SUSCEPTIBILITY OF HUMAN MACROPHAGES TO CHLAMYDIAPNEUMONIAE INFECTION IN VITRO, ACTA UNIVERSITATIS OULUENSIS D Medica 1050

Chlamydia pneumoniae is an obligate intracellular gram-negative bacterium, which causes\nrespiratory infections in humans and may participate in the development of chronic diseases like\natherosclerosis, chronic obstructive lung disease, adult-onset asthma and late-onset Alzheimer¡¯s\ndisease. It can infect various cell types, e.g. vascular endothelial cells, smooth muscle cells and\nmonocyte-derived macrophages in vitro. It has been speculated that circulating macrophages\ndisseminate the infection in the body, and that genetically susceptible individuals become\nchronically infected.\nQuantification of C. pneumoniae growth inside cultured cells is needed when studying e.g. the\neffect of drugs or host cell factors on infectivity and replication. Conventionally this has been done\nby immunofluorescence staining and microscopic counting of chlamydial inclusions. However,\nthis method is usable only if the cell numbers do not fluctuate in cell culture vials and the\ninclusions are uniform. In macrophages, inclusions are often aberrant, their sizes vary and multiple\ninclusions are also seen. Therefore we developed a new method based on the real-time PCR\nquantification of chlamydial genomes adjusted to the number of human genomes and used it to\nquantify the exact amounts of C. pneumoniae in infected cells.\nThe susceptibility of monocyte-macrophages from healthy individuals to C. pneumoniae\ninfection in vitro was studied first. Intracellular growth of C. pneumoniae was used as an indicator\nof susceptibility to infection, and it was compared to serum levels of CRP, soluble CD14, human\nHSP-IgG, human HSP-IgA, C. pneumoniae IgG and IgA antibodies. The growth of C.\npneumoniae in infected macrophages was highly variable, ranging from 0 to 638 chlamydial\ngenomes per human genome. C. pneumoniae growth associated positively with serum C.\npneumoniae IgA (titer ¡Ý10) and hHSP-IgG and negatively with soluble CD14 concentration. The\nassociation between chlamydial IgA antibodies, hHSP-IgG and C. pneumoniae growth was\nstatistically significant only among men. Age did not correlate with the growth. Therefore we\nhypothesize that persons whose macrophages cannot restrict the growth of C. pneumoniae are\nmore prone to chronic infection by this agent.\nIn the next study, we evaluated the effects of innate immunity genes CD14 -260 C>T, TLR2\nArg753Gln, TLR4 Asp299Gly, LBP Phe436Leu and IL-6 -174 G>C polymorphisms on C.\npneumoniae growth in human macrophages in vitro. The growth of C. pneumoniae was highest in\nCD14 -260 C>T TT genotype cells and the difference to CC or CT genotype was statistically\nsignificant. The G-allele of the IL6 -174 G>C polymorphism had a positive influence on\nchlamydial growth; the difference was statistically significant only between CC and GC\ngenotypes. TLR2 Arg753Gln, TLR4 Asp299Gly, LBP Phe436Leu polymorphisms showed no\neffect on chlamydial growth.

ISBN-10:
978-951-42-6161-9
Kieli:
eng.
Sivumäärä:
114 s.
Tekijät:
Poikonen Kari
Tuotekoodi 013964
20,00 €