Atopic dermatitis-derived Staphylococcus aureus strains: what makes them special in the interplay with the host.

Background: Atopic dermatitis (AD) is a chronic inflammatory skin condition whose pathogenesis involves genetic predisposition, epidermal barrier dysfunction, alterations in the immune responses and microbial dysbiosis. Clinical studies have shown a link between Staphylococcus aureus and the pathogenesis of AD, although the origins and genetic diversity of S. aureus colonizing patients with AD is poorly understood. The aim of the study was to investigate if specific clones might be associated with the disease. Methods: WGS analyses were performed on 38 S. aureus strains, deriving from AD patients and healthy carriers. Genotypes (i.e. MLST, spa-, agr- and SCCmec-typing), genomic content (e.g. virulome and resistome), and the pan-genome structure of strains have been investigated. Phenotypic analyses were performed to determine the antibiotic susceptibility, the biofilm production and the invasiveness within the investigated S. aureus population. Results: Strains isolated from AD patients revealed a high degree of genetic heterogeneity and a shared set of virulence factors and antimicrobial resistance genes, suggesting that no genotype and genomic content are uniquely associated with AD. The same strains were characterized by a lower variability in terms of gene content, indicating that the inflammatory conditions could exert a selective pressure leading to the optimization of the gene repertoire. Furthermore, genes related to specific mechanisms, like post-translational modification, protein turnover and chaperones as well as intracellular trafficking, secretion and vesicular transport, were significantly more enriched in AD strains. Phenotypic analysis revealed that all of our AD strains were strong or moderate biofilm producers, while less than half showed invasive capabilities. Conclusions: We conclude that in AD skin, the functional role played by S. aureus may depend on differential gene expression patterns and/or on post-translational modification mechanisms rather than being associated with peculiar genetic features.

Identification of the Lipid Antigens Recognized by rHIgM22, a Remyelination-Promoting Antibody.

Failure of the immune system to discriminate myelin components from foreign antigens plays a critical role in the pathophysiology of multiple sclerosis. In fact, the appearance of anti-myelin autoantibodies, targeting both proteins and glycolipids, is often responsible for functional alterations in myelin-producing cells in this disease. Nevertheless, some of these antibodies were reported to be beneficial for remyelination. Recombinant human IgM22 (rHIgM22) binds to myelin and to the surface of O4-positive oligodendrocytes, and promotes remyelination in mouse models of chronic demyelination. Interestingly, the identity of the antigen recognized by this antibody remains to be elucidated. The preferential binding of rHIgM22 to sulfatide-positive cells or tissues suggests that sulfatide might be part of the antigen pattern recognized by the antibody, however, cell populations lacking sulfatide expression are also responsive to rHIgM22. Thus, we assessed the binding of rHIgM22 in vitro to purified lipids and lipid extracts from various sources to identify the antigen(s) recognized by this antibody. Our results show that rHIgM22 is indeed able to bind both sulfatide and its deacylated form, whereas no significant binding for other myelin sphingolipids has been detected. Remarkably, binding of rHIgM22 to sulfatide in lipid monolayers can be positively or negatively regulated by the presence of other lipids. Moreover, rHIgM22 also binds to phosphatidylinositol, phosphatidylserine and phosphatidic acid, suggesting that not only sulfatide, but also other membrane lipids might play a role in the binding of rHIgM22 to oligodendrocytes and to other cell types not expressing sulfatide.

A Possible Link between Gut Microbiome Composition and Cardiovascular Comorbidities in Psoriatic Patients.

Cardiovascular disease (CVD) is one of the most common comorbidities that may affect psoriatic patients. Several exogenous and endogenous factors are involved in the etiology and progression of both psoriasis and CVD. A potential genetic link between the two diseases has emerged; however, some gaps remain in the understanding of the CVD prevalence in psoriatic patients. Recently, the role of the gut microbiome dysbiosis was documented in the development and maintenance of both diseases. To investigate whether gut microbiome dysbiosis might influence the occurrence of CVD in psoriatic patients, 16S rRNA gene sequencing was performed to characterize the gut microbiome of 28 psoriatic patients, including 17 patients with and 11 without CVD. The comparison of the gut microbiome composition between patients with and without CVD showed a higher prevalence of Barnesiellaceae and Phascolarctobacterium in patients with CVD. Among patients with CVD, those undergoing biologic therapy had lower abundance levels of Barnesiellaceae, comparable to those found in patients without CVD. Overall, these findings suggest that the co-occurrence of psoriasis and CVD might be linked to gut microbiome dysbiosis and that therapeutic strategies could help to restore the intestinal symbiosis, potentially improving the clinical management of psoriasis and its associated comorbidities.

