ABSTRACT
Objective To investigate the function of triggering receptor expresses on myeloid cells receptor-1 (TREM-1) in lymphocyte differentiation and regulation of Aspergillus infected immunosuppressed rats.Methods Cyclophosphamide (CTX) was intraperitoneally injected and Fumigatus spore suspension was inhaled by percutaneous tracheostomy to establish the immunosuppressive invasive pulmonary aspergillosis (IPA) rat model.After 24 h, 48 h, 72 h and 96 h inoculation, rats were sacrificed.Lung tissue specimens, bronchoalveolar lavage fluid (BALF) , and plasma samples were collected.Plasma and BALF sTREM-1, plasma T cell-specific transcription factor (T-box expressed in T cells, T-bet) and eomesodermin(Eomes) were detected by ELISA.Biopsy specimens of lung tissue were used for periodic acid-schiff (PAS) staining and culture.Results The mortality rate of immunosuppressed rats after Aspergillus inhalation for 96 h was as high as 54.4％.Biopsy of lung tissue suggested acute inflammatory cell infiltration, interstitial lung congestion, alveolar structural damage, and visible Aspergillus hyphae in alveoli.Compared with normal control group[(110.50 ± 7.70)ng/L], plasma sTREM-1 in study groups were significantly increased [IPA : (146.77 ± 10.41) ng/L;CXT + IPA at 24 h : (226.00 ± 11.88) ng/L;CTX + IPA at 48 h : (200.77 ± 10.63) ng/L;P ＜ 0.05], so were T-bet levels [IPA : (561.17 ± 7.23) μg/L;CXT + IPA at 24 h : (647.00 ± 33.03) μg/L;CTX + IPA at 48 h : (619.23 ± 87.44) μg/L;control group : (340.03 ± 26.32) μg/L;respectively, P ＜0.05].However, plasma Eomes levels in IPA group, CTX + IPA at 24 h and 48 h were significantly lower compared with that in normal controls [IPA : (7.96 ± 0.65) ng/L;CXT + IPA at 24 h : (3.97 ± 0.35) ng/L;CTX + IPA at 48 h : (4.00 ± 0.74) ng/L;control group : (8.38 ± 0.51) ng/L;respectively,P ＜0.001].Compared with those in CTX + IPA vaccination after 24 h and 48 h, plasma sTREM-1 [(106.67 ±7.64)ng/L;(133.27 ± 32.79) ng/L] and T-bet [(299.64±63.07)μg/L;(398.02 ± 109.22) μg/L] in CTX + IPA at 72 h and 96 h inoculation were significantly lower (P ＜ 0.001).While Eomes [(8.38 ± 0.54) ng/L;(8.40 ± 0.70) ng/L] raised significantly higher (P ＜ 0.001).Compared with the control group, sTREM-1 levels in BALF of IPA + CTX 24 h, 48 h, 72 h, and 96 h groups were consistently high (P ＜ 0.05).Pearson correlation analysis showed that sTREM-1 and T-bet had a significant positive correlation (r =0.91, P ＜ 0.001), yet Eomes was negatively correlated with them (r =-0.788, P ＜ 0.001).Conclusions sTREM-1 in rat plasma and BALF appears highly expressed in immune compromised Aspergillus infected rat model.Plasma sTREM-1 is closely correlated with T-bet and Eomes levels, which suggests that TREM-1 may be involved in lymphocytic regulation and differentiation during fungal infection.