Dermatology
Abstract
Thy-1 (CD90) is a well-known marker of fibroblasts implicated in organ fibrosis, but its contribution to skin fibrosis remains unknown. We examined Thy-1 expression in scleroderma skin and its potential role as a biomarker and pathogenic factor in animal models of skin fibrosis. Skin from patients with systemic sclerosis demonstrates markedly elevated Thy-1 expression compared to controls, co-localizes with fibroblast activator protein (FAP) in the deep dermis, and is correlated with the severity of skin involvement (MRSS). Serial imaging of skin from Thy-1 YFP reporter mice by IVIS showed an increase in Thy-1 expression which correlated with onset and progression of fibrosis. In contrast to lung fibrosis, Thy-1 KO mice had attenuated skin fibrosis in both bleomycin and Tsk-1 murine models. Moreover, Thy-1 regulated key pathogenic pathways involved in fibrosis including inflammation, myofibroblast differentiation, apoptosis and multiple additional canonical fibrotic pathways. Therefore, while Thy-1 deficiency leads to exacerbated lung fibrosis, in skin it is protective. Moreover, Thy-1 may serve as a longitudinal marker to assess skin fibrosis.
Authors
Roberta G. Marangoni, Poulami Datta, Ananta Paine, Stacey Duemmel, Marc A. Nuzzo, Laura Sherwood, John Varga, Christopher Ritchlin, Benjamin D. Korman
Abstract
The epidermis is the outermost layer of skin. Here, we use targeted lipid profiling to characterize the biogeographic alterations of human epidermal lipids across 12 anatomically distinct body sites, and use single-cell RNA sequencing to compare keratinocyte gene expression at acral and non-acral surfaces. We demonstrate that acral skin has low expression of EOS acyl-ceramides and the genes involved in their synthesis, as well as low expression of genes involved in filaggrin and keratin citrullination (PADI1 and PADI3) and corneodesmosome degradation, changes consistent with increased corneocyte retention. Several overarching principles governing epidermal lipid expression were also noted. For example, there is a strong negative correlation between the expression of 18-carbon and 22-carbon sphingoid base ceramides. Disease-specific alterations in epidermal lipid gene expression and their corresponding alterations to the epidermal lipidome were characterized. Lipid biomarkers with diagnostic utility for inflammatory and precancerous conditions were identified, and a two-analyte diagnostic model of psoriasis was constructed using a step-forward algorithm. Finally, gene co-expression analysis revealed a strong connection between lipid and immune gene expression. This work highlights mechanisms by which the epidermis is uniquely adapted for the specific environmental insults encountered at different body surfaces, and how inflammation-associated alterations in gene expression affect the epidermal lipidome.
Authors
Alexander A. Merleev, Stephanie T. Le, Claire Alexanian, Atrin Toussi, Yixuan Xie, Alina I. Marusina, Steven M. Watkins, Forum Patel, Allison C. Billi, Julie Wiedemann, Yoshihiro Izumiya, Ashish Kumar, Ranjitha Uppala, J. Michelle Kahlenberg, Fu-Tong Liu, Iannis E. Adamopoulos, Elizabeth A. Wang, Chelsea Ma, Michelle Y. Cheng, Halani Xiong, Amanda Kirane, Guillaume Luxardi, Bogi Andersen, Lam C. Tsoi, Carlito B. Lebrilla, Johann E. Gudjonsson, Emanual Maverakis
Abstract
Proprotein convertase subtilisin/kexin type-9 (PCSK9) is a post-translational regulator of the low-density lipoprotein receptor (LDLR). Recent studies have proposed a role for PCSK9 in regulating immune responses. Using RNA-sequencing-based variant discovery, we identified a novel psoriasis susceptibility locus at 1p32.3, located within PCSK9 (rs662145 C>T). This finding was verified in independently acquired genomic and RNA-sequencing datasets. Single-cell RNA-sequencing (scRNA-seq) identified keratinocytes as the primary source of PCSK9 in human skin. PCSK9 expression, however, was not uniform across keratinocyte subpopulations. scRNA-seq and immunohistochemistry demonstrated an epidermal gradient of PCSK9, with expression being highest in basal and early spinous layer keratinocytes and lowest in granular layer keratinocytes. IL-36G expression followed the opposite pattern, with expression highest in granular layer keratinocytes. PCSK9 siRNA knockdown experiments confirmed this inverse relationship between PCSK9 and IL36G expression. Other immune genes were also linked to PCSK9 expression including, IL27RA, IL1RL1, ISG20, and STX3. In both cultured keratinocytes and nonlesional human skin, homozygosity for PCSK9 SNP rs662145 C>T was associated with lower PCSK9 expression and higher IL36G expression, when compared to heterozygous skin or cell lines. Together these results support PCSK9 as a novel psoriasis susceptibility locus and establish a putative link between PCSK9 and inflammatory cytokine expression.
