Functional metagenomics reveals differential chitin degradation and utilization features across free-living and host-associated marine microbiomes.

BACKGROUND: Chitin ranks as the most abundant polysaccharide in the oceans yet knowledge of shifts in structure and diversity of chitin-degrading communities across marine niches is scarce. Here, we integrate cultivation-dependent and -independent approaches to shed light on the chitin processing potential within the microbiomes of marine sponges, octocorals, sediments, and seawater. RESULTS: We found that cultivatable host-associated bacteria in the genera Aquimarina, Enterovibrio, Microbulbifer, Pseudoalteromonas, Shewanella, and Vibrio were able to degrade colloidal chitin in vitro. Congruent with enzymatic activity bioassays, genome-wide inspection of cultivated symbionts revealed that Vibrio and Aquimarina species, particularly, possess several endo- and exo-chitinase-encoding genes underlying their ability to cleave the large chitin polymer into oligomers and dimers. Conversely, Alphaproteobacteria species were found to specialize in the utilization of the chitin monomer N-acetylglucosamine more often. Phylogenetic assessments uncovered a high degree of within-genome diversification of multiple, full-length endo-chitinase genes for Aquimarina and Vibrio strains, suggestive of a versatile chitin catabolism aptitude. We then analyzed the abundance distributions of chitin metabolism-related genes across 30 Illumina-sequenced microbial metagenomes and found that the endosymbiotic consortium of Spongia officinalis is enriched in polysaccharide deacetylases, suggesting the ability of the marine sponge microbiome to convert chitin into its deacetylated-and biotechnologically versatile-form chitosan. Instead, the abundance of endo-chitinase and chitin-binding protein-encoding genes in healthy octocorals leveled up with those from the surrounding environment but was found to be depleted in necrotic octocoral tissue. Using cultivation-independent, taxonomic assignments of endo-chitinase encoding genes, we unveiled previously unsuspected richness and divergent structures of chitinolytic communities across host-associated and free-living biotopes, revealing putative roles for uncultivated Gammaproteobacteria and Chloroflexi symbionts in chitin processing within sessile marine invertebrates. CONCLUSIONS: Our findings suggest that differential chitin degradation pathways, utilization, and turnover dictate the processing of chitin across marine micro-niches and support the hypothesis that inter-species cross-feeding could facilitate the co-existence of chitin utilizers within marine invertebrate microbiomes. We further identified chitin metabolism functions which may serve as indicators of microbiome integrity/dysbiosis in corals and reveal putative novel chitinolytic enzymes in the genus Aquimarina that may find applications in the blue biotechnology sector. Video abstract.

[Management of immune-related toxicities associated with immune checkpoints inhibitors: Data from the multidisciplinary meeting « ToxImmun ¼ in Eastern Occitania]. / Gestion des toxicités induites par les inhibiteurs de checkpoint immunologique : données de la réunion de concertation pluridisciplinaire « ToxImmun ¼ en Occitanie Est.

Immune checkpoint inhibitors (ICIs) can cause numerous and complex immune-related adverse events whose management need a multidisciplinary approach. Herein, we investigated 114 requests, mostly concerning patients suffering from lung cancer, that were submitted to the « ToxImmun ¼ multidisciplinary meeting in Eastern Occitania between December the 17th 2018 and January the 20th 2020. The leading reasons for the request concerned the putative causal link between immunotherapy and immune-toxicity and its management, followed by possible retreatment after temporary withdrawn because of adverse event, and finally the possibility to initiate ICIs in patients with pre-existing autoimmunity. Colitis, hepatitis and myocarditis were the most frequent immune-related adverse events (IRAEs), both all grade and grade 3-4. Sicca syndrome (with or without Sjogren criteria) was also frequent (26% of cases) and seems to be associated with severe toxicity and multi-toxicity. The mean time to first IRAE was 3.8 months, a time shortened with the use of anti-PD-L1 agents or ICI combination. A majority of requests came from initial evaluation by the internist confirming the early and main role of this specialty in the management of immunotoxicity. Expansion of this regional multidisciplinary meeting, coordinated by internists and medical oncologists, could improve management of immune-related adverse events for the patients' benefits.

Psoriatic epidermis is associated with upregulation of CDK2 and inhibition of CDK4 activity.

