The epithelial barrier: The gateway to allergic, autoimmune, and metabolic diseases and chronic neuropsychiatric conditions

Since the 1960 s, our health has been compromised by exposure to over 350,000 newly introduced toxic substances, contributing to the current pandemic in allergic, autoimmune and metabolic diseases. The "Epithelial Barrier Theory" postulates that these diseases are exacerbated by persistent periepithelial inflammation (epithelitis) triggered by exposure to a wide range of epithelial barrier-damaging substances as well as genetic susceptibility. The epithelial barrier serves as the body's primary physical, chemical, and immunological barrier against external stimuli. A leaky epithelial barrier facilitates the translocation of the microbiome from the surface of the afflicted tissues to interepithelial and even deeper subepithelial locations. In turn, opportunistic bacterial colonization, microbiota dysbiosis, local inflammation and impaired tissue regeneration and remodelling follow. Migration of inflammatory cells to susceptible tissues contributes to damage and inflammation, initiating and aggravating many chronic inflammatory diseases. The objective of this review is to highlight and evaluate recent studies on epithelial physiology and its role in the pathogenesis of chronic diseases in light of the epithelial barrier theory.

B cells: The many facets of B cells in allergic diseases

B cells play a key role in our immune system through their ability to produce antibodies, suppress a proinflammatory state, and contribute to central immune tolerance. We aim to provide an in-depth knowledge of the molecular biology of B cells, including their origin, developmental process, types and subsets, and functions. In allergic diseases, B cells are well known to induce and maintain immune tolerance through the production of suppressor cytokines such as IL-10. Similarly, B cells protect against viral infections such as severe acute respiratory syndrome coronavirus 2 that caused the recent coronavirus disease 2019 pandemic. Considering the unique and multifaceted functions of B cells, we hereby provide a comprehensive overview of the current knowledge of B-cell biology and its clinical applications in allergic diseases, organ transplantation, and cancer.

Effect of 5 weeks of oral acetazolamide on patients with pulmonary vascular disease: A randomized, double-blind, cross-over trial

BACKGROUND

The carbonic anhydrase inhibitor acetazolamide stimulates ventilation through metabolic acidosis mediated by renal bicarbonate excretion. In animal models, acetazolamide attenuates acute hypoxia-induced pulmonary hypertension (PH), but its efficacy in treating patients with PH due to pulmonary vascular disease (PVD) is unknown.

METHODS

28 PVD patients (15 pulmonary arterial hypertension, 13 distal chronic thromboembolic PH), 13 women, mean±SD age 61.6±15.0 years stable on PVD medications, were randomised in a double-blind crossover protocol to 5 weeks acetazolamide (250mg b.i.d) or placebo separated by a ≥2 week washout period. Primary endpoint was the change in 6-minute walk distance (6MWD) at 5 weeks. Additional endpoints included safety, tolerability, WHO functional class, quality of life, arterial blood gases, and hemodynamics (by echocardiography).

RESULTS

Acetazolamide had no effect on 6MWD compared to placebo (treatment effect: mean change [95%CI] -18 [-40 to 4]m, p=0.102) but increased arterial blood oxygenation through hyperventilation induced by metabolic acidosis. Other measures including pulmonary hemodynamics were unchanged. No severe adverse effects occurred, side effects that occurred significantly more frequently with acetazolamide vs. placebo were change in taste (22/0%), paraesthesia (37/4%) and mild dyspnea (26/4%).

CONCLUSIONS

In patients with PVD, acetazolamide did not change 6MWD compared to placebo despite improved blood oxygenation. Some patients reported a tolerable increase in dyspnoea during acetazolamide treatment, related to hyperventilation, induced by the mild drug-induced metabolic acidosis. Our findings do not support the use of acetazolamide to improve exercise in patients with PVD at this dosing.

CLINICALTRIALS

GOV IDENTIFIER

NCT02755298.

