KLK6 expression in skin induces PAR1-mediated psoriasiform dermatitis and inflammatory joint disease.

Kallikrein-related peptidase 6 (KLK6) is a secreted serine protease hypothesized to promote inflammation via cleavage of protease-activated receptor 1 (PAR1) and PAR2. KLK6 levels are elevated in multiple inflammatory and autoimmune conditions, but no definitive role in pathogenesis has been established. Here, we show that skin-targeted overexpression of KLK6 causes generalized, severe psoriasiform dermatitis with spontaneous development of debilitating psoriatic arthritis-like joint disease. The psoriatic skin and joint phenotypes are reversed by normalization of skin KLK6 levels and attenuated following genetic elimination of PAR1 but not PAR2. Conservation of this regulatory pathway was confirmed in human psoriasis using vorapaxar, an FDA-approved PAR1 antagonist, on explanted lesional skin from patients with psoriasis. Beyond defining a critical role for KLK6/PAR1 signaling in promoting psoriasis, our results demonstrate that KLK6/PAR1-mediated inflammation in the skin alone is sufficient to drive inflammatory joint disease. Further, we identify PAR1 as a promising cytokine-independent target in therapy of psoriasis and psoriatic arthritis.

Survivorship in adults with malignant brain and other central nervous system tumor from 2000-2014.

Background: The goal of this study was to provide up-to-date and comprehensive statistics on incidence, survival, and prevalence rates for selected malignant brain and other CNS tumors in adults. Methods: The current study used data from the Central Brain Tumor Registry of the United States, provided by the Centers for Disease Control and Prevention, to examine incidence and data from the Surveillance, Epidemiology, and End Results program to examine survival and prevalence in 16 distinct malignant brain and other CNS histologies in adults (aged 20 y and older at diagnosis) from 2000-2014 overall and by sex, age group, race, and ethnicity. Results: Glioblastoma had the highest incidence (4.40 per 100000) and prevalence (9.23 per 100000). Ependymal tumors had the highest 5- and 10-year relative survivals (87.8% and 84.5%, respectively), while glioblastoma had the lowest 5- and 10-year relative survivals (5.4% and 2.7%, respectively). Females generally had better survival and lower prevalence than males. Younger adults tended to have better survival than older adults, and prevalence varied greatly by age and histology. While survival did not vary significantly by race, white adults had higher prevalence than the other race groups. Hispanics generally had better survival rates and lower prevalence than non-Hispanics. Conclusions: Survival varied greatly by age and ethnicity. Prevalence differed by sex, age, race, and ethnicity.

Protection from Psoriasis-Related Thrombosis after Inhibition of IL-23 or IL-17A.

Psoriasis patients experience chronic systemic skin inflammation and develop cardiovascular comorbidities that shorten their lifespan. Whether cardiovascular disease is improved by treatment with current biologics that target disease-specific pathways is unclear. KC-Tie2 mice develop psoriasiform skin inflammation with increases in IL-23 and IL-17A and proinflammatory monocytosis and neutrophilia that precedes development of carotid artery thrombus formation. To examine whether targeted blockade of IL-23 or IL-17A in KC-Tie2 psoriasis mice improves cardiovascular outcomes, mice were treated systemically for 6 weeks with antibodies targeting IL-17A, IL-17RA, IL-12/23p40, or IL-23p19. Skin inflammation; thrombosis clotting times; and percentage of splenic monocytes, neutrophils, and CD4 T cells were examined. Skin inflammation significantly improved in KC-Tie2 mice treated with each of the antibodies targeting IL-23, IL-17A, or IL-17RA, consistent with clinical efficacy observed in psoriasis patients. The time to occlusive thrombus formation lengthened in these mice and correlated with attenuated acanthosis. This decrease in skin inflammation paralleled decreases in splenic neutrophils (CD11b+Ly6G+) but not monocytes (CD11b+Ly6Chigh) or T cells (CD4+). Our data show that targeted inhibition of IL-23 or IL-17A improves psoriasis-like skin disease and also improves cardiovascular disease in mice.

Evidence for biochemical barrier restoration: Topical solenopsin analogs improve inflammation and acanthosis in the KC-Tie2 mouse model of psoriasis.

