Follicular dendritic cell differentiation is associated with distinct synovial pathotype signatures in rheumatoid arthritis.

Follicular dendritic cells (FDCs) fundamentally contribute to the formation of synovial ectopic lymphoid-like structures in rheumatoid arthritis (RA) which is associated with poor clinical prognosis. Despite this critical role, regulation of FDC development in the RA synovium and its correlation with synovial pathotype differentiation remained largely unknown. Here, we demonstrate that CNA.42+ FDCs distinctively express the pericyte/fibroblast-associated markers PDGFR-ß, NG2, and Thy-1 in the synovial perivascular space but not in established follicles. In addition, synovial RNA-Seq analysis revealed that expression of the perivascular FDC markers was strongly correlated with PDGF-BB and fibroid synovitis, whereas TNF-α/LT-ß was significantly associated with lymphoid synovitis and expression of CR1, CR2, and FcγRIIB characteristic of mature FDCs in lymphoid follicles. Moreover, PDGF-BB induced CNA.42+ FDC differentiation and CXCL13 secretion from NG2+ synovial pericytes, and together with TNF-α/LT-ß conversely regulated early and late FDC differentiation genes in unsorted RA synovial fibroblasts (RASF) and this was confirmed in flow sorted stromal cell subsets. Furthermore, RASF TNF-αR expression was upregulated by TNF-α/LT-ß and PDGF-BB; and TNF-α/LT-ß-activated RASF retained ICs and induced B cell activation in in vitro germinal center reactions typical of FDCs. Additionally, FDCs trapped peptidyl citrulline, and strongly correlated with IL-6 expression, and plasma cell, B cell, and T cell infiltration of the RA synovium. Moreover, synovial FDCs were significantly associated with RA disease activity and radiographic features of tissue damage. To the best of our knowledge, this is the first report describing the reciprocal interaction between PDGF-BB and TNF-α/LT-ß in synovial FDC development and evolution of RA histological pathotypes. Selective targeting of this interplay could inhibit FDC differentiation and potentially ameliorate RA in clinically severe and drug-resistant patients.

Extracellular traps and PAD4 released by macrophages induce citrullination and auto-antibody production in autoimmune arthritis.

The mechanisms underlying the transition of rheumatoid arthritis (RA) systemic autoimmunity to the joints remain largely unknown. Here, we demonstrate that macrophages in the secondary lymphoid organs (SLOs) and synovial ectopic lymphoid-like structures (ELSs) express peptidylarginine deiminase 4 (PAD4) in murine collagen induced arthritis (CIA) and synovial biopsies from RA patients. Moreover, peptidyl citrulline colocalized with macrophages in SLOs and ELSs, and depletion of macrophages in CIA decreased lymphoid tissue citrullination and serum anti-citrullinated protein/peptide antibody (ACPA) levels. Furthermore, PAD was released from activated murine and RA synovial tissue and fluid (SF) macrophages which functionally deiminated extracellular proteins/peptides in vitro. Additionally, activated murine and SF macrophages displayed macrophage extracellular trap formation (METosis) and release of intracellular citrullinated histones. Moreover, presentation of citrullinated proteins induced ACPA production in vitro. Thus, lymphoid tissue macrophages contribute to self-antigen citrullination and ACPA production, indicating that their selective targeting would potentially ameliorate citrullination-dependent autoimmune disorders.

Etiology of hyperglycemia in critically ill children and the impact of organ dysfunction. / Etiologia da hiperglicemia em crianças críticas e o impacto da disfunção de órgãos.

OBJECTIVE: This study aimed to study the incidence of stress hyperglycemia in critically ill children and to investigate the etiological basis of the hyperglycemia based on homeostasis model assessment. METHODS: This was a prospective cohort study in one of the pediatric intensive care units of Cairo University, including 60 critically ill children and 21 healthy controls. Serum blood glucose, insulin, and C-peptide levels were measured within 24 hours of admission. Homeostasis model assessment was used to assess ß-cell function and insulin sensitivity. RESULTS: Hyperglycemia was estimated in 70% of patients. Blood glucose values ≥ 180mg/dL were associated with a poor outcome. Blood glucose levels were positively correlated with Pediatric Risk for Mortality (PRISM III) score and number of organ dysfunctions (p = 0.019 and p = 0.022, respectively), while insulin levels were negatively correlated with number of organ dysfunctions (r = -0.33, p = 0.01). Homeostasis model assessment revealed that 26 (43.3%) of the critically ill patients had low ß-cell function, and 18 (30%) had low insulin sensitivity. Combined pathology was detected in 2 (3.3%) patients only. Low ß-cell function was significantly associated with the presence of multi-organ dysfunction; respiratory, cardiovascular, and hematological dysfunctions; and the presence of sepsis. CONCLUSIONS: ß-Cell dysfunction appeared to be prevalent in our cohort and was associated with multi-organ dysfunction.