Advances and highlights in biomarkers of allergic diseases

During the past years, there has been a global outbreak of allergic diseases, presenting a considerable medical and socioeconomical burden. A large fraction of allergic diseases is characterized by a type 2 immune response involving Th2 cells, type 2 innate lymphoid cells, eosinophils, mast cells, and M2 macrophages. Biomarkers are valuable parameters for precision medicine as they provide information on the disease endotypes, clusters, precision diagnoses, identification of therapeutic targets, and monitoring of treatment efficacies. The availability of powerful omics technologies, together with integrated data analysis and network‐based approaches can help the identification of clinically useful biomarkers. These biomarkers need to be accurately quantified using robust and reproducible methods, such as reliable and point‐of‐care systems. Ideally, samples should be collected using quick, cost‐efficient and noninvasive methods. In recent years, a plethora of research has been directed toward finding novel biomarkers of allergic diseases. Promising biomarkers of type 2 allergic diseases include sputum eosinophils, serum periostin and exhaled nitric oxide. Several other biomarkers, such as pro‐inflammatory mediators, miRNAs, eicosanoid molecules, epithelial barrier integrity, and microbiota changes are useful for diagnosis and monitoring of allergic diseases and can be quantified in serum, body fluids and exhaled air. Herein, we review recent studies on biomarkers for the diagnosis and treatment of asthma, chronic urticaria, atopic dermatitis, allergic rhinitis, chronic rhinosinusitis, food allergies, anaphylaxis, drug hypersensitivity and allergen immunotherapy. In addition, we discuss COVID‐19 and allergic diseases within the perspective of biomarkers and recommendations on the management of allergic and asthmatic patients during the COVID‐19 pandemic.

A Preliminary Assessment of Skin Microbiome Diversity of Zebrafish (Danio rerio): South African Pet Shop Fish

The zebrafish (Danio rerio) is a well-known model organism used in an array of scientific research fields. Many microbiome studies conducted on fishes have focused on gut microbiome diversity. To our knowledge, no investigations into the skin microbiome diversity of pet shop zebrafish have been performed. In this pilot study we aimed to assess the microbiome diversity composition of different groups of zebrafish housed at the Department of Genetics, University of the Free State, South Africa. These fish originated from pet shops located in Bloemfontein, South Africa. We investigated the skin microbiome diversity between wild-type zebrafish and the well-known leopard colour morph. The microbiome compositions between zebrafish sexes were also assessed. No significant differences were observed between colour morphs. A core microbiome was identified for the zebrafish housed at our laboratories. Cetobacterium was significantly more abundant in females compared to males, with Limnobacter more abundant in males. Both these genera are known components of fish microbiomes, including zebrafish. The precise reason for this link should be further investigated. This research adds to the growing knowledge base linked to aquatic microbiome structure in different habitats.

Galactosylated wall teichoic acid, but not lipoteichoic acid, retains InlB on the surface of serovar 4b Listeria monocytogenes

Listeria monocytogenes is a Gram-positive, intracellular pathogen harboring the surface-associated virulence factor InlB, which enables entry into certain host cells. Structurally diverse wall teichoic acids (WTAs), which can also be differentially glycosylated, determine the antigenic basis of the various Listeria serovars. WTAs have many physiological functions; they can serve as receptors for bacteriophages, and provide a substrate for binding of surface proteins such as InlB. In contrast, the membrane-anchored lipoteichoic acids (LTAs) do not show significant variation and do not contribute to serovar determination. It was previously demonstrated that surface-associated InlB non-covalently adheres to both WTA and LTA, mediating its retention on the cell wall. Here, we demonstrate that in a highly virulent serovar 4b strain, two genes gtlB and gttB are responsible for galactosylation of LTA and WTA respectively. We evaluated the InlB surface retention in mutants lacking each of these two genes, and found that only galactosylated WTA is required for InlB surface presentation and function, cellular invasiveness and phage adsorption, while galactosylated LTA plays no role thereof. Our findings demonstrate that a simple pathogen-defining serovar antigen, that mediates bacteriophage susceptibility, is necessary and sufficient to sustain the function of an important virulence factor.

