Toll-like receptors and autophagy in interstitial lung diseases

Pasteurella multocida causes liver injury in ducks by mediating inflammatory, apoptotic and autophagic pathways

Pasteurella multocida.(PM) infection is a major cause of avian cholera, but the pathogenesis of the disease is unknown. The purpose of this study was to further understand the host response to infection by using a duck model of PM, 20 female ducks were divided into two groups (n = 10). One group was infected with PM, while the other served as an uninfected control group. The ducks were observed after infection and samples were collected for testing. In this study, we report the mechanism of PM-induced inflammation to further mediate apoptosis and autophagic signaling pathways in liver cells. Our results demonstrated that PM infection initially induces hemorrhagic and necrotic lesions in the liver tissue of duck, promoting inflammasome assembly and release, triggering inflammation. The TLR4/NF-κB axis activated and interacted with multiple inflammation-related proteins, including TNF-α and IL-1β, which affected apoptosis and autophagy. Tumor necrosis factor induced hepatocyte apoptosis was implicated in a wide range of liver diseases; the release of TNF-α and activation with NF-κB further incite apoptotic pathways,such as Bax/BCL2/caspase to promote apoptotic genes APAF1, Bax, Caspase3, BCL-2, p53, and Cytc expression. Finally, PM-induced autophagy suppressed liver injury by promoting the Beclin-1, LC3B, p62, and mTOR. Thus, liver injury caused by PM via promoting autophagy was induced. In conclusion, we analyzed the liver injury of ducks infected with PM, and confirmed that inflammation appeared in the liver; this was followed by the intricate interplay between inflammation, apoptosis, and autophagy signaling pathways. The observed results provided a reference basis for studying pathogenic mechanisms of PM-host interactions.

Role and clinical implication of autophagy in COVID-19

The ongoing coronavirus disease 2019 (COVID-19) pandemic constitutes a serious public health concern worldwide. Currently, more than 6 million deaths have occurred despite drastic containment measures, and this number is still increasing. Currently, no standard therapies for COVID-19 are available, which necessitates identifying effective preventive and therapeutic agents against COVID-19. However, developing new drugs and vaccines is a time-consuming process, and therefore, repurposing the existing drugs or redeveloping related targets seems to be the best strategy to develop effective therapeutics against COVID-19. Autophagy, a multistep lysosomal degradation pathway contributing to nutrient recycling and metabolic adaptation, is involved in the initiation and progression of numerous diseases as a part of an immune response. The key role of autophagy in antiviral immunity has been extensively studied. Moreover, autophagy can directly eliminate intracellular microorganisms by selective autophagy, that is, "xenophagy." However, viruses have acquired diverse strategies to exploit autophagy for their infection and replication. This review aims to trigger the interest in the field of autophagy as an antiviral target for viral pathogens (with an emphasis on COVID-19). We base this hypothesis on summarizing the classification and structure of coronaviruses as well as the process of SARS-CoV-2 infection and replication; providing the common understanding of autophagy; reviewing interactions between the mechanisms of viral entry/replication and the autophagy pathways; and discussing the current state of clinical trials of autophagy-modifying drugs in the treatment of SARS-CoV-2 infection. We anticipate that this review will contribute to the rapid development of therapeutics and vaccines against COVID-19.

Research Progress in the Molecular Mechanisms, Therapeutic Targets, and Drug Development of Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal interstitial lung disease. Recent studies have identified the key role of crosstalk between dysregulated epithelial cells, mesenchymal, immune, and endothelial cells in IPF. In addition, genetic mutations and environmental factors (e.g., smoking) have also been associated with the development of IPF. With the recent development of sequencing technology, epigenetics, as an intermediate link between gene expression and environmental impacts, has also been reported to be implicated in pulmonary fibrosis. Although the etiology of IPF is unknown, many novel therapeutic targets and agents have emerged from clinical trials for IPF treatment in the past years, and the successful launch of pirfenidone and nintedanib has demonstrated the promising future of anti-IPF therapy. Therefore, we aimed to gain an in-depth understanding of the underlying molecular mechanisms and pathogenic factors of IPF, which would be helpful for the diagnosis of IPF, the development of anti-fibrotic drugs, and improving the prognosis of patients with IPF. In this study, we summarized the pathogenic mechanism, therapeutic targets and clinical trials from the perspective of multiple cell types, gene mutations, epigenetic and environmental factors.

