High normal serum levels of C3 and C1 inhibitor, two acute-phase proteins belonging to the complement system, occur more frequently in patients with Crohn's disease than ulcerative colitis

Complement lectin pathway activation is associated with COVID-19 disease severity, independent of MBL2 genotype subgroups

Introduction

While complement is a contributor to disease severity in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections, all three complement pathways might be activated by the virus. Lectin pathway activation occurs through different pattern recognition molecules, including mannan binding lectin (MBL), a protein shown to interact with SARS-CoV-2 proteins. However, the exact role of lectin pathway activation and its key pattern recognition molecule MBL in COVID-19 is still not fully understood.

Methods

We therefore investigated activation of the lectin pathway in two independent cohorts of SARS-CoV-2 infected patients, while also analysing MBL protein levels and potential effects of the six major single nucleotide polymorphisms (SNPs) found in the MBL2 gene on COVID-19 severity and outcome.

Results

We show that the lectin pathway is activated in acute COVID-19, indicated by the correlation between complement activation product levels of the MASP-1/C1-INH complex (p=0.0011) and C4d (p<0.0001) and COVID-19 severity. Despite this, genetic variations in MBL2 are not associated with susceptibility to SARS-CoV-2 infection or disease outcomes such as mortality and the development of Long COVID.

Conclusion

In conclusion, activation of the MBL-LP only plays a minor role in COVID-19 pathogenesis, since no clinically meaningful, consistent associations with disease outcomes were noted.

Potential of myricetin to restore the immune balance in dextran sulfate sodium-induced acute murine ulcerative colitis

OBJECTIVES

Myricetin is a bioactive compound in many edible plants with anti-inflammatory and anticarcinogenic activity. The current study aimed to determine the protective effects and mechanism of myricetin against ulcerative colitis (UC).

METHODS

Myricetin was orally administered at doses of 40 and 80 mg/kg to C57BL/6 mice with UC induced using dextran sulfate sodium. The disease-associated index and colon length were determined at the end of the experiment, the proportion of Treg, Th1 and Th17 was analysed by cytometry, and cytokines were detected using ELISA.

KEY FINDINGS

Myricetin (80 mg/kg) ameliorated the severity of inflammation in acute UC and significantly improved the condition. Myricetin (80 mg/kg) elevated the levels of IL-10 and transforming growth factor β. In addition, the proportion of regulatory T cells significantly increased in mice in the myricetin treatment group.

CONCLUSIONS

Taking together, these results suggest that myricetin exhibits significant protective effects against UC and it could be used as a potential treatment for UC.

Pleiotropic Effects of Risk Factors in Age-Related Macular Degeneration and Seemingly Unrelated Complex Diseases

Age-related macular degeneration (AMD) is a complex disease with both environmental and genetic factors influencing disease risk. Genome-wide case-control association studies, candidate gene analyses, and epidemiological studies reinforced the notion that AMD is predominantly a disease of an impaired complement system and an altered high-density lipoprotein (HDL) metabolism. Recent reports demonstrated the pleiotropic role of the complement system and HDL in complex diseases such as cardiovascular disease, autoimmune disorders, cancer, and Alzheimer's disease. In light of these findings, we explore current evidence for a shared genetic and environmental risk of AMD and unrelated complex diseases based on epidemiological studies. Shared risk factors may indicate common pathways in disease pathology and thus may have implications for novel treatment options of AMD pathology.

The complement system in inflammatory bowel disease

Complement is well appreciated to be a potent innate immune defense against microbes and is important in the housekeeping act of removal of apoptotic and effete cells. It is also understood that hyperactivation of complement, or the lack of regulators, may underlie chronic inflammatory diseases. A pipeline of products to intervene in complement activation, some already in clinical use, is being studied in various chronic inflammatory diseases. To date, the role of complement in inflammatory bowel disease has not received a lot of research interest. Novel genetically modified laboratory animals and experiments using antagonists to complement effector molecules have kindled important research observations implicating the complement system in inflammatory bowel disease pathogenesis. We review the evidence base for the role and potential therapeutic manipulation of the complement cascade in inflammatory bowel disease.

C1 inhibitor: quantification and purification

C1 inhibitor is a multipotent serpin capable of inhibiting the classical and the lectin pathways of complement, the fibrinolytic system, and contact/kinin system of coagulation. Deficiency of C1 inhibitor manifest as hereditary angioedema (HAE), an autosomal dominant hereditary disease. Measuring the C1 inhibitor level is of vital importance for the diagnosis of HAE and also for monitoring patients receiving C1 inhibitor for therapy. Determination of the antigenic C1 inhibitor level by the radial immunodiffusion (RID) technique is described in detail in this chapter. The presented purification method of plasma C1 inhibitor is primarily based on its high carbohydrate content and its affinity to the lectin jacalin.

Plasma profiles in active systemic juvenile idiopathic arthritis: Biomarkers and biological implications

Systemic juvenile idiopathic arthritis (SJIA) is a chronic arthritis of children characterized by a combination of arthritis and systemic inflammation. There is usually non-specific laboratory evidence of inflammation at diagnosis but no diagnostic test. Normalized volumes from 89/889 2-D protein spots representing 26 proteins revealed a plasma pattern that distinguishes SJIA flare from quiescence. Highly discriminating spots derived from 15 proteins constitute a robust SJIA flare signature and show specificity for SJIA flare in comparison to active polyarticular juvenile idiopathic arthritis or acute febrile illness. We used 7 available ELISA assays, including one to the complex of S100A8/S100A9, to measure levels of 8 of the15 proteins. Validating our DIGE results, this ELISA panel correctly classified independent SJIA flare samples, and distinguished them from acute febrile illness. Notably, data using the panel suggest its ability to improve on erythrocyte sedimentation rate or C-reactive protein or S100A8/S100A9, either alone or in combination in SJIA F/Q discriminations. Our results also support the panel's potential clinical utility as a predictor of incipient flare (within 9 wk) in SJIA subjects with clinically inactive disease. Pathway analyses of the 15 proteins in the SJIA flare versus quiescence signature corroborate growing evidence for a key role for IL-1 at disease flare.

