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CD11b+ cells markedly express the itch cytokine interleukin-31 in polymorphic light eruption Interleukin (IL)-31 is a novel cytokine of the IL-6 family, also described as a "pruritogenic cytokine" owing to its link between the immune and neuronal systems to induce itch.[5] IL-31 is expressed by a variety of inflammatory cells.[5] It binds to the IL-31 receptor alpha complex (IL-31RA), and mediates inflammatory itch by forming a functional receptor through coupling to oncostatin M receptor (OSMR) .[6] In psoriatic skin, overall expression of IL-31 (48-0 ± 19-4 cells/mm SP 2 sp ) and OSMR (5-9 ± 3-9 cells/mm SP 2 sp ) was lower compared with PLE, while IL-31RA (36-9 ± 8-2 cells/mm SP 2 sp ) was expressed at similar levels. [Extracted from the article]

Background: To study the correlation of different variables of Vogt striae to other attributes of keratoconus and to suggest a new grading system for Vogt striae to exactly represent the configuration and extent in each individual keratoconic cornea., Methods: The study was an observational and data review study. A total of 386 eyes of 207 keratoconus patients were screened from February 2016 to August 2018. Patients with prior history of collagen cross linking were excluded from the study as measurement of corneal thickness is less reliable for many months after collagen cross linking, and patients may have superficial corneal striae and scarring after collagen cross linking. Patients with history or clinical features suggestive of corneal hydrops or who had undergone lamellar or full thickness corneal transplants and intracorneal ring segments were also excluded from the study., Results: Of total 52 eyes with Vogt striae, 31 eyes (59.6%) had vertical orientation, 3 (5.8%) had horizontal, 11 (21.2%) had oblique while 7 eyes (13.5%) had mixed orientation of Vogt striae. Mean uncorrected distance visual acuity (UCVA) in the vertical group was 0.76 logMAR, horizontal group was 0.80 logMAR, oblique group was 0.65 logMAR, and mixed group was 1.17 logMAR units. Corneal scarring was present in 15 eyes (28.8%) and absent in 37 (71.2%) eyes with Vogt striae. In the mixed Vogt striae group, 85.7% eyes (6 eyes of 7) had corneal scarring, while 16.1% in vertical group (5 eyes of 31), and 27.3% in oblique group (3 of 11) had corneal scarring. Based on three attributes of Vogt striae, that is orientation, number, and corneal scarring, a new grading for Vogt striae was also suggested., Conclusion: This is the first study to report the presence of mixed Vogt striae (combination of horizontal and/or vertical and/or oblique Vogt striae in a single cornea) in cases of keratoconus. For the first time, oblique Vogt striae have been described, and clear limits have been set to call it horizontal, oblique, or vertical striae. A new grading for Vogt striae is also suggested., Competing Interests: The authors have none to declare., (© 2022 Director General, Armed Forces Medical Services. Published by Elsevier, a division of RELX India Pvt. Ltd.)

