PAS-1, an Ascaris suum Protein, Modulates Allergic Airway Inflammation via CD8+ ãäTCR+ and CD4+ CD25+ FoxP3+ T Cells

We have previously demonstrated that PAS-1, a 200 kDa protein from Ascaris suum, has a potent immunomodulatory effect on humoral and cell-mediated responses induced by APAS-3 (an allergenic protein from A. suum) or unrelated antigens. In this study, we investigated the mechanisms by which PAS-1 is able to induce this effect on an allergic airway inflammation induced by OVA in mice. C57BL/6 mice were adoptively transferred on day 0 with seven different PAS-1-primed cell populations: PAS-1-primed CD19+ or B220+ or CD3+ or CD4+ or CD8+ or CD4+ CD25- or CD4+ CD25+ lymphocytes. These mice were immunized twice with OVA and alum by intraperitoneal route (days 0 and 7) and challenged twice by intranasal route (days 14 and 21). Two days after the last challenge, the airway inflammation was evaluated by antibody levels, cellular migration, eosinophil peroxidase levels, cytokine and eotaxin production, and pulmonary mechanical parameters. Among the adoptively transferred primed lymphocytes, only CD4+ CD25+, CD8+ or the combination of both T cells impaired the production of total IgE and OVA-specific IgE and IgG1 antibodies, eosinophilic airway inflammation, Th2-type cytokines (IL-4, IL-5 and IL-13), eotaxin release and airway hyperreactivity. Moreover, airway recruited cells from CD4+ CD25+ and CD8+ T-cell recipient secreted more IL-10/TGF-â and IFN-ã, respectively. Moreover, we found that PAS-1 expands significantly the number of CD4+ CD25+ FoxP3+ and CD8+ ãäTCR+ cells. In conclusion, these findings demonstrate that the immunomodulatory effect of PAS-1 is mediated by these T-cell subsets.

PAS-1, a protein from Ascaris suum, modulates allergic inflammationvia IL-10 and IFN-c, but not IL-12

Helminths and their products have a profound immunomodulatory effect upon the inductive and effectorphases of inflammatory responses, including allergy. We have demonstrated that PAS-1, a protein isolatedfrom Ascaris suum worms, has an inhibitory effect on lung allergic inflammation due to its abilityto down-regulate eosinophilic inflammation, Th2 cytokine release and IgE antibody production. Here,we investigated the role of IL-12, IFN-c and IL-10 in the PAS-1-induced inhibitory mechanism using amurine model of asthma. Wild type C57BL/6, IL-12 / , IFN-c / and IL-10 / mice were immunized withPAS-1 and/or OVA and challenged with the same antigens intranasally. The suppressive effect of PAS-1was demonstrated on the cellular influx into airways, with reduction of eosinophil number and eosinophilperoxidase activity in OVA + PAS-1-immunized wild type mice. This effect well correlated with a significantreduction in the levels of IL-4, IL-5, IL-13 and eotaxin in BAL fluid. Levels of IgE and IgG1antibodies were also impaired in serum from these mice. The inhibitory activity of PAS-1 was alsoobserved in IL-12 / mice, but not in IFN-c / and IL-10 / animals. These data show that IFN-c andIL-10, but not IL-12, play an important role in the PAS-1 modulatory effect.

Early stages ofAscaris suuminduce airway inflammation andhyperreactivity in a mouse model

The inflammatory and functional changes that occur in murinelung after infection with 2500 infectiveAscaris suumeggswere studied in this work. A sequential influx of neutrophils,mononuclear cells and eosinophils occurred into airwaysconcomitantly with migration of larvae from liver to thelungs. Histological analysis of the lung showed a severe intraalveolarhaemorrhage at the peak of larval migration (day 8)and the most intense inflammatory cell infiltrate on day 14.AscarisL3 were found in alveolar spaces and inside bronchioleson day 8. The number of eosinophils was elevated inthe blood on days 8 and 14. The peak of eosinophil influx intothe lung was at day 14, as indicated by the high levels of eosinophilperoxidase activity, followed by their migration into theairways. The antibody response against egg and larval antigensconsisted mainly of IgG1 and IgM, and also of IgE andanaphylactic IgG1, that cross-reacted with adult worm antigens.Total IgE levels were substantially elevated during theinfection. Measurement of lung mechanical parametersshowed airway hyperreactivity in infected mice. In conclusion,the murine model ofA. suuminfection mimics the Th2-induced parameters observed in pigs and humans and can beused to analyse the immunoregulatory properties of thishelminth.

Anti-inflammatory activity of PAS-1, a protein component of Ascaris suum

Background: Recently, we identified a 200 kDa protein (PAS-1) from Ascaris suum worms, that suppresses the humoral immune response. Here, the effect of PAS-1 on inflammatory leukocyte migration induced by bacterial lipopolysaccharide (LPS) was investigated. Methods: Cellular migration and cytokine release, stimulated by LPS or LPS+PAS-1, were analyzed in air pouches induced in the shaved back of BALB/c mice. Cytokines were determined by ELISA and RT-PCR on air pouch exudates and in vitro stimulated peritoneal macrophages. Results: The significant cellular influx induced by LPS, consisting predominantly of neutrophils, was highly suppressed in the presence of PAS-1, but not a non-related protein. PAS-1 led also to a marked reduction of TNF-á, IL-1â and IL-6 levels in both LPS-stimulated air pouches and peritoneal macrophage cultures. In contrast, PAS-1 induced a significant increase of IL-10 and TGF-â production. Conclusions: These results demonstrate that PAS-1 has a potent anti-inflammatory activity, probably due to the stimulation of regulatory cytokines in macrophages, thus leading to the inhibition of pro-inflammatory cytokine production.

Immunoglobulin E is not required for but enhances airway inflammation and hyperresponsiveness

The aim of this study was to investigate the role of immunoglobulin E (IgE) in the late phase reaction (LPR) of murine experimental asthma. Our model consisted of an implant of DNP-conjugated, heat-coagulated hen's egg white (DNP-EWI), followed 14 days later by an intratracheal challenge with aggregated DNP-ovalbumin. Airway inflammation was analyzed 48 h after challenge and compared with a similarly immunized group of mice with highly suppressed humoral response due to anti-ì and anti-ä antibody treatment. Total number of cells in the bronchoalveolar lavage (BAL) (with predominance of eosinophils) and EPO activity in the lung homogenate were increased in the DNP-EWI-immunized group compared with immunosuppressed or nonimmunized mice. However, the cellular infiltration and EPO activity observed in the immunosuppressed group were still significantly above those obtained in the nonimmunized group, indicating that inhibition of antibody production did not completely prevent the inflammatory manifestations in BAL and lung. Airway hyperresponsiveness to methacoline was obtained in DNP-EWI-immunized mice, but the respiratory mechanical parameters returned to normal levels in the immunosuppressed group. When these mice were reconstituted with monoclonal anti-DNP antibodies, only IgE, but not IgG1, restored lung inflammation and decreased the conductance of the respiratory system, therefore, increasing hyperresponsiveness. These results indicate that antibodies are not essential for induction of LPR in the lung. However, IgE enhances pulmonary inflammation and hyperresponsiveness.