Targeting autophagy regulation in NLRP3 inflammasome-mediated lung inflammation in COVID-19

Carbon black nanoparticles and cadmium co-exposure aggravates bronchial epithelial cells inflammation via autophagy-lysosome pathway

Carbon black nanoparticles (CBNPs) and cadmium (Cd) are major components of various air pollutants and cigarette smoke. Autophagy and inflammation both play critical roles in understanding the toxicity of particles and their components, as well as maintaining body homeostasis. However, the effects and mechanisms of CBNPs and Cd (CBNPs-Cd) co-exposure on the human respiratory system remain unclear. In this study, a CBNPs-Cd exposure model was constructed to explore the respiratory toxicity and combined mechanism of these chemicals on the autophagy-lysosome pathway in the context of respiratory inflammation. Co-exposure of CBNPs and Cd significantly increased the number of autophagosomes and lysosomes in human bronchial epithelial cells (16HBE) and mouse lung tissues compared to the control group, as well as the groups exposed to CBNPs and Cd alone. Autophagic markers, LC3II and P62 proteins, were up-regulated in 16HBE cells and mouse lung tissues after CBNPs-Cd co-exposure. However, treatment with Cq inhibitor (an indicator of lysosomal acid environment) resulted in a substantial decreased co-localization fluorescence of LC3 and lysosomes in the CBNPs-Cd combination group compared with the CBNPs-Cd single and control groups. No difference in LAMP1 protein expression was observed among the exposed groups. Adding 3 MA alleviated inflammatory responses, while applying the Baf-A1 inhibitor aggravated inflammation both in vitro and in vivo following CBNPs-Cd co-exposure. Factorial analysis showed no interaction between CBNPs and Cd in their effects on 16HBE cells. We demonstrated that co-exposure to CBNPs-Cd increases the synthesis of autophagosomes and regulates the acidic environment of lysosomes, thereby inhibiting autophagy-lysosome fusion and enhancing the inflammatory response in both 16HBE cells and mouse lung. These findings provide evidence for a comprehensive understanding of the interaction between CBNPs and Cd in mixed pollutants, as well as for the prevention and control of occupational exposure to these two chemicals.

Pathway analysis of spermidine anti-oxidative stress and inducing autophagy in granulosa cells of Sichuan white geese

Spermidine, a natural polyamine, has been proven antioxidant function, but its pathway and mechanism of action remain unclear. Based on the oxidative stress model by 3-nitropropionic acid (3-NPA), the study explored the pathways by spermidine to rescue oxidative stress via autophagic process in goose granulosa cells by RNA-seq and RNA interference. In transcriptional regulation, in addition to KEGG pathways related to cell proliferation and differentiation, lots of KEGG pathways associated with inflammation, metabolism, and signaling were also significantly enriched in 3-NPA vs. 3-NPA + spermidine treatments. Six key genes (JUN, CD44, KITLG, RND2, BMP4 and KALRN) involved in spermidine-mediated anti-oxidative stress were screened. Furthermore, the experimental results showed that spermidine (80 μmol/L) significantly increased autophagic gene expression in goose granulosa cells, while EP300-siRNA or MAP1S-siRNA also significantly increased autophagic process. The autophagic gene expressions were no difference between EP300-siRNA and EP300-siRNA + spermidine treatments, although spermidine significantly increased autophagic process of granulosa cells compared to MAP1S-siRNA alone. In addition, inhibition of mTOR pathway significantly increased autophagic gene expression, which was further enhanced by spermidine in combined with mTOR inhibitor. These results suggest that spermidine can alleviate oxidative stress by inducing autophagy regulated by EP300, MAP1S and mTOR as well as regulating other independent gene expressions in goose granulosa cells.

Rapamycin-based inhaled therapy for potential treatment of COPD-related inflammation: production and characterization of aerosolizable nano into micro (NiM) particles

Our paper describes the production and characterization of inhalable microparticles loaded with nanoparticles for the lung administration of rapamycin (Rapa). In detail, core-shell lipid/polymer hybrid nanoparticles loaded with Rapa (Rapa@Man-LPHNPs) were produced with mean size of about 128 nm and slightly negative ζ potential (-13.8 mV). A fluorescent graft polyaspartamide-poly(lactic-co-glycolic acid) copolymer (PHEA-g-RhB-g-PLGA) for use as the polymeric core was obtained by nanoprecipitation, while an appropriate mixture of DPPC and mannosylated phospholipid (DSPE-PEG2000-Man) was used to provide the macrophage-targeting lipid shell. The successful formation of Rapa@Man-LPHNPs was confirmed by TEM and DSC analyses. The loaded drug (4.3 wt% of the total weight) was slowly released from the polymeric core and protected from hydrolysis, with the amount of intact drug after 24 h of incubation in the medium being equal to 74 wt% (compared to 40% when the drug is freely incubated at the same concentration). To obtain a formulation administrable by inhalation, Rapa@Man-LPHNPs were entrapped inside PVA : LEU microparticles by using the nano into micro (NiM) strategy, specifically by spray drying (SD) in the presence of a pore-forming agent. In this way, NiM particles with geometric and theoretical aerodynamic diameters equal to 4.52 μm and 3.26 μm, respectively, were obtained. Furthermore, these particles showed optimal nebulization performance, having an FPF and an MMAD equal to 27.5% and 4.3 μm, respectively.

