Interface Gain-of-Function Mutations in TLR7 Cause Systemic and Neuro-inflammatory Disease.

TLR7 recognizes pathogen-derived single-stranded RNA (ssRNA), a function integral to the innate immune response to viral infection. Notably, TLR7 can also recognize self-derived ssRNA, with gain-of-function mutations in human TLR7 recently identified to cause both early-onset systemic lupus erythematosus (SLE) and neuromyelitis optica. Here, we describe two novel mutations in TLR7, F507S and L528I. While the L528I substitution arose de novo, the F507S mutation was present in three individuals from the same family, including a severely affected male, notably given that the TLR7 gene is situated on the X chromosome and that all other cases so far described have been female. The observation of mutations at residues 507 and 528 of TLR7 indicates the importance of the TLR7 dimerization interface in maintaining immune homeostasis, where we predict that altered homo-dimerization enhances TLR7 signaling. Finally, while mutations in TLR7 can result in SLE-like disease, our data suggest a broader phenotypic spectrum associated with TLR7 gain-of-function, including significant neurological involvement.

Long term use of interleukin-1 inhibitors reduce flare activity in patients with fibrodysplasia ossificans progressiva.

OBJECTIVES: Fibrodysplasia ossificans progressiva (FOP) is one of the most catastrophic forms of genetic heterotopic ossification (HO). FOP is characterized by severe, progressive inflammatory flare-ups, that often lead to HO. The flare-ups are associated with increased inflammatory cytokine production, suggesting auto-inflammatory features driven by interleukin-1ß (IL-1ß). This study describes the short- and long-term responses of FOP patients to anti-IL-1 therapy. METHODS: Previously, we reported that a patient with FOP treated with anti-IL-1 agents showed dramatically lower rates of flare-ups, improved flare-up symptoms, decreased use of glucocorticoids, and apparently decreased size of residual lesions. Plasma analyses also showed marked elevation in IL-1ß levels during a FOP flare, further supporting a role of IL-1ß in the pathogenesis of FOP flares. Here, we report results from long-term therapy with IL-1 inhibitors in that patient, and describe 3 additional patients, from two medical centers. RESULTS: All 4 patients showed persistent improvement in flare activity during treatment with IL-1 inhibitors, with minimal formation of new HO sites. Two patients who stopped therapy experienced resurgence of flare activity that was re-suppressed upon re-initiation. These patients had IL-1ß levels comparable to those in IL-1ß-driven diseases. Child Health Assessment Questionnaires confirmed extensive subjective improvements in the pain and general health visual analogue scales. CONCLUSION: This case series demonstrates significant benefits from IL-1 inhibitors for reducing flare activity and improving the general health of patients with FOP. These data provide strong support for additional studies to better understand the function of IL-1 inhibition, primarily in reducing formation new HO. FUNDING: RH received support from the International FOP Association ACT grant; ECH received support from NIH/NIAMS R01AR073015 and the UCSF Robert Kroc Chair in Connective Tissue and Rheumatic Diseases III.

Expansion of CD4dimCD8+ T cells characterizes macrophage activation syndrome and other secondary HLH.

CD8+ T-cell activation has been demonstrated to distinguish patients with primary and infection-associated hemophagocytic lymphohistiocytosis (HLH) from patients with early sepsis. We evaluated the activation profile of CD8+ T cells in patients with various forms of secondary HLH (sHLH), including macrophage activation syndrome (MAS). Peripheral blood mononuclear cells from children with inactive systemic juvenile idiopathic arthritis (sJIA, n = 17), active sJIA (n = 27), MAS in sJIA (n = 14), infection-associated HLH (n = 7), and with other forms of sHLH (n = 9) were analyzed by flow cytometry. Compared with patients with active sJIA, in patients with MAS and sHLH of different origins, beside a significant increase in the frequency of CD38high/HLA-DR+CD8+ T cells, we found a significant increase in the frequency of CD8+ T cells expressing the CD4 antigen (CD4dimCD8+ T cells). These cells expressed high levels of the activation markers CD38 and HLA-DR, suggesting they were a subset of CD38high/HLA-DR+CD8+ T cells, as well as of the activation/exhaustion markers CD25, PD1, CD95, and interferon-γ. The frequency of CD4dimCD8+ T cells strongly correlated with most of the laboratory parameters of MAS severity and with circulating levels of CXCL9 and interleukin-18. These findings were confirmed in a prospective replication cohort in which no expansion of any particular T-cell receptor Vß family in CD3+ T cells of patients with sHLH was found. Finally, frequency of CD4dimCD8+, but not of CD38high/HLA-DR+CD8+ T cells, significantly correlated with a clinical severity score, further supporting the involvement of these cells in MAS/sHLH pathogenesis.