Psoriasis is a chronic inflammatory skin disease affecting 2.5-6 million patients in the United States. The cause of psoriasis remains unknown. Previous human and animal studies suggest that patients with a susceptible genetic background and some stimulus, such as barrier disruption, leads to a coordinated signaling events involving cytokines between keratinocytes, endothelial cells, T cells, macrophages and dendritic cells. Ceramides are endogenous skin lipids essential for maintaining skin barrier function and loss of ceramides may underlie inflammatory and premalignant skin. Ceramides act as a double-edged sword, promoting normal skin homeostasis in the native state, but can be metabolized to sphingosine-1-phosphate (S1P), linked to inflammation and tumorigenesis. To overcome this difficulty, we synthesized solenopsin analogs which biochemically act as ceramides, but cannot be metabolized to S1P. We assess their in vivo bioactivity in a well-established mouse model of psoriasis, the KC-Tie2 mouse. Topical solenopsin derivatives normalized cutaneous hyperplasia in this model, decreased T cell infiltration, interleukin (IL)-22 transcription, and reversed the upregulation of calprotectin and Toll-like receptor (TLR) 4 in inflamed skin. Finally, they stimulated interleukin (IL)-12 production in skin dendritic cells. Thus suggesting barrier restoration has both a biochemical and physical component, and both are necessary for optimal barrier restoration.

Imiquimod has strain-dependent effects in mice and does not uniquely model human psoriasis.

BACKGROUND: Imiquimod (IMQ) produces a cutaneous phenotype in mice frequently studied as an acute model of human psoriasis. Whether this phenotype depends on strain or sex has never been systematically investigated on a large scale. Such effects, however, could lead to conflicts among studies, while further impacting study outcomes and efforts to translate research findings. METHODS: RNA-seq was used to evaluate the psoriasiform phenotype elicited by 6 days of Aldara (5% IMQ) treatment in both sexes of seven mouse strains (C57BL/6 J (B6), BALB/cJ, CD1, DBA/1 J, FVB/NJ, 129X1/SvJ, and MOLF/EiJ). RESULTS: In most strains, IMQ altered gene expression in a manner consistent with human psoriasis, partly due to innate immune activation and decreased homeostatic gene expression. The response of MOLF males was aberrant, however, with decreased expression of differentiation-associated genes (elevated in other strains). Key aspects of the IMQ response differed between the two most commonly studied strains (BALB/c and B6). Compared with BALB/c, the B6 phenotype showed increased expression of genes associated with DNA replication, IL-17A stimulation, and activated CD8+ T cells, but decreased expression of genes associated with interferon signaling and CD4+ T cells. Although IMQ-induced expression shifts mirrored psoriasis, responses in BALB/c, 129/SvJ, DBA, and MOLF mice were more consistent with other human skin conditions (e.g., wounds or infections). IMQ responses in B6 mice were most consistent with human psoriasis and best replicated expression patterns specific to psoriasis lesions. CONCLUSIONS: These findings demonstrate strain-dependent aspects of IMQ dermatitis in mice. We have shown that IMQ does not uniquely model psoriasis but in fact triggers a core set of pathways active in diverse skin diseases. Nonetheless, our findings suggest that B6 mice provide a better background than other strains for modeling psoriasis disease mechanisms.

Induction of Alternative Proinflammatory Cytokines Accounts for Sustained Psoriasiform Skin Inflammation in IL-17C+IL-6KO Mice.

IL-6 inhibition has been unsuccessful in treating psoriasis, despite high levels of tissue and serum IL-6 in patients. In addition, de novo psoriasis onset has been reported after IL-6 blockade in patients with rheumatoid arthritis. To explore mechanisms underlying these clinical observations, we backcrossed an established psoriasiform mouse model (IL-17C+ mice) with IL-6-deficient mice (IL-17C+KO) and examined the cutaneous phenotype. IL-17C+KO mice initially exhibited decreased skin inflammation; however, this decrease was transient and reversed rapidly, concomitant with increases in skin Tnf, Il36α/ß/γ, Il24, Epgn, and S100a8/a9 to levels higher than those found in IL-17C+ mice. A comparison of IL-17C+ and IL-17C+KO mouse skin transcriptomes with that of human psoriasis skin revealed significant correlation among transcripts of skin of patients with psoriasis and IL-17C+KO mouse skin, and confirmed an exacerbation of the inflammatory signature in IL-17C+KO mice that aligns closely with human psoriasis. Transcriptional analyses of IL-17C+ and IL-17C+KO primary keratinocytes confirmed increased expression of proinflammatory molecules, suggesting that in the absence of IL-6, keratinocytes increase production of numerous additional proinflammatory cytokines. These preclinical findings may provide insight into why patients with arthritis being treated with IL-6 inhibitors develop new onset psoriasis and why IL-6 blockade for the treatment of psoriasis has not been clinically effective.

