A review of the immune activity of chitooligosaccharides

Under the influence of the COVID-19, people's awareness of physical health and immunity has increased significantly. Chitooligosaccharide is an oligomer of β-(1, 4)-linked D-glucosamine, furthermore, is one of the most widely studied immunomodulators. Chitooligosaccharide can be prepared from the chitin or chitosan polymers through enzymatically, chemically or physically processes. Chitooligosaccharide and its derivatives have been proven to have a wide range of biological activities including intestinal flora regulation, immunostimulant, anti-tumor, anti-obesity and anti-oxidation effects. This review summarizes the latest research of the preparation methods, biological activities in immunity and safety profiles of Chitooligosaccharide and its derivatives. We recapped the effect mechanisms of Chitooligosaccharide basing on overall immunity. Comparing the effects of Chitooligosaccharide with different molecular weights and degree of aggregation, a reference range for usage has been provided. This may provide a support for the application of Chitooligosaccharide in immune supplements and food. In addition, future research directions are also discussed. © 2023, Sociedade Brasileira de Ciencia e Tecnologia de Alimentos, SBCTA. All rights reserved.

A review of the immune activity of chitooligosaccharides

Under the influence of the COVID-19, people's awareness of physical health and immunity has increased significantly. Chitooligosaccharide is an oligomer of β-(1, 4)-linked D-glucosamine, furthermore, is one of the most widely studied immunomodulators. Chitooligosaccharide can be prepared from the chitin or chitosan polymers through enzymatically, chemically or physically processes. Chitooligosaccharide and its derivatives have been proven to have a wide range of biological activities including intestinal flora regulation, immunostimulant, anti-tumor, anti-obesity and anti-oxidation effects. This review summarizes the latest research of the preparation methods, biological activities in immunity and safety profiles of Chitooligosaccharide and its derivatives. We recapped the effect mechanisms of Chitooligosaccharide basing on overall immunity. Comparing the effects of Chitooligosaccharide with different molecular weights and degree of aggregation, a reference range for usage has been provided. This may provide a support for the application of Chitooligosaccharide in immune supplements and food. In addition, future research directions are also discussed. © 2023, Sociedade Brasileira de Ciencia e Tecnologia de Alimentos, SBCTA. All rights reserved.

Modulating effect of Xuanfei Baidu granule on host metabolism and gut microbiome in rats.

Xuanfei Baidu granule (XFBD) is a recommended patented drug for the prevention and treatment of Corona Virus Disease 2019 (COVID-19), which is approved by the National Medical Products Administration. XFBD suppresses the over-activated immune response caused by inflammatory factor storms in COVID-19 infection. The intestine plays a crucial role in the immune system. The mass spectrometry based fecal metabolomics with 16S rDNA sequencing were combined to evaluate the effects of XFBD on host metabolism and gut microbiome. Short-chain fatty acids (SCFAs) contents in fecal matter were quantified by gas chromatography-mass spectrometry (GC-MS). Plasma samples were used to detect immune and inflammatory levels. The results were verified with a rat model of intestinal disorder. Results indicated that XFBD could increase the immune level of Immunoglobulin A (IgA), Immunoglobulin G (IgG) and Immunoglobulin M (IgM) (p < 0.05). The OPLS-DA analysis results showed that a total of 271 differential metabolites (178 up-regulated and 93 down-regulated) were identified based on the VIP ≥1, p < 0.05, FC ≥ 2 and FC ≤ 0.5. The metabolic pathways mainly involved D-Glutamine and D-glutamate metabolism, Arginine biosynthesis, Biotin metabolism, et al. XFBD modified the gut bacteria structure according to the principal component analysis (PCA), that is, 2 phyla, 3 classes, 5 orders, 11 families and 14 genera were significantly different based on taxonomic assignment. In addition, it could partially callback the relative abundance of intestinal microflora in bacterial disorder rats caused by antibiotics. It is suggested that the intervention mechanism of XFBD might be related to the regulation of intestinal flora composition. The evidence obtained in the study provides a useful reference for understanding the mechanism of XFBD.