OBJETIVO: Verificar a incidência da hiperglicemia de estresse em crianças em condição grave e investigar a etiologia da hiperglicemia com base em um modelo de avaliação da homeostasia. MÉTODOS: Estudo prospectivo de coorte, conduzido em uma unidade de terapia intensiva pediátrica da Cairo University, que incluiu 60 crianças com doença grave e 21 controles saudáveis. Utilizaram-se os níveis séricos de glicose, insulina e peptídeo C, avaliados em até 24 horas após a admissão. O modelo de avaliação da homeostasia foi utilizado para analisar a função das células beta e a sensibilidade à insulina. RESULTADOS: A hiperglicemia foi estimada em 70% dos pacientes. Valores de glicemia ≥ 180mg/dL se associaram com desfechos piores. Os níveis de glicemia se correlacionaram de forma positiva com o Pediatric Risk for Mortality (PRISM III) e o número de órgãos com disfunção (p = 0,019 e p = 0,022, respectivamente), enquanto os níveis de insulina se correlacionaram de forma negativa com o número de órgãos com disfunção (r = -0,33; p = 0,01). O modelo de avaliação da homeostasia revelou que 26 (43,3%) das crianças em condições graves tinham baixa função de células beta e 18 (30%) baixa sensibilidade à insulina. Detectou-se patologia combinada em apenas dois (3,3%) pacientes. Baixa função de células beta se associou de forma significante com a presença de disfunção de múltiplos órgãos, disfunção respiratória, cardiovascular e hematológica, e presença de sepse. CONCLUSÕES: A disfunção de células beta pareceu ser prevalente em nossa coorte e se associou com disfunção de múltiplos órgãos.

Etiologia da hiperglicemia em crianças críticas e o impacto da disfunção de órgãos / Etiology of hyperglycemia in critically ill children and the impact of organ dysfunction

RESUMO Objetivo: Verificar a incidência da hiperglicemia de estresse em crianças em condição grave e investigar a etiologia da hiperglicemia com base em um modelo de avaliação da homeostasia. Métodos: Estudo prospectivo de coorte, conduzido em uma unidade de terapia intensiva pediátrica da Cairo University, que incluiu 60 crianças com doença grave e 21 controles saudáveis. Utilizaram-se os níveis séricos de glicose, insulina e peptídeo C, avaliados em até 24 horas após a admissão. O modelo de avaliação da homeostasia foi utilizado para analisar a função das células beta e a sensibilidade à insulina. Resultados: A hiperglicemia foi estimada em 70% dos pacientes. Valores de glicemia ≥ 180mg/dL se associaram com desfechos piores. Os níveis de glicemia se correlacionaram de forma positiva com o Pediatric Risk for Mortality (PRISM III) e o número de órgãos com disfunção (p = 0,019 e p = 0,022, respectivamente), enquanto os níveis de insulina se correlacionaram de forma negativa com o número de órgãos com disfunção (r = -0,33; p = 0,01). O modelo de avaliação da homeostasia revelou que 26 (43,3%) das crianças em condições graves tinham baixa função de células beta e 18 (30%) baixa sensibilidade à insulina. Detectou-se patologia combinada em apenas dois (3,3%) pacientes. Baixa função de células beta se associou de forma significante com a presença de disfunção de múltiplos órgãos, disfunção respiratória, cardiovascular e hematológica, e presença de sepse. Conclusões: A disfunção de células beta pareceu ser prevalente em nossa coorte e se associou com disfunção de múltiplos órgãos.