BACKGROUND: The cyclin-dependent kinases (CDKs) CDK2 and CDK4 are involved in regulation of cell-cycle progression, and psoriasis is characterized by hyperproliferation of basal epidermal cells. CDK inhibitory proteins (CKIs) such as p16INK 4A (p16) bind CDK4/6 kinases and prevent their interaction with D-type cyclins. CKIs such as p21Cip1 (p21) and p27Kip1 (p27) associate with CDK-cyclin complexes and prevent their activation. OBJECTIVES: To gain insight into the molecular implication of CDK2 and CDK4 kinases in psoriasis, we sought to characterize expression of these kinases and associated cyclins, as well as of CKIs, and addressed the status of CDK2 and CDK4 activity in human psoriatic epidermis. METHODS: A cohort of 24 patients with psoriasis participated in the study. Biopsies were removed from a chronic plaque and from nonlesional skin. CDK2, CDK4, cyclin D1, cyclin E and CKI protein expression was assessed by immunoblotting, immunohistochemistry and immunofluorescence. CDK4 and CDK2 mRNA expression was determined by real-time polymerase chain reaction. Specific kinase activities of CDK2 and CDK4 were evaluated using fluorescent peptide biosensors. RESULTS: CDK2-cyclin E expression and activity were significantly increased in psoriatic epidermis compared with uninvolved adjacent skin. In contrast, CDK4-cyclin D1 activity was inhibited, although its expression was increased in psoriatic epidermis and its transcription slightly inhibited. p27 expression was reduced, while p16 and p21 expression was induced in psoriatic epidermis. CONCLUSIONS: Epidermal CDK2 activity is increased in psoriatic epidermis while CDK4 activity is completely inhibited. These alterations are not associated with changes in CDK transcription and instead involve post-translational control mediated by decreased expression of p27 and p16 overexpression, respectively. What's already known about this topic? Cyclin-dependent kinases (CDKs) are involved in cell-cycle progression. The levels of cyclin partners and CDK inhibitors regulate their activity. Psoriasis is a chronic T-cell-driven inflammatory skin disease characterized by hyperproliferation of basal epidermal cells. What does this study add? Thanks to fluorescent peptide biosensors, this study demonstrates that epidermal CDK2 activity is increased in psoriatic epidermis while CDK4 activity is completely inhibited. These alterations involve post-translational control mediated by decreased expression of p27, and p16 overexpression, respectively. What is the translational message? CDK2 and CDK4 are involved in regulation of cell-cycle progression, and psoriasis is characterized by hyperproliferation of basal epidermal cells. Epidermal CDK2 activity is increased in psoriatic epidermis while CDK4 activity is completely inhibited. These alterations are not associated with changes in CDK transcription and instead involve post-translational control mediated by decreased expression of p27 and p16 overexpression, respectively. Pharmacological modulation of CDK2 and CDK4 may constitute a promising therapeutic strategy.

Loss of PRP4K drives anoikis resistance in part by dysregulation of epidermal growth factor receptor endosomal trafficking.

Anoikis acts as a critical barrier to metastasis by inducing cell death upon cancer cell detachment from the extracellular matrix (ECM), thereby preventing tumor cell dissemination to secondary sites. The induction of anoikis requires the lysosomal-mediated downregulation of epidermal growth factor receptors (EGFRs) leading to termination of pro-survival signaling. In this study, we demonstrate that depletion of pre-mRNA splicing factor 4 kinase (PRP4K; also known as PRPF4B) causes dysregulation of EGFR trafficking and anoikis resistance. We also report a novel cytoplasmic localization of PRP4K at the late endosome, and demonstrate both nuclear and cytoplasmic localization in breast, lung and ovarian cancer tissue. Mechanistically, depletion of PRP4K leads to reduced EGFR degradation following cell detachment from the ECM and correlates with increased TrkB, vimentin and Zeb1 expression. As a result, PRP4K loss promotes sustained growth factor signaling and increased cellular resistance to anoikis in vitro and in a novel zebrafish xenotransplantation model of anoikis sensitivity, as well as increased metastasis in a mouse model of ovarian cancer. Thus, PRP4K may serve as a potential biomarker of anoikis sensitivity in ovarian and other epithelial cancers.

The Cdc42/Rac1 regulator CdGAP is a novel E-cadherin transcriptional co-repressor with Zeb2 in breast cancer.