Background: The contribution of Staphylococcus aureus to the exacerbation of atopic dermatitis (AD) is widely documented, but its role as a primary trigger of AD skin symptoms remains poorly explored., Objectives: This study sought to reappraise the main bacterial factors and underlying immune mechanisms by which S aureus triggers AD-like inflammation., Methods: This study capitalized on a preclinical model, in which different clinical isolates were applied in the absence of any prior experimental skin injury., Results: The development of S aureus-induced dermatitis depended on the nature of the S aureus strain, its viability, the concentration of the applied bacterial suspension, the production of secreted and nonsecreted factors, as well as the activation of accessory gene regulatory quorum sensing system. In addition, the rising dermatitis, which exhibited the well-documented AD cytokine signature, was significantly inhibited in inflammasome adaptor apoptosis-associated speck-like protein containing a CARD domain- and monocyte/macrophage-deficient animals, but not in T- and B-cell-deficient mice, suggesting a major role for the innate response in the induction of skin inflammation. However, bacterial exposure generated a robust adaptive immune response against S aureus, and an accumulation of S aureus-specific γδ and CD4 + tissue resident memory T cells at the site of previous dermatitis. The latter both contributed to worsen the flares of AD-like dermatitis on new bacteria exposures, but also, protected the mice from persistent bacterial colonization., Conclusions: These data highlight the induction of unique AD-like inflammation, with the generation of proinflammatory but protective tissue resident memory T cells in a context of natural exposure to pathogenic S aureus strains., Competing Interests: Disclosure statement This study was supported by institutional grants from the Institut National de la Santé et de la Recherche Médicale (INSERM) and from Pfizer. Disclosure of potential conflict of interest: The authors declare that they have no relevant conflicts of interest., (Copyright © 2024 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: Varicose vein is a chronic condition that affects the lower extremities of the human body. Several factors have been implicated in the development of this disease, viz age, gender, weight, height and prolonged standing. Recently, genome-wide studies have identified genetic biomarkers that are associated with varicose veins in different ethnic groups. Such genetic studies are lacking in South Asians specifically in Indians where the prevalence of varicose veins is high, and it is important to replicate these variants in the stated population. The study aimed to replicate the association of genetic variants associated with varicose veins in this target population, which were found to be associated with the other ethnic groups., Methodology: The studied cohort is of the Indian population comprising unrelated 104 varicose veins cases and 448 non-varicose vein controls. The samples were genotyped using the Illumina Global Screening Array. Using the genomic data from UK BioBank and 23andMe studied cohorts; eight genetic variants were selected to replicate in our dataset. The allelic association was performed to identify the effective allele and risk was estimated using odds ratio and p-value as level of significance. Multifactor Dimensionality Reduction was used to estimate the cumulative effect of variants in Indians., Result: Variant rs3791679 of EFEMP1 was found to be associated with varicose veins in Indians. After observing the association of the EFEMP1 with varicose veins, we further ensued to identify all genetic variants within EFEMP1 to uncover the additional variants associated with this trait. Interestingly, we identified six new variants of EFEMP1 gene that have shown association. Moreover, the cumulative effect of all associated variations was estimated and the risk was 2.7 times higher in cases than controls whereas independently their effect ranges from 0.37-1.58., Conclusion: This study identifies EFEMP1 as a potential gene related to the risk of varicose veins in Indians. It also highlights that evaluating the maximum number of variants of a gene rather than focusing solely on replicating single variations offers a more comprehensive and nuanced understanding of the genetic factors contributing to a complex trait like varicose veins., (© 2024. The Author(s).)

Polymorphic light eruption (PLE) has been mechanistically linked to cytokine abnormalities. Emerging preclinical evidence posits the skin microbiome as a critical modulator of ultraviolet (UV)-induced cytokine expression, thereby influencing subsequent immune responses. This intricate relationship remains underexplored in the context of PLE. Hence, we investigated the differential responses between disinfected and non-disinfected skin following both single and repetitive exposures to solar-simulated UV radiation in patients with PLE. An experimental, half-body pilot study was conducted involving six PLE patients and 15 healthy controls. Participants' skin was exposed to single and multiple doses of solar-simulated UV radiation, both in disinfected and in non-disinfected skin areas. The co-primary outcomes were PLE score and cytokine expression in blister fluid analysed through OLINK proteomic profiling. Secondary outcomes were erythema, pigmentation, induction of apoptotic cells in vacuum-generated suction blisters, and density of infiltrate in skin biopsies of PLE patients. Among the 71 cytokines analysed, baseline expression levels of 20 specific cytokines-integral to processes such as apoptosis, inflammation, immune cell recruitment, cellular growth, and differentiation-were significantly impaired in PLE patients compared with healthy controls. Notably, skin disinfection reversed the observed cytokine imbalances following a single UV exposure at the minimal erythema dose (MED) level and exhibited even more pronounced effects after multiple UV exposures. However, no significant differences were evident in PLE score, erythema, pigmentation, or rates of apoptotic cell induction upon UV radiation. These findings provide evidence for UV-driven cytokine regulation by the skin microbiota and imply microbiome involvement in the PLE immune response., (© 2024 The Authors. Experimental Dermatology published by John Wiley & Sons Ltd.)

Competing Interests: Competing interests: None declared.

