Decreased expression of protectin (CD59) in gut epithelium in ulcerative colitis and Crohn's disease

Without adequate protection, the cells of the human body would be susceptible to destruction by the complement system. The main defense against complement lysis is a molecule called protectin (CD59) that is widely distributed in human tissues. Because the complement system has been suggested to be involved in the pathogenesis of inflammatory bowel diseases, we examined the expression of protectin in the colonic epithelium of patients with ulcerative colitis or Crohn's disease and controls. Colorectal specimens from 6 patients with ulcerative colitis, 8 patients with Crohn's disease, and 4 controls were obtained from surgical resections. Frozen sections of the specimens were immunostained for protectin using the Bric 229 monoclonal antibody. The expression of protectin was found to be decreased in the epithelium of patients with ulcerative colitis. In patients with Crohn's disease, the epithelial expression of protectin was decreased in diseased areas of gut while the expression did not significantly differ from that in controls in macroscopically normal areas. There was no difference in the expression of protectin on vascular endothelium, mononuclear cells, or smooth muscle. The reduction in epithelial expression of protectin in patients with ulcerative colitis or Crohn's disease may render epithelial cells vulnerable to complement lysis and lead to the destruction of gut epithelium as seen typically in these diseases.     

The complement system in primary Sjögren’s syndrome: the expression of certain cascade and regulatory proteins in labial salivary glands – observational study

IntroductionThe complement cascade and regulatory proteins are involved in the pathogenesis of the Sjögren’s syndrome and other autoimmune diseases. The complement activation via the alternative pathway was recognized as a major pathogenic mechanism in autoimmune conditions. The aim of this study was to assess expression of complement cascade components and regulatory proteins in minor salivary glands in patients with primary Sjögren’s syndrome (pSS).Materials and methodsThe expression of C1q and C5b-9 – membrane attack complex and regulatory proteins such as: membrane cofactor protein (MCP), decay-accelerating factor (DAF) and protectin were examined using immunochemistry method in specimens from biopsy of minor salivary glands in pSS patients. The biopsy material was obtained from 20 pSS patients, 5 patients with non-specific sialadenitis and from 5 patients with suspicion of dryness syndrome without sialadenitis confirmation.ResultsNone of the examined samples showed the expression of C1q or the effector C5b-9. Membrane cofactor protein expression was lower in pSS group than in both non-specific sialadenitis and noninflamed salivary glands. The inflammatory cells in pSS samples partially expressed MCP. There were differences in the sites and intensity of membrane protectin expression exclusively on the luminal surfaces in pSS; on the luminal and, partially, antiluminal surface in non-specific inflammation, and on the entire cell surface in unaffected salivary glands. There were no DAF expression in salivary gland tissue in biopsy specimens in all studied subjects.ConclusionsThe study demonstrated the absence of complement-cascade proteins (C1q, MAC) in the salivary glands of pSS patients, which may indicated a lack of local complement activation via the classical pathway and the observed gland tissue damage being due to a mechanism other than MAC-induced cytolysis. The differences in the expression of complement regulatory proteins between pSS, non-specific sialadenitis, and normal salivary glands may indicate that alternative functions of these regulatory proteins may be of greater significance in pSS. Low MCP expression in pSS in comparison with non-specific sialadenitis and normal salivary glands, may suggest altered modulation of cell-mediated immunity in pSS. The differences in the location and intensity of protectin (CD59) expression indicates a possibility of reducing the proinflammatory effect of protectin in pSS.     

Cerebrospinal fluid concentrations of the complement MAC inhibitor CD59 in multiple sclerosis and patients with other neurological disorders

Rodent oligodendrocytes have a unique susceptibility among glia to the lytic effects of complement, due in part to a deficiency in CD59 (protectin), a key surface inhibitor of the complement membrane attack complex (MAC). The possibility that shedding of CD59 by human oligodendrocytes contributes to complement-mediated oligodendrocyte injury in inflammatory demyelinating disease has been investigated by estimating levels of CD59 in cerebrospinal fluid samples from 12 patients with demyelinating disease of the central nervous system and 13 with other neurological diseases. No significant differences were found between patients and controls, or between patients with active and those with clinically inactive demyelinating disease, providing no direct support for oligodendrocyte shedding of CD59 in multiple sclerosis.     

Protectin DX ameliorates palmitate‐induced hepatic insulin resistance through AMPK/SIRT1‐mediated modulation of fetuin‐A and SeP expression

The role as well as the molecular mechanisms of protectin DX (PDX) in the prevention of hepatic insulin resistance, a hallmark of type 2 diabetes, remains unknown. Therefore, the present study was designed to explore the direct impact of PDX on insulin resistance and to investigate the expression of fetuin‐A and selenoprotein P (SeP), hepatokines that are involved in insulin signalling, in hepatocytes. Human serum levels of PDX as well as fetuin‐A and SeP were determined by high‐performance liquid chromatography (HPLC). Human primary hepatocytes were treated with palmitate and PDX. NF‐κB phosphorylation as well as expression of insulin signalling associated genes and hepatokines were determined by Western blotting analysis. FOXO1 binding levels were measured by quantitative real‐time PCR. Selected genes from candidate pathways were evaluated by small interfering (si) RNA‐mediated gene suppression. Serum PDX levels were significantly (P < 0.05) downregulated, whereas serum fetuin‐A and SeP levels were increased (P < 0.05) in obese subjects compared with healthy subjects. In in vitro experiments, PDX treatment increased AMP‐activated protein kinase (AMPK) phosphorylation and SIRT1 expression and attenuated palmitate‐induced fetuin‐A and SeP expression and insulin resistance in hepatocytes. AMPK or SIRT1 siRNA mitigated the suppressive effects of PDX on palmitate‐induced fetuin‐A through NF‐κB and SeP expression linked to FOXO1 and insulin resistance. Recombinant fetuin‐A and SeP reversed the suppressive effects of fetuin‐A and SeP expression on palmitate‐mediated impairment of insulin signalling. The current finding provides novel insight into the underlying mechanism linking hepatokines to the pathogenesis of hepatic insulin resistance.     