Plasmatic profiles of cytokines/chemokines, glial fibrillary acidic protein (GFAP) and MRI brain damage in neonates with hypoxic ischemic encephalopathy (HIE).

BACKGROUND: Perinatal hypoxia triggers the release of cytokines and chemokines by neurons, astrocytes and microglia. In response to hypoxia-ischemia resting/ramified microglia proliferate and undergo activation, producing proinflammatory molecules. The brain damage extension seems to be related to both the severity of hypoxia and the balance between pro and anti-inflammatory response and can be explored with neuroimaging. AIMS: The aim of this preliminary study was to explore possible relationships between plasma levels of inflammatory cytokines/chemokines and the severe brain damage detectable by Magnetic Resonance Imaging (MRI), performed during the hospitalization. METHODS: In 10 full terms neonates with hypoxic ischemic encephalopathy (HIE) undergoing therapeutic hypothermia (TH), divided into cases and controls, according to MRI results, we measured and compared the plasma levels of CCL2/MCP-1, CXCL8, GFAP, IFN y, IL-10, IL-18, IL-6, CCL3, ENOLASE2, GM-CSF, IL-1b, IL-12p70, IL-33, TNFα, collected at four different time points during TH (24, 25-48, 49-72 h of life, and 7-10 days from birth). Five of enrolled babies had pathological brain MRI (cases) and 5 had a normal MRI examination (controls). Cytokines were measured by Magnetic Luminex Assay. MRI images were classified according to Barkovich's score. RESULTS: Mean levels of all cytokines and molecules at time T1 were not significantly different in the two groups. Comparing samples paired by day of collection, the greatest differences between cases and controls were found at times T2 and T3, during TH. At T4, levels tended to get closer again (except for IL-6, IL10 and IL18). Infants with worse MRI showed higher plasmatic GFAP levels than those with normal MRI, while their IL-18 was lower. The mean levels of CCL3MIP1alpha, GMCSF, IL1BETA overlapped throughout the observation period in both groups. CONCLUSION: In a small number of infants with worse brain MRI, we found higher levels of GFAP and of IL-10 at T4 and a trend toward low IL-18 levels than in infants with normal MRI, considered early biomarker of brain damage and a predictor of adverse outcome, respectively. The greatest, although not significant, difference between the levels of molecules was found in cases and controls at time points T2 and T3, during TH.

Common bone marrow signature in COVID-19-associated multisystem inflammatory syndrome in children: A first-wave small case series experience.

The hyper-inflammatory response, also known as multisystem inflammatory syndrome in children (MIS-C), represents a major concern in children with SARS-CoV-2 infection. We report bone marrow features of three patients with MIS-C who were diagnosed during the first wave of the SARS-CoV-2 pandemic. A bone marrow evaluation was performed at onset of the inflammatory condition in order to exclude secondary hemophagocytic lymphohistiocytosis (sHLH). The bone marrows of the patients presented common features: the erythroid and megakaryocytic lineages were prominently affected and hemophagocytosis was moderately increased, differently than observed in sHLH. Megakaryocytopoiesis was increased, representing a peculiar feature of MIS-C differing from sHLH. SARS-CoV-2 RT-PCR and viral panel were studied in bone marrow aspiration samples. MIS-C is a rare complication of SARS-CoV-2 infections in children. An immuno-dysregulation considering both innate and adaptive immunity together with vascular inflammation and endothelial dysfunction play a major role. Our observations, although limited due to the small sample size, suggest that there are unique features in the bone marrow of patients with MIS-C that are likely secondary to immuno-dysregulation, and there are notable differences in bone marrow features compared to those reported in sHLH.

Chitotriosidase as a Novel Biomarker for Therapeutic Monitoring of Nephropathic Cystinosis.