Dangi, Meenu, Arnab Sadhukhan, Poninder Kumar, S. Bandopadhayay, Vijay K. Sharma, V.K. Patra, Manu Chaudhary, and Vipin Rana. Retinal manifestations in high altitude. High Alt Med Biol . 24:296-301, 2023. Aim: To study the high altitude (HA)-related retinal manifestations among security personnel and thus to provide new insights into the characteristics and mechanisms of retinopathy. Materials and Methods: This was a multicentric, nonrandomized prospective observational and descriptive study. We studied 54 security personnel over 1 year, who were referred from HA areas of northern India and north-eastern India for ocular problems. Complete coagulation profile was performed among patients with vascular occlusion. Results: There were total of 54 patients with ages ranging from 22 to 55 years. HA retinopathy was noticed in 28 patients: central retinal vein occlusion (6 patients), branch retinal vein occlusion (4 patients), branch retinal artery occlusion (1 patient), central retinal artery occlusion (4 patients), ocular ischemic syndrome (1 patient), central serous chorioretinopathy (7 patients), acetazolamide-induced maculopathy (1 patient), and solar retinopathy (2 patients). Along with an increased hematocrit, serum homocysteine was raised in the majority of vascular occlusions. The mean age was 38.16 years, the mean altitude was 14,716 ft, and the mean duration of stay was 11.2 weeks. Conclusion: Hypobaric hypoxia due to HA is a potential risk for HA retinopathy and associated vascular occlusions. Aside from increased hematocrit, hyperhomocysteinemia is a potential cause of vascular occlusions.

Objective: To elucidate the pathogenesis of dupilumab (Dupixent®)-associated ocular surface disease (DAOSD)., Design: Prospective single-center cohort study., Subjects: Twenty patients with moderate-to-severe atopic dermatitis (AD) who received dupilumab and 10 age- and sex-matched healthy controls were enrolled in the study., Methods: The study cohort underwent a thorough slit-lamp and entire-body dermatologic examination. Conjunctival swabs and smears were collected at baseline, 4 and 16 weeks after treatment initiation, and during the conjunctivitis episode. To analyse the ocular surface microbiome, 16S ribosomal RNA sequencing was performed, smears were hematoxylin and eosin stained, and serum cytokines were measured by using a multiplex immunobead assay., Main Outcome Measures: Composition of ocular surface microbiome and cellular component as well as serum cytokine levels., Results: Six of the 20 patients with AD developed DAOSD after dupilumab initiation; these patients responded after a delay to treatment as quantified by Eczema Area and Severity Index and Investigator's Global Assessment score. Conjunctival smears showed massive neutrophilic infiltration and serum analysis revealed increased systemic levels of neutrophil-priming proinflammatory cytokines, in particular interleukin-1β and tumor necrosis factor α, in patients with DAOSD compared with those without it. The ocular surface microbiome of patients with DAOSD was characterized by a diverse and persistent microbial colonization, particularly by Acetobacter aceti . In contrast, microbial diversity decreased in patients with AD without DAOSD after the initiation of dupilumab treatment, especially the abundance of Staphylococcus aureus . In vitro experiments substantiated the potential role of the microbiome, showing increased growth of A. aceti and decreased growth of S. aureus in presence of dupilumab., Conclusions: Persistent neutrophilic infiltration and a unique microbial landscape on the ocular surface associated with elevated levels of systemic proinflammatory cytokines typify DAOSD., Financial Disclosures: Proprietary or commercial disclosure may be found after the references., (© 2023 by the American Academy of Ophthalmology.)

Skin metabolites (< 1500 Da) play a critical role in barrier function, hydration, immune response, microbial invasion, and allergen penetration. We aimed to understand the global metabolic profile changes of the skin in relation to the microbiome and UV exposure and exposed germ-free (devoid of microbiome), disinfected mice (partially devoid of skin microbiome) and control mice with intact microbiome to immunosuppressive doses of UVB radiation. Targeted and untargeted lipidome and metabolome profiling was performed with skin tissue by high-resolution mass spectrometry. UV differentially regulated various metabolites such as alanine, choline, glycine, glutamine, and histidine in germ-free mice compared to control mice. Membrane lipid species such as phosphatidylcholine, phosphatidylethanolamine, and sphingomyelin were also affected by UV in a microbiome-dependent manner. These results shed light on the dynamics and interactions between the skin metabolome, microbiome, and UV exposure and open new avenues for the development of metabolite- or lipid-based applications to maintain skin health., (© 2023. The Author(s).)

