Gastrointestinal mucosal immunity and COVID-19

As the gastrointestinal tract may also be a crucial entry or interaction site of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),the role of the gut mucosal immune system as a first-line physical and immunological defense is critical.Furthermore,gastrointestinal involvement and symptoms in coronavirus disease 2019(COVID-19)patients have been linked to worse clinical outcomes.This review discusses recent data on the interactions between the virus and the immune cells and molecules in the mucosa during the infection.By carrying out appropriate investigations,the mucosal immune system role in SARS-CoV-2 infection in therapy and prevention can be established.In line with this,COVID-19 vaccines that stimulate mucosal immunity against the virus may have more advantages than the others.

Immunogenicity and Prediction of Epitopic Region of Antigen Ag Ⅰ/Ⅱ and Glucosyltransferase from Streptococcus mutans

The levels of Streptococcus（S.） mutans infections in saliva were evaluated and a comparison for specific antibody levels among children with different levels of S. mutans infection was made. The promising epitopic regions of antigen AgⅠ/ Ⅱ（PAc） and glucosyltransferase（GTF） for potential vaccine targets related to S. mutans adherence were screened. A total of 94 children aged 3–4 years were randomly selected, including 53 caries-negative and 41 caries-positive children. The values of S. mutans and those of salivary total secretory immunoglobulin A（s Ig A）, anti-PAc and anti-Glucan binding domain（anti-GLU） were compared to determine the correlation among them. It was found the level of s-Ig A against specific antigens did not increase with increasing severity of S. mutans infection, and the complete amino acid sequence of PAc and GTFB was analyzed using the DNAStar Protean system for developing specific anti-caries vaccines related to S. mutans adherence. A significantly positive correlation between the amount of S. mutans and children decayed, missing, and filled teeth index was observed. No significant difference was detected in specific s Ig A against PAc or GLU between any two groups. No significant correlation was found between such specific s Ig A and caries index. A total of 16 peptides from PAc as well as 13 peptides from GTFB were chosen for further investigation. S. mutans colonization contributed to early children caries as an important etiological factor. The level of s Ig A against specific antigens did not increase with increasing severity of S. mutans infection in children. The epitopes of PAc and GTF have been screened to develop the peptide-based or protein-based anti-caries vaccines.

Chimeric Newcastle Disease Virus-like Particles Containing DC-Binding Peptide-Fused Haemagglutinin Protect Chickens from Virulent Newcastle Disease Virus and H9N2 Avian Influenza Virus Challenge

Newcastle disease virus(NDV)and H9N2 subtype Avian influenza virus(AIV)are two notorious avian respiratory pathogens that cause great losses in the poultry industry.Current inactivated commercial vaccines against NDV and AIV have the disadvantages of inadequate mucosal responses,while an attenuated live vaccine bears the risk of mutation.Dendritic cell(DC)targeting strategies are attractive for their potent mucosal and adaptive immune-stimulating ability against respiratory pathogens.In this study,DC-binding peptide(DCpep)-decorated chimeric virus-like particles(cVLPs),containing NDV haemagglutinin–neuraminidase(HN)and AIV haemagglutinin(HA),were developed as a DC-targeting mucosal vaccine candidate.DCpep-decorated cVLPs activated DCs in vitro,and induced potent immune stimulation in chickens,with enhanced secretory immunoglobulin A(sIgA)secretion and splenic T cell differentiation.40μg cVLPs can provide full protection against the challenge with homologous,heterologous NDV strains,and AIV H9N2.In addition,DCpep-decorated cVLPs could induce a better immune response when administered intranasally than intramuscularly,as indicated by robust s IgA secretion and a reduced virus shedding period.Taken together,this chimericVLPs are a promising vaccine candidate to control NDV and AIV H9N2 and a useful platform bearing multivalent antigens.

