Host response during Yersinia pestis infection of human bronchial epithelial cells involves negative regulation of autophagy and suggests a modulation of survival-related and cellular growth pathways

The Messenger Apps of the cell: Extracellular Vesicles as Regulatory Messengers of Microglial Function in the CNS

The intense effort of investigators, in particular during the past decade, has highlighted the importance of extracellular vesicles (EVs) such as exosomes in regulating both innate and adaptive immunity in the course of a variety of infections, with clear implications for development of novel vaccines, therapeutics, and diagnostics. Current and future efforts now need to focus strongly on teasing apart the intricate and complex molecular mechanisms that operate during EV regulation of immunity. In this review, we discuss recent advances that bear on our current understanding of how EVs, including exosomes, can contribute to the innate immune functions of microglia within the central nervous system (CNS), and we also highlight future important mechanistic questions that need to be addressed. In particular, recent findings that highlight the crosstalk between autophagy and exosome pathways and their implications for innate immune functions of microglia will be presented. Microglial activation has been shown to play a key role in neuroAIDS, a neuro-infectious disease for which the importance of exosome functions, including exosome-autophagy interplay, has been reported. The importance of exosomes and exosome-autophagy crosstalk involving microglia has also been shown for the Parkinson's disease (PD), a neurodegenerative disease that is thought to be linked with immune dysfunction and involve infectious agents as trigger. Considering the accumulation of recent findings and the vibrancy of the EV field, we anticipate that future studies will continue to have a deep impact on our understanding of the CNS pathologies that are influenced by the functions of microglia and of the infectious disease mechanisms in general. Graphical Abstract.

A Comprehensive Review of Autophagy and Its Various Roles in Infectious, Non-Infectious, and Lifestyle Diseases: Current Knowledge and Prospects for Disease Prevention, Novel Drug Design, and Therapy

Autophagy (self-eating) is a conserved cellular degradation process that plays important roles in maintaining homeostasis and preventing nutritional, metabolic, and infection-mediated stresses. Autophagy dysfunction can have various pathological consequences, including tumor progression, pathogen hyper-virulence, and neurodegeneration. This review describes the mechanisms of autophagy and its associations with other cell death mechanisms, including apoptosis, necrosis, necroptosis, and autosis. Autophagy has both positive and negative roles in infection, cancer, neural development, metabolism, cardiovascular health, immunity, and iron homeostasis. Genetic defects in autophagy can have pathological consequences, such as static childhood encephalopathy with neurodegeneration in adulthood, Crohn's disease, hereditary spastic paraparesis, Danon disease, X-linked myopathy with excessive autophagy, and sporadic inclusion body myositis. Further studies on the process of autophagy in different microbial infections could help to design and develop novel therapeutic strategies against important pathogenic microbes. This review on the progress and prospects of autophagy research describes various activators and suppressors, which could be used to design novel intervention strategies against numerous diseases and develop therapeutic drugs to protect human and animal health.

The responses of lungs and adjacent lymph nodes in responding to Yersinia pestis infection: A transcriptomic study using a non-human primate model

Initiation of treatment during the pre-symptomatic phase of Yersinia pestis (Y. pestis) infection is particularly critical. The rapid proliferation of Y. pestis typically couples with the manifestation of common flu-like early symptoms that often misguides the medical intervention. Our study used African green monkeys (AGM) that did not exhibit clear clinical symptoms for nearly two days after intranasal challenge with Y. pestis and succumbed within a day after showing the first signs of clinical symptoms. The lung, and mediastinal and submandibular lymph nodes (LN) accumulated significant Y. pestis colonization immediately after the intranasal challenge. Hence, organ-specific molecular investigations are deemed to be the key to elucidating mechanisms of the initial host response. Our previous study focused on the whole blood of AGM, and we found early perturbations in the ubiquitin-microtubule-mediated host defense. Altered expression of the genes present in ubiquitin and microtubule networks indicated an early suppression of these networks in the submandibular lymph nodes. In concert, the upstream toll-like receptor signaling and downstream NFκB signaling were inhibited at the multi-omics level. The inflammatory response was suppressed in the lungs, submandibular lymph nodes and mediastinal lymph nodes. We posited a causal chain of molecular mechanisms that indicated Y. pestis was probably able to impair host-mediated proteolysis activities and evade autophagosome capture by dysregulating both ubiquitin and microtubule networks in submandibular lymph nodes. Targeting these networks in a submandibular LN-specific and time-resolved fashion could be essential for development of the next generation therapeutics for pneumonic plague.