A review on possible mechanistic insights of Nitazoxanide for repurposing in COVID-19

The global pandemic of Coronavirus Disease 2019 (COVID-19) has brought the world to a grinding halt. A major cause of concern is the respiratory distress associated mortality attributed to the cytokine storm. Despite myriad rapidly approved clinical trials with repurposed drugs, and time needed to develop a vaccine, accelerated search for repurposed therapeutics is still ongoing. In this review, we present Nitazoxanide a US-FDA approved antiprotozoal drug, as one such promising candidate. Nitazoxanide which is reported to exert broad-spectrum antiviral activity against various viral infections, revealed good in vitro activity against SARS-CoV-2 in cell culture assays, suggesting potential for repurposing in COVID-19. Furthermore, nitazoxanide displays the potential to boost host innate immune responses and thereby tackle the life-threatening cytokine storm. Possibilities of improving lung, as well as multiple organ damage and providing value addition to COVID-19 patients with comorbidities, are other important facets of the drug. The review juxtaposes the role of nitazoxanide in fighting COVID-19 pathogenesis at multiple levels highlighting the great promise the drug exhibits. The in silico data and in vitro efficacy in cell lines confirms the promise of nitazoxanide. Several approved clinical trials world over further substantiate leveraging nitazoxanide for COVID-19 therapy.

γ-d-Glutamyl-meso-diaminopimelic acid induces autophagy in bovine hepatocytes during nucleotide-binding oligomerization domain 1-mediated inflammation

Autophagy is a crucial cellular homeostatic process and an important part of the host defense system. Dysfunction in autophagy enhances tissue susceptibility to infection and multiple diseases. However, the role of nucleotide oligomerization domain 1 (NOD1) in autophagy in bovine hepatocytes is not well known. Therefore, our aim was to study the contribution of NOD1 to autophagy during inflammation in response to a specific ligand γ-d-glutamyl-meso-diaminopimelic acid (iE-DAP). To achieve this aim, hepatocytes separated from cows at ∼160 days in milk (DIM) were divided into six groups: the nontreated control (CON) group, the rapamycin-treated (RAP) group as a positive control, the iE-DAP-treated (DAP) group, the 3-MA-treated (MA) group, the rapamycin with 3-MA (RM) group, and the iE-DAP with 3-MA (DM) group. iE-DAP administration significantly increased the mRNA expression of NOD1, ATG16L1, RIPK2, ULK1, AMBRA1, DFCP1, WIPI1, ATG5, ATG7, ATG10, ATG4A, IκBα, NF-κB, CXCL1, IL-8, and STAT6 and significantly decreased PIK3C3. The protein expression of NOD1, p-IκBα, p-NF-κB/p-p65, LC3-II, ATG5, and beclin 1 were significantly upregulated and that of SQSTM1/p62, p-mTOR, and FOXA2 were significantly downregulated in response to iE-DAP. iE-DAP also induced the formation of LC3-GFP autophagic puncta in bovine hepatocytes. We also knocked down the NOD1 with siRNA. NOD1 silencing suppressed the autophagy and inflammation-related genes and proteins. The application of the autophagy inhibitor increased the expression of inflammatory molecules and alleviated autophagy-associated molecules. Taken together, these findings suggest that NOD1 is a key player for regulating both ATG16L1 and RIPK2-ULK1 directed autophagy during inflammation in response to iE-DAP in bovine hepatocytes.

