Effects Of Hemagglutinin On The Levels Of Complement (C3, C4) And Cytokines (IL-8, IL-18) In Rats

Nowadays,influenza virus infection spreads all over the world every year.When a new type of influenza virus appears in the population,it is easy to cause serious outbreak of influenza disease,causing widespread disease spread and death of a large number of patients,which seriously endangers human health and social and economic development.Viral hemagglutinin(HA)is a major component of influenza viruses.HA is an envelope glycoprotein that binds to host cell membrane receptors and mediates viral and cell membrane fusion-infected cells.Previous studies have shown that viral hemagglutinin can trigger the body's inflammatory response,leading to tissue and organ damage.In addition,viral hemagglutinin,as an envelope glycoprotein,can activate the innate immunity in the immune system after entering the body,causing abnormalities in the complement system and cytokines,ultimately leading to tissue and organ damage.We speculate that influenza virus hemagglutinin may have an important pathogenic role in acute lung tissue damage.Objective:The effects of hemagglutinin on the levels of complement(C3,C4)and cytokines(IL-8,IL-18)in rats were studied experimentally to further explore the pathogenic role of hemagglutinin in acute lung injury.Methods:A total of 42 healthy and clean SD rats weighing between 170 g and 200 g,male or female,were randomly divided into three groups,each group containing 6 rats,respectively,a blank control group,PHA group(concentration was 5 mg/ml,10 mg/ml,20 mg/ml)and inactivated PHA group(concentration was 5 mg/ml,10 mg/ml,20 mg/ml).Then,0.9% saline,three different concentrations of PHA,and the corresponding concentrations of inactivated PHA were injected from the tail vein of the rats at a dose of 1.5 ml per 100 g of body weight.After 12 hours,the rats were anesthetized,blood was taken from the inferior vena cava,and the contents of complement(C3,C4)and cytokines(IL-8,IL-18)in the plasma were detected by ELISA.Results:1.Rat plasma C4 content:The C4 contents in the plasma of 5 mg/ml,10 mg/ml and 20 mg/ml PHA rats were(44057.71±1101.03)ng/ml,(48768.70±1940.07)ng/ml,(57534.03±4614.21)ng/ml,respectively.Significantly higher than the blank control group(39950.48±1724.38)ng/ml and the corresponding inactivated PHA group(39581.77±1438.94,40252.82±1899.87,38810.98±1683.44)ng/ml,the difference was statistically significant(P<0.05).However,there was no significant difference in plasma C4 levels between the inactivated PHA groups and the control group(P>0.1).2.Rat plasma C3 content:The corresponding content of plasma C3 in the 5mg/ml,10mg/ml,20mg/ml PHA group was(2346.19±152.39,2582.73±245.89,3926.705±566.42)ug/ml,which was significantly higher than the blank control group(1498.05±122.72)ug/ml and the corresponding concentration of inactivated PHA group(1464.95±141.94,1453.25±90.65,1457.25±117.88)ug/ml,the difference was statistically significant(P<0.05).There were no significant differences in plasma C3 levels between the three groups of inactivated PHA rats at different concentrations(P>0.1).3.Rat plasma IL-8 content:The corresponding levels of IL-8 in the plasma of 5 mg/ml,10 mg/ml and 20 mg/ml PHA rats were(103.71±2.75)ng/L,(112.83±3.94)ng/L,(135.94±8.54)ng/ L,were significantly higher than the blank control group(82.27±2.43)ng / L and the corresponding concentration of inactivated PHA group(86.81 ± 7.08,95.37 ± 3.97,116.00 ± 3.40)ng / L,the difference was statistically significant(both P <0.05).There were no significant differences in plasma IL-8 levels between the three groups of inactivated PHA rats at different concentrations(P>0.1).4.Rat plasma IL-18 content:The corresponding levels of IL-18 in the plasma of 5 mg/ml,10 mg/ml and 20 mg/ml PHA rats were(0.15±0.01)ng/ml,(0.18±0.01)ng/ml,(0.56±0.12)ng/ml,significantly higher than the blank group(0.06 ± 0.02)ng / ml and the corresponding concentration of inactivated PHA group(0.08 ± 0.02,0.11 ± 0.01,0.10 ± 0.01)ng / ml,the difference was statistically significant(P <0.01).There was no significant difference in plasma IL-18 levels between the inactivated PHA rats and the blank group(P>0.1).Conclusion:Influenza virus hemagglutinin can stimulate the body to activate complement(C3,C4),cause elevated inflammatory factors(IL-8,IL-18),and the interaction between complement activation and inflammatory response exacerbates the pathological damage of the body.Finally,the patient's condition is aggravated,and severe pneumonia,ARDS,and MODS are present.This is of great significance for further exploration of the pathogenesis of influenza virus.