Atopic dermatitis (AD) is a common chronic inflammatory skin disease that significantly affects the patient's quality of life. A disrupted skin barrier, type 2 cytokine-dominated inflammation, and microbial dysbiosis with increased Staphylococcus aureus colonization are critical components of AD pathogenesis. Patients with AD exhibit decreased expression of antimicrobial peptides (AMPs) which is linked to increased colonization by Staphylococcus aureus . The skin microbiome itself is a source of several AMPs. These host- and microbiome-derived AMPs define the microbial landscape of the skin based on their differential antimicrobial activity against a range of skin microbes or their quorum sensing inhibitory properties. These are particularly important in preventing and limiting dysbiotic colonization with Staphylococcus aureus . In addition, AMPs are critical for immune homeostasis. In this article, we share our perspectives about the implications of microbial derived AMPs in AD patients and their potential effects on overlapping factors involved in AD. We argue and discuss the potential of bacterial AMPs as therapeutics in AD., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Joshi, Vocanson, Nicolas, Wolf and Patra.)

Abstract: This study investigates the relationship among defense styles and learning through academic procrastination and psychological well-being. The sample comprises 628 social science students from a Greek university. Path analysis is used to explore associations and interactions among the variables. The results show that academic procrastination and psychological well-being mediate the relationship between defense styles and approaches to learning, indicating the expected direct and indirect effects. Defense styles are directly related to approaches to learning. Mature defense styles are associated with learning through psychological well-being in a positive way, and immature defense styles are associated with learning through academic procrastination in a negative way. This study supports the current line of research in associations between defense styles and learning and the importance of linking mental health variables with learning., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

The cutaneous microbiota contributes to skin barrier function, ensuring effective protection against pathogens and contributing to the maintenance of epidermal integrity. Dysbiosis is frequently present in atopic dermatitis (AD), a chronic inflammatory disease associated with skin barrier defects. Dysbiosis is associated with reduced bacterial diversity and marked Staphylococcus aureus colonization, which is favoured in the case of certain local AD-specific properties such as reduced skin acidity, eased bacterial adhesion and decreased antimicrobial peptide production. Furthermore, S. aureus-associated skin dysbiosis, via the production of staphylococcal virulence factors, may also participate in the immunopathology of AD by altering the epidermal barrier and inducing an inflammatory response. However, there are currently no arguments for recommending screening for, and treatment of S. aureus-associated dysbiosis outside the setting of cutaneous superinfection. Nonetheless, modulation of the skin microbiota may hold promise for AD management. Here, we describe the relationships that exist between the skin microbiota and AD.

Patients with polymorphic light eruption (PLE) develop lesions upon the first exposure to sun in spring/summer, but lesions usually subside during season due to the natural (or medical) photohardening. However, these lesions tend to reappear the following year and continue to do so in most patients, suggesting the presence of a disease memory. To study the potential role of skin resident memory T cells (Trm), we investigated the functional phenotype of Trm and the expression of IL-15 in PLE. IL-15 is known to drive Trm proliferation and survival. Multiplex immunofluorescence was used to quantify the expression of CD3, CD4, CD8, CD69, CD103, CD49a, CD11b, CD11c, CD68, granzyme B (GzmB), interferon-gamma (IFN-γ), and IL-15 in formalin-fixed, paraffin-embedded lesional skin samples from PLE patients and healthy skin from control subjects. Unlike the constitutive T cell population in healthy skin, a massive infiltration of T cells in the dermis and epidermis was observed in PLE, and the majority of these belonged to CD8 + T cells which express Trm markers (CD69, CD103, CD49a) and produced cytotoxic effector molecules GzmB and IFN-γ. Higher numbers of CD3 + T cells and CD11b + CD68 + macrophages produced IL-15 in the dermis as compared to healthy skin. The dominant accumulation of cytotoxic Trm cells and increased expression of IL-15 in lesional skin of PLE patients strongly indicates the potential role of skin Trm cells in the disease manifestation and recurrence., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Patra, Strobl, Atzmüller, Reininger, Kleissl, Gruber-Wackernagel, Nicolas, Stary, Vocanson and Wolf.)