Limitations of high urgency listing--ventricular assist device support in a neonate for 452 days

The Eurotransplant International Foundation in Leiden, the Netherlands, is responsible for mediation and allocation of organ donation procedures to its member countries Austria, Belgium, Croatia, Germany, Luxembourg, the Netherlands and Slovenia. To provide organs for the patients who require urgent transplantation, the "high urgent (HU)" status was introduced in 2001 in Germany . This new HU allocation system is applicable to neonates as well as adults. However, waiting times on HU status exceed several weeks to months. Therefore an increasing number of pediatric patients has to undergo implantation of a ventricular assist device (VAD). In the present report we discuss the current Eurotransplant heart allocation system for pediatric heart transplantation in the light of a neonate with 452 days on mechanical support. We compare the average waiting time of patients on HU status at our center and their outcome in 2007 and 2008 (Data obtained from Eurotransplant International Foundation). Waiting time on HU status in our center increased significantly from 2007 to 2008. Therefore more patients require VAD support as bridging to transplantation. The case of a neonate under long-term VAD support is an outstanding example of the negative effects of this development.

The effect of a calcium hydroxide paste on wound healing and osseointegration of dental implants. A pilot study in beagle dogs

The aim of this investigation was to evaluate the effect of a new calcium hydroxide suspension (Osteoinductal) on the healing process of endosseous dental implants after placement. The material, composed of 25% calcium hydroxide, 25% Oleum pedum tauri and 50% vaselinum album, was developed with the intention to accelerate and to increase the mineralized bone to implant contact during the healing phase. Eight adult beagle dogs were used in this study. Prior to the beginning of the study the dogs had all mandibular premolars extracted. After the extraction sites had healed for 3 months, implant osteotomies were performed. On one side of the mandibular premolars extracted. After the extraction sites had healed for 3 months, implant osteotomies were performed. On one side of the mandible Osteoinductal was applied into the osteotomies before placement of the implants, whereas the other side did not receive Osteoinductal. A total of 48 implants were placed with two losses during the entire study period. Two dogs were sacrificed 1 week, 2 weeks, 4 weeks and 3 months after implant placement. The specimens were evaluated histologically and histomorphometrically. In the histological evaluation an intense inflammatory reaction towards the calcium hydroxide suspension was found leading to a destruction of the bone surrounding the implants after 1 and 2 weeks. A giant cell reaction against the test material was visible at 4 weeks. At 3 months no inflammatory and no giant cell reaction could be depicted in the test group. The mean direct bone to implant contact or inflammatory tissue to implant contact showed no differences between test and control group for 1 and 2 weeks. Although statistically not significant, there was a clinical significant difference in the mineralized bone to implant contact between test and control group for the last two timepoints (i.e. 4-week specimens: test group 2.3 +/- 0.9%, control group 26.8 +/- 11.1%; 3-month specimens: test group 10.5 +/- 12.7%, control group 60.7 +/- 13.7%). This study indicates that the use of the calcium hydroxide suspension Osteoinductal has a detrimental effect on wound healing and osseointegration of dental implants and cannot be recommended for use with dental implants.

Sex differences in investigatory and grooming behaviors of laboratory rats (Rattus norvegicus) following exposure to novelty

Prior research suggested that during exposure to novel stimuli, rodent investigation and self-grooming behaviors may be sexually dimorphic and interact with ambient illumination. To test this notion we compared the behavior of adult male and female groups of Long-Evans hooded rats in normal room lighting (860 lx) and in very dim, red light (0.2 lx) following exposure to a novel juvenile conspecific. Illuminance level had little or no effect, but investigatory and subsequent self-grooming behaviors of males were substantially greater than those of females, and females engaged in greater ambulatory activity than did males. In a second experiment adult males and females were exposed to a novel inanimate object. No reliable sex differences were observed. We conclude that social novelty, as provided by exposure to a juvenile conspecific, stimulates greater investigation and postinvestigatory self-grooming than exposure to a novel inanimate object and that exposure to novel conspecifics presents a useful method for the investigation of sex differences, gonadal hormone effects, and interactions of hormones with neurotransmitter systems governing motor control systems.