Protective role for C3aR in experimental chronic pyelonephritis.

Emerging evidence suggest that C3aR plays important roles in homeostasis, host defense and disease. Although it is known that C3aR is protective in several models of acute bacterial infections, the role for C3aR in chronic infection is largely unknown. Here we show that C3aR is protective in experimental chronic pyelonephritis. Global C3aR deficient (C3ar-/- ) mice had higher renal bacterial load, more pronounced renal histological lesions, increased renal apoptotic cell accumulation, tissue inflammation and extracellular matrix deposition following renal infection with uropathogenic E. coli (UPEC) strain IH11128, compared to WT control mice. Myeloid C3aR deficient (Lyz2-C3ar-/- ) mice exhibited a similar disease phenotype to global C3ar-/- mice. Pharmacological treatment with a C3aR agonist reduced disease severity in experimental chronic pyelonephritis. Furthermore, macrophages of C3ar-/- mice exhibited impaired ability to phagocytose UPEC. Our data clearly demonstrate a protective role for C3aR against experimental chronic pyelonephritis, macrophage C3aR plays a major role in the protection, and C3aR is necessary for phagocytosis of UPEC by macrophages. Our observation that C3aR agonist curtailed the pathology suggests a therapeutic potential for activation of C3aR in chronic infection.

The atmospheric microplastics deposition contributes to microplastic pollution in urban waters.

Identifying and understanding the potential sources delivering microplastics into the urban water environment is imperative for microplastic pollution control. However, how atmospheric deposition contributes to microplastic pollution in the urban water environment is unclear. Therefore, this study investigated the contribution of atmospheric deposition to microplastic pollution in urban waters based on the analysis of the atmospheric deposition characteristics in the urban area. The results showed that microplastic deposition fluxes during wet weather and dry weather varied from 1.1 × 103±0.06×103 to 3.5 × 103±0.3 × 103 particles/m2/day and 0.91×103±0.09×103 to 1.6 × 103±0.1 × 103 particles/m2/day, respectively. The microplastics deposition flux showed moderate to strong correlations to atmospheric particulate matter concentrations, especially the PM2.5 concentration (R2 = 0.76-0.93), suggesting the regularly monitored PM2.5 concentration might be served as an indicator for microplastics deposition flux estimation. The deposited microplastics were mainly transparent fragments with an average size of 51-67 µm. Polyethylene and polypropylene were the most abundant plastic polymer, followed by polyethylene terephthalate and polyamide. The comparison of microplastics collected during different weather conditions suggested that rain events could increase microplastics deposition fluxes when air quality conditions are similar. Particularly, rains promoted the deposition of fibrous microplastics as well as smaller microplastics. The estimated daily microplastics deposition in the whole city region suggested more microplastics were deposited in summer and winter. The total quantity of microplastics deposited in the urban environment could reach 1.7-12 times of those discharged from treated wastewater. Among them, 10% would directly deposit to urban waters in the studied city region, while the others may also enter the urban waters through runoff. The results of this study highlighted that the atmospheric microplastics deposition is an important source for microplastics, especially smaller ones, to enter the urban waters, which could not be ignored during microplastics pollution control.

Revisiting Microplastics in Landfill Leachate: Unnoticed Tiny Microplastics and Their Fate in Treatment Works.

Due to the environmental risks caused by microplastics, understanding the sources and characteristics of microplastics and cutting off their routes into the environment are crucial. However, so far, studies on microplastics in the landfill leachate system (a major pathway of microplastics into the environment) are still limited, especially for tiny particles <50 µm that might have higher risks to the environment. This study investigated the microplastics in landfill leachate and in leachate treatment works, with a size detection limit down to 10 µm. The results showed that the microplastics particle and mass concentrations in the untreated leachate were 235.4 ± 17.1 item/L and 11.4 ± 0.8 µg/L, respectively, with tiny particles (<50 µm) accounting for over 50%. Overall, 27 polymeric materials were detected in leachate samples, with polyethylene and polypropylene being the most abundant in the untreated leachate. The neutral buoyancy of microplastics (average density: 0.94 g/cm3), together with irregular shapes, suggested they may be difficult to be removed by sedimentation. Further exploring the fate of microplastics in leachate treatment works showed that the membrane treatment effectively reduced microplastics loading to 0.14% for particle and 0.01% for mass, but the average particle density rose. The differences in polymeric materials distribution at different sampling locations and the presence of membrane-related polymer in membrane treatment effluent suggested tiny microplastics could be generated and released from membrane systems. Moreover, this study discovered that the sludge dewatering liquor could contain a high amount of microplastics, and the estimated particle loading was about 3.6 times higher than that in dewatered sludge. This suggested a new approach to microplastics mitigation through separating microplastics from the sludge dewatering liquor before its recirculation.

Effects of PAK4/LIMK1/Cofilin-1 signaling pathway on proliferation, invasion, and migration of human osteosarcoma cells.

PURPOSE: To explore the effects of PAK4/LIMK1/Cofilin-1 signaling pathway on the proliferation, invasion, and migration of human osteosarcoma cells. METHODS: The expression of PAK4/LIMK1/Cofilin-1 was detected by immunohistochemistry in osteosarcoma tissues. The osteosarcoma cell line MG63 was transfected and divided into Mock, Control siRNA, si-PAK4, LIMK1, and si-PAK4+LIMK1 groups. Then, the cellular biological features of MG63 cells were detected by CCK-8, wound-healing, Transwell, and flow cytometry methods. The relationship of PAK4 and LIMK1 was performed by co-immunoprecipitation test, and the protein expression of PAK4/LIMK1/Cofilin-1 was determined by Western blotting. Finally, the effect of PAK4 on the growth of osteosarcoma was verified by subcutaneous transplantation model of osteosarcoma in nude mice. RESULTS: The expression of PAK4/LIMK1/Cofilin-1 in both osteosarcoma tissues and cells was up-regulated. Positive PAK4, LIMK1, and Cofilin-1 expressions in osteosarcoma were associated with the clinical stage, distant metastasis, and tumor grade. The MG63 cell viability, migration, and invasion, as well as the expression of PAK4, p-LIMK/LIMK, and p-Cofilin-1/Cofilin-1, were restrained by the knock down of PAK4 while it promoted apoptosis. PAK4 silencing also suppressed the growth of subcutaneous transplanted tumor in nude mice. Co-immunocoprecipitation showed that LIMK and PAK4 protein can form complex in osteosarcoma cells. Besides, LIMK1 overexpression reversed the inhibition effect of PAK4 siRNA on the growth of osteosarcoma cells. CONCLUSION: The expression of PAK4/LIMK1/Cofilin-1 pathway in osteosarcoma tissues was up-regulated. Thus, PAK4 inhibition may restrict the osteosarcoma cell proliferation, invasion, and migration but promote its apoptosis via decreasing the activity of LIMK1/Cofilin-1 pathway.