Objective: To highlight safety and efficacy of sine wave technique (SWT) in superficializing deep arterio venous fistula (AVF) and managing infiltrations and other complications., Methods: It is a single center observational study done from Jul 2017 to July 2020. All successive cases of deep AVFs, aneurysm / pseudoaneurysms of AVFs, and AVFs requiring open venoplasty were managed with SWT. Data was collected prospectively and analyzed. SWT is based on random pattern skin flaps. Using ultrasound, a line is marked on either side of centre line (AVF) at a distance of approximately 1.5-2 cm. A sine wave is drawn starting from either of the lines to the other with multiple crests and troughs. The base of flap should be double the height of the flap, that is, about 3-4 cm. Skin is incised and flaps are raised at level of AVF. Excess fat is removed. A sliver of unhealthy skin can be sacrificed if required. Flaps are sutured back to restore sine wave continuity., Results: SWT was used in a total of eleven patients. Median age was 58 years (range 10-67 years). Eight were females and three males. One was radio-cephalic and rest were brachio-cephalic AVFs. Eight AVFs were deep with median depth of 10.25mm (range 8-13mm), median body mass index of 25.5 kg/m 2 (range 23.9-26.5kg/m 2 ), median vein diameter of 7 mm (range 6-8 mm), and median flow rate of 1137.5ml/min (range 650- 1380 ml/min). Out of eight, four AVFs presented with infiltration. In other three, SWT was used for exposing AVF to treat underlying pathology (one case each of aneurysm, pseudoaneurysm & stenosis). Ten cases were done under local or regional anesthesia and one under general anesthesia. There was no peri-operative mortality or loss of AVF. Transient limb oedema developed in one case. Median time to cannulate was 20 days (range 13-28 days). Median follow up was 13 months (range 6 - 31months). Cumulative patency at 18 months was 90% (95% CI 47.3%-98.53%) and 45 % (95% CI 9.9%-87.1%) at 24months and at the end of the study., Conclusion: SWT is safe and effective in superficialization of deep / difficult to cannulate AVF as well a good approach to treat complications like infiltration. Post procedure cannulation time is reasonably short., (Copyright © 2021. Published by Elsevier Inc.)

A 31-year-old woman was referred to vascular surgeons with the history of recurrent ischaemic strokes in two cerebral artery territories over a span of 1 year. On investigation, she was found to have a right internal carotid artery web, with thrombus and a fetal right posterior cerebral artery (PCA), which explained the ischaemic strokes in right middle cerebral and PCA territory. The rare association of these two infrequent entities makes the case a singular one in the medical literature. Successful surgical excision was done after multidisciplinary teamwork. The carotid web was excised as part of carotid artery endarterectomy and repaired with great saphenous vein patch angioplasty. The patient made a good recovery., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

Topical dithranol is effective in autoimmune conditions like alopecia areata, inducing hair regrowth in a high percentage of cases. Exact mechanisms of dithranol in alopecia areata, with seemingly healthy epidermis besides altered hair follicles, are not well understood. To better understand dithranol's mechanisms on healthy skin, we analysed its effect on normal murine as well as xenografted human skin. We found a strong increase in mRNA expression of anti-microbial peptides (AMPs) (eg Lcn2, Defb1, Defb3, S100a8, S100a9), keratinocyte differentiation markers (eg Serpinb3a, Flg, Krt16, Lce3e) and inflammatory cytokines (eg Il1b and Il17) in healthy murine skin. This effect was paralleled by inflammation and disturbed skin barrier, as well as an injury response resulting in epidermal hyperproliferation, as observed in murine and xenografted adult human skin. This contact response and disturbed barrier induced by dithranol might lead via a vicious loop between AMPs such as S100a8/a9 (that led to skin swelling itself after topical application) and cytokines such as IL-1β to an immune suppressive environment in the skin. A better understanding of the skin's physiologic response to dithranol may open up new avenues for the establishment of novel therapeutics (including AMP-related/interfering molecules) for certain skin conditions, such as alopecia areata., (© 2021 The Authors. Experimental Dermatology published by John Wiley & Sons.)

