Histamine and its receptors (H1R–H4R) play a crucial and significant role in the development of various allergic diseases. Mast cells are multifunctional bone marrow-derived tissue-dwelling cells that are the major producer of histamine in the body. H1R are expressed in many cells, including mast cells, and are involved in Type 1 hypersensitivity reactions. H2R are involved in Th1 lymphocyte cytokine production. H3R are mainly involved in blood–brain barrier function. H4R are highly expressed on mast cells where their stimulation exacerbates histamine and cytokine generation. Both H1R and H4R have important roles in the progression and modulation of histamine-mediated allergic diseases. Antihistamines that target H1R alone are not entirely effective in the treatment of acute pruritus, atopic dermatitis, allergic asthma, and other allergic diseases. However, antagonists that target H4R have shown promising effects in preclinical and clinical studies in the treatment of several allergic diseases. In the present review, we examine the accumulating evidence suggesting novel therapeutic approaches that explore both H1R and H4R as therapeutic targets for histamine-mediated allergic diseases.

Interleukin-33 (IL-33) is a member of the interleukin-1 (IL-1) cytokine family. It is preferentially and constitutively expressed in different structural cells such as epithelial cells, endothelial cells, and smooth muscle cells. During necrosis of these cells (after tissue injury or cell damage), the IL-33 that is released may be recognized by different types of immune cells, such as eosinophils, basophils and, especially, mast cells. IL-33 needs the specific receptor ST2 (membrane-bound receptor) and Interleukin-1 receptor accessory protein heterodimer for its binding, which instigates the production of different types of cytokines and chemokines that have crucial roles in the exacerbation of allergic diseases and inflammation. IL-33 and mast cells have been influentially associated to the pathophysiology of allergic diseases and inflammation. IL-33 is a crucial regulator of mast cell functions and might be an attractive therapeutic target for the treatment of allergic and inflammatory diseases. In this review, we summarize the current knowledge regarding the roles of IL-33 and mast cells in the pathogenesis of allergies and inflammation.

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Traditional use of enzymes for food processing and production of food ingredients resulted in fast-growing enzyme industries world over. The advances in technologies gave rise to exploring newer enzymes and/or modified enzymes for specific application. Search for novel enzymes that can augment catalytic efficiency and advances in molecular biology techniques including sequencing has targeted microbial diversity through metagenomic approaches for sourcing enzymes from difficult to culture organisms. Such mining studies have received more attention in characterizing hydrolases, their prevalence, broad substrate specificities, stability, and independence of cofactors. The focus on glycosyl hydrolases from metagenome for their application in food sector is reviewed.

The understanding that enzymatic degradation of fruit pectin can clarify juices and improve juice yields resulted in the search for microbial pectinases and application in vegetable- and fruit-processing industries. Identified enzymes were classified on the basis of their catalytic activity to pectin or its derivatives and in terms of industrial use. Discovery of gene sequences that coded the enzymes, protein engineering, and molecular biology tools resulted in defined microbial strains that over-produced the enzymes for cost-effective technologies. Recent perspectives on the use of pectin and its derivatives as dietary fibers suggest enzymatic synthesis of the right oligomers from pectin for use in human nutrition. While summarizing the activities of pectin-degrading enzymes, their industrial applications, and gene sources, this review projects another application for pectinases, which is the use of enzymatically derived pectin moieties in functional food preparation.

Background: The disease severity, ranging from being asymptomatic to having acute illness, and associated inflammatory responses has suggested that alterations in the gut microbiota may play a crucial role in the development of chronic disorders due to COVID-19 infection. This study describes gut microbiota dysbiosis in COVID-19 patients and its implications relating to the disease. Design: A cross sectional prospective study was performed on thirty RT-PCR-confirmed COVID-19 patients admitted to the All India Institute of Medical Sciences, Bhopal, India, between September 10 and 20, 2020. Ten healthy volunteers were recruited as the control group. IFN, TNF, and IL-21 profiling was conducted using plasma samples, and gut bacterial analysis was performed after obtaining the metagenomics data of stool samples. Results: Patients with a variable COVID-19 severity showed distinct gut microflora and peripheral interleukin-21 levels. A low Firmicute/Bacteroidetes ratio, caused by the depletion of the fibre-utilizing bacteria, F. prausnitzii, B. Plebius, and Prevotella, and an increase in Bacteroidetes has associated gut microbiota dysbiosis with COVID-19 disease severity. Conclusions: The loss of the functional attributes of signature commensals in the gut, due to dysbiosis, is a predisposing factor of COVID-19 pathophysiology.

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Hibiscus sabdariffa commonly named as "red sorrel" or "roselle" is a member of malvaceae family. It is a medicinal plant with a worldwide fame and has more than three hundred species which are distributed in tropical and subtropical regions around the world. Roselle can adapt to a variety of soil in a warmer and more humid climate. Roselle is rich in organic acids including citric, malic, tartaric and allo-hydroxycitric acids. The plant is also known for its Beta carotene, vitamin C, protein and total sugar. Roselle, having various medically important compounds called photochemical, is well known for its nutritional and medicinal properties. Many parts of Roselle including seeds, leaves, fruits and roots are used in various foods as well as in herbal medicine as a potential non-pharmacological treatment. Different extracts from Roselle plays a crucial role in treating different medical problems including many cardiovascular disorders, helmenthic disease and cancer. The plant also act as an anti oxidant and used in obesity management.