Identification of complement C3 as an autoantigen in inflammatory bowel disease

OBJECTIVE

Autoantibodies against goblet cells in the gastrointestinal mucosa have been described in patients with inflammatory bowel disease (IBD) but a corresponding autoantigen has not yet been identified. The aim of this study was to identify such an antigen.

METHODS

First, 10 candidate autoantigens were discarded based on double stainings of appendiceal sections and a mucin-producing cell line (HT29-mtx). Second, an appendiceal cDNA library was immunoscreened with IBD sera.

RESULTS

Three out of 48 positive clones were identified as complement C3. Using immunoprecipitation of in vitro transcribed and translated C3, seven of 17 primary sclerosing cholangitis patient sera, 15 of 65 IBD sera, and none out of 54 sera from healthy blood donors showed C3 immunoreactivity. The results were confirmed using western blot and an enzyme-linked immunosorbent assay with alternative sources of C3 protein.

CONCLUSION

In conclusion, we have identified complement C3 as a potential autoantigen in IBD and primary sclerosing cholangitis.

Predictive factors of efficacy of leukocytapheresis for steroid-resistant ulcerative colitis patients

BACKGROUND

The effectiveness of leukocytapheresis against ulcerative colitis has been reported. However, the efficacy of this therapy for steroid-resistant ulcerative colitis patients has hardly been examined.

AIMS

The aims of this study are to evaluate the efficacy of leukocytapheresis for steroid-resistant ulcerative colitis patients and to identify clinical factors that predict the efficacy of this therapy for these patients.

METHODS

Clinical factors of 71 steroid-resistant ulcerative colitis patients who underwent leukocytapheresis analysed.

RESULTS

Of those analysed, 53 (75%) patients showed an initial response to leukocytapheresis. Among cases with initial response, however, only 19 (27%) patients maintained remission for more than 6 months. Steroid-dependent course (Odds ratio =5.53, 95% confidence interval; 1.24-24.73) and a high C-reactive protein degree (Odds ratio=1.6, confidence interval; 1.09-2.35) were predictors of initial response to leukocytapheresis. Rapid response, which means remission induction within three leukocytapheresis sessions, was the only predictor of maintenance of remission for more than 6 months after successful leukocytapheresis therapy (odds ratio=8.01, confidence interval; 1.08-59.37).

CONCLUSIONS

Leukocytapheresis was effective for steroid-resistant ulcerative colitis patients. However, relapse was frequently observed within short periods after the initial response to this therapy. Patients without a rapid response should be treated with alternative or additional therapies.

ADOA3R as a therapeutic target in experimental colitis: proof by validated high-density oligonucleotide microarray analysis

Adenosine A3 receptors (ADOA3Rs) are emerging as novel purinergic targets for treatment of inflammatory diseases. Our goal was to assess the protective effect of the ADOA3R agonist N(6)-(3-iodobenzyl)-adenosine-5-N-methyluronamide (IB-MECA) on gene dysregulation and injury in a rat chronic model of 2,4,6-trinitrobenzene sulfonic acid (TNBS)--induced colitis. It was necessary to develop and validate a microarray technique for testing the protective effects of purine-based drugs in experimental inflammatory bowel disease. High-density oligonucleotide microarray analysis of gene dysregulation was assessed in colons from normal, TNBS-treated (7 days), and oral IB-MECA-treated rats (1.5 mg/kg b.i.d.) using a rat RNU34 neural GeneChip of 724 genes and SYBR green polymerase chain reaction. Analysis included clinical evaluation, weight loss assessment, and electron paramagnetic resonance imaging/spin-trap monitoring of free radicals. Remarkable colitis-induced gene dysregulation occurs in the most exceptional cluster of 5.4% of the gene pool, revealing 2 modes of colitis-related dysregulation. Downregulation occurs in membrane transporter, mitogen-activated protein (MAP) kinase, and channel genes. Upregulation occurs in chemokine, cytokine/inflammatory, stress, growth factor, intracellular signaling, receptor, heat shock protein, retinoid metabolism, neural, remodeling, and redox-sensitive genes. Oral IB-MECA prevented dysregulation in 92% of these genes, histopathology, gut injury, and weight loss. IB-MECA or adenosine suppressed elevated free radicals in ex vivo inflamed gut. Oral IB-MECA blocked the colitis-induced upregulation (<or=20-fold) of Bzrp, P2X1R, P2X4R, P2X7R, P2Y2R, P2Y6R, and A2aR/A2bR but not A1R or A3R genes or downregulated P2X2R, P2Y1R, and P2Y4R. Real-time SYBR green polymerase chain reaction validated gene chip data for both induction of colitis and treatment with IB-MECA for >90% of genes tested (33 of 37 genes). We conclude that our validated high-density oligonucleotide microarray analysis is a powerful technique for molecular gene dysregulation studies to assess the beneficial effects of purine-based or other drugs in experimental colitis. ADOA3R is new potential therapeutic target for inflammatory bowel disease.