Interleukin 6 regulates psoriasiform inflammation-associated thrombosis.

Psoriasis patients are at increased risk of heart attack and stroke and have elevated MRP8/14 levels that predict heart attack. The KC-Tie2 psoriasiform mouse model exhibits elevated MRP8/14 and is prothrombotic. Mrp14-/- mice, in contrast, are protected from thrombosis, but, surprisingly, KC-Tie2xMrp14-/- mice remain prothrombotic. Treating KC-Tie2xMrp14-/- mice with anti-IL-23p19 antibodies reversed the skin inflammation, improved thrombosis, and decreased IL-6. In comparison, IL-6 deletion from KC-Tie2 animals improved thrombosis despite sustained skin inflammation, suggesting that thrombosis improvements following IL-23 inhibition occur secondary to IL-6 decreases. Psoriasis patient skin has elevated IL-6 and IL-6 receptor is present in human coronary atheroma, supporting a link between skin and distant vessel disease in patient tissue. Together, these results identify a critical role for skin-derived IL-6 linking skin inflammation with thrombosis, and shows that in the absence of IL-6 the connection between skin inflammation and thrombosis comorbidities is severed.

Antimicrobial Peptide LL37 and MAVS Signaling Drive Interferon-ß Production by Epidermal Keratinocytes during Skin Injury.

Type 1 interferons (IFNs) promote inflammation in the skin but the mechanisms responsible for inducing these cytokines are not well understood. We found that IFN-ß was abundantly produced by epidermal keratinocytes (KCs) in psoriasis and during wound repair. KC IFN-ß production depended on stimulation of mitochondrial antiviral-signaling protein (MAVS) by the antimicrobial peptide LL37 and double stranded-RNA released from necrotic cells. MAVS activated downstream TBK1 (TANK-Binding Kinase 1)-AKT (AKT serine/threonine kinase 1)-IRF3 (interferon regulatory factor 3) signaling cascade leading to IFN-ß production and then promoted maturation of dendritic cells. In mice, the production of epidermal IFN-ß by LL37 required MAVS, and human wounded and/or psoriatic skin showed activation of MAVS-associated IRF3 and induction of MAVS and IFN-ß gene signatures. These findings show that KCs are an important source of IFN-ß and MAVS is critical to this function, and demonstrates how the epidermis triggers unwanted skin inflammation under disease conditions.

Deficiency of myeloid-related proteins 8 and 14 (Mrp8/Mrp14) does not block inflammaging but prevents steatosis.

The Mrp8 and Mrp14 proteins (calprotectin) accumulate within tissues during aging and may contribute to chronic inflammation. To address this possibility, we evaluated female calprotectin-deficient Mrp14-KO and wild-type (WT) mice at 5 and 24 months of age. However, there was no evidence that age-related inflammation is blunted in KO mice. Inflammation markers were in fact elevated in livers from old KO mice, and microarray analysis revealed more consistent elevation of genes specifically expressed by B-cells and T-cells. Adipose-specific genes, however, were less consistently elevated in aged KO mice, suggesting an anti-steatosis effect of Mrp8/14 deficiency. Consistent with this, genes decreased by the anti-steatosis agent SRT1720 were decreased in old KO compared to old WT mice. Expression of lipid metabolism genes was altered in KO mice at 5 months of age, along with genes associated with development, biosynthesis and immunity. These early-age effects of Mrp8/14 deficiency, in the absence of any external stressor, were unexpected. Taken together, our findings demonstrate a pro-steatosis rather than pro-inflammatory role of calprotectin within the aging liver. This appears to reflect a developmental-metabolic phenotype of Mrp14-KO mice that is manifest at a young age in the absence of pro-inflammatory stimuli.

Transgenic expression of human amphiregulin in mouse skin: inflammatory epidermal hyperplasia and enlarged sebaceous glands.