Effect of Dampness on the Enteric Bacilli，SlgA and Pathological Studies in Rate

Thirty rats were divided into three groups: Damp group ( relative humidity was over 90% andtemperature 18 ￣25 ) , Cold group ( T : 2 2 , RH : 54 4% ) and normal control group ( T : 18 ￣ 25 , RH :54 4% ) . The results showed that number of Escherichia coli increased greatly while number of bifidobac-terium reduced in high moisture. In Damp group, Ievel of secretory IgA was much higher as compared withthat of the normal controlled and Oold group. Th/i and Ts/c in Cold group and in Damp group were slighttylower than that in the normal group. Light microscopic examinations showed that there were intiltration ot in-flammatory colls and low-grade hyperemla in the phalangeal joints' synovium of rats of the Damp group inpathological section. Meanwhile there were low-grade erosion, degeneration, necrosis and exfoliation in ep-ithelium mucosa of small intestine.

Effects of Qigong Exercises on 3 Different Parameters of Human Saliva

Objective： To analyze the effects of a Qigong program on various parameters of unstimulated saliva, including volume, pH and secretory immunoglobulin A （S-IgA） level. Methods： Twice a day from the beginning of Fall 2005, twenty-three healthy volunteers aged 22-24 did special Qigong exercises and massage of acupuncture points which stimulated the energy cycle and increased body water energy. The unstimulated saliva volume and pH were recorded every week in Spring （April, May, June） 2005 before the volunteers started to learn and exercise Qigong, and after Qigong intervention in Spring （April, May, June） 2006. During the period of study, saliva was collected in the same location and on similar dates at the Dental Faculty of Tehran University of Medical Sciences. The S-IgA levels of the last samples of the last week of Spring 2005 and 2006 were measured. Results： The unstimulated saliva volume after Qigong exercises （2.94±0.20 mL/5min） was significantly higher as compared to the pre-Qigong phase （1.65±0.102 mL/5min, P〈0.05）. The S-IgA level was 105.45±69.41 mg/mL before doing Qigong exercises, and 156.23±88.56 mg/mL after doing Qigong exercises, and a statistically significant difference was seen between the two measurements （P=0.005）. The change in pH was not statistically significant. Conclusions： The application of Qigong is beneficial for increasing salivary volume and other parameters. Moreover, the results suggest that Qigong may be a useful medication for patients with salivary hyposecretion. Further research is recommended in examining the long-term effects of Qigong on improving salivary volume and other parameters in individuals with salivary hyposecretion.

Intestinal immune barrier integrity in rats with nonalcoholic hepatic steatosis and steatohepatitis

Background Nonalcoholic fatty liver disease （NAFLD） has emerged as the major cause of chronic liver injury.Intestinal barrier plays an important role in the pathogenis of NAFLD.The aim of this article was to assess intestinal immune barrier function during the development of NAFLD.Methods Totally 60 male Sprague-Dawley （SD） rats were divided into 2 groups：normal diet （ND） group and high-fat diet （HFD） group.NAFLD rat model was established in the HFD rat group.Portal blood endotoxin level was assessed by limulus test.The percentage of CD4＋ cells and CD8＋ cells in peripheral blood mononuclear cells （PBMC） and lymphocytes in Peyer＇s patches （PP） were analysed by flow cytometry.Intestinal secretory immunoglobulin A （SIgA） level was evaluated by enzyme-linked immunosorbent assay.Paired Student＇s t test was used for the statistic analysis.Results HFD rats presented with simple steatosis at the 4th and 8th week and progressed to nonalcoholic steatohepatitis at the 12th week.Elevated lipopolysaccharides （LPS） level in HFD rats was observed at the 8th week （（1.54±0.30） times of ND group,P 〈0.01）.CD4/CD8 ratios in PBMC and PP of HFD rats were increased at the 4th week （（1.50±0.47） and （1.63±0.34） times of ND group,P 〈0.05） and decreased at the 8th week （（0.50±0.16） and （0.61±0.26）times of ND group,P 〈0.05）.At the 12th week,CD4/CD8 ratio （（1.47±0.46） times,P 〈0.05） in PP increased to levels observed in the 4th week.Intestinal SIgA expression of HFD rats was remarkably up-regulated at 12th week （（2.70±1.65）times,P 〈0.05）.Conclusion Liver-gut axis in rats with NAFLD may mediate and improve intestinal immune function by increased CD4/CD8 ratio in PP and increased production of SIgA.