Transcriptome in Human Mycoses

Mycoses are infectious diseases caused by fungi, which incidence has increased in recent decades due to the increasing number of immunocompromised patients and improved diagnostic tests. As eukaryotes, fungi share many similarities with human cells, making it difficult to design drugs without side effects. Commercially available drugs act on a limited number of targets and have been reported fungal resistance to commonly used antifungal drugs. Therefore, elucidating the pathogenesis of fungal infections, the fungal strategies to overcome the hostile environment of the host, and the action of antifungal drugs is essential for developing new therapeutic approaches and diagnostic tests. Large-scale transcriptional analyses using microarrays and RNA sequencing (RNA-seq), combined with improvements in molecular biology techniques, have improved the study of fungal pathogenicity. Such techniques have provided insights into the infective process by identifying molecular strategies used by the host and pathogen during the course of human mycoses. This chapter will explore the latest discoveries regarding the transcriptome of major human fungal pathogens. Further we will highlight genes essential for host–pathogen interactions, immune response, invasion, infection, antifungal drug response, and resistance. Finally, we will discuss their importance to the discovery of new molecular targets for antifungal drugs. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2014, 2022.

The Role of Microbiota in Gut Inflammation and Sepsis

In healthy individuals, the microbiome and human gut are in homeostasis. Upon dysbiosis, disease and injury, homeostasis is disrupted, which can lead to inflammation and sepsis. In this review, we will focus on how the microbiome interacts with the gut epithelium, underlying vasculature and immune system to maintain homeostasis and how disruption leads to inflammatory bowel disease (IBD), type II diabetes (T2D), novel coronavirus disease-19 (COVID-19) and sepsis. We will discuss antibiotics and the potential for fecal microbiota transplantation (FMT) in sepsis treatment. Finally, we will examine the role of diet and review current experimental models for studying host-microbiome interactions. © 2022 Elsevier Inc. All rights reserved.

Destiny of airway disease: interplay between epithelial barrier and the innate immune system.

When the organism encounters a foreign substance, it responds with mutual and regular interactions at different stages of the immune system. In airway diseases, the first encounter is at the epithelial level, where innate immune cells and their responses form the first leg of the protective mechanism. The most important barrier for environmental damage is the epithelial barrier. However, the epithelial barrier is not just a mechanical barrier. The formation of the microbiome on the epithelium and the tolerance or intolerance to environmental factors are vital. This vital balance is maintained between the epithelial surface and the subepithelial innate immune system. This is achieved by the epithelial line, which is a mechanical and functional barrier between them. In this respect, epithelial barrier function preservation has an important role in the development and prognosis of airway disease.

Eugenol alleviates transmissible gastroenteritis virus-induced intestinal epithelial injury by regulating NF-κB signaling pathway.

Increasing evidence supports the ability of eugenol to maintain intestinal barrier integrity and anti-inflammatory in vitro and in vivo; however, whether eugenol alleviates virus-mediated intestinal barrier damage and inflammation remains a mystery. Transmissible gastroenteritis virus (TGEV), a coronavirus, is one of the main causative agents of diarrhea in piglets and significantly impacts the global swine industry. Here, we found that eugenol could alleviate TGEV-induced intestinal functional impairment and inflammatory responses in piglets. Our results indicated that eugenol improved feed efficiency in TGEV-infected piglets. Eugenol not only increased serum immunoglobulin concentration (IgG) but also significantly decreased serum inflammatory cytokine concentration (TNF-α) in TGEV-infected piglets. In addition, eugenol also significantly decreased the expression of NF-κB mRNA and the phosphorylation level of NF-κB P65 protein in the jejunum mucosa of TGEV-infected piglets. Eugenol increased villus height and the ratio of villus height to crypt depth in the jejunum and ileum, and decreased serum D-lactic acid levels. Importantly, eugenol increased tight junction protein (ZO-1) and mRNA expression levels of nutrient transporter-related genes (GluT-2 and CaT-1) in the jejunum mucosa of TGEV-infected piglets. Meanwhile, compared with TGEV-infected IPEC-J2 cells, treatment with eugenol reduced the cell cytopathic effect, attenuated the inflammatory response. Interestingly, eugenol did not increase the expression of ZO-1 and Occludin in IPEC-J2 cells. However, western blot and immunofluorescence results showed that eugenol restored TGEV-induced down-regulation of ZO-1 and Occludin, while BAY11-7082 (The NF-κB specific inhibitor) enhanced the regulatory ability of eugenol. Our findings demonstrated that eugenol attenuated TGEV-induced intestinal injury by increasing the expression of ZO-1 and Occludin, which may be related to the inhibition of NF-κB signaling pathway. Eugenol may offer some therapeutic opportunities for coronavirus-related diseases.

