Aspergillus fumigatus escape mechanisms from its harsh survival environments

Aspergillus fumigatus is a ubiquitous pathogenic mold and causes several diseases, including mycotoxicosis, allergic reactions, and systemic diseases (invasive aspergillosis), with high mortality rates. In its ecological niche, the fungus has evolved and mastered many reply strategies to resist and survive against negative threats, including harsh environmental stress and deficiency of essential nutrients from natural environments, immunity responses and drug treatments in host, and competition from symbiotic microorganisms. Hence, treating A. fumigatus infection is a growing challenge. In this review, we summarized A. fumigatus reply strategies and escape mechanisms and clarified the main competitive or symbiotic relationships between A. fumigatus, viruses, bacteria, or fungi in host microecology. Additionally, we discussed the contemporary drug repertoire used to treat A. fumigatus and the latest evidence of potential resistance mechanisms. This review provides valuable knowledge which will stimulate further investigations and clinical applications for treating and preventing A. fumigatus infections. KEY POINTS: • Harsh living environment was a great challenge for A. fumigatus survival. • A. fumigatus has evolved multiple strategies to escape host immune responses. • A. fumigatus withstands antifungal drugs via intrinsic escape mechanisms.

Arginine deprivation as a treatment approach targeting cancer cell metabolism and survival: A review of the literature

Amino acid requirement of metabolically active cells is a key element in cellular survival. Of note, cancer cells were shown to have an abnormal metabolism and high-energy requirements including the high amino acid requirement needed for growth factor synthesis. Thus, amino acid deprivation is considered a novel approach to inhibit cancer cell proliferation and offer potential treatment prospects. Accordingly, arginine was proven to play a significant role in cancer cell metabolism and therapy. Arginine depletion induced cell death in various types of cancer cells. Also, the various mechanisms of arginine deprivation, e.g., apoptosis and autophagy were summarized. Finally, the adaptive mechanisms of arginine were also investigated. Several malignant tumors had high amino acid metabolic requirements to accommodate their rapid growth. Antimetabolites that prevent the production of amino acids were also developed as anticancer therapies and are currently under clinical investigation. The aim of this review is to provide a concise literature on arginine metabolism and deprivation, its effects in different tumors, its different modes of action, as well as the related cancerous escape mechanisms.

Human respiratory viral infections: Current status and future prospects of nanotechnology-based approaches for prophylaxis and treatment

Respiratory viral infections are major cause of highly mortal pandemics. They are impacting socioeconomic development and healthcare system globally. These emerging deadly respiratory viruses develop newer survival strategies to live inside host cells and tricking the immune system of host. Currently, medical facilities, therapies and research -development teams of every country kneel down before novel corona virus (SARS-CoV-2) which claimed ~2,828,629 lives till date. Thus, there is urgent requirement of novel treatment strategies to combat against these emerging respiratory viral infections. Nanocarriers come under the umbrella of nanotechnology and offer numerous benefits compared to traditional dosage forms. Further, unique physicochemical properties (size, shape and surface charge) of nanocarriers provide additional advantage for targeted delivery. This review discusses in detail about the respiratory viruses, their transmission mode and cell invasion pathways, survival strategies, available therapies, and nanocarriers for the delivery of therapeutics. Further, the role of nanocarriers in the development of treatment therapy against SARS-CoV-2 is also overviewed.

Interactions between Salmonella and host macrophages - Dissecting NF-κB signaling pathway responses

Salmonella not only invades host cells, but also replicates intracellularly to cause a range of diseases, including gastroenteritis and systemic infections such as typhoid fever. The body's first line of defense against pathogens is the innate immune response system that can protect against Salmonella invasion and replication. Nuclear factor κB (NF-κB) is an important transcriptional regulator that plays an important role in host inflammatory responses to pathogens. Both the canonical and non-canonical NF-κB signaling pathways are activated by Salmonella in many different ways through its virulence factors, leading to the release of inflammatory factors and the activation of inflammatory responses in mammalian hosts. Equally, Salmonella, as an enteropathogen, has accordingly evolved strategies to disturb NF-κB activation, such as secreting some effector proteins by type III secretion systems as well as inducing host cells to express NF-κB pathway inhibitors, allowing it to colonize and persistently infect the hosts. This review focuses on how Salmonella activates NF-κB signaling pathway and the strategies used by Salmonella to interfere with the NF-κB pathway activation.

Prediction of anti-angiogenesis escape

Many clinical trials have demonstrated the benefit of anti-angiogenesis therapy in the treatment of gynecologic cancer. However, these benefits have often been in terms of progression-free rather than overall survival and in some cases, the magnitude of benefit demonstrated in the pivotal phase 3 trials has been disappointing when compared with the percentage of patients who responded in earlier phase 2 trials. Two potential explanations for this are the current inability to stratify patients according to chance of benefit and the development of resistance mechanisms within the tumor. In this article, we review the prediction of response and the proposed resistance and escape mechanisms involved in anti-angiogenesis therapy, including the up-regulation of alternative proangiogenic pathways, vascular co-option, and resistance to hypoxia. These insights may offer a personalized strategy for anti-angiogenesis therapy and help us to consider the best selection of other therapies that should be combined with anti-angiogenesis therapy to improve the outcome of patients with gynecologic cancer.

Interaction of hepatitis C virus with the type I interferon system

Hepatitis C virus (HCV) needs to tightly manipulate host defences in order to establish infection. The innate immune response slows down viral replication by activating cytokines such as the type I interferons (IFN-α/β), which trigger the synthesis of antiviral proteins and modulate the adaptive immune system. HCV has therefore developed a number of countermeasures to stay ahead of the IFN system. Here, I will attempt to summarize the current state of research regarding IFN responses against HCV and the viral escape strategies. Particular emphasis will be put on the newly discovered mechanisms HCV employs to avoid the induction of IFN in infected cells.