Xuanfei Baidu decoction attenuates intestinal disorders by modulating NF-κB pathway, regulating T cell immunity and improving intestinal flora.

BACKGROUND: A number of studies have shown that gastrointestinal manifestations co-exist with respiratory symptoms in coronavirus disease 2019 (COVID-19) patients. Xuanfei Baidu decoction (XFBD) was recommended by the National Health Commission to treat mild and moderate COVID-19 patients and proved to effectively alleviate intestinal symptoms. However, the exact mechanisms remain elusive. PURPOSE: This study aimed at exploring potential mechanisms of XFBD by utilizing a mouse model of dextran sulfate sodium (DSS)-induced acute experimental colitis, mimicking the disease conditions of intestinal microecological disorders. METHODS: The network pharmacology approach was employed to identify the potential targets and pathways of XFBD on the intestinal disorders. Mice with DSS-induced intestinal disorders were utilized to evaluate the protective effect of XFBD in vivo, including body weight, disease activity index (DAI) score, colon length, spleen weight, and serum tumor necrosis factor-α (TNF-α) level. Colon tissues were used to perform hematoxylin-eosin (H&E) staining, western blot analysis, and transcriptome sequencing. Macrophages, neutrophils and the proportions of T helper cell (Th) 1 and Th2 cells were measured by flow cytometry. Intestinal contents were collected for 16S rRNA gene sequencing. RESULTS: Network pharmacology analysis indicated that XFBD inhibited the progression of COVID-19-related intestinal diseases by repressing inflammation. In mice with DSS-induced intestinal inflammation, XFBD treatment significantly reduced weight loss, the spleen index, the disease activity index, TNF-α levels, and colonic tissue damage, and prevented colon shortening. Transcriptomics and flow cytometry results suggested that XFBD remodeled intestinal immunity by downregulating the Th1/Th2 ratio. Western blot analysis showed that XFBD exerted its anti-inflammatory effects by blocking the nuclear factor-κB (NF-κB) signaling pathway. Indicator analysis of microbiota showed that 75 operational taxonomic units (OTUs) were affected after XFBD administration. Among them, Akkermansia, Muribaculaceae, Lachnospiraceae, and Enterorhabdus were simultaneously negatively correlated with intestinal disorders' parameters, and Bacteroides, Escherichia-Shigella, Eubacterium nodatum,Turicibacter, and Clostridium sensu stricto 1, showed positive correlations with intestinal disorders' parameters. CONCLUSIONS: Our data indicate that XFBD treatment attenuated intestinal disorders associated with inhibiting inflammation, remodeling of intestinal immunity, and improving intestinal flora. These findings provide a scientific basis for the clinical use of XFBD and offer a potential therapeutic approach for the treatment of COVID-19 patients with intestinal symptoms.

Intestinal Flora: A Pivotal Role in Investigation of Traditional Chinese Medicine.

Intestinal flora is essential for maintaining host health and plays a unique role in transforming Traditional Chinese Medicine (TCM). TCM, as a bodyguard, has saved countless lives and maintained human health in the long history, especially in this COVID-19 pandemic. Pains of diseases have been removed from the effective TCM therapy, such as TCM preparation, moxibustion, and acupuncture. With the development of life science and technology, the wisdom and foresight of TCM has been more displayed. Furthermore, TCM has been also inherited and developed in innovation to better realize the modernization and globalization. Nowadays, intestinal flora transforming TCM and TCM targeted intestinal flora treating diseases have been important findings in life science. More and more TCM researches showed the significance of intestinal flora. Intestinal flora is also a way to study TCM to elucidate the profound theory of TCM. Processing, compatibility, and properties of TCM are well demonstrated by intestinal flora. Thus, it is no doubt that intestinal flora is a core in TCM study. The interaction between intestinal flora and TCM is so crucial for host health. Therefore, it is necessary to sum up the latest results in time. This paper systematically depicted the profile of TCM and the importance of intestinal flora in host. What is more, we comprehensively summarized and discussed the latest progress of the interplay between TCM and intestinal flora to better reveal the core connotation of TCM.