The loss of E-cadherin causes dysfunction of the cell-cell junction machinery, which is an initial step in epithelial-to-mesenchymal transition (EMT), facilitating cancer cell invasion and the formation of metastases. A set of transcriptional repressors of E-cadherin (CDH1) gene expression, including Snail1, Snail2 and Zeb2 mediate E-cadherin downregulation in breast cancer. However, the molecular mechanisms underlying the control of E-cadherin expression in breast cancer progression remain largely unknown. Here, by using global gene expression approaches, we uncover a novel function for Cdc42 GTPase-activating protein (CdGAP) in the regulation of expression of genes involved in EMT. We found that CdGAP used its proline-rich domain to form a functional complex with Zeb2 to mediate the repression of E-cadherin expression in ErbB2-transformed breast cancer cells. Conversely, knockdown of CdGAP expression led to a decrease of the transcriptional repressors Snail1 and Zeb2, and this correlated with an increase in E-cadherin levels, restoration of cell-cell junctions, and epithelial-like morphological changes. In vivo, loss of CdGAP in ErbB2-transformed breast cancer cells impaired tumor growth and suppressed metastasis to lungs. Finally, CdGAP was highly expressed in basal-type breast cancer cells, and its strong expression correlated with poor prognosis in breast cancer patients. Together, these data support a previously unknown nuclear function for CdGAP where it cooperates in a GAP-independent manner with transcriptional repressors to function as a critical modulator of breast cancer through repression of E-cadherin transcription. Targeting Zeb2-CdGAP interactions may represent novel therapeutic opportunities for breast cancer treatment.

Expression of Stem Cell Markers in Preinvasive Tubal Lesions of Ovarian Carcinoma.

In order to better understand the ovarian serous carcinogenic process with tubal origin, we investigated the expression of stem cell markers in premalignant tubal lesions (serous tubal intraepithelial carcinoma or STIC). We found an increased stem cell marker density in the normal fallopian tube followed by a high CD117 and a low ALDH and CD44 expression in STICs raising the question of the role of the stem cell markers in the serous carcinogenic process.

[Type I interferonopathies]. / Interféronopathies de type I.

Type I interferonopathies are a group of Mendelian disorders characterized by a common physiopathology: the up-regulation of type I interferons. To date, interferonopathies include Aicardi-Goutières syndrome, familial chilblain lupus, spondyenchondromatosis, PRoteasome-associated auto-inflammatory syndrome (PRAAS) and Singleton-Merten syndrome. These diseases present phenotypic overlap including cutaneous features like chilblain lupus, that can be inaugural or present within the first months of life. This novel set of inborn errors of immunity is evolving rapidly, with recognition of new diseases and genes. Recent and improved understanding of the physiopathology of overexpression of type I interferons has allowed the development of targeted therapies, currently being evaluated, like Janus-kinases or reverse transcriptase inhibitors.

[Massive localized lymphedema]. / Lymphœdèmes massifs localisés.

BACKGROUND: Massive localized lymphedema (MLL) is a benign soft-tissue lesion that usually presents as a large and isolated mass in morbidly obese adults. PATIENTS AND METHODS: We report the case of a 39-year-old woman presenting obesity and multiple MLL. There was a large tumor in the left groin and two smaller lesions on the backs of the thighs. DISCUSSION: MLL is a benign tumor that must be removed wherever possible because such tumors may degenerate into angiosarcomas in 13% of cases. MLL is probably secondary to a prolonged obstruction of lymphatic vessels due to marked excess of adipose tissue.

[Metastatic cervical fasciitis revealing invasive lobular breast carcinoma]. / Fasciite cervicale métastatique révélant un carcinome lobulaire infiltrant du sein.

BACKGROUND: We describe the case of a 71-year-old woman presenting cervical metastatic fasciitis with invasive lobular carcinoma (ILC) of the breast. PATIENTS AND METHODS: The patient consulted for a deep and painless skin infiltration of the neck associated with dysphagia and restricted cervical mobility. Skin and muscle biopsies were normal. Muscle fascia biopsy showed a linear infiltration of metastatic cells in "single file", revealing ILC of the right breast. DISCUSSION: ILCs have a particular metastatic pattern. They can permeate through tissue planes, infiltrate solid organs and spread on serous membranes in an insidious fashion. CONCLUSION: Our case shows that ILC can metastasise into muscular fascia, causing "fasciitis-like" symptoms. Dermatologists should be aware of this particular pattern of dissemination.

