PKC-η-MARCKS Signaling Promotes Intracellular Survival of Unopsonized Burkholderia thailandensis

The regulatory role and mechanism of autophagy in energy metabolism-related hepatic fibrosis

Hepatic fibrosis is a key pathological process of chronic liver diseases, caused by alcohol, toxic and aberrant energy metabolism. It progresses to cirrhosis or even hepatic carcinoma without effective treatment. Studies have shown that autophagy has important regulatory effects on hepatic stellate cells (HSCs) energy metabolism, and then affect the activation state of HSCs. Autophagy maintains hepatic energy homeostasis, and the dysregulation of autophagy can lead to the activation of HSCs and the occurrence and development of hepatic fibrosis. It is necessary to explore the mechanism of autophagy in energy metabolism-related hepatic fibrosis. Herein, the current study summarizes the regulating mechanisms of autophagy through different targets and signal pathways in energy metabolism-related hepatic fibrosis, and discusses the regulatory effect of autophagy by natural plant-derived, endogenous and synthetic compounds for the treatment of hepatic fibrosis. A better comprehension of autophagy in hepatic stellate cells energy metabolism-related hepatic fibrosis may provide effective intervention of hepatic fibrosis, explore the potential clinical strategies and promote the drug treatment of hepatic fibrosis.

Autophagy May Allow a Cell to Forbear Pyroptosis When Confronted With Cytosol-Invasive Bacteria

Inflammatory caspases detect cytosol-invasive Gram-negative bacteria by monitoring for the presence of LPS in the cytosol. This should provide defense against the cytosol-invasive Burkholderia and Shigella species by lysing the infected cell via pyroptosis. However, recent evidence has shown caspase-11 and gasdermin D activation can result in two different outcomes: pyroptosis and autophagy. Burkholderia cepacia complex has the ability invade the cytosol but is unable to inhibit caspase-11 and gasdermin D. Yet instead of activating pyroptosis during infection with these bacteria, the autophagy pathway is stimulated through caspases and gasdermin D. In contrast, Burkholderia thailandensis can invade the cytosol where caspasae-11 and gasdermin D is activated but the result is pyroptosis of the infected cell. In this review we propose a hypothetical model to explain why autophagy would be the solution to kill one type of Burkholderia species, but another Burkholderia species is killed by pyroptosis. For pathogens with high virulence, pyroptosis is the only solution to kill bacteria. This explains why some pathogens, such as Shigella have evolved methods to inhibit caspase-11 and gasdermin D as well as autophagy. We also discuss similar regulatory steps that affect caspase-1 that may permit the cell to forbear undergoing pyroptosis after caspase-1 activates in response to bacteria with partially effective virulence factors.

Transcriptional profiling of human macrophages during infection with Bordetella pertussis

Bordetella pertussis, a strictly human re-emerging pathogen and the causative agent of whooping cough, exploits a broad variety of virulence factors to establish efficient infection. Here, we used RNA sequencing to analyse the changes in gene expression profiles of human THP-1 macrophages resulting from B. pertussis infection. In parallel, we attempted to determine the changes in intracellular B. pertussis-specific transcriptomic profiles resulting from interaction with macrophages. Our analysis revealed that global gene expression profiles in THP-1 macrophages are extensively rewired 6 h post-infection. Among the highly expressed genes, we identified those encoding cytokines, chemokines, and transcription regulators involved in the induction of the M1 and M2 macrophage polarization programmes. Notably, several host genes involved in the control of apoptosis and inflammation which are known to be hijacked by intracellular bacterial pathogens were overexpressed upon infection. Furthermore, in silico analyses identified large temporal changes in expression of specific gene subsets involved in signalling and metabolic pathways. Despite limited numbers of the bacterial reads, we observed reduced expression of majority of virulence factors and upregulation of several transcriptional regulators during infection suggesting that intracellular B. pertussis cells switch from virulent to avirulent phase and actively adapt to intracellular environment, respectively.

Protein Kinase C Isozymes and Autophagy during Neurodegenerative Disease Progression

Protein kinase C (PKC) isozymes are members of the Serine/Threonine kinase family regulating cellular events following activation of membrane bound phospholipids. The breakdown of the downstream signaling pathways of PKC relates to several disease pathogeneses particularly neurodegeneration. PKC isozymes play a critical role in cell death and survival mechanisms, as well as autophagy. Numerous studies have reported that neurodegenerative disease formation is caused by failure of the autophagy mechanism. This review outlines PKC signaling in autophagy and neurodegenerative disease development and introduces some polyphenols as effectors of PKC isozymes for disease therapy.