Expression of CXCR-1 and CXCR-2 chemokine receptors on synovial neutrophils in inflammatory arthritides: Does persistent or increasing expression of CXCR-2 contribute to the chronic inflammation or erosive changes?

A comprehensive overview on the genetics of Behçet's disease

Behçet's disease (BD) is a systemic and inflammatory disease, characterized mainly by recurrent oral and genital ulcers, eye involvement, and skin lesions. Although the exact etiopathogenesis of BD remains unrevealed, a bulk of studies have implicated the genetic contributing factors as critical players in disease predisposition. In countries along the Silk Road, human leukocyte antigen (HLA)-B51 has been reported as the strongest genetically associated factor for BD. Genome-wide association studies, local genetic polymorphism studies, and meta-analysis of combined data from Turkish, Iranian, and Japanese populations have also identified new genetic associations with BD. Among these, other HLA alleles such as HLA-B*15, HLA-B*27, HLA-B*57, and HLA-A*26 have been found as independent risk factors for BD, whereas HLA-B*49 and HLA-A*03 are independent protective alleles for BD. Moreover, other genes have also reached the genome-wide significance level of association with BD susceptibility, including IL10, IL23R-IL12RB2, IL12A, CCR1-CCR3, STAT4, TNFAIP3, ERAP1, KLRC4, and FUT2. Also, several rare nonsynonymous variants in TLR4, IL23R, NOD2, and MEFV genes have been reported to be involved in BD pathogenesis. According to genetic determinants in the loci outside the MHC region that are contributed to the host defense, immunity, and inflammation pathways, it is suggested that immune responses to the pathogen as an important environmental factor and mucosal immunity contribute to BD susceptibility.

Relationship of ultrasonographic findings with synovial angiogenesis modulators in different forms of knee arthritides

Angiogenesis is controlled by a variety of angiogenesis stimulators and inhibitors. The increased power Doppler (PD) signals determined by ultrasonography is an indirect marker of synovial vascularity in arthritis. We aimed to investigate relationship between ultrasonographic findings and synovial angiogenesis modulators. Thirteen Behcet's disease (BD), 15 spondyloarthropathy, 21 rheumatoid arthritis (RA), and 15 osteoarthritis (OA) patients with knee arthritis were included. Cumulative effusion, synovial hypertrophy, and PD signal scores were calculated in arthritic joints. In synovial fluid samples, angiogenesis inhibitors (angiostatin, thrombospondin-1, and endostatin) and stimulators [bFGF (basic fibroblast growth factor), angiopoietin-1] were studied. The comparisons between groups were made by Kruskal-Wallis test, and correlation analysis was calculated with Pearson and Spearman tests. Effusion scores were significantly higher in inflammatory arthritis than in OA. Synovial hypertrophy scores were higher in RA and spondylarthritis than in OA and BD. PD scores were not different between the groups. Synovial angiostatin and bFGF levels were significantly higher in patients with inflammatory arthritis than in OA. Cumulative effusion scores were positively correlated with angiopoietin-1, angiostatin, and bFGF and negatively correlated with thrombospondin-1 levels. Synovial hypertrophy scores were positively correlated with angiostatin and bFGF levels and negatively correlated with thrombospondin-1. No correlation was found between PD scores and modulators of angiogenesis. In large joints like knee, detecting PD signals alone was not sufficient to assess the angiogenesis. However, cumulative activity scores were positively correlated with angiogenesis stimulators. Therefore, when investigating the angiogenesis, PD technique should be added to gray-scale examinations.

Strain differences in alveolar neutrophil infiltration and macrophage phenotypes in an acute lung inflammation model

Pulmonary infection is a major cause of mortality and morbidity, and the magnitude of the lung inflammatory response correlates with patient survival. Previously, we have shown that neutrophil migration into joints is regulated by arthritis severity quantitative trait loci (QTLs). However, it is unclear whether these QTLs contribute to the regulation of lung inflammation in pneumonias. Therefore, to more clearly define the factors regulating acute inflammatory responses in the lung, we examined two inbred rat strains, DA and F344, that differ in these QTLs and their susceptibility to joint inflammation. Staphylococcal cell wall components lipoteichoic acid (LTA) and peptidoglycan (PGN), administered intratracheally, significantly increased the numbers of neutrophils retrieved in the bronchoalveolar lavage fluid (BALF). F344 had approximately 10-fold more neutrophils in the BALF compared with DA (P < 0.001) and higher BALF concentrations of total protein, tumor necrosis factor-α and macrophage inflammatory protein 2. LTA/PGN administration in DA×F344 congenic strains (Cia3d, Cia4, Cia5a, and Cia6) resulted in inflammation similar to that in DA, demonstrating that the genes responsible for the differences in pulmonary inflammation are not contained within the chromosomal intervals carried by these congenic strains. Alveolar macrophages (AMs) isolated from naïve F344 stimulated in vitro with LTA/PGN produced significantly higher levels of keratinocyte-derived chemokine and macrophage inflammatory protein 2 than alveolar macrophages from DA rats. The differences were related to differential mitogen-activated protein kinase phosphorylation. We conclude that the factors contributing to inflammation can be site and challenge dependent. A better understanding of site-specific inflammation may lead to more effective treatment of acute lung inflammation and injury.

