| [Objective] To investigate the association between Chlamydia peneumoniae(Cpn),human papillomavirus(HPV)and the risk of lung cancer.[Methods] 1.A case-control study was conducted.449 newly diagnosed cases with lung cancer and 512 healthy control subjects were frequency matched by gender and age.Serum Cpn Ig A and Ig G infections were detected by micro-immunofluorescence,and dietary risk scores were calculated using dietary frequency tables.The methods of chi-square test,stratified analysis,and unconditional logistic regression analysis were used to calculate the adjusted odds ratio(OR)and 95% confidence interval(95%CI).Crossover analysis,logistic regression and the excel table made by Andersson were used to analyze the combined and interaction effects of risk factors.2.Each six primary lung cancer patients with serological Cpn antibody positive and negative were selected for integrative analyses of methylome and transcriptome by microarrays.Differentially methylation sites and differentially expressed genes were identified in the methylation and expression profiles,respectively.Cpn-related lung cancer methylation genes(target genes)were introduced into the gene ontology(GO)and KEGG function enrichment analysis to reveal potentially functional methylation abnormal genes associated with Cpn infection.The methylation levels of the differentially methylated sites were verified quantitatively,and the average methylation levels of each DNA fragment and Cp G site were compared by t-test or Wilcoxon Rank Sum test.3.A series of 140 lung cancer patients were examined with HPV DNA in both lung tumor specimens and adjacent normal specimens from Fujian province.Twenty-one of the most clinically relevant HPV types from the highly conserved L1 region of the viral genome were analyzed using the PCR amplification and was followed by reverse hybridization with specific probes.Chi-square test of paired design was used to test the differences of HPV positive rates between lung cancer specimens and adjacent normal specimens.Chi-square test and Fisher's exact test were used to analyze the differences of HPV positive rate of tumor specimens on factors as gender,age,histological subtype,clinical stage,smoking status and alcohol consumption.In HPV negative and positive groups of lung cancer specimens,the distribution of blood and lung function indicators was analyzed by rank sum test.4.We did a literature search on Pub Med,Ovid and Web of Science to identify case-control studies and cohort studies that detected HPV in lung carcinomas through a system review and meta-analysis.We included studies that tested 30 or more cases and were published before Feb 28,2017.We collected information about gender,smoking status,HPV detection methods,HPV types,materials and clinical features.If it was not possible to abstract the required information directly from the papers,we contacted the authors.A meta-analysis was performed to calculate the pooled effect sizes(OR/RR)with 95%CI including subgroup analysis and meta-regression to explore sources of heterogeneity,by Stata 13.0 software.[Results] 1.Cpn infection was a risk factor of lung cancer.After adjustment for confounding factors,the risk of lung cancer in patients with Cpn Ig G antibody positive was 1.37 times higher than that with Cpn Ig G antibody negative(95%CI: 0.98-1.92).The risk of lung cancer in patients with Cpn Ig A antibody positive was 1.65 times higher than that with Cpn Ig A antibody negative(95%CI: 1.19-2.30).The risk of lung cancer was obviously elevated,along with the increase of antibodies positive numbers as well as the antibody titers,and all of them met dose-response relationship(P trend < 0.05).Cpn infection was more closely associated with smokers,drinkers,and men in lung cancer.Cpn infection and smoking had a synergistic effect on lung cancer.The association between Chlamydia trachomatis(Ctr),Chlamydia psittaci(Cps)infection and the risk of lung cancer was not statistically significant.2.Diet could be having an influence on lung cancer.Reducing wheat flour(<3 times per week),potatoes(<1 time per week),vegetables(<2 times per day),fruits(<3 times per week)and fish(<3 times per week)intake was significantly associated with increased risk of lung cancer,and a comprehensive diet risk score was established accordingly.The stratification results of Cpn Ig G and Ig A showed that the higher the dietary risk score,the greater the risk of lung cancer(Ptrend<0.05),and the strength of the association between dietary risk score and lung cancer risk in Cpn-positive was higher than that in Cpn-negative.There was combination and synergy between Cpn infection and dietary risk scores on lung cancer.3.293 aberrant methylation genes(target genes)of Cpn-associated lung cancer was found.The target genes were enriched in several representative pathways,including NEFM and NEFL enrichment in neurofilament cytoskeleton organization(GO: 0060052)and neurofilament bundle assembly(GO: 0033693)in biological processes,neurofilament(GO: 0005883)in cellular components and amyotrophic lateral sclerosis(KEGGID: 05014)in KEGG pathway;DRD5 enrichment in dopamine neurotransmitter receptor activity,coupled via Gs(GO: 0001588)and dopamine neurotransmitter receptor activity(GO: 0004952)in molecular functions;IKBKE and RIPK3 enrichment in nuclear factor-kappa B-inducing kinase activity(GO: 0004704)in molecular functions;TGFBR1 enrichment in transforming growth factor beta receptor homodimeric complex(GO: 0070022)in cellular components and TGF-? signaling pathway(KEGGID: 04350)in KEGG pathway.According to the quantitative analysis of DNA methylation,only the methylation level of RIPK3 promoter region was significantly different between Cpn-positive cancer and adjacent tissues,but not between Cpn-negative cancer and adjacent tissues.4.HPV was detected in 13 of the 140 tumor specimens and in 16 of the paired normal lung tissues.There was no significant correlation between HPV and lung cancer(P=0.607).Neither demographic characteristics nor clinical features were found with significant differences on HPV in lung cancer tissues(P>0.05).There were differences in platelet count,plateletcrit,residual volume,functional residualcapacity and residual volume / total lung capacity in HPV negative group and positive group(P<0.05).5.36 case-control studies,contributing data for 6,980 cases of lung cancer and 7,474 controls from 17 countries and one cohort study with 24,162 exposed and 1,026,986 unexposed from China were included.HPV infection was associated with cancer of lung,pooled OR was 3.64(95%CI: 2.60-5.08),calculated with the random-effects model.Pooled OR for allogeneic case-control studies,self-matched case-control studies and nested case-control studies were 6.71(95%CI: 4.07-11.07),2.59(95%CI: 1.43-4.69)and 0.92(95%CI: 0.63-1.36),respectively.Pooled OR for HPV 16 and HPV 18 infection,were 3.14(95%CI: 2.07-4.76)and 2.25(95%CI: 1.49-3.40),respectively.We also found that HPV infection may be associated with squamous cell carcinoma,adenocarcinoma and small cell carcinoma.Subgroup analyses revealed the possible sources of heterogeneity: study design,gender,smoking,HPV detection method,HPV subtype,histological type,pathological stage and tissue differentiation.[Conclusions] 1.Chronic Cpn infection is a risk factor of lung cancer(especially for men with a history of smoking and drinking).Compared with Cpn Ig G,Ig A is more closely associated with lung cancer,and combined detection of both antibodies is more effective in predicting the risk of lung cancer.The timely treatment of lung infections and dietary patterns rich in wheat flour,potatoes,vegetables,fruits,and fish may have public health implications for lung cancer prevention.2.RIPK3 Overexpression,through the hypomethylation of its promoter region,which may play a key role in regulating programmed necrosis and activating NF-?B transcription factors,may be involved in the development and progression of Cpn-related lung cancer.3.Our data showed that HPV was not significantly associated with the risk of lung cancer in Fujian.HPV infection may affect lung residual function by causing condyloma lesions of bronchial epithelial.4.There is evidence that HPV infection,especially HPV 16 and HPV 18 infection,significantly increase the risk of lung cancer.Future research needs to focus attention toward whether an HPV vaccine can effectively reduce the incidence of lung cancer. |
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