Review: The Nose as a Route for Therapy. Part 2 Immunotherapy.

The nose provides a route of access to the body for inhalants and fluids. Unsurprisingly it has a strong immune defense system, with involvement of innate (e.g., epithelial barrier, muco- ciliary clearance, nasal secretions with interferons, lysozyme, nitric oxide) and acquired (e.g., secreted immunoglobulins, lymphocytes) arms. The lattice network of dendritic cells surrounding the nostrils allows rapid uptake and sampling of molecules able to negotiate the epithelial barrier. Despite this many respiratory infections, including SARS-CoV2, are initiated through nasal mucosal contact, and the nasal mucosa is a significant "reservoir" for microbes including Streptococcus pneumoniae, Neisseria meningitidis and SARS -CoV-2. This review includes consideration of the augmentation of immune defense by the nasal application of interferons, then the reduction of unnecessary inflammation and infection by alteration of the nasal microbiome. The nasal mucosa and associated lymphoid tissue (nasopharynx-associated lymphoid tissue, NALT) provides an important site for vaccine delivery, with cold-adapted live influenza strains (LAIV), which replicate intranasally, resulting in an immune response without significant clinical symptoms, being the most successful thus far. Finally, the clever intranasal application of antibodies bispecific for allergens and Intercellular Adhesion Molecule 1 (ICAM-1) as a topical treatment for allergic and RV-induced rhinitis is explained.

Immune-Mediated Inflammatory Responses of Alveolar Epithelial Cells: Implications for COVID-19 Lung Pathology.

BACKGROUND: Clinical and experimental evidence point to a dysregulated immune response caused by SARS-CoV-2 as the primary mechanism of lung disease in COVID-19. However, the pathogenic mechanisms underlying COVID-19-associated ARDS (Acute Respiratory Distress Syndrome) remain incompletely understood. This study aims to explore the inflammatory responses of alveolar epithelial cells to either the spike S1 protein or to a mixture of cytokines secreted by S1-activated macrophages. METHODS AND RESULTS: The exposure of alveolar A549 cells to supernatants from spike-activated macrophages caused a further release of inflammatory mediators, with IL-8 reaching massive concentrations. The investigation of the molecular pathways indicated that NF-kB is involved in the transcription of IP-10 and RANTES, while STATs drive the expression of all the cytokines/chemokines tested, with the exception of IL-8 which is regulated by AP-1. Cytokines/chemokines produced by spike-activated macrophages are also likely responsible for the observed dysfunction of barrier integrity in Human Alveolar Epithelial Lentivirus-immortalized cells (hAELVi), as demonstrated by an increased permeability of the monolayers to mannitol, a marked decrease of TEER and a disorganization of claudin-7 distribution. CONCLUSION: Upon exposure to supernatants from S1-activated macrophages, A549 cells act both as targets and sources of cytokines/chemokines, suggesting that alveolar epithelium along with activated macrophages may orchestrate lung inflammation and contribute to alveolar injury, a hallmark of ARDS.

Immunosuppressive glucocorticoids at epithelial barriers in the regulation of anti-viral immune response.

The anti-inflammatory action of adrenal-derived glucocorticoids has been recognized since several decades. This knowledge has found broad application in the clinics and today synthetic glucocorticoids are widely used in the treatment of various inflammatory diseases. However, the use of synthetic glucocorticoids in the treatment of diseases associated with viral infections of epithelial surfaces, like the lung or the intestine, is still under debate and seems not as efficient as desired. Basic research on the anti-viral immune responses and on regulatory mechanisms in the prevention of immunopathological disorders, however, has led us back again to focus on endogenous glucocorticoid synthesis. It has become established that this synthesis is not restricted to the adrenal glands alone, but that numerous tissues also produce glucocorticoids in situ. Extra-adrenal derived glucocorticoids have the capacity to locally control and maintain immune homeostasis under steady-state and inflammatory conditions. Here, we discuss the current knowledge of extra-adrenal glucocorticoid synthesis in the lung and the intestine, and its role in the regulation of anti-viral immune responses.

Molecular Mechanisms of Vascular Damage During Lung Injury.

