Acanthamoeba profilin elicits allergic airway inflammation in mice

The Recombinant Profilin from Free-Living Amoebae Induced Allergic Immune Responses via TLR2

Background

Repeated exposure to recombinant profilin from Acanthamoeba (rAc-PF) induces allergic airway responses in vitro and in vivo. Based on the role of toll-like receptors (TLRs) in allergic airway diseases, TLRs play a central role in innate immune responses and the adaptive immune system and regulate responses against antigens through antigen-specific receptors. In this study, we attempted to determine the molecular mechanisms underlying rAc-PF-induced allergic inflammatory responses.

Methods

We determined the correlation between rAc-PF and TLRs and analyzed changes in allergic immune responses after blocking multiple TLR signaling under rAc-PF treatment conditions in vitro. We also compared allergic inflammatory responses in TLR2 knockout (KO) and wild-type (WT) mice. To investigate the effect of TLR2 on antigen prototyping and T cell activation in the inflammatory response induced by rAc-PF, we assessed maturation of BMDCs and polarization of naïve T cells by rAc-PF stimulation. Additionally, we compared changes in inflammation-related gene expression by rAc-PF treatment in primary lung epithelial cells isolated from TLR2 KO and WT mice.

Results

The rAc-PF treatment was increased the expression level of TLR2 and 9 in vitro. But, there were not significantly differ the others TLRs expression by rAc-PF treated group. And then, the mRNA expression levels of inflammation-related genes were reduced in the TLR2 or TLR9 antagonist-treated groups compared to those in the rAc-PF alone, were no difference the treated with the other TLRs (TLR4, 6, and 7/8) antagonist. The difference was higher in the TLR2 antagonist group. Additionally, the levels of airway inflammatory disease indicators were lower in the TLR2 KO group than in the WT group after rAc-PF treatment. Furthermore, the expression of bone marrow-derived dendritic cell (BMDC) surface molecular markers following rAc-PF stimulation was lower in TLR2 KO mice than in WT mice, and TLR2 KO in BMDCs resulted in a remarkable decline in Th2/17-related cytokine production and Th2/17 subset differentiation. In addition, the expression levels of rAc-PF-induced inflammatory genes were reduced inTLR2 KO primary lung cells compared to those in normal primary lung cells.

Conclusion

These results suggest that the rAc-PF-induced airway inflammatory response is regulated by TLR2 signaling.

Toxoplasma gondii profilin induces NLRP3 activation and IL-1β production/secretion in THP-1 cells

Toxoplasma gondii is a highly prevalent protozoan that infects a broad spectrum of warm-blooded animals. Profilin is a critical protein that plays a role in the movement and invasion of T. gondii. In the current study, we assessed how profilin stimulates inflammasomes and how it induces transcription and secretion of IL-1β. For this purpose, we assessed the level of TLR 2, 4, 5, and 9 expressions in a THP-1 cell line treated with profilin from T. gondii (TgP). In addition, we analyzed the expression levels of various inflammasomes, as well as IL-1β, and IL-18 in THP-1 cells treated with the NLRP3 inhibitor MCC950. TgP significantly increased the expression of TLR5 but the expression of TLR2, 4, and 9 was not significantly increased. In addition, TgP did not significantly increase the level of inflammasomes after 5 h. Treatment with MCC950 significantly reduced NLRP3 and IL-1β on both transcription and protein levels. Although the transcription level of NLRP3 was reduced 5 h after treatment with TgP, western blot analysis showed an increase in NLRP3. The western blot and ELISA analysis also showed that TgP increased both pro- and mature IL-1β. In summary, our study showed that NLRP3 most probably plays a pivotal role in the expression and production levels of IL-1β during the interaction between TgP and macrophages.

Toll-like receptor 2 mediates Acanthamoeba-induced allergic airway inflammatory response in mice

BACKGROUND

Repeated intranasal exposure to Acanthamoeba has been revealed to induce allergic airway inflammatory responses in mice. Based on the role of toll-like receptors (TLRs) in the pathogenesis of allergic asthma, TLRs form a link between innate and adaptive immune responses, and play an important role in the activation of various cells in the innate immune system.

METHODOLOGY/PRINCIPAL FINDINGS

To determine the TLRs that are related to these immune responses, we assessed the expression levels of inflammation-related genes in mouse lung epithelial (MLE)-12 cells treated with excretory-secretory proteins (ES-P) of the Acanthamoeba strain (KA/E2) with or without the TLR antagonists. The expression levels of inflammation-related genes, such as eotaxin, TARC, macrophage-derived chemokine (MDC), and TSLP, in the TLR2 and TLR9 antagonist treatment groups were decreased, compared to those in the ES-P alone or other TLR antagonist treatment groups. In particular, a greater decrease in the relevant gene expression levels was found in the TLR2 antagonist treatment group than in the TLR9 antagonist treatment group. Allergic airway inflammation was evaluated in the wild-type (WT) and TLR2 knockout (KO) groups following KA/E2 exposure. Based on the results, allergic airway inflammatory responses (airway resistance value, inflammatory cell infiltration, Th2-related cytokine expression, mucin production, and metaplasia of lung epithelial cells and goblet cells) by KA/E2 were reduced in the TLR2 KO groups. In addition, TLR2 knockout BMDCs displayed lower activation of surface markers owing to ES-P stimulation than normal BMDCs, and KA/E2 ES-P-treated TLR2-depleted BMDCs produced fewer Th2 cytokine-expressing cells from naïve T cells than WT BMDCs. When ES-P was administered after primary lung cells were obtained from WT and TLR2 KO mice, the expression levels of inflammation-related genes were found to be significantly decreased in TLR2 KO cells compared to those in WT cells.