Authors
Alexander Merleev, Antonio Ji-Xu, Atrin Toussi, Lam C. Tsoi, Stephanie T. Le, Guillaume Luxardi, Xianying Xing, Rachael Wasikowski, William Liakos, Marie-Charlotte Brüggen, James T. Elder, Iannis E. Adamopoulos, Yoshihiro Izumiya, Annie Riera-Leal, Qinyuan Li, Nikolay Yu Kuzminykh, Amanda Kirane, Alina I. Marusina, Johann E. Gudjonsson, Emanual Maverakis
Abstract
Psoriasis is a chronic, inflammatory skin disease, frequently associated with dyslipidemia. Lipid disturbance in psoriasis affects both circulatory system and cutaneous tissue. Epidermal Langerhans cells (LCs) are tissue-resident DCs that maintain skin immune surveillance and mediate various cutaneous disorders, including psoriasis. However, the role of LCs in psoriasis development and their lipid metabolic alternation remains unclear. Here, we demonstrate that epidermal LCs of psoriasis patients enlarge with longer dendrites and possess elevated IL-23p19 mRNA and a higher level of neutral lipids when compared with normal LCs of healthy individuals. Accordantly, epidermal LCs from imiquimod-induced psoriasis-like dermatitis in mice display overmaturation, enhanced phagocytosis, and excessive secretion of IL-23. Remarkably, these altered immune properties in lesional LCs are tightly correlated with elevated neutral lipid levels. Moreover, the increased lipid content of psoriatic LCs might result from impaired autophagy of lipids. Bulk RNA-Seq analysis identifies dysregulated genes involved in lipid metabolism, autophagy, and immunofunctions in murine LCs. Overall, our data suggest that dysregulated lipid metabolism influences LC immunofunction, which contributes to the development of psoriasis, and therapeutic manipulation of this metabolic process might provide an effective measurement for psoriasis.
Authors
Xilin Zhang, Xiaorui Li, Yuanyuan Wang, Youdong Chen, Yijun Hu, Chunyuan Guo, Zengyang Yu, Peng Xu, Yangfeng Ding, Qing-Sheng Mi, Jianhua Wu, Jun Gu, Yuling Shi
Abstract
Vitiligo is an autoimmune skin disease characterized by the destruction of melanocytes by autoreactive CD8+ T cells. Melanocyte destruction in active vitiligo is mediated by CD8+ T cells but why white patches in stable disease persist is poorly understood. The interaction between immune cells, melanocytes, and keratinocytes in situ in human skin has been difficult to study due to the lack of proper tools. We combine non-invasive multiphoton microscopy (MPM) imaging and single-cell RNA sequencing (scRNA-seq) to identify subpopulations of keratinocytes in stable vitiligo patients. We show that, as compared to non-lesional skin, these keratinocytes are enriched in lesional vitiligo skin and shift their energy utilization towards oxidative phosphorylation. Systematic investigation of cell-cell communication networks show that this small population of keratinocyte secrete CXCL9 and CXCL10 to potentially drive vitiligo persistence. Pseudotemporal dynamics analyses predict an alternative differentiation trajectory that generates this new population of keratinocytes in vitiligo skin. Further MPM imaging of patients undergoing punch grafting treatment showed that keratinocytes favoring oxidative phosphorylation persist in non-responders but normalize in responders. In summary, we couple advanced imaging with transcriptomics and bioinformatics to discover cell-cell communication networks and keratinocyte cell states that can perpetuate inflammation and prevent repigmentation.