BACKGROUND: Nephropathic cystinosis, a hereditary lysosomal storage disorder caused by dysfunction of the lysosomal cotransporter cystinosin, leads to cystine accumulation and cellular damage in various organs, particularly in the kidney. Close therapeutic monitoring of cysteamine, the only available disease-modifying treatment, is recommended. White blood cell cystine concentration is the current gold standard for therapeutic monitoring, but the assay is technically demanding and is available only on a limited basis. Because macrophage-mediated inflammation plays an important role in the pathogenesis of cystinosis, biomarkers of macrophage activation could have potential for the therapeutic monitoring of cystinosis. METHODS: We conducted a 2-year prospective, longitudinal study in which 61 patients with cystinosis who were receiving cysteamine therapy were recruited from three European reference centers. Each regular care visit included measuring four biomarkers of macrophage activation: IL-1ß, IL-6, IL-18, and chitotriosidase enzyme activity. RESULTS: A multivariate linear regression analysis of the longitudinal data for 57 analyzable patients found chitotriosidase enzyme activity and IL-6 to be significant independent predictors for white blood cell cystine levels in patients of all ages with cystinosis; a receiver operating characteristic analysis ranked chitotriosidase as superior to IL-6 in distinguishing good from poor therapeutic control (on the basis of white blood cell cystine levels of <2 nmol 1/2 cystine/mg protein or ≥2 nmol 1/2 cystine/mg protein, respectively). Moreover, in patients with at least one extrarenal complication, chitotriosidase significantly correlated with the number of extrarenal complications and was superior to white blood cell cystine levels in predicting the presence of multiple extrarenal complications. CONCLUSIONS: Chitotriosidase enzyme activity holds promise as a biomarker for use in therapeutic monitoring of nephropathic cystinosis.

Blood-based test for diagnosis and functional subtyping of familial Mediterranean fever.

BACKGROUND AND OBJECTIVE: Familial Mediterranean fever (FMF) is the most common monogenic autoinflammatory disease (AID) worldwide. The disease is caused by mutations in the MEFV gene encoding the inflammasome sensor Pyrin. Clinical diagnosis of FMF is complicated by overlap in symptoms with other diseases, and interpretation of genetic testing is confounded by the lack of a clear genotype-phenotype association for most of the 340 reported MEFV variants. In this study, the authors designed a functional assay and evaluated its potential in supporting FMF diagnosis. METHODS: Peripheral blood mononuclear cells (PBMCs) were obtained from patients with Pyrin-associated autoinflammation with an FMF phenotype (n=43) or with autoinflammatory features not compatible with FMF (n=8), 10 asymptomatic carriers and 48 healthy donors. Sera were obtained from patients with distinct AIDs (n=10), and whole blood from a subset of patients and controls. The clinical, demographic, molecular genetic factors and other characteristics of the patient population were assessed for their impact on the diagnostic test read-out. Interleukin (IL)-1ß and IL-18 levels were measured by Luminex assay. RESULTS: The ex vivo colchicine assay may be performed on whole blood or PBMC. The functional assay robustly segregated patients with FMF from healthy controls and patients with related clinical disorders. The diagnostic test distinguished patients with classical FMF mutations (M694V, M694I, M680I, R761H) from patients with other MEFV mutations and variants (K695R, P369S, R202Q, E148Q) that are considered benign or of uncertain clinical significance. CONCLUSION: The ex vivo colchicine assay may support diagnosis of FMF and functional subtyping of Pyrin-associated autoinflammation.

Interleukin-18 in pediatric rheumatic diseases.

PURPOSE OF REVIEW: IL-18 is a pleiotropic cytokine involved in the regulation of innate and adaptive immune responses. IL-18 pro-inflammatory activities are finely regulated in vivo by the inhibitory effects of the soluble IL-18-binding protein (IL-18BP). The elevation of circulating levels of IL-18 has been described in children with systemic juvenile idiopathic arthritis (sJIA). In the recent years, the role of IL-18 in the pathogenesis of secondary haemophagocytic lymphohistiocytosis (sHLH), also referred to as macrophage activation syndrome (MAS), in the context of autoinflammatory diseases, including sJIA, is emerging. RECENT FINDINGS: A large number of studies in patients and animal models pointed to the imbalance in IL-18/IL-18BP levels, causing increased systemic levels of free bioactive IL-18, as a predisposing factor in the development of MAS. Although the exact mechanisms involved in the development of MAS are not clearly understood, increasing evidence demonstrate the role of IL-18 in upregulating the production of interferon (IFN)-γ. SUMMARY: On the basis of the first emerging data on the possibility of blocking IL-18, we here discuss the scientific rationale for neutralizing the IL-18/IFNγ axis in the prevention and treatment of sHLH and MAS.