CONCLUSIONS

These results suggest that TLR2 is involved in lung inflammatory response activation in KA/E2 intranasal infection, especially in airway tissue.

Free-Living Amoeba Vermamoeba vermiformis Induces Allergic Airway Inflammation

The high percentage of Vermamoeba was found in tap water in Korea. This study investigated whether Vermamoeba induced allergic airway inflammation in mice. We selected 2 free-living amoebas (FLAs) isolated from tap water, which included Korean FLA 5 (KFA5; Vermamoeba vermiformis) and 21 (an homolog of Acanthamoeba lugdunensis KA/ E2). We axenically cultured KFA5 and KFA21. We applied approximately 1 × 106 to mice’s nasal passages 6 times and investigated their pathogenicity. The airway resistance value was significantly increased after KFA5 and KFA21 treatments. The eosinophil recruitment and goblet cell hyperplasia were concomitantly observed in bronchial alveolar lavage (BAL) fluid and lung tissue in mice infected with KFA5 and KFA21. These infections also activated the Th2-related interleukin 25, thymic stromal lymphopoietin, and thymus and activation-regulated chemokines gene expression in mouse lung epithelial cells. The CD4+ interleukin 4+ cell population was increased in the lung, and the secretion of Th2-, Th17-, and Th1-associated cytokines were upregulated during KFA5 and KFA21 infection in the spleen, lung-draining lymph nodes, and BAL fluid. The pathogenicity (allergenicity) of KFA5 and KFA21 might not have drastically changed during the long-term in vitro culture. Our results suggested that Vermamoeba could elicit allergic airway inflammation and may be an airway allergen.

Decrease in LINC00963 attenuates the progression of pulmonary arterial hypertension via microRNA-328-3p/profilin 1 axis

Background

Pulmonary arterial hypertension (PAH) is a severe cardiopulmonary disease characterized by vascular hyperplasia and remodeling. Long noncoding RNA LINC00963 can regulate cell proliferation and metastasis in nonsmall cell lung cancer. However, the function of LINC00963 on PAH progression is rarely reported.

Methods

Quantitative real‐time PCR was used to determine the expression levels of LINC00963, microRNA (miRNA)‐328‐3p, and profilin 1 (PFN1), as well as vascular endothelial growth factor (VEGF), fibroblast growth factor 2 (FGF‐2), and hypoxia‐inducible factor (HIF)‐α. The protein level of PFN1 was measured by western blotting. The viability and migration of hypoxia‐induced pulmonary arterial smooth muscle cells (PASMCs) were assessed by 3‐(4, 5‐dimethyl‐2‐thiazolyl)‐2, 5‐diphenyl‐2‐h‐tetrazolium bromide, and transwell assays, respectively. The target relationships between miR‐328‐3p and LINC00963/PFN1 were confirmed by dual‐luciferase reporter assay. A PAH mouse model was conducted to explore the effects of hypoxia on cardiopulmonary functions.

Results

In hypoxia‐induced PASMCs and PAH mouse model, high expression levels of LINC00963 and PFN1, and low expression of miR‐328‐3p, were determined. The viability, migration of hypoxia‐induced PASMCs, the expression of VEGF, FGF‐2, and HIF‐α were significantly repressed by transfection of si‐LINC00963 or miR‐328‐3p mimics. The inhibitory effects of LINC00963 silencing on cell viability, migration, and the levels of VEGF, FGF‐2, and HIF‐α were partly eliminated by miR‐328‐3p inhibitor or increasing the expression of PFN1. Hypoxia treatment increased the levels of RVSP, mPAP, and RV/(LV+S), as well as the thickness of pulmonary artery wall.

Conclusions

Silencing of LINC00963 ameliorates PAH via modulating miR‐328‐3p/PFN1.

Comparative proteomic profiling of newly acquired, virulent and attenuated Neoparamoeba perurans proteins associated with amoebic gill disease

The causative agent of amoebic gill disease, Neoparamoeba perurans is reported to lose virulence during prolonged in vitro maintenance. In this study, the impact of prolonged culture on N. perurans virulence and its proteome was investigated. Two isolates, attenuated and virulent, had their virulence assessed in an experimental trial using Atlantic salmon smolts and their bacterial community composition was evaluated by 16S rRNA Illumina MiSeq sequencing. Soluble proteins were isolated from three isolates: a newly acquired, virulent and attenuated N. perurans culture. Proteins were analysed using two-dimensional electrophoresis coupled with liquid chromatography tandem mass spectrometry (LC-MS/MS). The challenge trial using naïve smolts confirmed a loss in virulence in the attenuated N. perurans culture. A greater diversity of bacterial communities was found in the microbiome of the virulent isolate in contrast to a reduction in microbial community richness in the attenuated microbiome. A collated proteome database of N. perurans, Amoebozoa and four bacterial genera resulted in 24 proteins differentially expressed between the three cultures. The present LC-MS/MS results indicate protein synthesis, oxidative stress and immunomodulation are upregulated in a newly acquired N. perurans culture and future studies may exploit these protein identifications for therapeutic purposes in infected farmed fish.