Lacking ARHGAP25 mitigates the symptoms of autoantibody-induced arthritis in mice.

Objective: Despite intensive research on rheumatoid arthritis, the pathomechanism of the disease is still not fully understood and the treatment has not been completely resolved. Previously we demonstrated that the GTPase-activating protein, ARHGAP25 has a crucial role in the regulation of basic phagocyte functions. Here we investigate the role of ARHGAP25 in the complex inflammatory process of autoantibody-induced arthritis. Methods: Wild-type and ARHGAP25 deficient (KO) mice on a C57BL/6 background, as well as bone marrow chimeric mice, were treated i.p. with the K/BxN arthritogenic or control serum, and the severity of inflammation and pain-related behavior was measured. Histology was prepared, leukocyte infiltration, cytokine production, myeloperoxidase activity, and superoxide production were determined, and comprehensive western blot analysis was conducted. Results: In the absence of ARHGAP25, the severity of inflammation, joint destruction, and mechanical hyperalgesia significantly decreased, similarly to phagocyte infiltration, IL-1ß, and MIP-2 levels in the tibiotarsal joint, whereas superoxide production or myeloperoxidase activity was unchanged. We observed a significantly mitigated phenotype in KO bone marrow chimeras as well. In addition, fibroblast-like synoviocytes showed comparable expression of ARHGAP25 to neutrophils. Significantly reduced ERK1/2, MAPK, and I-κB protein signals were detected in the arthritic KO mouse ankles. Conclusion: Our findings suggest that ARHGAP25 has a key role in the pathomechanism of autoantibody-induced arthritis in which it regulates inflammation via the I-κB/NF-κB/IL-1ß axis with the involvement of both immune cells and fibroblast-like synoviocytes.

Possible Curative Effects of Boric Acid and Bacillus clausii Treatments on TNBS-Induced Ulcerative Colitis in Rats.

Crohn's disease (CD) and ulcerative colitis (UC) are two chronic relapsing inflammatory bowel diseases (IBD). Although there are several treatment options available to improve the symptoms of IBD patients, there is no effective treatment that provides a definitive solution. In the present study, we aim to investigate the antioxidative/anti-inflammatory effects of oral administration of boric acid and Bacillus clausii in a rat trinitrobenzenesulfonic acid (TNBS)-induced colitis model. The effects of boric acid and B. clausii were examined in serum and colon tissues with the help of some biochemical and histological analyses. Elevated inflammation and oxidative damage were found in the blood and colon tissue samples in the TNBS-induced group according to the complete blood count (CBC), tumor necrosis factor (TNF) alpha, interleukin-35 (IL-35), malondialdehyde (MDA), glutathione peroxidase (GPx), myeloperoxidase (MPO), nitric oxide (NO), and histological findings. Particularly, the highest IL-35 level (70.09 ± 12.62 ng/mL) in the combined treatment group, highest catalase activity (5322 ± 668.1 U/mg protein) in the TNBS-induced group, and lower relative expression of inducible nitric oxide synthase in the TNBS-induced group than the control group were striking findings. According to our results, it can be concluded that boric acid showed more curative effects, even if B. clausii probiotics was partially ameliorative.

Anti-inflammatory and Immunomodulatory Potency of Selenium-Enriched Probiotic Mutants in Mice with Induced Ulcerative Colitis.

Selenium-enriched Lactobacillus plantarum and Bifidobacterium longum mutants were used as a protector against Piroxicam-induced ulcerative colitis (UC). In this study, 32 BALB/c male mice were distributed to four groups: the control group, the Piroxicam group which was given 0.8 mg Piroxicam, SP and SB groups which were given 0.8 mg Piroxicam, and plus Lactobacillus plantarum and Bifidobacterium longum selenium-enriched mutants, respectively. Bodyweight; serum content of IgG, IgM, TNF-α, IL-2, IL-6, and IL-10; CBC; myeloperoxidase enzyme activity; histopathological examination of colon and spleen; and expression of TNF-α, IL-2, IL-6, and IL-10 genes in colon and spleen with qRT-PCR were determined. Bodyweight was found to reduce in the Piroxicam group and then recovery in the SB group. Serum content of IgG, IL-2, and IL-10 reduced in the Piroxicam group, whereas IgG, TNF-α, and IL-6 increased in the Piroxicam group in comparison to the other groups. Myeloperoxidase activity witnessed a significant increase in the Piroxicam group compared with the other groups. No significant differences were observed between all groups in measurements of red cells, hemoglobin, neutrophil, monocyte, eosinophil, and basophil in blood. Meanwhile, the white blood cells and platelets recorded the highest and lowest value, respectively, in the Piroxicam group. The colon of the Piroxicam group showed a noticeably massive infiltration of inflammatory cells in the lamina propria. These inflammations were mildly reduced in the SP group, while the reduction in the SB group was significant. In the Piroxicam group, splenic parenchyma saw an increase in the number of melanomacrophages, while hypertrophic plasma cells were observed in the SP group. The spleen of the SB group exhibits a nearly normal form. TNF-α and IL-6 genes had significantly upregulated in the colon of the Piroxicam group compared to the control group, while they were significantly downregulated in the SB group. In contrast, IL-2 and IL-10 genes had upregulated in the colon of the SB group compared to the control groups, while they had downregulated in the Piroxicam group. The expression of these genes had not recorded significant differences between all groups in the spleen. Therefore, this study recommends Bifidobacterium longum selenium-enriched mutants as anti-inflammatory and immunomodulatory supplements.

