Abstract
Objective To explore the efficacy of ketogenic diet(KD)for airway inflammation in neutrophilic asthma(NA)mice and its effects on nucleotide-binding oligomerization domain-like receptor protein 3(NLRP3)/macrophage axis.Methods Twenty-four BALB/c female mice were randomly divided into 4 groups:normal diet(ND)group,neutrophilic asthma(NA)model group,etogenic diet intervention group(KD+NA),and NLRP3 inhibitor(MCC950)group.The mice in KD+NA group were fed with ketogenic diet,while the mice in the other groups were given normal diet.At day 1,7,14,chicken ovulin(OVA)combined with lipopolysaccharide(LPS)was intraperitoneally injected for sensitization in NA group,KD+NA group and MCC950 group,while phosphate buffered sa-line(PBS)was injected in ND group.At day 21-34,the mice in ND group were atomized with normal saline,the mice in the other groups were atomized and stimulated with 5%OVA solution.The mice in MCC950 group were intraperitoneally injected with NLRP3 inhibitor 30 min before atomization,once every other day,while the mice in the other groups were injected with the same amount of PBS.During the nebulization process,the symptoms of mice such as nasal scratching,sneezing and wheezing were scored according to the behavioral scoring criteria and summed up.At day 35,the mice were sacrificed to collect serum,bronchoalveolar lavage fluid(BALF)and lung tissue for subsequent analysis.HE staining was used to observe the infiltration and injury of airway inflammatory cells.The expressions of interleukin-1β(IL-1β),IL-17 and tumor necrosis factor-α(TNF-α)in BALF were detected by enzyme-linked immunosorbent assay.Immunohistochemical analysis was used to analyze the protein expression levels of NLRP3,cysteine protease-1(Caspase-1),and apoptosis-related granular protein(ASC)containing CARD domain in lung tissue.The ratio of M1/M2 type macro-phages was quantitatively analyzed by flow cytometry.Results Compared with ND group,the behavioral score of mice was signifi-cantly increased in NA group(P<0.001).Compared with NA group,the behavioral scores of mice in MCC950 group and KD+NA group were significantly decreased(P<0.01).Compared with ND group,HE staining results showed that airway inflammatory cell infil-tration and tissue damage were significantly aggravated in NA group,and the inflammation score increased significantly(P<0.001),the total number of inflammatory cells in BALF,the proportion of neutrophils,and the levels of inflammatory factors IL-1β,IL-17 and TNF-α significantly increased(P<0.001),and the protein expression levels of NLRP3,Caspase-1 and ASC in lung tissue and the pro-portion of M1/M2 type macrophages also increased significantly(P<0.001).Compared with NA group,HE staining results showed that the infiltration of airway inflammatory cells and tissue damage were significantly reduced in MCC950 group and KD+NA group,the in-flammation score decreased significantly(P<0.001),the total number of inflammatory cells,the proportion of neutrophils,and the le-vels of inflammatory factors IL-1β,IL-17 and TNF-α in BALF significantly decreased(P<0.01),and the expression levels of NLRP3,Caspase-1 and ASC proteins and the proportion of M1/M2 type macrophages in lung tissue also significantly decreased(P<0.01).Conclusion KD can effectively improve the airway inflammation in NA mice by inhibiting the activation of NLRP3 inflammasome,regulating the polarization of macrophages from M1 type to M2 type,and downregulating the expression of pro-inflammatory factors.关键词
哮喘/生酮饮食/中性粒细胞哮喘/中性粒细胞/NLRP3/巨噬细胞Key words
asthma/ketogenic diet/neutrophil asthma/neutrophils/NLRP3/macrophage分类
临床医学