[What's new in dermatological therapy?]. / Quoi de neuf en thérapeutique dermatologique?

This non-exhaustive review focuses on publications that have been the subject of randomized controlled trials. It will also include results from research that may lead to new therapeutic perspectives. The selected articles were published between October 2013 and September 2014. The vast majority of them were dedicated to the treatment of psoriasis (anti-TNF, ustekinumab, antibodies against IL-17 or its receptors, anti-IL-23, anti-CD6 and ponesimod). Selected papers will also address the following diseases: atopic dermatitis, urticaria, acne, bullous diseases, alopecia areata, skin infections, acne rosacea and leg ulcers.

[Multiple primary cutaneous plasmacytoma]. / Plasmocytomes cutanés primitifs multiples.

BACKGROUND: Primary cutaneous plasmacytoma is a rare form of cutaneous B-cell lymphoma. PATIENTS AND METHODS: A 51 year-old male with an unremarkable history gradually presented erythematous papulonodular lesions that had appeared gradually over the whole body throughout a two-year period and showing histologic and immunohistochemical features of cutaneous plasmacytoma. Staging investigations confirmed the primary character of the disease, and because of this and the absence of functional impairment, we opted for therapeutic abstention. No progression was noted after 4 years of regular monitoring. DISCUSSION: Primary cutaneous plasmacytoma (PCP) is characterized by clonal proliferation of plasma cells in skin. Multiple PCPs are extremely rare and to date have been treated in most cases by chemotherapy, either with or without radiotherapy. The prognosis is poor, with 2-year survival of only 25%. The present case is original, being the only one to our knowledge in which therapeutic abstention was followed by a lack of progression after 4 years of regular follow-up. Consequently, certain indolent forms of PCP do not warrant automatic institution of chemotherapy.

[Spontaneous remission of congenital leukemia cutis]. / Lésions cutanées à type de leucémie congénitale "aleucémique" de rémission spontanée.

BACKGROUND: Aleukaemic leukaemia--without blasts in the blood or the bone marrow--with isolated cutaneous manifestations has been very rarely reported since only seven patients have been described to date. The prognosis is variable, and the indications for an aggressive treatment such as polychemotherapy are currently unclear. We report a case of spontaneously remitting aleukaemic leukaemia in a newborn child and compare it with other cases in the literature. CASE REPORT: A male newborn presented diffuse, violaceous skin nodules reminiscent of the so-called "blueberry muffin syndrome" present since birth. Blood and marrow examinations did not show any blasts and karyotype was normal. Biopsy of a nodule established the diagnosis of acute myeloid leukaemia type 5. The course was spontaneously favourable despite the absence of specific therapy and the boy was asymptomatic after one year of follow-up. DISCUSSION: Of the eight reported infants (including ours), three died, including two through acute transformation of the leukaemia. The prognosis seems to be highly dependent on cytogenetic features with the 11q23 rearrangement being at higher risk of acute transformation, prompting recourse to aggressive chemotherapy. Our case further illustrates the favourable prognostic value of a normal karyotype, a situation in which therapeutic abstention seems possible, and is even recommended.

Proteolytic activity and expression of the 20S proteasome are increased in psoriasis lesional skin.

