The lung as a parasite retention and destruction site in Trichinella infection. Costimulation of common mucosal immune system

GENTILINI MV, CALCAGNO M, SARACINO P, FALDUTO G, VENTURIELLO SM

Simposio; Keystone Symposia X5 Mucosal Biology: A Fine Balance between Tolerance and Immunity. Immunity in the Respiratory Tract: Challenges of the Lung Environment (X6); 2011

The parasite disease caused by Trichinella spiralis induces a response of the mucosal immune system (MIS) which leads to the rejection of adult worms (AW) from the intestine. We have recently demonstrated in Wistar rats that simultaneously to this intestinal response, and probably due to a costimulation process between mucosae, an inflammatory lung tissue is generated, featured by humoral, cellular and functional changes that are finally biased towards a Th2-type immune response. Considering that this parasite has a migratory stage (ms) and that during its way to striated muscles (from day 5 pi on) it goes through different organs including lungs, the aims of this work were to evaluate (on days 0, 6, 9 and 13 pi): 1-the presence and titer of specific antibody (Ab) isotypes to the ms surface in lung tissue extracts (LTE, n=8/dpi) by the indirect immunofluorescence test, 2-the cytotoxic capacity of lung cells and antibodies against the ms by antibody-dependent cell cytotoxicity in vitro assays, 3-the presence of ms in lung sections (H&E) and in enzymatic lung homogenates. Results showed 1-local production of anti-ms surface Abs on day 13 pi in 100% of the infected rats: IgG2a (titer=8), IgE (titer=16), IgG1 (titer¡Ý16) and IgA (undiluted LTE), 2-cytotoxic capacity of lung cells in the presence of anti-ms Abs (% ms mortality with Abs 45¡À7 vs 10¡À3 without Abs). Preliminary studies suggest the existence of a higher cytotoxic capacity of lung cells on day 6 pi in the presence of anti-ms Abs, 3-presence of ms in alveoli, lung parenchyma and homogenates. These results suggest that the inflammatory milieu developed at lung level plays a role in the host protection against the ms and postulate the lung as one of the parasite retention and destruction sites. Thus, the immunological protective mechanisms against the parasite are developed at both the intestinal (AW) and lung levels (ms). Finally, the correct stimulation of the host¡¯s MIS by specific immunization protocols could lead to the protection against Trichinella infection.