Authors
Jessica Shiu, Lihua Zhang, Griffin Lentsch, Jessica L. Flesher, Suoqin Jin, Christopher M. Polleys, Seong Jin Jo, Craig Mizzoni, Pezhman Mobasher, Jasmine Kwan, Francisca Rius-Diaz, Bruce J. Tromberg, Irene Georgakoudi, Qing Nie, Mihaela Balu, Anand K. Ganesan
Abstract
It is currently thought that ultraviolet B (UVB) radiation drives photoaging of the skin primarily by generating reactive oxygen species (ROS). In this model, ROS purportedly activates AP-1 to upregulate matrix metalloproteinases (MMPs) 1, 3, and 9, which then degrade collagen and other extracellular matrix components to produce wrinkles. However, these MMPs are expressed at relatively low levels and correlate poorly with wrinkles, suggesting that another mechanism distinct from ROS and MMP1/3/9 may be more directly associated with photoaging. Here we show that MMP2, which degrades type IV collagen, is abundantly expressed in human skin, increases with age in sun-exposed skin, and correlates robustly with aryl hydrocarbon receptor (AhR), a transcription factor directly activated by UV-generated photometabolites. Through mechanistic studies with HaCaT keratinocytes, we found that AhR, SP1, and other pathways associated with DNA damage are required for the induction of both MMP2 and MMP11 (another MMP implicated in photoaging), but not MMP1/3. Lastly, we found that topical treatment with AhR antagonists vitamin B12 and folic acid ameliorated UVB-induced wrinkle formation in mice while dampening MMP2 expression in the skin. These results directly implicate DNA damage in photoaging and reveal AhR as a potential target for preventing wrinkles.
Authors
Daniel J. Kim, Akiko Iwasaki, Anna L. Chien, Sewon Kang
Abstract
Allergens have been identified as potential triggers in patients with atopic dermatitis (AD). AD patients are highly sensitive to cockroach allergen. The underlying mechanism, however, remains undetermined. Here, we established a cockroach allergen-induced AD-like mouse model and demonstrated that repeated exposure to cockroach allergen led to aggravated mouse skin inflammation, characterized by increased type 2 immunity, type 2 innate lymphoid cells (ILC2s), and mast cells. Increased skin mast cells were also observed in AD patients. AD mice with mast cell-deficient mice (kitW-sh/W-sh) showed diminished skin inflammation, suggesting that mast cells are required in allergen-induced skin inflammation. Furthermore, dendritic cell immuno-receptor (DCIR) is up-regulated in skin mast cells of AD patients and mediates allergen binding and uptake. DCIR-/- mice or reconstituted kitW-sh/W-sh mice with DCIR-/- mast cells showed a significant reduction in AD-like inflammation. Both in vitro and in vivo analyses demonstrated that DCIR-/- mast cells had reduced IgE-mediated mast cell activation and passive cutaneous anaphylaxis. Mechanistically, DCIR regulates allergen-induced IgE-mediated mast cell ROS generation and oxidation of calmodulin kinase II (ox-CaMKII). ROS-resistant CaMKII (MM-VVδ) prevents allergen-induced mast cell activation and inflammatory mediator release. Our study reveals a previously unrecognized DCIR-ROS-CaMKII axis that controls allergen-induced mast cell activation and AD-like inflammation.
