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IL-1 Mediates Tissue-Specific Inflammation and Severe Respiratory Failure in COVID-19
Figure 1. Concentrations of calprotectin (S100A8/A9) were measured in the plasma from HVs.
Figure 2. Concentrations of calprotectin in 20 patients with suPAR less than 6 ng/mL and in 20 patients with suPAR 6 ng/mL or more. | Product Name | Cat. No. | Applications | Host Species | Datasheet | Price | Add to Basket |
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Inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), is characterized by chronic remitting inflammatory flare-ups within and outside the gastrointestinal tract. IBD is caused by an inappropriate immune response to intestinal commensals in genetically susceptible individuals, resulting in inflammation and intestinal ulceration. Calprotectin (CP) is a clinical biomarker of inflammatory bowel disease with immunomodulatory functions. CP belongs to the evolutionarily conserved family of calcium-binding S100 leukocyte proteins, which in mammals consists of two monomers (S100A8 and S100A9). As early as the last century, researchers identified a protein complex under different inflammatory conditions, which subsequently became known as calprotectin, with the main emphasis on the protein's Ca2+-binding properties and its antifungal activity against Candida albicans.
CP is an abundant cell membrane protein complex (composed of S100A8 and S100A9) that is constitutively expressed in neutrophils, accounting for approximately 45% of total cytoplasmic proteins. In addition, CP is also constitutively expressed in monocytes, dendritic cells, activated macrophages, oral keratinocytes, and squamous mucosal epithelium, and its expression can be specifically induced during inflammation. Both subunits, S100A8 and S100A9, have a wide range of intracellular and extracellular immunoregulatory properties, and the S100A8/S100A9 complex controls the intracellular pathways of innate immune cells and orchestrates inflammatory responses. CP modulates cytoskeletal rearrangement, recruits leukocytes, and promotes arachidonic acid transport to sites of inflammation. In addition, nuclear S100A9/CP acts as a coactivator to modify transcription during inflammatory processes and malignant transformation. Extracellular Toll-like receptor 4 (TLR4) and receptor for advanced glycation end products (RAGE) mediate the extracellular function of CP. However, extracellular CP can form complex protein conformations with different biological functions and equivalent receptors that may not be explained by these signaling pathways.
Figure 1. Calprotectin in the control of gut inflammation
(Source: Jukic A, et al. 2021)
The efficacy of fecal CP as a marker has been investigated in various areas of IBD diagnosis and treatment, including the differentiation of IBD from irritable bowel syndrome (IBS), the assessment of endoscopic activity of the disease, the assessment of histologic activity of the disease, and the prediction of disease relapse and response to therapy. Fecal CP has relatively high sensitivity and specificity in differentiating IBD from IBS, but lower sensitivity and specificity in predicting endoscopic and histologic remission. Therefore, despite its ease of measurement, fecal CP cannot be considered a reliable alternative to colonoscopy for assessing endoscopic activity in IBD.
Human CP ELISA
References
1. Khaki-Khatibi F, et al. Calprotectin in inflammatory bowel disease. Clin Chim Acta. 2020 Nov;510:556-565.
2. Jukic A, et al. Calprotectin: from biomarker to biological function. Gut. 2021 Oct;70(10):1978-1988.