The human skin hosts innumerable microorganisms and maintains homeostasis with the local immune system despite the challenges offered by environmental factors such as ultraviolet radiation (UVR). UVR causes cutaneous alterations such as acute (i.e., sunburn) and chronic inflammation, tanning, photoaging, skin cancer, and immune modulation. Phototherapy on the other hand is widely used to treat inflammatory skin diseases such as psoriasis, atopic dermatitis, polymorphic light eruption and graft-versus-host disease (GvHD), as well as neoplastic skin diseases such as cutaneous T cell lymphoma, among others. Previous work has addressed the use of pro- and pre-biotics to protect against UVR through anti-oxidative, anti-inflammatory, anti-aging, anti-carcinogenic and/or pro-and contra-melanogenic properties. Herein, we discuss and share perspectives of the potential benefits of novel treatment strategies using microbes and pro- and pre-biotics as modulators of the skin response to UVR, and how they could act both for protection against UVR-induced skin damage and as enhancers of the UVR-driven therapeutic effects on the skin.

Despite the introduction of biologics, topical dithranol (anthralin) has remained one of the most effective anti-psoriatic agents. Serial biopsies from human psoriatic lesions and both the c-Jun/JunB and imiquimod psoriasis mouse model allowed us to study the therapeutic mechanism of this drug. Top differentially expressed genes in the early response to dithranol belonged to keratinocyte and epidermal differentiation pathways and IL-1 family members (i.e. IL36RN) but not elements of the IL-17/IL-23 axis. In human psoriatic response to dithranol, rapid decrease in expression of keratinocyte differentiation regulators (e.g. involucrin, SERPINB7 and SERPINB13 ), antimicrobial peptides (e.g. ß-defensins like DEFB4A, DEFB4B, DEFB103A, S100 proteins like S100A7, S100A12 ), chemotactic factors for neutrophils (e.g. CXCL5, CXCL8 ) and neutrophilic infiltration was followed with much delay by reduction in T cell infiltration. Targeting keratinocytes rather than immune cells may be an alternative approach in particular for topical anti-psoriatic treatment, an area with high need for new drugs., Competing Interests: TB, CP, VP, SD, MH, BL, MS, PW No competing interests declared, (© 2020, Benezeder et al.)

The skin microbiota plays a prominent role in health and disease; however, its contribution to skin tumorigenesis is not well understood. We comparatively assessed the microbial community compositions from excision specimens of the main human non-melanoma skin cancers, actinic keratosis (AK), squamous cell carcinoma (SCC) and basal cell carcinoma (BCC). Keratinocyte skin tumors are characterized by significantly different microbial community compositions, wherein AK and SCC are more similar to each other than to BCC. Notably, in SCC, which represents the advanced tumor entity and frequently develops from AK, overabundance of Staphylococcus aureus, a known skin pathogen, was noted. Moreover, S. aureus overabundance was significantly associated with increased human β-defensin-2 (hBD-2) expression in SCC. By challenging human SCC cell lines with S. aureus , a specific induction of hBD-2 expression and increased tumor cell growth was seen. Increased proliferation was also induced by directly challenging SCC cells with hBD-2. Together, our data indicate that a changed microbial community composition in SCC, specified by S. aureus overabundance, might promote tumor cell growth via modulation of hBD-2 expression., Competing Interests: The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

The skin is colonized by a diverse microbiome intricately involved in various molecular and cellular processes within the skin and beyond. UV radiation is known to induce profound changes in the skin and modulate the immune response. However, the role of the microbiome in UV-induced immune suppression has been overlooked. By employing the standard model of contact hypersensitivity (using germ-free mice) we found diminished UV-induced systemic immune suppression in the presence of microbiome. Upon UV exposure, we found enhanced epidermal hyperplasia and neutrophilic infiltration in the presence and enhanced numbers of mast cells and monocyte or macrophages in the absence of microbiome. Transcriptome analysis revealed a predominant expression of cytokine genes related to pro-inflammatory milieu in the presence versus immunosuppressive milieu (with increased interleukin-10) in the absence of microbiome. Collectively, microbiome abrogates the immunosuppressive response to UV by modulating gene expression and cellular microenvironment of the skin., (Copyright © 2019 The Author(s). Published by Elsevier Inc. All rights reserved.)