Autophagy as a double-edged sword in pulmonary epithelial injury: a review and perspective

Pulmonary epithelial cells form the first line of defense of human airways against foreign irritants and also represent as the primary injury target of these pathogenic assaults. Autophagy is a revolutionary conserved ubiquitous process by which cytoplasmic materials are delivered to lysosomes for degradation when facing environmental and/or developmental changes, and emerging evidence suggests that autophagy plays pivotal but controversial roles in pulmonary epithelial injury. Here we review recent studies focusing on the roles of autophagy in regulating airway epithelial injury induced by various stimuli. Articles eligible for this purpose are divided into two groups according to the eventual roles of autophagy, either protective or deleterious. From the evidence summarized in this review, we draw several conclusions as follows: 1) in all cases when autophagy is decreased from its basal level, autophagy is protective; 2) when autophagy is deleterious, it is generally upregulated by stimulation; and 3) a plausible conclusion is that the endosomal/exosomal pathways may be associated with the deleterious function of autophagy in airway epithelial injury, although this needs to be clarified in future investigations.

Human bocavirus induces apoptosis and autophagy in human bronchial epithelial cells

Human bocavirus (HBoV) is classified in the Bocavirus genus within the Parvoviridae family, first identified from children with respiratory diseases. Previous studies have investigated the stimulating effect of HBoV on cell apoptosis and autophagy. In the present study, human bronchial epithelial cells (HBECs) were utilized to examine the mechanism of HBoV recombination expressing vector (pWHL-1) on the promotion of cell apoptosis and autophagy. The results from the present study indicated that pWHL-1 inhibited the proliferation of HBECs in a time-dependent manner. Additionally, pWHL-1induced apoptosis, as substantiated by an increased apoptotic rate and presence of autophagosomes. Following pWHL-1 transfection, proliferating cell nuclear antigen, caspase-3 and B cell lymphoma 2 (Bcl-2) protein expression levels were decreased, with the exception of Bcl-2 associated × (Bax) protein, which increased. mRNA and protein expression levels of microtubule-associated protein 1A/1B-light chain 3 (LC3) II and autophagy protein 5 were increased in pWHL-1-transfected HBECs, whereas, the mRNA and protein levels of LC3I and sequestosome 1 were decreased. Notably, pWHL-1 also enhanced the activation of p53 and inhibited AKT activation in HBECs. Results from the present study suggest that pWHL-1 induces apoptosis and autophagy, thus providing a novel insight into the effect of HBoV and its uses in respiratory diseases.

Proteomic discovery of host kinase signaling in bacterial infections

Protein phosphorylation catalyzed by protein kinases acts as a reversible molecular switch in signal transduction, providing a mechanism for the control of protein function in cellular processes. During microbial infection, cellular signaling essentially contributes to immune control to restrict the dissemination of invading pathogens within the host organism. However, pathogenic microbes compete for the control of host signaling to create a beneficial environment for successful invasion and infection. Although efforts to achieve a better understanding of the host–pathogen interaction and its molecular consequences have been made, there is urgent need for a comprehensive characterization of infection‐related host signaling processes. System‐wide and hypothesis‐free analysis of phosphorylation‐mediated host signaling during host–microbe interactions by mass spectrometry (MS)‐based methods is not only promising in view of a greater understanding of the pathogenesis of the infection but also may result in the identification of novel host targets for preventive or therapeutic intervention. Here, we review state‐of‐the‐art MS‐based techniques for the system‐wide identification and quantitation of protein phosphorylation and compare them to array‐based phosphoprotein analyses. We also provide an overview of how phosphoproteomics and kinomics have contributed to our understanding of protein kinase‐driven phosphorylation networks that operate during host–microbe interactions.

A reverse-phase protein microarray-based screen identifies host signaling dynamics upon Burkholderia spp. infection

Burkholderia is a diverse genus of gram-negative bacteria that causes high mortality rate in humans, equines and cattle. The lack of effective therapeutic treatments poses serious public health threats. Developing insights toward host-Burkholderia spp. interaction is critical for understanding the pathogenesis of infection as well as identifying therapeutic targets for drug development. Reverse-phase protein microarray technology was previously proven to identify and characterize novel biomarkers and molecular signatures associated with infectious disease and cancer. In the present study, this technology was utilized to interrogate changes in host protein expression and phosphorylation events in macrophages infected with a collection of geographically diverse strains of Burkholderia spp. The expression or phosphorylation state of 25 proteins was altered during Burkholderia spp. infections of which eight proteins were selected for further characterization by immunoblotting. Increased phosphorylation of AMPK-α1, Src, and GSK3β suggested the importance of their roles in regulating Burkholderia spp. mediated innate immune response. Modulating the inflammatory response by perturbing their activities may provide therapeutic routes for future treatments.