Familial Mediterranean fever mutations lift the obligatory requirement for microtubules in Pyrin inflammasome activation.

Familial Mediterranean fever (FMF) is the most common monogenic autoinflammatory disease worldwide. It is caused by mutations in the inflammasome adaptor Pyrin, but how FMF mutations alter signaling in FMF patients is unknown. Herein, we establish Clostridium difficile and its enterotoxin A (TcdA) as Pyrin-activating agents and show that wild-type and FMF Pyrin are differentially controlled by microtubules. Diverse microtubule assembly inhibitors prevented Pyrin-mediated caspase-1 activation and secretion of IL-1ß and IL-18 from mouse macrophages and human peripheral blood mononuclear cells (PBMCs). Remarkably, Pyrin inflammasome activation persisted upon microtubule disassembly in PBMCs of FMF patients but not in cells of patients afflicted with other autoinflammatory diseases. We further demonstrate that microtubules control Pyrin activation downstream of Pyrin dephosphorylation and that FMF mutations enable microtubule-independent assembly of apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) micrometer-sized perinuclear structures (specks). The discovery that Pyrin mutations remove the obligatory requirement for microtubules in inflammasome activation provides a conceptual framework for understanding FMF and enables immunological screening of FMF mutations.

Neutralization of IFN-γ reverts clinical and laboratory features in a mouse model of macrophage activation syndrome.

BACKGROUND: The pathogenesis of macrophage activation syndrome (MAS) is not clearly understood: a large body of evidence supports the involvement of mechanisms similar to those implicated in the setting of primary hemophagocytic lymphohistiocytosis. OBJECTIVE: We sought to investigate the pathogenic role of IFN-γ and the therapeutic efficacy of IFN-γ neutralization in an animal model of MAS. METHODS: We used an MAS model established in mice transgenic for human IL-6 (IL-6TG mice) challenged with LPS (MAS mice). Levels of IFN-γ and IFN-γ-inducible chemokines were evaluated by using real-time PCR in the liver and spleen and by means of ELISA in plasma. IFN-γ neutralization was achieved by using the anti-IFN-γ antibody XMG1.2 in vivo. RESULTS: Mice with MAS showed a significant upregulation of the IFN-γ pathway, as demonstrated by increased mRNA levels of Ifng and higher levels of phospho-signal transducer and activator of transcription 1 in the liver and spleen and increased expression of the IFN-γ-inducible chemokines Cxcl9 and Cxcl10 in the liver and spleen, as well as in plasma. A marked increase in Il12a and Il12b expression was also found in livers and spleens of mice with MAS. In addition, mice with MAS had a significant increase in numbers of liver CD68+ macrophages. Mice with MAS treated with an anti-IFN-γ antibody showed a significant improvement in survival and body weight recovery associated with a significant amelioration of ferritin, fibrinogen, and alanine aminotransferase levels. In mice with MAS, treatment with the anti-IFN-γ antibody significantly decreased circulating levels of CXCL9, CXCL10, and downstream proinflammatory cytokines. The decrease in CXCL9 and CXCL10 levels paralleled the decrease in serum levels of proinflammatory cytokines and ferritin. CONCLUSION: These results provide evidence for a pathogenic role of IFN-γ in the setting of MAS.

A Heterozygous RAB27A Mutation Associated with Delayed Cytolytic Granule Polarization and Hemophagocytic Lymphohistiocytosis.

Frequently fatal, primary hemophagocytic lymphohistiocytosis (HLH) occurs in infancy resulting from homozygous mutations in NK and CD8 T cell cytolytic pathway genes. Secondary HLH presents after infancy and may be associated with heterozygous mutations in HLH genes. We report two unrelated teenagers with HLH and an identical heterozygous RAB27A mutation (c.259G→C). We explore the contribution of this Rab27A missense (p.A87P) mutation on NK cell cytolytic function by cloning it into a lentiviral expression vector prior to introduction into the human NK-92 cell line. NK cell degranulation (CD107a expression), target cell conjugation, and K562 target cell lysis was compared between mutant- and wild-type-transduced NK-92 cells. Polarization of granzyme B to the immunologic synapse and interaction of mutant Rab27A (p.A87P) with Munc13-4 were explored by confocal microscopy and proximity ligation assay, respectively. Overexpression of the RAB27A mutation had no effect on cell conjugate formation between the NK and target cells but decreased NK cell cytolytic activity and degranulation. Moreover, the mutant Rab27A protein decreased binding to Munc13-4 and delayed granzyme B polarization toward the immunologic synapse. This heterozygous RAB27A mutation blurs the genetic distinction between primary and secondary HLH by contributing to HLH via a partial dominant-negative effect.