Authors
Xiaoyan Luo, Jingsi Chen, Huan Yang, Xinyue Hu, Martin P. Alphonse, Yingchun Shen, Yuko Kawakami, Xiaoying Zhou, Wei Tu, Toshiaki Kawakami, Mei Wan, Nathan K. Archer, Hua Wang, Peisong Gao
Abstract
Systemic sclerosis (SSc) is a chronic multisystem orphan disease with a highly variable clinical course, significant mortality and a poorly understood complex pathogenesis. We identify an important role for a subpopulation of monocyte/macrophages characterized by surface expression of the scavenger receptor MARCO (MAcrophage Receptor with COllagenous structure) in chronic inflammation and fibrosis in SSc and in preclinical disease model. We show that MARCO+ monocytes and macrophages accumulate in lesional skin and lung in SSc patients and in the bleomycin-induced mouse model of SSc in topographic proximity to activated myofibroblasts. Short-term treatment of mice with a novel nanoparticle composed of a carboxylated FDA-approved biodegradable polymer, poly(lactic-co-glycolic) acid (PLG), which modulates activation and trafficking of MARCO+ inflammatory monocytes, markedly attenuated bleomycin-induced skin and lung inflammation and fibrosis. Mechanistically, in isolated cells in culture PLG nanoparticles inhibited TGF-β-dependent fibrotic responses in vitro. Thus MARCO+ monocytes are potent effector cells of skin and lung fibrosis, and can be therapeutically targeted in SSc using PLG nanoparticles.
Authors
Dan Xu, Swati Bhattacharyya, Wenxia Wang, Igal Ifergan, Ming-Yi Alice Chiang Wong, Daniele Procissi, Anjana Yeldandi, Swarna Bale, Roberta G. Marangoni, Craig Horbinski, Stephen D. Miller, John Varga
Abstract
Hidradenitis suppurativa (HS) is a chronic, inflammatory skin disorder characterized by recurrent abscesses in the groin and flexural areas. HS is associated with a wide range of comorbidities that complicate the disease course. Although these comorbidities have been well-described, it remains unclear how these comorbidities co-associate and whether comorbidity profiles affect disease trajectory. In addition, it is unknown how comorbidity associations are modulated by race and gender. In this comprehensive analysis of 77 million patients in a large U.S. population-based cohort, we examine co-association patterns among HS comorbidities and identify clinically relevant phenotypic subtypes within HS. We demonstrate that these subtypes not only differ among races, but also influence clinical outcomes as measured by HS-related emergency department (ED) visits and cellulitis. Taken together, our findings provide key insights that elucidate the unique disease trajectories experienced by HS patients, and equip clinicians with a novel framework for risk stratification and improved targeted care in HS.
Authors
Vivian J. Hua, James M. Kilgour, Hyunje G. Cho, Shufeng Li, Kavita Y. Sarin
Abstract
The migrating keratinocyte wound front is required for skin wound closure. Despite significant advances in wound healing research, we do not fully understand the molecular mechanisms that orchestrate collective keratinocyte migration. Here, we show that, in the wound front, the epidermal transcription factor Grainyhead like-3 (GRHL3) mediates decreased expression of the adherens junction protein E-cadherin; this results in relaxed adhesions between suprabasal keratinocytes, thus promoting collective cell migration and wound closure. Wound fronts from mice lacking GRHL3 in epithelial cells (Grhl3-cKO) have lower expression of Fascin-1 (FSCN1), a known negative regulator of E-cadherin. Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq) on wounded keratinocytes shows decreased wound-induced chromatin accessibility near the Fscn1 gene in Grhl3-cKO mice, a region enriched for GRHL3 motifs. These data reveal a wound-induced GRHL3/FSCN1/E-cadherin pathway that regulates keratinocyte-keratinocyte adhesion during wound-front migration; this pathway is activated in acute human wounds and is altered in diabetic wounds in mice, suggesting translational relevance.
Authors
Ghaidaa Kashgari, Sanan Venkatesh, Samuel Refuerzo, Brandon Pham, Anita Bayat, Rachel Herndon Klein, Raul Ramos, Albert Paul Ta, Maksim V. Plikus, Ping H. Wang, Bogi Andersen
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