Cerebrospinal fluid molecular demonstration of Chlamydia pneumoniae DNA is associated to clinical and brain magnetic resonance imaging activity in a subset of patients with relapsing-remitting multiple sclerosis

To further explore the link between Chlamydia pneumoniae and multiple sclerosis (MS), we examined cerebrospinal fluid (CSF) samples from 71 patients with MS and from 72 patients suffering from other inflammatory neurological disorders (OIND) or noninflammatory neurological disorders (NIND). All samples were analysed by a touchdown nested polymerase chain reaction (n-PCR) for C. pneumoniae with primer sets which amplify target sequence genes encoding the major outer membrane protein (MOMP), the 16S rRNA and the Hsp-70 protein. A molecular study was also performed to evaluate genetic diversity among isolates of C. pneumoniae and to compare chlamydial sequences. PCR was found positive in 36.6% of total MS, in 28.1% of OIND and in 37.5% of NIND patients, without any statistical differences among the various groups examined. CSF PCR evidence of C. pneumoniae was significantly more frequent in relapsing-remitting (RR) than in secondary progressive (SP) (P < 0.001) and in primary progressive (PP)MS (P < 0.05), in clinically active than in clinically stable MS (P < 0.05) and in MRI active than in MRI inactive MS (P < 0.001). The analysis of CSF expression of each single C. pneumoniae-specific gene revealed that detectable levels of MOMP were significantly more frequent in MS patients with relapse (P < 0.05), whereas PCR positivity for MOMP and 16S rRNA genes were more represented in MS patients with clinical and MRI evidence of disease activity (P < 0.05). Similar rates for MOMP and 16S rRNA genes were detected in CSF of both MS patients and controls, whereas CSF PCR positivity for Hsp-70 gene was observed in only three active RR MS patients. Sequence analysis revealed significant homologies with C. pneumoniae compared to other Chlamydial spp. These findings confirm that the C. pneumoniae detection within the central nervous system (CNS) is not selectively restricted to MS, but accounts in a variety of neurological diseases. In addition, our results suggest that CSF C. pneumoniae-specific DNA detection can occur in a subset of MS patients with clinical and MRI active RR form in whom a C. pneumoniae brain chronic persistent infection may play a significant role in the development of disease.