GeGen QinLian decoction alleviate influenza virus infectious pneumonia through intestinal flora.

Influenza in humans is often accompanied by gastroenteritis-like symptoms. GeGen QinLian decoction (GQD), a Chinese herb formula, has been widely used to treat infectious diarrhea for centuries and has the effect of restoring intestinal flora. Studies have also reported that GQD were used to treat patients with influenza. However, whether regulating the intestinal flora is one of the ways GQD treats influenza has not been confirmed. In present research, we conducted a systemic pharmacological study, and the results showed that GQD may acts through multiple targets and pathways. In influenza-infected mice, GQD treatment reduced mortality and lung inflammation. Most importantly, the mortality and lung inflammation were also reduced in influenza-infected mice that have undergone fecal microbiota transplantation (FMT) from GQD (FMT-GQD) treated mice. GQD treatment or FMT-GQD treatment restores the intestinal flora, resulting in an increase in Akkermansia_muciniphila, Desulfovibrio_C21_c20 and Lactobacillus_salivarius, and a decrease in Escherichia_coli. FMT-GQD treatment inhibited the NOD/RIP2/NF-κB signaling pathway in the intestine and affected the expression of downstream related inflammatory cytokines in mesenteric lymph nodes (mLNs) and serum. In addition, FMT-GQD treatment showed systemic protection by restraining the inflammatory differentiation of CD4+ T cells. In conclusion, our study shows that GQD can affect systemic immunity, at least in part, through the intestinal flora, thereby protect the mice against influenza virus infectious pneumonia.

Attaching clinical significance to COVID-19-associated diarrhea.

The Corona Virus Disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), erupted in 2020 and created severe public health and socioeconomic challenges worldwide. A subset of patients, in addition to presenting with typical features such as fever, cough and dyspnea, was also afflicted with diarrhea. However, the clinical features and prognoses related to COVID-19-associated diarrhea have not attracted sufficient attention. This review of the medical literature examines the incidence, pathogenesis, clinical characteristics, fecal virus changes, prognoses and influencing factors of COVID-19-associated diarrhea. The reported incidence of diarrhea in patients with COVID-19 ranged from 2% to 49.5%. The main cause of diarrhea was found to be invasive by SARS-CoV-2 of ACE-2-expressing epithelial cells of the small intestine, causing local intestinal damage. This cellular invasion may be the key factor for the much longer duration of SARS-CoV-2 positivity observed for feces compared to pharyngeal swabs. The associated diarrhea in these patients upsets the balance of intestinal flora, resulting in more-severe disease intensity and worse prognosis. Clinicians should be vigilant to this kind of COVID-19-associated diarrhea, and design more effective prevention and treatment options for patients with positive fecal nucleic acid tests and intestinal microflora disorders.

Intestinal Flora as a Potential Strategy to Fight SARS-CoV-2 Infection.

The coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread rapidly worldwide, seriously endangering human health. In addition to the typical symptoms of pulmonary infection, patients with COVID-19 have been reported to have gastrointestinal symptoms and/or intestinal flora dysbiosis. It is known that a healthy intestinal flora is closely related to the maintenance of pulmonary and systemic health by regulating the host immune homeostasis. Role of the "gut-lung axis" has also been well-articulated. This review provides a novel suggestion that intestinal flora may be one of the mediators of the gastrointestinal responses and abnormal immune responses in hosts caused by SARS-CoV-2; improving the composition of intestinal flora and the proportion of its metabolites through probiotics, and personalized diet could be a potential strategy to prevent and treat COVID-19. More clinical and evidence-based medical trials may be initiated to determine the strategy.