RESEARCH ARTICLE International Microbiology (2014) 17:185-193 doi:10.2436/20.1501.01.221. ISSN (print): 1139-6709. e-ISSN: 1618-1095 www.im.microbios.org Transforming activities of Chlamydia pneumoniae in human mesothelial cells Antonietta Rizzo 1 *, Caterina Romano Carratelli 1 , Anna De Filippis 1 , Nazario Bevilacqua 2 , Maria Antonietta Tufano 1 , Elisabetta Buommino 1 1 Department of Experimental Medicine, Second University of Naples, Naples, Italy. 2 Department of Clinical Pathology, A. Cardarelli Hospital, Naples, Italy Received 17 June 2014 · 29 October 2014 Summary. Knowledge in viral oncology has made considerable progress in the feld of cancer fght. However, the role of bacteria as mediators of oncogenesis has not yet been elucidated. As cancer still is the leading cause of death in developed countries, understanding the long-term effects of bacteria has become of great importance as a possible means of cancer prevention. This study reports that Chlamydia pneumoniae infection induce transformation of human mesothelial cells. Mes1 cells infected with C. pneumoniae at a multiplicity of infection of 4 inclusion-forming units/cell showed many intracellular inclusion bodies. After a 7-day infection an increased proliferative activity was also observed. Real-time PCR analysis revealed a strong induction of calretinin, Wilms’ tumour gene 1, osteopontin, matrix metalloproteinases-2, and membrane-type 1 metal- matrix metalloproteinases-2, and membrane-type 1 metal- membrane-type 1 metal- loproteinases gene expression in Mes1 cell, infected for a longer period (14 days). The results were confrmed by western blot analysis. Zymography analysis showed that C. pneumoniae modulated the in-vitro secretion of MMP-2 in Mes1 cells both at 7 and 14 days. Cell invasion, as measured by matrigel-coated flter, increased after 7 and 14 days infection with C. pneumoniae, compared with uninfected Mes1 cells. The results of this study suggest that C. pneumoniae infection might support cellular transformation, thus increasing lung cancer risk. [Int Microbiol 2014; 17(4):185-193] Keywords: Chlamydia pneumoniae · cytotoxicity · human mesothelial cells · cellular transformation · tumoral markers * Corresponding author: A. Rizzo Department of Experimental Medicine Second University of Naples Via Santa Maria di Costantinopoli, 16 80138 Napoli, Italy Tel. +39-815665656. Fax +39-815665662 E-mail: antonietta.rizzo@unina2.it Introduction Cancer is commonly defned as the uncontrolled growth of abnormal cells that have accumulated enough DNA damage to be freed from the normal restraints of the cell cycle. Al- though viral infections have been strongly associated with cancer [34,35], bacterial associations are also signifcant. Im- portant mechanisms by which bacterial agents may induce carcinogenesis include chronic infection, immune evasion, and immune suppression. Several pathogenic bacteria, par- ticularly those that can establish a persistent infection, can promote or initiate abnormal cell growth by evading the im- mune system or suppressing apoptosis [22]. In particular, some species or their toxins can alter host cell cycles or stim- ulate the production of infammatory substances linked to DNA damage [7,37]. A separate discussion applies to intracel- lular pathogens that survive by evading the ability of the host to identify them as foreign. Chlamydia pneumoniae is a Gram-negative bacillus and a compulsory intracellular parasite. Chlamydia pneumoniae in- fection is acquired during childhood, and the prevalence grad- ually increases to reach a maximum in middle age; it causes