To explore the role of amphiregulin in inflammatory epidermal hyperplasia, we overexpressed human AREG (hAREG) in FVB/N mice using a bovine K5 promoter. A construct containing AREG coding sequences flanked by 5' and 3' untranslated region sequences (AREG-UTR) led to a >10-fold increase in hAREG expression compared to an otherwise-identical construct containing only the coding region (AREG-CDR). AREG-UTR mice developed tousled, greasy fur as well as elongated nails and thickened, erythematous tail skin. No such phenotype was evident in AREG-CDR mice. Histologically, AREG-UTR mice presented with marked epidermal hyperplasia of tail skin (2.1-fold increase in epidermal thickness with a 9.5-fold increase in Ki-67(+) cells) accompanied by significantly increased CD4+ T-cell infiltration. Dorsal skin of AREG-UTR mice manifested lesser but still significant increases in epidermal thickness and keratinocyte hyperplasia. AREG-UTR mice also developed marked and significant sebaceous gland enlargement, with corresponding increases in Ki-67(+) cells. To determine the response of AREG-UTR animals to a pro-inflammatory skin challenge, topical imiquimod (IMQ) or vehicle cream was applied to dorsal and tail skin. IMQ increased dorsal skin thickness similarly in both AREG-UTR and wild type mice (1.7- and 2.2-fold vs vehicle, P < 0.001 each), but had no such effect on tail skin. These results confirm that keratinocyte expression of hAREG elicits inflammatory epidermal hyperplasia, and are consistent with prior reports of tail epidermal hyperplasia and increased sebaceous gland size in mice expressing human epigen.

Chronic, not acute, skin-specific inflammation promotes thrombosis in psoriasis murine models.

BACKGROUND: Psoriasis patients exhibit an increased risk of atherothrombotic events, including myocardial infarction and stroke. Clinical evidence suggests that psoriasis patients with early onset and more severe disease have the highest risk for these co-morbidities, perhaps due to the extent of body surface involvement, subsequent levels of systemic inflammation, or chronicity of disease. We sought to determine whether acute or chronic skin-specific inflammation was sufficient to promote thrombosis. METHODS: We used two experimental mouse models of skin-specific inflammation generated in either an acute (topical Aldara application onto wild-type C57Bl/6 mice for 5 days) or chronic (a genetically engineered K5-IL-17C mouse model of psoriasiform skin inflammation) manner. Arterial thrombosis was induced using carotid artery photochemical injury (Rose Bengal-green light laser) and carotid artery diameters were measured post-clot formation. We also examined measures of clot formation including prothrombin (PT) and activated partial thromboplastin time (aPTT). Skin inflammation was examined histologically and we profiled plasma-derived lipids. The number of skin-draining lymph-node (SDLN) and splenic derived CD11b(+)Ly6C(high) pro-inflammatory monocytes and CD11b(+)Ly6G(+) neutrophils was quantified using multi-color flow cytometry. RESULTS: Mice treated with topical Aldara for 5 days had similar carotid artery thrombotic occlusion times to mice treated with vehicle cream (32.2 ± 3.0 vs. 31.4 ± 2.5 min, p = 0.97); in contrast, K5-IL-17C mice had accelerated occlusion times compared to littermate controls (15.7 ± 2.1 vs. 26.5 ± 3.5 min, p < 0.01) while carotid artery diameters were similar between all mice. Acanthosis, a surrogate measure of inflammation, was increased in both Aldara-treated and K5-IL-17C mice compared to their respective controls. Monocytosis, defined as elevated SDLN and/or splenic CD11b(+)Ly6C(high) cells, was significantly increased in both Aldara-treated (SDLN: 3.8-fold, p = 0.02; spleen: 2.0-fold, p < 0.01) and K5-IL-17C (SDLN: 3.4-fold, p = 0.02; spleen: 3.5-fold, p < 0.01) animals compared to controls while neutrophilia, defined as elevated SDLN and/or splenic CD11b(+)Ly6G(+) cells, was significantly increased in only the chronic K5-IL-17C model (SDLN: 11.6-fold, p = 0.02; spleen: 11.3-fold, p < 0.01). Plasma-derived lipid levels, PT and aPTT times showed no difference between the Aldara-treated mice or the K5-IL-17C mice and their respective controls. CONCLUSIONS: Chronic, but not acute, skin-specific inflammation was associated with faster arterial thrombotic occlusion. Increased numbers of splenic and SDLN monocytes were observed in both acute and chronic skin-specific inflammation, however, increased splenic and SDLN neutrophils were observed only in the chronic skin-specific inflammation model. Understanding the cellular response to skin-specific inflammation may provide insights into the cellular participants mediating the pathophysiology of major adverse cardiovascular events associated with psoriasis.

Proteomics of skin proteins in psoriasis: from discovery and verification in a mouse model to confirmation in humans.

