RESUMO
Hemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS) are life-threatening hyperinflammatory syndromes. Familial HLH is caused by genetic impairment of granule-mediated cytotoxicity (eg, perforin deficiency). MAS is linked to excess activity of the inflammasome-activated cytokine interleukin-18 (IL-18). Though individually tolerated, mice with dual susceptibility (Prf1â»/â»Il18tg; DS) succumb to spontaneous, lethal hyperinflammation. We hypothesized that understanding how these susceptibility factors synergize would uncover key pathomechanisms in the activation, function, and persistence of hyperactivated CD8 T cells. In IL-18 transgenic (Il18tg) mice, IL-18 effects on CD8 T cells drove MAS after a viral (lymphocytic choriomeningitis virus), but not innate (toll like receptor 9), trigger. In vitro, CD8 T cells also required T-cell receptor (TCR) stimulation to fully respond to IL-18. IL-18 induced but perforin deficiency impaired immunoregulatory restimulation-induced cell death (RICD). Paralleling hyperinflammation, DS mice displayed massive postthymic oligoclonal CD8 T-cell hyperactivation in their spleens, livers, and bone marrow as early as 3 weeks. These cells increased proliferation and interferon gamma production, which contrasted with increased expression of receptors and transcription factors associated with exhaustion. Broad-spectrum antibiotics and antiretrovirals failed to ameliorate the disease. Attempting to genetically "fix" TCR antigen-specificity instead demonstrated the persistence of spontaneous HLH and hyperactivation, chiefly on T cells that had evaded TCR fixation. Thus, drivers of HLH may preferentially act on CD8 T cells: IL-18 amplifies activation and demand for RICD, whereas perforin supplies critical immunoregulation. Together, these factors promote a terminal CD8 T-cell activation state, combining features of exhaustion and effector function. Therefore, susceptibility to hyperinflammation may converge on a unique, unrelenting, and antigen-dependent state of CD8 T-cell hyperactivation.
Assuntos
Linfo-Histiocitose Hemofagocítica , Camundongos , Animais , Linfo-Histiocitose Hemofagocítica/etiologia , Perforina/genética , Perforina/metabolismo , Interleucina-18/metabolismo , Linfócitos T CD8-Positivos/metabolismo , Receptores de Antígenos de Linfócitos T/metabolismoRESUMO
OBJECTIVES: Interest in using bedside C-reactive protein (CRP) and ferritin levels to identify patients with hyperinflammatory sepsis who might benefit from anti-inflammatory therapies has piqued with the COVID-19 pandemic experience. Our first objective was to identify patterns in CRP and ferritin trajectory among critically ill pediatric sepsis patients. We then examined the association between these different groups of patients in their inflammatory cytokine responses, systemic inflammation, and mortality risks. DATA SOURCES: A prospective, observational cohort study. STUDY SELECTION: Children with sepsis and organ failure in nine pediatric intensive care units in the United States. DATA EXTRACTION: Two hundred and fifty-five children were enrolled. Five distinct clinical multi-trajectory groups were identified. Plasma CRP (mg/dL), ferritin (ng/mL), and 31 cytokine levels were measured at two timepoints during sepsis (median Day 2 and Day 5). Group-based multi-trajectory models (GBMTM) identified groups of children with distinct patterns of CRP and ferritin. DATA SYNTHESIS: Group 1 had normal CRP and ferritin levels ( n = 8; 0% mortality); Group 2 had high CRP levels that became normal, with normal ferritin levels throughout ( n = 80; 5% mortality); Group 3 had high ferritin levels alone ( n = 16; 6% mortality); Group 4 had very high CRP levels, and high ferritin levels ( n = 121; 11% mortality); and Group 5 had very high CRP and very high ferritin levels ( n = 30; 40% mortality). Cytokine responses differed across the five groups, with ferritin levels correlated with macrophage inflammatory protein 1α levels and CRP levels reflective of many cytokines. CONCLUSIONS: Bedside CRP and ferritin levels can be used together to distinguish groups of children with sepsis who have different systemic inflammation cytokine responses and mortality risks. These data suggest future potential value in personalized clinical trials with specific targets for anti-inflammatory therapies.
Assuntos
COVID-19 , Sepse , Criança , Humanos , Proteína C-Reativa/metabolismo , Estudos Prospectivos , Pandemias , Biomarcadores , Ferritinas , Inflamação , Citocinas/metabolismoRESUMO
ABSTRACT: A 15-month-old full-term boy of African descent with an asymptomatic sickle cell trait presented with episodes of transient erythematous subcutaneous nodules involving the entire body except the face, since 2 weeks of age. The skin lesions evolved to areas of lipoatrophy and hyperpigmentation. An initial skin biopsy, studied at a different department at 2 months, was initially misinterpreted as subcutaneous fat necrosis of the newborn, despite the lack of the typical radiated crystals and needle-shaped clefts characterizing that entity. At 4 months of age, he developed systemic inflammatory manifestations, including fever, a new rash, significant periorbital edema, and failure to thrive. An extensive workup showed leukocytosis, hypercalcemia, elevated inflammatory markers, hypertriglyceridemia, and transaminitis. A new skin biopsy of the eyelid was diagnosed as neutrophilic lobular panniculitis with necrotic adipocytes. An initial whole-exome sequencing did not identify any causative mutations, but a WES reanalysis focused on autoinflammatory disorders was requested based on additional clinicopathologic data and revealed a mosaic intronic mutation in IKBKG c. 671+3 G > C. This mutation encodes an mRNA missing exon 5 resulting in NF-kB essential modulator (NEMO) Δ-exon 5-autoinflammatory syndrome (NDAS). NEMO-NDAS is one of the systemic autoinflammatory diseases that may appear as an unexplained panniculitis in young children, who should be monitored for immunodeficiency and/or autoinflammatory diseases. The differential diagnosis of autoinflammatory disorders should be considered in such cases incorporating the use of the whole-genome/exome sequencing in the investigation. The inhibitor of kappa-B kinase regulatory subunit gamma (IKBKG) is located on chromosome Xq28 and encodes the NEMO, a critical molecule upstream of NF-kB activation.
