OUTBREAK MDR STRAINS OF M. TUBERCULOSIS (MTB) INDUCE DIFFERENTIAL TNF-ALPHA SECRETION BY MACROPHAGES ALTERING CD54 EXPRESSION ON BRONCHIAL EPITHELIAL CELLS

KVIATCOVSKY D; BALBOA L; SCHIERLOH P; LÓPEZ B

Mar del Plata

Congreso; LXII Reunión Anual de la Sociedad Argentina de Inmunología; 2014

Sociedad Argentina de Inmunología (SAI)

Mtb infects mainly the lung by interacting with airway epithelium and resident macrophages (Mac). The bronchial epithelium secretes cytokines (CKs) upon interaction with Mtb or infected Mac. We have previously demonstrated that certain soluble factors released by Mac stimulated with MDR strains, M and Ra differentially modulate CD54 expression in the human bronchial epithelial cell line Calu-6. Thus, the aim of this work was to identify those soluble factors involved in CD54 regulation in airway epithelial cells. To do so, monocytes-derived Mac from healthy donors were stimulated with M, Ra or H37Rv strains for 6h at Mtb:Mac 1:2 or 1:5 ratios and TNF-alpha levels were determined by FACS and ELISA. In addition, Calu-6 cells were co-cultured with Mac or stimulated Mac-derived supernatants (Mac-SN) and CD54 expression was evaluated. To confirm the role of CKs on CD54 modulation, Calu-6 cells were treated with Mac-SN in the presence of a synthetic soluble TNF-alpha receptor (Etanercept) and/or anti-IL-1beta monoclonal antibody. Results: 1) M-stimulated Mac produced lower levels of released (n=7) or intracellular (n=9) TNF-alpha than H37Rv-stimulated Mac (p 0,05); 2) CD54 expression on Calu-6 cells was enhanced either by co-culturing with H37Rv- or Ra-stimulated Mac (p 0,05, n=6) or with its Mac-SN (p 0,05, n=7) unlike M strain. 3) This increase of CD54 expression on Calu-6 triggered by H37Rv- or Ra-stimulated Mac-SN could be inhibited by TNF-alpha neutralization but not by IL-1beta neutralization. Conclusion: CD54 modulation on bronchial epithelial cells could be mediated by early TNF-alpha release in Mtb stimulated Mac. Lack of CD54 up-regulation by M strain could be due to a deficie nt TNF-alpha production by Mac, being probably a new evasion mechanism employed by this strain to avoid adhesion/infiltration of immune-competent cells to pulmonary epithelium and their further activation, a necessary fact to control Mtb infection.