Aucubin alleviates methotrexate-induced enteritis in rats by inducing autophagy

One of the toxic side effects of methotrexate (MTX) is enteritis. Aucubin, an iridoid glycoside derived from traditional medicinal herbs, has been proven to have anti-inflammation, anti-apoptosis and anti-oxidation properties. This work explored the effect and mechanism of aucubin in treating MTX-induced enteritis in a rat model. Two doses of aucubin (5 and 10 mg/kg) were adopted for the assessment of its pharmacological activity. We observed that in rats with MTX-induced enteritis, the body weight and small intestinal weight decreased. The intestine barrier was injured, as reflected by pathological examinations and an increase in D-lactate and diamine oxidase concentration in serum. Intestinal inflammation was shown by the observation of macrophages in the intestine and the concentrations of inflammatory cytokines tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in serum. The NLR family pyrin domain containing 3 (NLRP3) inflammasome was shown to be activated by the enhancement of NLRP3, cleaved-caspase 1, IL-18 and IL-1β. Moreover, autophagy was reflected by transmission electron microscopy as slightly induced, along with changes in autophagy-related markers microtubule-associated protein 1 light chain 3 (LC3) and Beclin1. Remarkably, aucubin treatment attenuated the MTX-induced disease activity index increase, intestinal damage, inflammatory response and NLRP3 inflammasome activation, but provoked autophagy. Rapamycin, an autophagy activator, showed similar therapeutic effects to aucubin on MTX-induced enteritis. However, 3-methyladenine, an autophagy inhibitor, reversed the protective effects of aucubin. These findings prompted the hypothesis that aucubin alleviates MTX-induced enteritis by aggravating autophagy. This study might provide evidence for further investigation on the therapeutic role of aucubin in MTX-resulted enteritis.

Role of α-synuclein in microglia: autophagy and phagocytosis balance neuroinflammation in Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is the second most common neurodegenerative disease, and is characterized by accumulation of α-synuclein (α-syn). Neuroinflammation driven by microglia is an important pathological manifestation of PD. α-Syn is a crucial marker of PD, and its accumulation leads to microglia M1-like phenotype polarization, activation of NLRP3 inflammasomes, and impaired autophagy and phagocytosis in microglia. Autophagy of microglia is related to degradation of α-syn and NLRP3 inflammasome blockage to relieve neuroinflammation. Microglial autophagy and phagocytosis of released α-syn or fragments from apoptotic neurons maintain homeostasis in the brain. A variety of PD-related genes such as LRRK2, GBA and DJ-1 also contribute to this stability process.

OBJECTIVES

Further studies are needed to determine how α-syn works in microglia.

METHODS

A keyword-based search was performed using the PubMed database for published articles.

CONCLUSION

In this review, we discuss the interaction between microglia and α-syn in PD pathogenesis and the possible mechanism of microglial autophagy and phagocytosis in α-syn clearance and inhibition of neuroinflammation. This may provide a novel insight into treatment of PD.

Exploring the Role of Immune System and Inflammatory Cytokines in SARS-CoV-2 Induced Lung Disease: A Narrative Review

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative pathogen of coronavirus disease 19 (COVID-19). COVID-19 can manifest with a heterogenous spectrum of disease severity, from mild upper airways infection to severe interstitial pneumonia and devastating acute respiratory distress syndrome (ARDS). SARS-CoV-2 infection may induce an over activation of the immune system and the release of high concentrations of pro-inflammatory cytokines, leading to a "cytokine storm", a recognized pathogenetic mechanism in the genesis of SARS-CoV-2-induced lung disease. This overproduction of inflammatory cytokines has been recognized as a poor prognostic factor, since it can lead to disease progression, organ failure, ARDS and death. Moreover, the immune system shows dysregulated activity, particularly through activated macrophages and T-helper cells and in the co-occurrent exhaustion of lymphocytes. We carried out a non-systematic literature review aimed at providing an overview of the current knowledge on the pathologic mechanisms played by the immune system and the inflammation in the genesis of SARS-CoV-2-induced lung disease. An overview on potential treatments for this harmful condition and for contrasting the "cytokine storm" has also been presented. Finally, a look at the experimented experimental vaccines against SARS-CoV-2 has been included.