Elevated circulating levels of interferon-γ and interferon-γ-induced chemokines characterise patients with macrophage activation syndrome complicating systemic juvenile idiopathic arthritis.

OBJECTIVES: Interferon-γ (IFNγ) is the pivotal mediator in murine models of primary haemophagocytic lymphohistiocytosis (pHLH). Given the similarities between primary and secondary HLH (sec-HLH), including macrophage activation syndrome (MAS), we investigate the involvement of the IFNγ pathway in MAS by evaluating levels of IFNγ and of the induced chemokines, and their relation with laboratory parameters of MAS in systemic juvenile idiopathic arthritis (sJIA) patients with MAS and in a murine MAS model. METHODS: The Luminex multiplexing assay was used to assess serum levels of interleukin (IL)-1ß, IL-6, IFNγ and of the IFNγ-induced chemokines CXCL9, CXCL10 and CXCL11 in patients with sec-HLH (n=11) and in patients with sJIA (n=54), of whom 20 had active MAS at sampling. Expression of IFNγ-induced chemokines was assessed in IL-6 transgenic mice in which MAS is induced by TLR4 stimulation with lipopolysaccharide. RESULTS: Levels of IFNγ and of IFNγ-induced chemokines were markedly elevated during active MAS and sec-HLH and were significantly higher in patients with MAS compared with active sJIA without MAS. Levels in patients with active sJIA without MAS were comparable to those of patients with clinically inactive sJIA. During MAS, ferritin and alanine transferase levels and neutrophil and platelet counts were significantly correlated with serum levels of IFNγ and CXCL9. In murine MAS, serum levels of ferritin were significantly correlated with mRNA levels of Cxcl9 in liver and spleen. CONCLUSIONS: The high levels of IFNγ and of IFNγ-induced chemokines and their correlation with the severity of laboratory abnormalities of MAS suggest a pivotal role of IFNγ in MAS.

Inflammatory events during food protein-induced enterocolitis syndrome reactions.

BACKGROUND: An increasing number of infants are diagnosed with food protein-induced enterocolitis syndrome (FPIES), a non-IgE-mediated food allergy. Until now, T-cell, food-specific mechanisms have been hypothesized. METHODS: Sixteen children (11M, 5F), affected by FPIES from cow's milk, wheat, fruit, rice, and others, experienced 25 acute episodes managed at our emergency department (ED) and eight FPIES reactions during oral food challenges (OFC). We compared the laboratory data in resting conditions, in the absence of infectious diseases, with data collected during the 25 acute ED episodes (blood samples drawn at 2-12 hours) and the eight positive OFCs (three samples at 2, 6, and 12 hours). The onset of symptoms was used as a reference time point. RESULTS: In basal conditions, total IgE, WBC, neutrophil and eosinophil count, CRP, and SGPT were found normal. LDH and SGOT values were high (627.81±97.88 and 45.75±10.26 UI/L, respectively). During ED reactions, LDH and SGOT increased to 794.21±247.28 (P=.028) and 51.08±16.99 UI/L (P=.14) and neutrophils count and CRP to 8.44±3.82×103 /µL (P=.0009) and 3.27±5.73 mg/dL (P=.0014), respectively. During positive OFC, LDH and SGOT did not vary significantly; CRP increased from 0.14±0.18 to 2.49±3.65 mg/dL (P=.00189) and neutrophil count from 2.79±1.42 to 7.10±3.98×103 /µL (P=.00096). CONCLUSIONS: FPIES reactions are characterized by neutrophilia and by a time-dependent, significant increase in CRP, indicating that inflammatory mechanisms are in place. This suggests new directions for research on FPIES pathogenesis.

Nerve growth factor downregulates inflammatory response in human monocytes through TrkA.