Herein, we demonstrate the efficacy of an unbiased proteomics screening approach for studying protein expression changes in the KC-Tie2 psoriasis mouse model, identifying multiple protein expression changes in the mouse and validating these changes in human psoriasis. KC-Tie2 mouse skin samples (n = 3) were compared with littermate controls (n = 3) using gel-based fractionation followed by label-free protein expression analysis. 5482 peptides mapping to 1281 proteins were identified and quantitated: 105 proteins exhibited fold-changes ≥2.0 including: stefin A1 (average fold change of 342.4 and an average p = 0.0082; cystatin A, human ortholog); slc25a5 (average fold change of 46.2 and an average p = 0.0318); serpinb3b (average fold change of 35.6 and an average p = 0.0345; serpinB1, human ortholog); and kallikrein related peptidase 6 (average fold change of 4.7 and an average p = 0.2474; KLK6). We independently confirmed mouse gene expression-based increases of selected genes including serpinb3b (17.4-fold, p < 0.0001), KLK6 (9-fold, p = 0.002), stefin A1 (7.3-fold; p < 0.001), and slc25A5 (1.5-fold; p = 0.05) using qRT-PCR on a second cohort of animals (n = 8). Parallel LC/MS/MS analyses on these same samples verified protein-level increases of 1.3-fold (slc25a5; p < 0.05), 29,000-fold (stefinA1; p < 0.01), 322-fold (KLK6; p < 0.0001) between KC-Tie2 and control mice. To underscore the utility and translatability of our combined approach, we analyzed gene and protein expression levels in psoriasis patient skin and primary keratinocytes versus healthy controls. Increases in gene expression for slc25a5 (1.8-fold), cystatin A (3-fold), KLK6 (5.8-fold), and serpinB1 (76-fold; all p < 0.05) were observed between healthy controls and involved lesional psoriasis skin and primary psoriasis keratinocytes. Moreover, slc25a5, cystatin A, KLK6, and serpinB1 protein were all increased in lesional psoriasis skin compared with normal skin. These results highlight the usefulness of preclinical disease models using readily-available mouse skin and demonstrate the utility of proteomic approaches for identifying novel peptides/proteins that are differentially regulated in psoriasis that could serve as sources of auto-antigens or provide novel therapeutic targets for the development of new anti-psoriatic treatments.

Keratinocyte overexpression of IL-17C promotes psoriasiform skin inflammation.

IL-17C is a functionally distinct member of the IL-17 family that binds IL-17 receptor E/A to promote innate defense in epithelial cells and regulate Th17 cell differentiation. We demonstrate that IL-17C (not IL-17A) is the most abundant IL-17 isoform in lesional psoriasis skin (1058 versus 8 pg/ml; p < 0.006) and localizes to keratinocytes (KCs), endothelial cells (ECs), and leukocytes. ECs stimulated with IL-17C produce increased TNF-α and KCs stimulated with IL-17C/TNF-α produce similar inflammatory gene response patterns as those elicited by IL-17A/TNF-α, including increases in IL-17C, TNF-α, IL-8, IL-1α/ß, IL-1F5, IL-1F9, IL-6, IL-19, CCL20, S100A7/A8/A9, DEFB4, lipocalin 2, and peptidase inhibitor 3 (p < 0.05), indicating a positive proinflammatory feedback loop between the epidermis and ECs. Psoriasis patients treated with etanercept rapidly decrease cutaneous IL-17C levels, suggesting IL-17C/TNF-α-mediated inflammatory signaling is critical for psoriasis pathogenesis. Mice genetically engineered to overexpress IL-17C in KCs develop well-demarcated areas of erythematous, flakey involved skin adjacent to areas of normal-appearing uninvolved skin despite increased IL-17C expression in both areas (p < 0.05). Uninvolved skin displays increased angiogenesis and elevated S100A8/A9 expression (p < 0.05) but no epidermal hyperplasia, whereas involved skin exhibits robust epidermal hyperplasia, increased angiogenesis and leukocyte infiltration, and upregulated TNF-α, IL-1α/ß, IL-17A/F, IL-23p19, vascular endothelial growth factor, IL-6, and CCL20 (p < 0.05), suggesting that IL-17C, when coupled with other proinflammatory signals, initiates the development of psoriasiform dermatitis. This skin phenotype was significantly improved following 8 wk of TNF-α inhibition. These findings identify a role for IL-17C in skin inflammation and suggest a pathogenic function for the elevated IL-17C observed in lesional psoriasis skin.