SpikeOnChip : A Custom Embedded Platform for Neuronal Activity Recording and Analysis.

In this paper we present SpikeOnChip, a custom embedded platform for neuronal activity recording and online analysis. The SpikeOnChip platform was developed in the context of automated drug testing and toxicology assessments on neural tissue made from human induced pluripotent stem cells. The system was developed with the following goals: to be small, autonomous and low power, to handle micro-electrode arrays with up to 256 electrodes, to reduce the amount of data generated from the recording, to be able to do computation during acquisition, and to be customizable. This led to the choice of a Field Programmable Gate Array System-On-Chip platform. This paper focuses on the embedded system for acquisition and processing with key features being the ability to record electrophysiological signals from multiple electrodes, detect biological activity on all channels online for recording, and do frequency domain spectral energy analysis online on all channels during acquisition. Development methodologies are also presented. The platform is finally illustrated in a concrete experiment with bicuculline being administered to grown human neural tissue through microfluidics, resulting in measurable effects in the spike recordings and activity. The presented platform provides a valuable new experimental instrument that can be further extended thanks to the programmable hardware and software.

A pathogenic HEXA missense variant in wild boars with Tay-Sachs disease.

Gangliosidoses are inherited lysosomal storage disorders caused by reduced or absent activity of either a lysosomal enzyme involved in ganglioside catabolism, or an activator protein required for the proper activity of a ganglioside hydrolase, which results in the intra-lysosomal accumulation of undegraded metabolites. We hereby describe morphological, ultrastructural, biochemical and genetic features of GM2 gangliosidosis in three captive bred wild boar littermates. The piglets were kept in a partially-free range farm and presented progressive neurological signs, starting at 6 months of age. Animals were euthanized at approximately one year of age due to their poor conditions. Neuropathogens were excluded as a possible cause of the signs. Gross examination showed a reduction of cerebral and cerebellar consistency. Central (CNS) and peripheral (PNS) nervous system neurons were enlarged and foamy, with severe and diffuse cytoplasmic vacuolization. Transmission electron microscopy (TEM) of CNS neurons demonstrated numerous lysosomes, filled by parallel or concentric layers of membranous electron-dense material, defined as membranous cytoplasmic bodies (MCB). Biochemical composition of gangliosides analysis from CNS revealed accumulation of GM2 ganglioside; furthermore, Hex A enzyme activity was less than 1% compared to control animals. These data confirmed the diagnosis of GM2 gangliosidosis. Genetic analysis identified, at a homozygous level, the presence of a missense nucleotide variant c.1495C > T (p Arg499Cys) in the hexosaminidase subunit alpha gene (HEXA), located within the GH20 hexosaminidase superfamily domain of the encoded protein. This specific HEXA variant is known to be pathogenic and associated with Tay-Sachs disease in humans, but has never been identified in other animal species. This is the first report of a HEXA gene associated Tay-Sachs disease in wild boars and provides a comprehensive description of a novel spontaneous animal model for this lysosomal storage disease.

Lipid rafts as platforms for sphingosine 1-phosphate metabolism and signalling.

Spontaneous segregation of cholesterol and sphingolipids as a liquid-ordered phase leads to their clustering in selected membrane areas, the lipid rafts. These specialized membrane domains enriched in gangliosides, sphingomyelin, cholesterol and selected proteins involved in signal transduction, organize and determine the function of multiprotein complexes involved in several aspects of signal transduction, thus regulating cell homeostasis. Sphingosine 1-phosphate, an important biologically active mediator, is involved in several signal transduction processes regulating a plethora of cell functions and, not only several of its downstream effectors tend to localize in lipid rafts, some of the enzymes involved in its pathway, of receptors involved in its signalling and its transporters have been often found in these membrane microdomains. Considering this, in this review we address what is currently known regarding the relationship between sphingosine 1-phosphate metabolism and signalling and plasma membrane lipid rafts.