Nerve growth factor (NGF) levels are highly increased in inflamed tissues, but their role is unclear. We show that NGF is part of a regulatory loop in monocytes: inflammatory stimuli, while activating a proinflammatory response through TLRs, upregulate the expression of the NGF receptor TrkA. In turn, NGF, by binding to TrkA, interferes with TLR responses. In TLR-activated monocytes, NGF reduces inflammatory cytokine production (IL-1ß, TNF-α, IL-6, and IL-8) while inducing the release of anti-inflammatory mediators (IL-10 and IL-1 receptor antagonist). NGF binding to TrkA affects TLR signaling, favoring pathways that mediate inhibition of inflammatory responses: it increases Akt phosphorylation, inhibits glycogen synthase kinase 3 activity, reduces IκB phosphorylation and p65 NF-κB translocation, and increases nuclear p50 NF-κB binding activity. Use of TrkA inhibitors in TLR-activated monocytes abolishes the effects of NGF on the activation of anti-inflammatory signaling pathways, thus increasing NF-κB pathway activation and inflammatory cytokine production while reducing IL-10 production. PBMC and mononuclear cells obtained from the synovial fluid of patients with juvenile idiopathic arthritis show marked downregulation of TrkA expression. In ex vivo experiments, the addition of NGF to LPS-activated juvenile idiopathic arthritis to both mononuclear cells from synovial fluid and PBMC fails to reduce the production of IL-6 that, in contrast, is observed in healthy donors. This suggests that defective TrkA expression may facilitate proinflammatory mechanisms, contributing to chronic tissue inflammation and damage. In conclusion, this study identifies a novel regulatory mechanism of inflammatory responses through NGF and its receptor TrkA, for which abnormality may have pathogenic implications for chronic inflammatory diseases.

Inflammasome activation by cystine crystals: implications for the pathogenesis of cystinosis.

Intralysosomal cystine crystal accumulation, due to mutations in the CTNS gene, is a hallmark of nephropathic cystinosis, but the role of these crystals in disease pathogenesis remains unclear. We hypothesized that, similar to other host-derived crystalline moieties, cystine crystals can induce IL-1ß production through inflammasome activation. Thus, we investigated the proinflammatory effects of cystine crystals in primary human PBMCs. LPS-primed PBMCs stimulated with cystine crystals secreted IL-1ß in a dose-dependent manner. Similarly to IL-1ß secretion induced by other crystalline inflammasome activators, cystine crystal-induced IL-1ß secretion required activation of caspase-1. Additionally, exogenous cystine crystals were internalized by monocytes, and inhibition of phagocytosis, cathepsin B leakage, generation of reactive oxygen species, and potassium efflux reduced cystine crystal-induced IL-1ß secretion. Patients with cystinosis had higher levels of circulating IL-1ß and IL-18 compared with controls. Analysis of inflammasome-related gene expression in PBMCs from patients with cystinosis revealed a significant increase in IL-1ß and CASP-1 transcript levels compared with controls. Moreover, knockout of cystinosin in mice led to significant increases in serum IL-18 levels and kidney expression of inflammasome-related genes (Casp-1, Pycard, Il-18, Il18r1, Il1r1, and Il1rl2). Taken together, these data demonstrate that cystine crystals are endogenous inflammasome-activating stimuli, suggesting a novel role for cystine crystals in the pathogenesis of nephropathic cystinosis.

MBL2 gene polymorphisms increase the risk of adverse neurological outcome in preterm infants: a preliminary prospective study.

BACKGROUND: As described in animal models, the lectin-complement pathway is central to the propagation of ischemia-reperfusion injuries in many tissues, including the brain. Similarly, it might affect the genesis of brain damage in preterm infants. MBL2 gene single-nucleotide polymorphisms (SNPs), regulating mannose-binding lectin (MBL) serum levels, could predict the risk of adverse neurological outcome in these infants. METHODS: To evaluate the association between SNPs of the MBL2 gene and long-term neurological outcomes in preterm infants, 75 infants (gestational age (GA) ≤ 32 wk) were observed in a prospective longitudinal study and assessed by clinical and instrumental exams at 12 and 24 mo of corrected age (CA). They were genotyped for the promoter polymorphism -221 and for the exon-1 variant alleles (at codons 52, 54, and 57) of the MBL2 gene. RESULTS: The MBL2 exon-1 OO genotype was more frequent in children with an adverse neurological outcome (5/35; 7%) than in controls (0/40; 0%), P = 0.045. The risk of intraventricular hemorrhage in carriers of the genotype OO was marked, without reaching statistical significance (odds ratio: 8.67; 95% confidence interval: 0.87-86.06; P = 0.07). CONCLUSION: Preterm infants who are carriers of MBL2 exon-1 OO genotype are exposed to an increased risk of adverse neurological outcomes.