Assuntos
Doenças Hereditárias Autoinflamatórias , Síndromes de Imunodeficiência , Paniculite , Criança , Pré-Escolar , Doenças Hereditárias Autoinflamatórias/diagnóstico , Doenças Hereditárias Autoinflamatórias/genética , Doenças Hereditárias Autoinflamatórias/patologia , Humanos , Quinase I-kappa B/genética , Síndromes de Imunodeficiência/genética , Lactente , Recém-Nascido , Masculino , NF-kappa B , Paniculite/genética , Paniculite/patologia , Pele/patologiaRESUMO
Hemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS) are life-threatening hyperinflammatory syndromes typically associated with underlying hematologic and rheumatic diseases, respectively. Familial HLH is associated with genetic cytotoxic impairment and thereby to excessive antigen presentation. Extreme elevation of serum interleukin-18 (IL-18) has been observed specifically in patients with MAS, making it a promising therapeutic target, but how IL-18 promotes hyperinflammation remains unknown. In an adjuvant-induced MAS model, excess IL-18 promoted immunopathology, whereas perforin deficiency had no effect. To determine the effects of excess IL-18 on virus-induced immunopathology, we infected Il18-transgenic (Il18tg) mice with lymphocytic choriomeningitis virus (LCMV; strain Armstrong). LCMV infection is self-limited in wild-type mice, but Prf1-/- mice develop prolonged viremia and fatal HLH. LCMV-infected Il18-transgenic (Il18tg) mice developed cachexia and hyperinflammation comparable to Prf1-/- mice, albeit with minimal mortality. Like Prf1-/- mice, immunopathology was largely rescued by CD8 depletion or interferon-γ (IFNg) blockade. Unlike Prf1-/- mice, they showed normal target cell killing and normal clearance of viral RNA and antigens. Rather than impairing cytotoxicity, excess IL-18 acted on T lymphocytes to amplify their inflammatory responses. Surprisingly, combined perforin deficiency and transgenic IL-18 production caused spontaneous hyperinflammation specifically characterized by CD8 T-cell expansion and improved by IFNg blockade. Even Il18tg;Prf1-haplosufficient mice demonstrated hyperinflammatory features. Thus, excess IL-18 promotes hyperinflammation via an autoinflammatory mechanism distinct from, and synergistic with, cytotoxic impairment. These data establish IL-18 as a potent, independent, and modifiable driver of life-threatening innate and adaptive hyperinflammation and support the rationale for an IL-18-driven subclass of hyperinflammation.
Assuntos
Linfócitos T CD8-Positivos/imunologia , Inflamação/patologia , Peptídeos e Proteínas de Sinalização Intercelular/fisiologia , Interleucina-18/metabolismo , Coriomeningite Linfocítica/complicações , Vírus da Coriomeningite Linfocítica/patogenicidade , Perforina/fisiologia , Animais , Feminino , Inflamação/etiologia , Inflamação/metabolismo , Interferon gama/metabolismo , Interleucina-18/genética , Ativação Linfocitária , Coriomeningite Linfocítica/virologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos TransgênicosRESUMO
Hemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS) are life-threatening hyperferritinemic systemic inflammatory disorders. Although profound cytotoxic impairment causes familial HLH (fHLH), the mechanisms driving non-fHLH and MAS are largely unknown. MAS occurs in patients with suspected rheumatic disease, but the mechanistic basis for its distinction is unclear. Recently, a syndrome of recurrent MAS with infantile enterocolitis caused by NLRC4 inflammasome hyperactivity highlighted the potential importance of interleukin-18 (IL-18). We tested this association in hyperferritinemic and autoinflammatory patients and found a dramatic correlation of MAS risk with chronic (sometimes lifelong) elevation of mature IL-18, particularly with IL-18 unbound by IL-18 binding protein, or free IL-18. In a mouse engineered to carry a disease-causing germ line NLRC4T337S mutation, we observed inflammasome-dependent, chronic IL-18 elevation. Surprisingly, this NLRC4T337S-induced systemic IL-18 elevation derived entirely from intestinal epithelia. NLRC4T337S intestines were histologically normal but showed increased epithelial turnover and upregulation of interferon-γ-induced genes. Assessing cellular and tissue expression, classical inflammasome components such as Il1b, Nlrp3, and Mefv predominated in neutrophils, whereas Nlrc4 and Il18 were distinctly epithelial. Demonstrating the importance of free IL-18, Il18 transgenic mice exhibited free IL-18 elevation and more severe experimental MAS. NLRC4T337S mice, whose free IL-18 levels were normal, did not. Thus, we describe a unique connection between MAS risk and chronic IL-18, identify epithelial inflammasome hyperactivity as a potential source, and demonstrate the pathogenicity of free IL-18. These data suggest an IL-18-driven pathway, complementary to the cytotoxic impairment of fHLH, with potential as a distinguishing biomarker and therapeutic target in MAS.