Gut microbiome profile in psoriatic patients treated and untreated with biologic therapy.

There are increasing data about the role of the gut microbiome in various autoimmune diseases, including psoriasis, a chronic inflammatory and immune-mediated disease. Current treatment strategies in psoriasis include immunomodulating biologic agents. A variable response to this type of therapy has been reported in psoriatic patients. A possible effect of biologic therapy on the gut microbiome composition has been suggested, but data are still limited. The aim of this study was to compare the gut microbiome composition between psoriatic patients treated and untreated with biologic drugs in order to identify differences which may highlight the potential impact of the treatment on the gut microbiome. 16S rRNA sequencing and bioinformatic analyses were performed on the fecal samples of 30 psoriatic patients with similar clinicopathological features, 10 of whom were undergoing biologic therapy and 20 not receiving systemic therapy. Alpha and beta diversity significantly differed between the two groups of patients. A reduced bacterial biodiversity in the group of treated patients compared with the group of untreated patients was observed. Differential relative abundances of key gut microbial communities, including Akkermansia muciniphila and Bacteroides plebeius, were identified between the two groups of patients. This study showed that biologic therapy may have an impact on the composition of the gut microbiome of psoriatic patients. Gut microbiome composition could be used as an indicator of response to therapy and the modulation of the microbial composition could help to restore the intestinal symbiosis in psoriatic patients.

Frontal Fibrosing Alopecia: A New Association with Lichen Sclerosus in Men.

BACKGROUND: Frontal fibrosing alopecia (FFA) is a scarring alopecia that has been reported mostly in postmenopausal women and is characterized by frontotemporal hairline. Currently, there are only a few reports about FFA in male patients. OBJECTIVE: This study sought to analyze clinical and trichoscopic features of FFA in a case series of men and to describe the main features of FFA in male patients through a review of the literature. METHODS: Male patients with clinical and trichoscopical signs of FFA, histologically confirmed, who attended to our clinic from 2014 to 2019 were included in our study. From each patient, clinical and trichoscopic data were collected. RESULTS: Eight men with an average age of 59 years were recruited. In five patients, serrated hairline recession (i.e., a "zig-zag" pattern) was present, while three presented with linear hairline recession. Also, the eyebrows (n=3 patients), sideburns (n=2 patients), and beard (n=2 patients) were involved. Surprisingly, in two patients, an association with lichen sclerosus (LS) was present. CONCLUSION: To the best of our knowledge, this is the first report of a serrated hairline recession pattern in male patients with FFA. A new association between FFA and LS in men was also found. Further studies need to establish the extent of this association and facilitate a better comprehension of the pathophysiologic mechanisms underlying these two diseases.

Frontal fibrosing alopecia and genital Lichen sclerosus: Single-center experience.

BACKGROUND: Despite the incidence of Frontal fibrosing alopecia (FFA) has been increasing in last two decades, the pathophysiology and trigger factors of FFA have not been yet fully understood. AIMS: The aim of this study was to describe epidemiology, clinical and trichoscopic features and comorbidities of FFA patients, in order to improve the understanding of this disease. PATIENTS/METHODS: A retrospective, observational monocentric study was conducted from 2003 to 2019. Data concerning epidemiology (age, gender, age of menopause, and age of FFA onset), comorbidities, current therapies, localization of FFA (such as frontotemporal hairline, occipital, eyebrow, eyelash, beard, sideburns, and body hair), presence of papules and sign of Lichen planus (LP) at skin, mucosae and/or nail were collected for each patient included. RESULTS: A total of 119 Caucasian, adult patients (8 men and 111 female) with FFA were enrolled in the study. Cutaneous, mucosal, or nail localization of LP were found in 16% of our subjects. Interestingly, 15 out of 119 subjects (10.61%) were affected by concomitant genital Lichen sclerosus (LS) and 5 out of these 15 patients (4.38%) presented both LS and LP in association with FFA. CONCLUSION: Considering the high prevalence of LS in FFA patients in our case series, and the frequency of autoimmune comorbidities in both LS and FFA, it is possible to hypothesize an autoimmune process in both conditions. Further studies are needed for a better understanding of the nature of the association between LS and FFA.

Isolation and Analysis of Lipid Rafts from Neural Cells and Tissues.