A variety of pulmonary and systemic insults promote an inflammatory response causing increased vascular permeability, leading to the development of acute lung injury (ALI), a condition necessitating hospitalization and intensive care, or the more severe acute respiratory distress syndrome (ARDS), a disease with a high mortality rate. Further, COVID-19 pandemic-associated ARDS is now a major cause of mortality worldwide. The pathogenesis of ALI is explained by injury to both the vascular endothelium and the alveolar epithelium. The disruption of the lung endothelial and epithelial barriers occurs in response to both systemic and local production of pro-inflammatory cytokines. Studies that evaluate the association of genetic polymorphisms with disease risk did not yield many potential therapeutic targets to treat and revert lung injury. This failure is probably due in part to the phenotypic complexity of ALI/ARDS, and genetic predisposition may be obscured by the multiple environmental and behavioral risk factors. In the last decade, new research has uncovered novel epigenetic mechanisms that control ALI/ARDS pathogenesis, including histone modifications and DNA methylation. Enzyme inhibitors such as DNMTi and HDACi may offer new alternative strategies to prevent or reverse the vascular damage that occurs during lung injury. This review will focus on the latest findings on the molecular mechanisms of vascular damage in ALI/ARDS, the genetic factors that might contribute to the susceptibility for developing this disease, and the epigenetic changes observed in humans, as well as in experimental models of ALI/ADRS.

Lung Barrier Function in COVID-19?

The novel coronavirus COVID-19 appears to strike some people more intensely than others. Some people only experience mild symptoms while others require hospitalization and ventilation. With the virus becoming more prevalent day by day, it is not just the elderly, but even young people are falling seriously ill. Various researchers across the world state that specific cells in the nasal passages, intestines, and lungs may be more susceptible to the infection. Shifting the focus and research towards epithelium might provide new insight towards understanding COVID-19. This article is an overview of how epithelium permeability in COVID-19 may associate with comorbidities and other factors.

S1P lyase inhibition protects against sepsis by promoting disease tolerance via the S1P/S1PR3 axis.

BACKGROUND: One-third of all deaths in hospitals are caused by sepsis. Despite its demonstrated prevalence and high case fatality rate, antibiotics remain the only target-oriented treatment option currently available. Starting from results showing that low-dose anthracyclines protect against sepsis in mice, we sought to find new causative treatment options to improve sepsis outcomes. METHODS: Sepsis was induced in mice, and different treatment options were evaluated regarding cytokine and biomarker expression, lung epithelial cell permeability, autophagy induction, and survival benefit. Results were validated in cell culture experiments and correlated with patient samples. FINDINGS: Effective low-dose epirubicin treatment resulted in substantial downregulation of the sphingosine 1-phosphate (S1P) degrading enzyme S1P lyase (SPL). Consequent accumulation and secretion of S1P in lung parenchyma cells stimulated the S1P-receptor type 3 (S1PR3) and mitogen-activated protein kinases p38 and ERK, reducing tissue damage via increased disease tolerance. The protective effects of SPL inhibition were absent in S1PR3 deficient mice. Sepsis patients showed increased expression of SPL, stable expression of S1PR3, and increased levels of mucin-1 and surfactant protein D as indicators of lung damage. INTERPRETATION: Our work highlights a tissue-protective effect of SPL inhibition in sepsis due to activation of the S1P/S1PR3 axis and implies that SPL inhibitors and S1PR3 agonists might be potential therapeutics to protect against sepsis by increasing disease tolerance against infections. FUNDING: This study was supported by the Center for Sepsis Control and Care (CSCC), the German Research Foundation (DFG), RTG 1715 (to M. H. G. and I. R.) and the National Institutes of Health, Grant R01GM043880 (to S. S.).

Factors preventing materno-fetal transmission of SARS-CoV-2.

Although many pregnant women have been infected by coronavirus, the presence of intrauterine vertical transmission has not been conclusively reported yet. What prevents this highly contagious virus from reaching the fetus? Is it only the presence of a strong placental barrier, or is it the natural absence of the some receptor that the viruses use for transmission? We, therefore, need to comprehensively understand the mechanism of action of the mammalian epithelial barriers located in two different organs with functional similarity. The barriers selected as potential targets by SARS-CoV-2 are the alveolo-capillary barrier (ACB), and the syncytio-capillary barrier (SCB). Caveolae are omega-shaped structures located on the cell membrane. They consist of caveolin-1 protein (Cav-1) and are involved in the internalisation of some viruses. By activating leukocytes and nuclear factor-κB, Cav-1 initiates inflammatory reactions. The presence of more than one Cav-1 binding sites on coronavirus is an important finding supporting the possible relationship between SARS-CoV-2-mediated lung injury. While the ACB cells express Cav-1 there is no caveolin expression in syncytiotrophoblasts. In this short review, we will try to explain our hypothesis that the lack of caveolin expression in the SCB is one of the most important physiological mechanisms that prevents vertical transmission of SARS-CoV-2. Since the physiological Cav-1 deficiency appears to prevent acute cell damage treatment algorithms could potentially be developed to block this pathway in the non-pregnant population affected by SARS-CoV-2.