Immunopathogenesis of Behçet's disease with special emphasize on the possible role of antigen presenting cells

Behçet's disease (BD) is a systemic vasculitis with unclear etiology and pathogenesis. Although several viral and bacterial causes have been investigated in detail for several years, of late it is widely accepted that microorganisms may play a role as a trigger, or as a cross-reactive antigens that interfere with self-antigens, such as heat-shock proteins. Genes such as HLA-B51, MICA and TNF, considered to play a crucial role in the pathogenesis of BD, are located in the major histocompatibility complex (MHC). However, it has been accepted that, only HLA-B51 is directly related with pathogenesis of the disease, and others have strong linkage disequilibrium with HLA-B51. Some other genes such as IL1, Factor V and ICAM-1, KIR and eNOS assumed to take a part in the pathogenesis are settled out of the MHC region. In patients with BD, several abnormalities in innate and acquired immunity were detected. Mainly, the hypersensitivity of T lymphocytes to different types of antigens plays a critical role in the pathogenesis. However, it is not clear that whether defective signal transduction or antigen presenting cell (APC) dysfunction is responsible for T cell hypersensitivity. Cytokines and chemokines secreted from APCs and T cells are suggested to cause the neutrophil hyperactivation. Activated neutrophils secrete some cytokines, which prime themselves and also stimulate Th1 cells. These relationships among APCs, Th1 lymphocytes and neutrophils constitute the basis of immune responses in BD. In this review, we focus on the possible role of APC in the pathogenesis of BD with an attempt to take attention of researchers in this field to these cells at the crossroads of innate and adaptive immunity, and discuss other potential contributors including cells of the immune system and mediators.

Synovial angiostatic non-ELR CXC chemokines in inflammatory arthritides: does CXCL4 designate chronicity of synovitis?

In our previous studies, we found higher synovial fluid (SF) levels of angiogenic ELR(+) CXC chemokines such as CXCL1, CXCL5, CXCL6 and CXCL8, which play an important role in neutrophil migration and angiogenesis, and more abundant synovial CXCR2 chemokine receptor expression in patients with rheumatoid arthritis (RA) than those with Behçet's disease (BD), familial Mediterranean fever and osteoarthritis (OA). As a continuation of our previous studies, we investigated synovial levels of angiostatic non-ELR CXC chemokines (CXCL4, CXCL9 and CXCL10) in patients with RA, BD, spondyloarthritis (SpA), and OA. Seventy (17 RA, 15 BD, 19 SpA, and 19 OA) patients were enrolled in the study. The levels of CXCL4, CXCL9, and CXCL10 were measured by ELISA. The SF levels of CXCL4 in patients with RA were higher than those of the patients with BD, SpA, and OA (P = 0.007, P = 0.022, and P = 0.017, respectively). No difference was found with respect to CXCL4 levels among the BD, SpA, and OA patients. The synovial CXCL9 levels of patients with RA and SpA were found to be higher than those of the patients with OA (P = 0.002 and P = 0.005, respectively), while no statistically significant difference was detected among the other groups. With regard to SF CXCL10 levels, patients with RA had higher levels as compared to patients with OA (P = 0.002), but no significant difference was found among the other groups. CXCL9 correlated with CXCL4 and CXCL10 (P < 0.05 for both) in patients with RA. No correlation was found in other parameters. The angiostatic non-ELR CXC chemokines were expressed in synovial inflammation. We proposed that angiostatic non-ELR CXC chemokines may increase to balance angiogenic ELR (+) CXC chemokines in which increased levels were shown in patients with inflammatory arthritides and CXCL4 may contribute to designate the chronicity of synovitis in patients with RA. In addition, as CXCL-9 and CXCL-10 play crucial role in inflammation characterized by Th1 polarization, we suggested that they may contribute to the commencement and the perpetuation of synovitis seen in these groups of arthritides.