CX3CL1-induced CD16+ monocytes extravasation in myeloperoxidase-ANCA-associated vasculitis correlates with renal damage.

Background: Monocytes are involved in the pathogenesis of ANCA-associated vasculitis (AAV). Monocyte/macrophages are the dominant infiltrating cells in the glomeruli of patients with myeloperoxidase-AAV (MPO-AAV). However, how human monocyte subsets extravasate to the kidney in MPO-AAV with renal damage is unclear. Methods: 30 MPO-AAV patients with renal damage and 22 healthy controls were enrolled in this study. Monocyte subsets and monocyte-related chemokines in the blood and kidneys of MPO-AAV patients were detected. The chemoattractant activity of the CX3CL1-CX3CR1 axis on CD16+ monocytes was observed. The effect of MPO-ANCA on the migration of CD16+ monocytes to human glomerular endothelial cells (HGECs) was detected by flow cytometry and transwell migration assay. Results: Compared with controls, CD16+ monocytes were significantly decreased in the blood and increased in the glomeruli of MPO-AAV patients with renal damage. The level of CX3CL1, but not CCL2, was significantly increased in the plasma of MPO-AAV patients. CX3CL1 co-localized with glomerular endothelial cells in MPO-AAV patients with renal damage. Moreover, we initially found that MPO-ANCA promotes an increase of the chemokine CX3CL1 on HGECs, imposing recruitment on CD16+ monocytes. Finally, the percentage of CD16+ monocytes in the blood was found to be positively correlated with estimated glomerular filtration rate (eGFR) and negatively correlated with urinary protein creatinine ratio in MPO-AAV patients with renal damage. Furthermore, the urinary protein creatinine ratio was positively correlated with the infiltrating of CD14+ and CD16+ cells in the kidneys. Conclusion: Enhanced extravasation of CD16+ monocytes to the kidney via the CX3CL1-CX3CR1 axis may be involved in renal damage in MPO-AAV.

Binding of myeloperoxidase to the extracellular matrix of smooth muscle cells and subsequent matrix modification.

The extracellular matrix (ECM) of tissues is susceptible to modification by inflammation-associated oxidants. Considerable data support a role for hypochlorous acid (HOCl), generated by the leukocyte-derived heme-protein myeloperoxidase (MPO) in these changes. HOCl can modify isolated ECM proteins and cell-derived matrix, with this resulting in decreased cell adhesion, modulated proliferation and gene expression, and phenotypic changes. Whether this arises from free HOCl, or via site-specific reactions is unresolved. Here we examine the mechanisms of MPO-mediated changes to human coronary smooth muscle cell ECM. MPO is shown to co-localize with matrix fibronectin as detected by confocal microscopy, and bound active MPO can initiate ECM modification, as detected by decreased antibody recognition of fibronectin, versican and type IV collagen, and formation of protein carbonyls and HOCl-mediated damage. These changes are recapitulated by a glucose/glucose oxidase/MPO system where low continuous fluxes of H2O2 are generated. HOCl-induced modifications enhance MPO binding to ECM proteins as detected by ELISA and MPO activity measurements. These data demonstrate that MPO-generated HOCl induces ECM modification by interacting with ECM proteins in a site-specific manner, and generates alterations that increase MPO adhesion. This is proposed to give rise to an increasing cycle of alterations that contribute to tissue damage.

Comparative Cardiac Safety of Selective Serotonin Reuptake Inhibitors among Individuals Receiving Maintenance Hemodialysis.

