiation/immunology , GTP Phosphohydrolases/immunology , Malaria, Cerebral/immunology , Plasmodium berghei/immunology , Adoptive Transfer , Animals , Antigens, Protozoan/immunology , Brain/immunology , Brain/parasitology , Brain/pathology , CD8-Positive T-Lymphocytes/cytology , CD8-Positive T-Lymphocytes/transplantation , Cell Proliferation/genetics , Chemokine CCL2/biosynthesis , Chemokine CCL3/biosynthesis , Chemokine CCL4/biosynthesis , GTP Phosphohydrolases/genetics , GTP-Binding Proteins/genetics , GTP-Binding Proteins/immunology , Inflammation/genetics , Inflammation/immunology , Interferon Type I/biosynthesis , Interferon-gamma/immunology , Interleukin-6/biosynthesis , Malaria, Cerebral/parasitology , Mice , Mice, Inbred C57BL , Mice, Knockout , RNA, Messenger/genetics
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