Correlation between persistent chlamydia pneumoniae infection and primary IgA nephropathy

To investigate the correlation between chlamydia pneumoniae (CP) infection and IgG nephropathy (IgAN). Seventy cases with primary IgAN were chosen along with 70 healthy blood donors and 12 cases which died of accidents, from which serum samples and kidney tissues obtained at autopsies were collected, respectively. CP IgG and CP IgA antibody titers in the serum were detected by using indirect immunofluorescence assay (IIF), and CP DNA in kidney tissues was detected using quantitative fluorescence PCR. The correlations of CP infection to positive CP DNA in kidney tissues, clinical manifestations of IgAN and pathological changes in kidney tissues were investigated. IgAN group had a significantly higher incidence of persistent CP infection than healthy blood donor group (P<0.01). No significant difference was found in the proportion of acute CP infection, previous infection and non-infection between different clinical subtypes of IgAN (P>0.05). The incidence of persistent CP infection in cases with severe proteinuria and persistent renal insufficiency was higher than in cases without severe proteinuria (P<0.05). Glomerular pathological injury scores and tubulointerstitial scores in cases with persistent CP infection were higher than those in cases without persistent CP infection (P<0.05). Renal pathological changes of cases with persistent CP infection were more severe than those of cases without persistent CP infection. Positive rate of CP DNA was higher among cases with severe proteinuria and persistent renal insufficiency than in cases without severe proteinuria (P=0.012). Glomerular pathological injury scores (P<0.05) and tubulointerstitial scores (P<0.01) in cases positive for CP DNA in kidney tissues were higher compared to negative cases; cases positive for CP DNA presented with more severe pathological changes than negative cases. Persistent CP infection was correlated with positive CP DNA in kidney tissues (P<0.01). The onset of IgAN was associated with persistent CP infection, but not significantly correlated with previous CP infection and acute CP infection.