BACKGROUND: Individuals receiving maintenance hemodialysis may be particularly susceptible to the lethal cardiac consequences of drug-induced QT prolongation because they have a substantial cardiovascular disease burden and high level of polypharmacy, as well as recurrent exposure to electrolyte shifts during dialysis. Electrophysiologic data indicate that among the selective serotonin reuptake inhibitors (SSRIs), citalopram and escitalopram prolong the QT interval to the greatest extent. However, the relative cardiac safety of SSRIs in the hemodialysis population is unknown. METHODS: In this retrospective cohort study, we used data from a cohort of Medicare beneficiaries receiving hemodialysis included in the US Renal Data System registry (2007-2014). We used a new-user design to compare the 1-year risk of sudden cardiac death among hemodialysis patients initiating SSRIs with a higher potential for prolonging the QT interval (citalopram, escitalopram) versus the risk among those initiating SSRIs with lower QT-prolonging potential (fluoxetine, fluvoxamine, paroxetine, sertraline). We estimated adjusted hazard ratios using inverse probability of treatment weighted survival models. Nonsudden cardiac death was treated as a competing event. RESULTS: The study included 30,932 (47.1%) hemodialysis patients who initiated SSRIs with higher QT-prolonging potential and 34,722 (52.9%) who initiated SSRIs with lower QT-prolonging potential. Initiation of an SSRI with higher versus lower QT-prolonging potential was associated with higher risk of sudden cardiac death (adjusted hazard ratio, 1.18; 95% confidence interval, 1.05 to 1.31). This association was more pronounced among elderly individuals, females, patients with conduction disorders, and those treated with other non-SSRI QT-prolonging medications. CONCLUSIONS: The heterogeneous QT-prolonging potential of SSRIs may differentially affect cardiac outcomes in the hemodialysis population.

Bell pepper allergy: different sensitization profiles

No disponible

Toll-like receptor 2 induces Th17 myeloperoxidase autoimmunity while Toll-like receptor 9 drives Th1 autoimmunity in murine vasculitis.

OBJECTIVE: Autoantibodies constitute the hallmark of antineutrophil cytoplasmic antibody-associated vasculitis (AAV); however, CD4+ T cells play an essential role in the development of autoimmunity. Infection is associated with vasculitis, with Toll-like receptors (TLRs) a potential link between infection and autoimmunity. This study was undertaken to investigate the role of TLR ligation on cellular and humoral autoimmunity and glomerular injury in experimental myeloperoxidase (MPO)-induced AAV. METHODS: We analyzed autoimmune responses in wild-type mice immunized with MPO alone or coimmunized with MPO and a TLR-2 or TLR-9 ligand. The major vascular injury found in human disease, glomerulonephritis with focal necrosis, was triggered by administering a subnephritogenic dose of nephrotoxic serum. RESULTS: MPO alone induced low-titer antineutrophil cytoplasmic antibodies (ANCAs) without delayed-type hypersensitivity or CD4 cytokine responses. However, when MPO was given with either TLR ligand, cellular and humoral autoimmunity was enhanced, but with distinctly different CD4 subsets and IgG ANCA isotypes. TLR-2 ligand induced Th17 autoimmunity, with retinoic acid receptor-related orphan nuclear receptor γt-dependent interleukin-17A (IL-17A) production. TLR-9 ligand promoted Th1 autoimmunity, with enhanced production of interferon-γ (IFNγ) and Th1-associated IgG subclasses. Glomerular vasculitis developed only after the administration of nephrotoxic serum in mice immunized with either TLR ligand and MPO. Glomerulonephritis directed by MPO and TLR-2 ligation was attenuated when IL-17A was neutralized, while glomerulonephritis induced by MPO and TLR-9 ligation was attenuated when IFNγ was neutralized. CONCLUSION: Our findings indicate a pathogenic role of TLRs in initiating autoimmune AAV. TLR-2 induces Th17 CD4 cells while TLR-9 can also direct vasculitis, by directing Th1 autoimmunity.

Infliximab reduces myeloperoxidase concentration in chronic inflammatory joint diseases.

UNLABELLED: The present study evaluated the effect of infliximab on the myeloperoxidase (MPO) concentration in chronic inflammatory joint disease. Eighteen patients were divided into active and inactive groups. Erythrocyte sedimentation rate, C-reactive protein, white blood cell counts, MPO concentration, and biomarkers of oxidative stress were measured before and after the infusion of infliximab. Patients with active disease showed increases in concentrations of MPO and biomarkers of oxidation, but decreases in antioxidant parameters. After infliximab treatment, both inflammatory parameters and MPO concentrations were normalized. IN CONCLUSION: (1) the MPO concentration is related to inflammatory activity and could play an important role in the maintenance and outbreak of oxidative stress present in these diseases, and (2) infliximab inhibits MPO concentration.