ABSTRACT Objective: This study aimed to study the incidence of stress hyperglycemia in critically ill children and to investigate the etiological basis of the hyperglycemia based on homeostasis model assessment. Methods: This was a prospective cohort study in one of the pediatric intensive care units of Cairo University, including 60 critically ill children and 21 healthy controls. Serum blood glucose, insulin, and C-peptide levels were measured within 24 hours of admission. Homeostasis model assessment was used to assess β-cell function and insulin sensitivity. Results: Hyperglycemia was estimated in 70% of patients. Blood glucose values ≥ 180mg/dL were associated with a poor outcome. Blood glucose levels were positively correlated with Pediatric Risk for Mortality (PRISM III) score and number of organ dysfunctions (p = 0.019 and p = 0.022, respectively), while insulin levels were negatively correlated with number of organ dysfunctions (r = −0.33, p = 0.01). Homeostasis model assessment revealed that 26 (43.3%) of the critically ill patients had low β-cell function, and 18 (30%) had low insulin sensitivity. Combined pathology was detected in 2 (3.3%) patients only. Low β-cell function was significantly associated with the presence of multi-organ dysfunction; respiratory, cardiovascular, and hematological dysfunctions; and the presence of sepsis. Conclusions: β-Cell dysfunction appeared to be prevalent in our cohort and was associated with multi-organ dysfunction.

ADAM10-Mediated ICOS Ligand Shedding on B Cells Is Necessary for Proper T Cell ICOS Regulation and T Follicular Helper Responses.

The proper regulation of ICOS and ICOS ligand (ICOSL) has been shown to be essential for maintaining proper immune homeostasis. Loss of either protein results in defective humoral immunity, and overexpression of ICOS results in aberrant Ab production resembling lupus. How ICOSL is regulated in response to ICOS interaction is still unclear. We demonstrate that a disintegrin and metalloproteinase (ADAM)10 is the primary physiological sheddase of ICOSL in mice and humans. Using an in vivo system in which ADAM10 is deleted only on B cells, elevated levels of ICOSL were seen. This increase is also seen when ADAM10 is deleted from human B cell lines. Identification of the primary sheddase has allowed the characterization of a novel mechanism of ICOS regulation. In wild-type mice, interaction of ICOS/ICOSL results in ADAM10-induced shedding of ICOSL on B cells and moderate ICOS internalization on T cells. When this shedding is blocked, excessive ICOS internalization occurs. This results in severe defects in T follicular helper development and TH2 polarization, as seen in a house dust mite exposure model. In addition, enhanced TH1 and TH17 immune responses are seen in experimental autoimmune encephalomyelitis. Blockade of ICOSL rescues T cell ICOS surface expression and rescues, at least in part, T follicular helper numbers and the abnormal Ab production previously reported in these mice. Overall, we propose a novel regulation of the ICOS/ICOSL axis, with ADAM10 playing a direct role in regulating ICOSL, as well as indirectly regulating ICOS, thus controlling ICOS/ICOSL-dependent responses.

Isolation and Characterization of Mouse and Human Follicular Dendritic Cells.

Follicular dendritic cells (FDCs) reside in the B cell follicles of secondary and tertiary lymphoid tissues where they play key roles in the development and maintenance of lymphoid tissue architecture and function. FDCs trap native antigens for extended periods of time in the form of immune complexes which critcally regulate germinal center reactions in health and disease. Here, we describe how to isolate and characterize FDCs from murine and human lymphoid tissues.

Incidence and outcome of cardiac injury in patients with severe head trauma.

BACKGROUND: Although cardiac injury has been reported in patients with various neurological conditions, few data report cardiac injury in patients with traumatic brain injury (TBI). The aim of this work is to report the incidence of cardiac injury in patients with TBI and its impact on patient outcome. METHODS: A prospective observational study was conducted on a cohort of 50 patients with severe TBI. Only patients with isolated severe TBI defined as Glascow coma scale (GCS) < 8 were included in the study. Acute physiology and chronic health evaluation (APACHE) II score, GCS, hemodynamic data, serum Troponin I, electrocardiogram (ECG), and echocardiographic examination, and patients' outcome were recorded. A neurogenic cardiac injury score (NCIS) was calculated for all patients (rising troponin = 1, abnormal echocardiography = 1, hypotension = 1). Univariate and multivariate analyses for risk factors for mortality were done for all risk factors. RESULTS AND DISCUSSION: Fifty patients were included; age was 31 ± 12, APACHE II was 21 ± 5, and male patients were 45 (90 %). Troponin I was elevated in 27 (54 %) patients, abnormal echocardiography and hypotension were documented in 14 (28 %) and 16 (32 %) patients, respectively. The in-hospital mortality was 36 %. Risk factors for mortality by univariate analysis were age, GCS, APACHE II score, serum troponin level, NCIS, and hypotension. However, in multivariate analysis, the only two independent risk factors for mortality were APACHE II score (OR = 1.25, 95 % confidence interval: 1.02-1.54, P = 0.03) and NCIS score (OR = 8.38, 95 % confidence interval: 1.44-48.74, P = 0.018). CONCLUSIONS: Cardiac injury is common in patients with TBI and is associated with increased mortality. The association of high NCIS and poor outcome in these patients warrants a further larger study.