Effects of New NSAID-CAI Hybrid Compounds in Inflammation and Lung Fibrosis

Pulmonary fibrosis is a severe lung disease with progressive worsening of dyspnea, characterized by chronic inflammation and remodeling of lung parenchyma. Carbonic anhydrases are a family of zinc-metallo-enzymes that catalyze the reversible interconversion of carbon-dioxide and water to bicarbonate and protons. Carbonic Anhydrase Inhibitor (CAI) exhibited anti-inflammatory effects in animals with permanent-middle-cerebral artery occlusion, arthritis and neuropathic pain. The pharmacological profile of a new class of hybrid compounds constituted by a CAI connected to a Nonsteroidal-Anti-Inflammatory Drug (NSAID) was studied in the modulation of inflammation and fibrosis. In-vitro tests were performed to assess their effects on cyclo-oxygenase enzyme (COX)-1 and COX-2, namely inhibition of platelet aggregation and thromboxane B2 production in the human-platelet-rich plasma, and reduction of Prostaglandin-E2 production in lipopolysaccharide-treated-RAW-264.7 macrophage cell line. The activity of compound 3, one of the most active, was studied in a model of bleomycin-induced lung fibrosis in C57BL/6 mice. The hybrid compounds showed a higher potency in inhibiting PGE₂ production, but not in modifying the platelet aggregation and the TXB₂ production in comparison to the reference molecules, indicating an increased activity in COX-2 inhibition. In the in-vivo murine model, the compound 3 was more effective in decreasing inflammation, lung stiffness and oxidative stress in comparison to the reference drugs given alone or in association. In conclusion, these CAI-NSAID hybrid compounds are promising new anti-inflammatory drugs for the treatment of lung chronic inflammatory diseases.

Xenophagy in innate immunity: A battle between host and pathogen

Autophagy is a fundamental bulk intracellular degradation and recycling process that directly eliminates intracellular microorganisms through "xenophagy" in various types of cells, especially in macrophages. Meanwhile, bacteria have evolved strategies and cellular self-defense mechanisms to prevent autophagosomal degradation and even attack the immune system of host. The lack of knowledge about the roles of autophagy in innate immunity severely limits our understanding of host defensive system and the development of farmed industry consisting of aquaculture. Increasing evidence in recent decades has shown the importance of autophagy. This review focuses on the triggering of xenophagy, targeting of invading pathogens to autophagosomes and elimination in the autophagolysosomes during pathogen infection. How the pathogen can escape from the xenophagy pathway was also discussed. Overall, we aim to reduce diseases and improve industrial production in aquaculture by providing theoretical and technical guidance on xenophagy.

Normal lung development needs self-eating

Autophagy is a Greek-derived concept that means "self-eating" and is increasingly recognized as an important regulator of homeostasis and disease. In this issue of the JCI, Yeganeh et al. report the important finding that intrinsic autophagy is required for normal progression of lung development. Conditional deletion of the beclin 1-encoding gene (Becn1) specifically within lung epithelial cells of embryonic mice resulted in neonatal lethal respiratory distress that was associated with negative impacts on airway branching and differentiation of airway epithelial cell lineages. The authors draw speculative parallels with the alveolar simplification phenotype of bronchopulmonary dysplasia in premature human infants and suggest that stimulation of autophagy by cAMP-dependent kinase activation might conceivably rescue these phenotypes.

The Processes and Mechanisms of Cardiac and Pulmonary Fibrosis

Fibrosis is the formation of fibrous connective tissue in response to injury. It is characterized by the accumulation of extracellular matrix components, particularly collagen, at the site of injury. Fibrosis is an adaptive response that is a vital component of wound healing and tissue repair. However, its continued activation is highly detrimental and a common final pathway of numerous disease states including cardiovascular and respiratory disease. Worldwide, fibrotic diseases cause over 800,000 deaths per year, accounting for ~45% of total deaths. With an aging population, the incidence of fibrotic disease and subsequently the number of fibrosis-related deaths will rise further. Although, fibrosis is a well-recognized cause of morbidity and mortality in a range of disease states, there are currently no viable therapies to reverse the effects of chronic fibrosis. Numerous predisposing factors contribute to the development of fibrosis. Biological aging in particular, interferes with repair of damaged tissue, accelerating the transition to pathological remodeling, rather than a process of resolution and regeneration. When fibrosis progresses in an uncontrolled manner, it results in the irreversible stiffening of the affected tissue, which can lead to organ malfunction and death. Further investigation into the mechanisms of fibrosis is necessary to elucidate novel, much needed, therapeutic targets. Fibrosis of the heart and lung make up a significant proportion of fibrosis-related deaths. It has long been established that the heart and lung are functionally and geographically linked when it comes to health and disease, and thus exploring the processes and mechanisms that contribute to fibrosis of each organ, the focus of this review, may help to highlight potential avenues of therapeutic investigation.