Myeloperoxidase modulates lung epithelial responses to pro-inflammatory agents.

During extensive inflammation, neutrophils undergo secondary necrosis causing myeloperoxidase (MPO) release that may damage resident lung cells. Recent observations suggest that MPO has pro-inflammatory properties, independent of its enzymatic activity. The aims of the present study were to characterise MPO internalisation by lung epithelial cells and to investigate the effect of MPO on oxidative stress, DNA damage and cytokine production by lung epithelial cells. Human alveolar and bronchial epithelial cells were stimulated with MPO, with or without priming the cells with pro-inflammatory stimuli. MPO protein was detected in the cell cytoplasm. Expression of haemoxygenase (HO)-1 and DNA strand breakage were determined. The production of interleukin (IL)-8 and -6 were measured. Analyses of MPO-stimulated cells demonstrated MPO presence in the cells. HO-1 expression was increased after MPO stimulation and increased further when cells were primed before MPO stimulation. MPO exposure also induced DNA strand breakage. Interestingly, MPO inhibited IL-8 production in bronchial, but not alveolar epithelium. In conclusion, alveolar and bronchial epithelial cells can internalise myeloperoxidase. Stimulation with myeloperoxidase increases haemoxygenase-1 expression and DNA strand breakage, suggesting cell damaging capacity of myeloperoxidase. In addition, myeloperoxidase inhibited interleukin-8 production by bronchial epithelial cells, indicating a negative feedback loop for neutrophil recruitment.

In vivo and in vitro anti-inflammatory activity of Mangifera indica L. extract (VIMANG).

A standard aqueous extract of Mangifera indica L., used in Cuba as an antioxidant under the brand name of VIMANG, was tested in vivo for its anti-inflammatory activity using commonly accepted assays. M. indica extract, administered topically (0.5-2 mg per ear), reduced ear edema induced by arachidonic acid (AA) and phorbol myristate acetate (PMA, ED50 = 1.1 mg per ear) in mice. In the PMA model, M. indica extract also reduced myeloperoxidase (MPO) activity. This extract p.o. administered also inhibited tumor necrosis factor alpha (TNFalpha) serum levels in both models of inflammation (AA, ED50 = 106.1 mg kg(-1) and PMA, ED50 = 58.2 mg kg(-1)). In vitro studies were performed using the macrophage cell line RAW264.7 stimulated with pro-inflammatory stimuli (LPS-IFNgamma or the calcium ionophore A23187) to determine PGE2 or LTB4 release, respectively. The extract inhibited the induction of PGE2 with IC50 = 64.1 microg ml(-1) and LTB4 IC50 = 22.9 microg ml(-1). M. indica extract also inhibited human synovial secretory phospholipase (PL)A2 with IC 50 = 0.7 microg ml(-1). These results represent an important contribution to the elucidation of the mechanism involved in the anti-inflammatory and anti-nociceptive effects reported by the standard M. indica extract VIMANG.

Neutrophil functions of patients with vasculitis related to myeloperoxidase-specific anti-neutrophil antibody.

Neutrophils are hypothesized to cause tissue damage resulting in the development of vasculitis and glomerulonephritis, although they are known to primarily take part in host defense functions. The infiltration of inflammatory cells. notably neutrophils and macrophages, is observed in the progression of vasculitis. Neutrophils with activated status and anti-neutrophil cytoplasmic antibodies (ANCAs), especially myeloperoxidase-specific (MPO)-ANCA, have been implicated in the development of vasculitis. The target molecule of MPG-ANCA is a lysosomal enzyme MPO that usually acts to kill bacteria, viruses, and fungi and that causes damage to the tissue due to the toxicity of its product, hypochlorite (OCl-). To elucidate the role of MPO-ANCA in the progression of vasculitis, a set of MPO-peptide fragments has been developed, and the corresponding epitope site for the specific monoclonal and/or oligoclonal antibody resulting in vasculitis has been determined. Recently some mouse models have been used for analyzing the correlation between MPO and MPO-ANCA in relation to damage of blood vessels followed by the development of vasculitis. This review focuses on the role of activated neutrophils in the development of vasculitis associated with MPO-ANCA and the target molecules of ANCA. In addition, the reactivities of ANCA and inflammatory cytokines involving leukocyte-derived chemotaxin 2 (LECT2) are also discussed.