A novel mutation in the CIAS1/NLRP3 gene associated with an unexpected phenotype of cryopyrin-associated periodic syndromes.

OBJECTIVES: Cryopyrin-associated periodic syndromes (CAPS) comprise a spectrum of distinct, rare, autosomal dominant autoinflammatory disorders of increasing severity caused by NLRP3 gene mutations. METHODS: We describe a 13-year-old female who presented, in the initial phase of the disease, recurrent episodes of high fever, pericarditis, arthralgia, arthritis of the knees, abdominal pain and marked increase in inflammatory markers. In the subsequent months she developed recurrent episodes of chest pain, skin rash and swelling of the subcutaneous tissue, without fever, and with spontaneous resolution. RESULTS: Molecular analysis of the CIAS1 gene revealed the presence of the Q703K variant and also a c.1105C>A mutation in the heterozygous state, that predicts a L369M amino acid substitution. The latter variant has never been reported. The L369M mutation was predicted to significantly affect protein structure (scoring as 'dangerous' and 'deleterious') by the Variant Effect Predictor tool. Therapy with anakinra was started with rapid disappearance of clinical symptoms and normalization of CRP levels in 24 hours. CONCLUSIONS: The rapid response to IL-1 inhibition suggests that the disease of this patient is driven by IL-1 and supports the conclusion that this novel mutation is pathogenic and may be associated with a new CAPS phenotype. The role played by the concomitant presence of the mutation Q703K remains to be clarified.

Mechanisms of mesothelial cell response to viral infections: HDAC1-3 inhibition blocks poly(I:C)-induced type I interferon response and modulates the mesenchymal/inflammatory phenotype.

Infectious peritonitis is a leading cause of peritoneal functional impairment and a primary factor for therapy discontinuation in peritoneal dialysis (PD) patients. Although bacterial infections are a common cause of peritonitis episodes, emerging evidence suggests a role for viral pathogens. Toll-like receptors (TLRs) specifically recognize conserved pathogen-associated molecular patterns (PAMPs) from bacteria, viruses, and fungi, thereby orchestrating the ensuing inflammatory/immune responses. Among TLRs, TLR3 recognizes viral dsRNA and triggers antiviral response cascades upon activation. Epigenetic regulation, mediated by histone deacetylase (HDAC), has been demonstrated to control several cellular functions in response to various extracellular stimuli. Employing epigenetic target modulators, such as epidrugs, is a current therapeutic option in several cancers and holds promise in treating viral diseases. This study aims to elucidate the impact of TLR3 stimulation on the plasticity of human mesothelial cells (MCs) in PD patients and to investigate the effects of HDAC1-3 inhibition. Treatment of MCs from PD patients with the TLR3 agonist polyinosinic:polycytidylic acid (Poly(I:C)), led to the acquisition of a bona fide mesothelial-to-mesenchymal transition (MMT) characterized by the upregulation of mesenchymal genes and loss of epithelial-like features. Moreover, Poly(I:C) modulated the expression of several inflammatory cytokines and chemokines. A quantitative proteomic analysis of MCs treated with MS-275, an HDAC1-3 inhibitor, unveiled altered expression of several proteins, including inflammatory cytokines/chemokines and interferon-stimulated genes (ISGs). Treatment with MS-275 facilitated MMT reversal and inhibited the interferon signature, which was associated with reduced STAT1 phosphorylation. However, the modulation of inflammatory cytokine/chemokine production was not univocal, as IL-6 and CXCL8 were augmented while TNF-α and CXCL10 were decreased. Collectively, our findings underline the significance of viral infections in acquiring a mesenchymal-like phenotype by MCs and the potential consequences of virus-associated peritonitis episodes for PD patients. The observed promotion of MMT reversal and interferon response inhibition by an HDAC1-3 inhibitor, albeit without a general impact on inflammatory cytokine production, has translational implications deserving further analysis.