Diagnostic values of CD64, C-reactive protein and procalcitonin in ventilator-associated pneumonia in adult trauma patients: a pilot study.

BACKGROUND: Ventilator-associated pneumonia (VAP) is one of the most common nosocomial infections; however, its diagnosis remains difficult to establish in the critical care setting. We investigated the potential role of neutrophil CD64 (nCD64) expression as an early marker for the diagnosis of VAP. METHODS: Forty-nine consecutive patients with clinically suspected VAP were prospectively included in a single-center study. The levels of nCD64, C-reactive protein (CRP), and serum procalcitonin (PCT) were analyzed for diagnostic evaluation at the time of intubation (baseline), at day 0 (time of diagnosis), and at day 3. The receiver operating characteristic curves were analyzed to identify the ideal cutoff values. RESULTS: VAP was confirmed in 36 of 49 cases. In patients with and without VAP, the median levels (interquartile range, IQR) of nCD64 did not differ either at baseline [2.4 (IQR, 1.8-3.1) and 2.6 (IQR, 2.3-3.2), respectively; p=0.3] or at day 0 [2 (IQR, 2.5-3.0) and 2.6 (IQR, 2.4-2.9), respectively; p=0.8]. CRP showed the largest area under the curve (AUC) at day 3. The optimum cutoff value for CRP according to the maximum Youden index was 133 mg/dL. This cutoff value had 69% sensitivity and 76% specificity for predicting VAP; the AUC was 0.73 (95% CI, 0.59-0.85). The nCD64 and PCT values could not discriminate between the VAP and non-VAP groups either at day 0 or day 3. CONCLUSIONS: The results of this pilot study suggest that neutrophil CD64 measurement has a poor role in facilitating the diagnosis of VAP and thus may not be practically recommended to guide the administration of antibiotics when VAP is suspected.

Serum Copeptin Level as a Predictor of Outcome in Pneumonia.

This cross-sectional study included 41 children (age 2 mo-12 y) with pneumonia and 40 healthy controls. Assay of serum copeptin was done using ELISA. Median serum copeptin levels were significantly higher (P=0.03) in children with pneumonia, and in those who died (P=0.04). We conclude that serum copeptin levels seem to be associated with poor outcome in pneumonia.

Functional modelling of a novel mutation in BBS5.

BACKGROUND: Bardet-Biedl syndrome (BBS) is an autosomal recessive ciliopathy disorder with 18 known causative genes (BBS1-18). The primary clinical features are renal abnormalities, rod-cone dystrophy, post-axial polydactyly, learning difficulties, obesity and male hypogonadism. RESULTS: We describe the clinical phenotype in three Saudi siblings in whom we have identified a novel mutation in exon 12 of BBS5 (c.966dupT; p.Ala323CysfsX57). This single nucleotide duplication creates a frame shift results in a predicted elongated peptide. Translation blocking Morpholino oligonucleotides were used to create zebrafish bbs5 morphants. Morphants displayed retinal layering defects, abnormal cardiac looping and dilated, cystic pronephric ducts with reduced cilia expression. Morphants also displayed significantly reduced dextran clearance via the pronephros compared to wildtype embryos, suggesting reduced renal function in morphants. The eye, kidney and heart defects reported in morphant zebrafish resemble the human phenotype of BBS5 mutations. The pathogenicity of the novel BBS5 mutation was determined. Mutant mRNA was unable to rescue pleiotropic phenotypes of bbs5 morphant zebrafish and in cell culture we demonstrate a mislocalisation of mutant BBS5 protein which fails to localise discretely with the basal body. CONCLUSIONS: We conclude that this novel BBS5 mutation has a deleterious function that accounts for the multisystem ciliopathy phenotype seen in affected human patients.