Neutrophil extracellular traps exacerbate Th1-mediated autoimmune responses in rheumatoid arthritis by promoting DC maturation.

Aberrant formation of neutrophil extracellular traps (NETs) is a key feature in rheumatoid arthritis (RA) and plays a pivotal role in disease pathogenesis. However, the mechanism through which NETs shape the autoimmune response in RA remains elusive. In this study, we demonstrate that inhibition of peptidylarginine deiminases activity in collagen-induced arthritis (CIA) mouse model significantly reduces NET formation, attenuates clinical disease activity, and prevents joint destruction. Importantly, peptidylarginine deiminase 4 blocking markedly reduces the frequency of collagen-specific IFN-γ-producing T helper 1 (Th1) cells in the draining lymph nodes of immunized mice. Exposure of dendritic cells (DCs) to CIA-derived NETs induces DC maturation characterized by significant upregulation of costimulatory molecules, as well as elevated secretion of IL-6. Moreover, CIA-NET-treated DCs promote the induction of antigen-specific Th1 cells in vitro. Finally, NETs from RA patients show an increased potential to induce the maturation of DCs from healthy individuals, corroborating the findings obtained in CIA mouse model. Collectively, our findings delineate an important role of NETs in the induction and expansion of Th1 pathogenic cells in CIA through maturation of DCs and reveal a novel role of NETs in shaping the RA-autoimmune response that could be exploited therapeutically.

Vascular endothelial growth factor-A gene polymorphism is associated with congenital renal lesions in children with urinary tract infections.

AIM: This study investigated the relationship between vascular endothelial growth factor-A (VEGF-A)-460C/T functional gene polymorphism and renal parenchymal lesions, vesicoureteral reflux and other urinary tract abnormalities in children with a urinary tract infection (UTI). METHODS: VEGF-A-460C/T gene polymorphism was investigated with restriction length polymorphism analysis in 76 children with their first UTI and in 63 controls without infections. Genotype and allele frequencies were compared between children with UTIs and controls and between different groups with UTIs. RESULTS: The VEGF-A-460C/T genotype frequencies differed significantly between those with and without renal parenchymal lesions in the UTI cohort. Allele C homozygosity was significantly more common in those with renal parenchymal lesions (36.6% versus 8.7%, p = 0.007). A separate analysis showed that allele C was associated with lesions compatible with hypodysplasia, rather than with focal ones associated with infections, with an odds ratio of 11.55 and 95% confidence interval of 3.03-43.9 (p = 0.0001). No significant differences in genotypes or allele frequencies were found between children with and without reflux or other urinary tract anomalies. CONCLUSION: In children with UTIs, C allele polymorphism of the VEGF-A gene was associated with hypodysplastic renal parenchymal lesions, which were possibly congenital and existed before the infection.

NLRP3 inflammasome expression in idiopathic pulmonary fibrosis and rheumatoid lung.

In this study we investigated the implication of NLRP3 inflammasomes in the pathogenesis of idiopathic pulmonary fibrosis (IPF) and rheumatoid arthritis-usual interstitial pneumonia (RA-UIP).NLRP3 inflammasome activation at baseline and following stimulation with lipopolysaccharide/ATP was evaluated by measuring interleukin (IL)-1ß and IL-18 levels released in the bronchoalveolar lavage fluid (BALF) fluid and by cultures of BALF cells. IL-1ß and IL-18 levels were significantly elevated in the BALF and BALF macrophage cultures from RA-UIP patients, consistent with pre-existing inflammasome activation in these patients. In contrast, in IPF, BALF levels of IL-1ß were significantly less elevated relative to RA-UIP and IL-18 was lower than controls. Furthermore, upon inflammasome stimulation, IPF BALF macrophage cultures failed to upregulate IL-1ß and partly IL-18 secretion, in contrast to controls, which showed robust IL-1ß and IL-18 upregulation. Interestingly, RA-UIP BALF cell cultures treated with lipopolysaccharide/ATP showed a potent stimulation of IL-18 secretion but not IL-1ß, the latter being already elevated in the unstimulated cultures, while examination of the intracellular IL-1ß levels in RA-UIP BALF cells upon NLRP3 inflammasome stimulation showed a significant upregulation of IL-1ß suggesting the NLRP3 pathway could be further activated.Taken together, our results suggest distinct inflammasome activation profiles between autoimmune and idiopathic lung fibrosis.