Lipid rafts are membrane areas characterized by the clustering of selected membrane lipids, as the result of their phase separation forming a liquid-ordered phase floating in the lipid-disordered bulk membrane. van Meer and Simons hypothesized the existence of lipid rafts to explain the differential composition of the apical and basolateral domains of polarized epithelial cells and proposed that association of given proteins with lipid rafts along the traffic route might represent an important mechanism for protein sorting. However, great attention was paid to the lipid raft theory after Simons and Ikonen highlighted the enrichment of several proteins involved in signal transduction in "detergent-insoluble, glycolipid-enriched complexes," and postulated that lipid rafts might serve as hubs in regulating intracellular signaling. Most notably, the feature of detergent-insolubility was incorporated in the definition of lipid rafts used in 1997 by these authors. "Lipid rafts" and "detergent-resistant membranes" became almost synonymous after the publication, in 1992, of the seminal paper by Brown and Rose, describing the separation of a low-density, Triton X-100-insoluble fraction from epithelial cells, enriched in GSL and apical GPI-anchored proteins and depleted of basolateral membrane marker proteins. This paper provided a working definition of lipid rafts and a putative biochemical method for their separation. More than 2000 papers have been published using "the Triton method." Evidences obtained by the use of alternative biochemical methods for the isolation of lipid rafts and of methods enabling to analyze the dynamics of lipid rafts in intact cells highlighted the several limitations of the Triton X-100 method. On the other hand, the main findings obtained by this method have not been confuted, and the method is still widely used.In this chapter, we will discuss the most relevant methodological aspects related to the preparation of detergent-resistant membrane fractions, with a special focus on neural cells and tissues.

Paradoxical Psoriasis Induced by Anti-TNFα Treatment: Evaluation of Disease-Specific Clinical and Genetic Markers.

Paradoxical psoriasis (PP) may occur during treatment with anti-tumor necrosis factor-alpha (TNF-α) drugs in various chronic immune-mediated diseases, mainly inflammatory bowel diseases (IBD) and psoriasis. In this study, clinical and genetic characteristics of PP arising in IBD and psoriatic patients were investigated to identify disease-specific markers of the paradoxical effect. A total of 161 IBD and psoriatic patients treated with anti-TNF-α drugs were included in the study. Of these patients, 39 developed PP. All patients were characterized for the main clinical-pathologic characteristics and genotyped for six candidate single nucleotide polymorphisms (SNPs) selected for their possible role in PP susceptibility. In IBD patients, the onset of PP was associated with female sex, presence of comorbidities, and use of adalimumab. IBD patients with PP had a higher frequency of the TNF-α rs1799964 rare allele (p = 0.006) compared with cases without the paradoxical effect, and a lower frequency of the human leucocyte antigen (HLA)-Cw06 rs10484554 rare allele (p = 0.03) compared with psoriatic patients with PP. Overall, these findings point to specific clinical and genetic characteristics of IBD patients with PP and provide data showing that genetic variability may be related to the paradoxical effect of anti-TNF-α drugs with possible implications into clinical practice.

Erythema ab igne induced by laptop computer: an emerging disease among adolescents?

Erythema ab igne (EAI) was a very common disease in the past, when it occurred mainly among people who worked with fire, or in people who had used heat sources in contact with the skin for warming purposes for long time. In the last decades, with the introduction of central heating in the buildings, EAI incidence was remarkably decreased in Western Countries, and it was found almost exclusively among elderly, and in people affected by defects in thermoregulation or alteration of periphery circulation. Recently, a new slight increase of EAI prevalence has been observed, although with some new features. Here, we describe three cases of adolescents who presented with brownish, reticulated patch on the anterior surface of their thighs. An accurate medical questioning revealed that the patients used to place the lower surface of laptop computer on the extensor side of their thighs in a cross-legged position for many hours (about 6-8 hours) every days. In particular, the patients supported the laptop computer always on the same leg. Laptop computer-induced EAI was diagnosed. Only a few cases of laptop computer-induced EAI have been reported in the literature. Although EAI is poorly symptomatic and it generally evolve to complete remission after an early discontinuance of heat source exposure, chronic lesions of EAI have been regarded as precancerous lesions. Therefore, it is important to implement diagnosis and prevention measures of this disease. Dermatologists should consider new causal agents for old diseases.