脂氧素A4、保护素D1、ResolvinD1抑制多种激动剂引起的NFκB的活化

目的探讨脂质小分子脂氧素A4(LXA4)、保护素D1(ProD1)、ResolvinD1(RvD1)对核因子κB(NFκB)活性的影响及作用机制。方法稳定表达NFκB荧光素酶报告基因的中国仓鼠卵巢细胞分别由100 nmol/L LXA4、ProD1、RvD1预处理30 min后,细胞被激动剂LPS、HSP70、HMGB1或S100A4刺激。通过检测荧光素酶活性以评价脂质小分子对激动剂激活NFκB活性的作用。细胞培养上清中TNFα的含量由ELISA检测,胞核中NFκB的含量由Western印迹检测。结果 LPS、HSP70、HMGB1和S100A4显著上调NFκB的活性,增加细胞分泌的TNFα的量。LXA4、ProD1、RvD1显著抑制NFκB激活,降低细胞分泌的TNFα含量,减少NFκB的入核。结论 LXA4、ProD1、RvD1显著抑制多种激动剂活化NFκB,其作用机制可能与其能降低NFκB的入核有关,这几个脂质小分子在研制新型抗炎药物方面具有进一步开发和研究的潜力。     

Resolvin E1 as a novel agent for the treatment of asthma

Background: Asthma is characterized by airway hyperresponsiveness and chronic airway inflammation. Inflammatory cells, including eosinophils and lymphocytes, infiltrate peribronchial tissue in patients with asthma. Resolvin E1 (RvE1) is an anti-inflammatory lipid mediator derived from the omega-3 fatty acid, eicosapentaenoic acid, and has been shown to be involved in resolving inflammation. Although little is known about the actions of RvE1 in the resolution of inflammation due to asthma, recent studies in a mouse model have shown the possibilities of RvE1 in asthma. Objective/methods: We review the current understanding of the mechanism of RvE1 action in connection with asthma pathogenesis and treatment. Results/conclusion: Findings provide evidence for the use of RvE1 as a pivotal counter-regulatory signal in allergic inflammation and offer the possibility of novel multi-pronged therapeutic approaches for human asthma.     

Variants within protectin (CD59) and CD44 genes linked to an inherited haplotype in a family with coeliac disease

Coeliac disease (CD) is an autoimmune disorder characterised by inflammation, villous atrophy and hyperplasia of the small intestinal mucosa that affects genetically susceptible individuals. A genome-wide scan was performed in 17 family members with high incidence of CD. Highest nonparametric linkage (NPL) and logarithm of odds (LOD) scores were of 6.21 ( P  = 0.0107) and 2.57, respectively, to a region on chromosome 11p13-12. Following fine mapping, NPL and LOD scores did not change, but the linkage interval on chromosome 11 was narrowed to a region that is approximately 50.94 cM from pTer. Two inherited haplotypes on chromosomes 11p13-12 and 9q21 were observed in all affected members but not in the majority of clinically normal individuals. Sequencing of genes at region 11p13-12 showed a number of sequence variants, two of which were linked with the inherited haplotype. One of these variants in the CD59 gene was found at a very low frequency in the population and could possibly affect pre-messenger RNA splicing. This study is of particular importance for the identification of novel genes that might be responsible for CD other than human leukocyte antigen.     

Protectin D1 promotes resolution of inflammation in a murine model of lipopolysaccharide-induced acute lung injury via enhancing neutrophil apoptosis

Background Protectin D1 （PD1）,derived from docosahexaenoic acid,has been shown to control and resolve inflammation in some experimental models of inflammatory disorders.We investigated the protective roles of protectin D1 in pulmonary inflammation and lung injury induced by lipopolysaccharide （LPS）.Methods Mice were randomly assigned to six groups （n=6 per group）：sham-vehicle group,sham-PD1 group,shamzVAD-fmk group,LPS-vehicle group,LPS-PD1 group,and LPS-PD1-zVAD-fmk group.Mice were injected intratracheally with 3 mg/kg LPS or saline,followed 24 hours later by intravenous injection of 200 μg/mouse PD1 or vehicle.At the same time,some mice were also injected intraperitoneally with the pan-caspase inhibitor zVAD-fmk.Seventy-two hours after LPS challenge,samples of pulmonary tissue and bronchoalveolar lavage fluid were collected.Optical microscopy was used to examine pathological changes in lungs.Cellularity and protein concentration in bronchoalveolar lavage fluid were analyzed.Lung wet/dry ratios and myeloperoxidase activity were measured.Apoptosis of neutrophils in bronchoalveolar lavage fluid （BALF） was also evaluated by flow cytometry.Results Intratracheal instillation of LPS increased neutrophil counts,protein concentration in bronchoalveolar lavage fluid and myeloperoxidase activity,it induced lung histological injury and edema,and also suppressed apoptosis of neutrophils in BALF.Posttreatment with PD1 inhibited LPS-evoked changes in BALF neutrophil counts and protein concentration and lung myeloperoxidase activity,with the outcome of decreased pulmonary edema and histological injury.In addition,PD1 promoted apoptosis of neutrophils in BALF.The beneficial effects of PD1 were blocked by zVAD-fmk.Conclusion Posttreatment with PD1 enhances resolution of lung inflammation during LPS-induced acute lung injury by enhancing apoptosis in emigrated neutrophils,which is,at least in part,caspase-dependent.