Lymphopenia in patients with chronic idiopathic neutropenia is associated with decreased number of T-lymphocytes containing T-cell receptor excision circles.

OBJECTIVES: Chronic idiopathic neutropenia (CIN) is a disorder of granulopoiesis characterized by the presence of activated T-lymphocytes that induce/sustain apoptosis of bone marrow (BM) granulocytic progenitors. T-cell lymphopenia is commonly found in CIN. The aim of the study is to probe the mechanisms underlying T-cell lymphopenia in CIN. METHODS: We investigated parameters of T-cell homeostasis namely the proliferation/apoptotic rate of naïve and memory T cells, the T-cell senescence by telomere measurement, the recent thymic T-cell production through quantification of T-cell receptor rearrangement excision circles (TRECs), and the production of interleukin (IL)-7. RESULTS: Patients with CIN (n = 44) displayed lower proportion of naïve CD45RA(+) cells within the CD4(+) and CD8(+) cells compared with controls (n = 15). The proportion of apoptotic cells within the CD8(+) fraction was higher in patients compared with controls and was correlated with the percentage of Ki-67(+) cells, indicating an activation-induced accelerated CD8(+) cell death. The TREC content of CD4(+) and CD8(+) cells was lower in patients compared with controls and was correlated with the proportion of CD45RA(+) CD4(+) and CD8(+) cells and with the levels of serum and BM IL-7, which were significantly decreased in the patients. The mean relative telomere length of CD4(+) and CD8(+) cells was significantly lower in patients with CIN compared with age-matched controls. CONCLUSIONS: The aberrant T-cell expansions associated with the pathogenesis of CIN result in increased proliferation/apoptosis and possibly exhaustion of peripheral blood T cells which, in association with the inadequate compensatory thymic export of new TREC expressing T cells partially because of IL-7 deficiency, may contribute to lymphopenia in CIN.

Different activity of the biological axis VEGF-Flt-1 (fms-like tyrosine kinase 1) and CXC chemokines between pulmonary sarcoidosis and idiopathic pulmonary fibrosis: a bronchoalveolar lavage study.

BACKGROUND: We have previously shown a different local and systemic angiogenic profile of CXC chemokines in Idiopathic Pulmonary Fibrosis (IPF) patients compared to sarcoidosis. In particular, sarcoidosis showed an angiostatic microenvironment, as compared with the angiogenic cytokine milieu seen in IPF. Purpose of the Study. Our aim was to further investigate the aforementioned finding by measuring the expression of different chemokines in granulomatous and fibrotic diseases. We estimated the levels of vascular endothelial growth factor (VEGF) and its high-affinity receptor, Flt-1 (fms-like tyrosine kinase 1), in bronchoalveolar lavage fluid (BALF) of patients with IPF and pulmonary sarcoidosis. We have also investigated the mRNA expression of angiogenetic chemokines' receptors such as CXCR2 and CXCR3 and the biological axis of stromal derived factor-1 alpha (SDF-1 alpha or CXCL12 alpha/CXCL12 beta) and receptor, CXCR4. METHODS: We studied prospectively three groups of patients: (i) one group of 18 patients with IPF, (ii) one group of 16 patients with sarcoidosis, and (iii) 10 normal subjects. RESULTS: A statistically significant increase has been detected in VEGF mRNA expression in IPF in comparison with pulmonary sarcoidosis (P = .03). In addition, a significant increase has been measured in CXCL12 alpha in sarcoidosis in comparison to IPF (P = .02). Moreover, a statistically significant decrease has been found in Flt-1 protein levels in pulmonary sarcoidosis in comparison with IPF (P = .03). A significant increase in VEGF (P = .03) and CXCR4 (P = .03) mRNA levels has been also detected in sarcoidosis' patients when compared with healthy controls. CONCLUSIONS: Our data suggest that increased expression of Flt-1 and downregulation of CXCL12 alpha in IPF may further support the hypothesis of a different angiogenetic profile between fibrotic and granulomatous diseases. However, further studies are needed in order to better investigate these enigmatic diseases.