BACKGROUND: Deregulation of the proteasome pathway has been shown to be involved in the pathogenesis of several inflammatory disorders. To date limited information exists on proteasome and immunoproteasome expression and activity in psoriasis skin. OBJECTIVES: To investigate the potential role of proteasomes in the pathogenesis of psoriasis. METHODS: Thirty-six patients with psoriasis and 40 healthy subjects were included. The protein and mRNA expression levels and proteolytic activity of proteasome and immunoproteasome subunits were determined using immunohistochemistry, quantitative polymerase chain reaction and fluorogenic peptide substrate in lesional and nonlesional psoriasis skin. We additionally measured the plasmatic proteasome (p-proteasome) levels using enzyme-linked immunosorbent assay. RESULTS: We reveal an increased expression of proteasome and immunoproteasome subunits but stable mRNA levels in lesional psoriasis skin as compared with nonlesional psoriasis skin (n = 19), suggesting that proteasome and immunoproteasome expression is regulated post-transcriptionally. This proteasome overexpression was associated with a significant increase of the proteasomal chymotrypsin-like activity that was threefold higher in lesional skin than in nonlesional skin (n = 3). p-Proteasome levels were enhanced in patients with psoriasis (mean ± SEM 3960 ± 299 ng mL(-1) , range 1484-8987) when compared with controls (2535±187 ng mL(-1) , range 654-6446, P<0·001) and were significantly higher in psoriatic arthritis (4937±572 ng mL(-1) , range 2600-8987). In addition, they were correlated to the body surface area involved and appeared thus as a new biomarker of psoriasis severity. CONCLUSIONS: Altogether these results strongly suggest the involvement of the proteasome system in the pathogenesis of psoriasis and support the relevance of proteasome inhibitors in local or systemic treatment of psoriasis.

[Necrotic arachnidism in the south of France: two clinical cases of loxoscelism]. / Envenimation nécrotique dans le Sud de la France : deux observations de loxoscélisme cutané

BACKGROUND: loxosceles spiders are found throughout the world and are responsible for numerous cases of envenomation in America and Southern Europe. We describe, to our knowledge for the first time in France, two clinical cases of cutaneous loxoscelism. CASE REPORT: two cases of skin necrosis arising after supposed spider bites were grouped together because of their similar clinical presentation: an initial painless bite and rapid development of an inflammatory and painful cutaneous lesion with a central hemorrhagic bulla surrounded by a perimeter of blanched skin (the "red, white, and blue" sign). The outcome in both cases was deep skin necrosis and chronic ulceration requiring surgical treatment. DISCUSSION: loxoscelism can result in dermonecrosis. Although our cases were not documented by capture of the spider, the diagnosis of cutaneous loxoscelism was supported by the characteristic appearance of the lesion, a typical clinical course, elimination of differential diagnoses, and the confirmed presence of Loxosceles rufescens in the region. CONCLUSION: loxoscelism can occur in the south of France and although rare, must be considered in this region as a possible cause of skin necrosis.

[Cutaneous metastasis revealing epithelioid angiosarcoma of the abdominal aorta]. / Métastases cutanées révélatrices d'un angiosarcome épithélioïde de l'aorte abdominale.

BACKGROUND: Epithelioid angiosarcomas (EAS) of the aorta are a rare form of tumour usually diagnosed by histopathological analysis of the aorta. We report a case revealed by skin metastasis. CASE REPORT: An 85-year-old man presented skin tumours associated with deterioration of his general condition and intense pain of the right lower limb. Physical examination showed three nodules of the lumbar area associated with an ipsilateral livedo extending to the right lower limb. The course of the disease involved distal ischaemia. Arterial ultrasound, aortography and CAT showed ectasia of the abdominal aorta with thrombosis and right subpopliteal occlusion. Histological examination of a nodule showed proliferation of malignant cells with expression of vimentin, CD 31, cytokeratins AE1/AE3 and cytokeratin 7. Stain for CD34 was negative. Histological investigation of the livedo showed a vascular embolus with epithelial-type cells positive for cytokeratin 7 and CD 31. The PET scan showed intense F-FDG uptake of the aorta extended to the iliac artery. Moreover, skin and osseous F-FDG uptake was seen. These findings suggested a diagnosis of EAS of the aorta with skin and osseous metastasis and vascular emboli. DISCUSSION: Only 27 previous case reports of EAS based on appropriate immunohistochemical analysis have been published in the literature. These tumours typically arise in the abdominal aorta in association with metastasis in more than 80% of cases. Skin metastasis causes papular eruption, nodules and peripheral vascular disease. Embolic vascular occlusion results in ischaemia and in rare cases vasculitis. Our case report emphasizes four key points: the diagnostic value of an association of localized malignant skin tumours, extensive livedo, ipsilateral distal ischaemia, deterioration of the general condition and intense pain; the diagnostic value of endothelial markers, especially CD31, and potentially misleading co-expression of cytokeratin markers; in selected cases, additional imaging, such as PET scans, performed in our case for the first time prior to surgery of the aorta, may be helpful for the diagnosis of such neoplastic lesions of the aortic wall.