IL-36γ promotes psoriasis-like features in keratinocytes in an imiquimod-induced murine model of psoriasis

IntroductionPsoriasis is a recurrent, chronic inflammatory skin disease with complex pathogenesis. The disease imposes a heavy burden on patients. Interleukin (IL)-36γ belongs to the IL-36 family and is predominantly expressed by epithelial cells. IL-36γ is upregulated in psoriasis lesions. However, the effects of IL-36γ in keratinocytes remain unclear.Material and methodsEighteen IL-36γ-deficient mice were divided into three groups: the vaseline group, the imiquimod (IMQ) group, and the IMQ/IL-36γ group. Vaseline or IMQ was administered for 6 consecutive days. The severity of psoriasis-like lesions was evaluated using a modified Psoriasis Area and Severity Index (PASI) scoring system. Production of cytokines and expression of differentiation markers were assessed by immunohistochemistry.ResultsIMQ-induced psoriasis lesions were significantly more severe in IMQ/IL-36γ-treated mice compared with vaseline-treated and IMQ-treated mice, as shown by an exacerbated inflammatory phenotype, increased numbers of blood vessels, increased infiltration of cells, and increased epidermal thickness. Expression of loricrin and keratin 5 in skin lesions was decreased following treatment with IL-36γ. Levels of IL-17A, interferon-γ, β-catenin and Dickkopf-related protein 1 were elevated in keratinocytes within psoriatic lesions following IL-36γ stimulation.ConclusionsTogether, these data showed that IL-36γ contribute to abnormal keratinocytes proliferation and keratinocyte-related proinflammatory cytokines, and suggest that IL-36γ may play an important role in the pathogenesis of psoriasis.

Damaged Keratin Filament Network Caused by KRT5 Mutations in Localized Recessive Epidermolysis Bullosa Simplex

Epidermolysis bullosa simplex (EBS) is a blistering dermatosis that is mostly caused by dominant mutations in KRT5 and KRT14. In this study, we investigated one patient with localized recessive EBS caused by novel homozygous c.1474T > C mutations in KRT5. Biochemical experiments showed a mutation-induced alteration in the keratin 5 structure, intraepidermal blisters, and collapsed keratin intermediate filaments, but no quantitative change at the protein levels and interaction between keratin 5 and keratin 14. Moreover, we found that MAPK signaling was inhibited, while desmosomal protein desmoglein 1 (DSG1) was upregulated upon KRT5 mutation. Inhibition of EGFR phosphorylation upregulated DSG1 levels in an in vitro model. Collectively, our findings suggest that this mutation leads to localized recessive EBS and that keratin 5 is involved in maintaining DSG1 via activating MAPK signaling.

Sarcomatoid Mesothelioma: A Clinicopathological and Immunohistochemical Study of 64 Cases

Sixty-four cases of sarcomatoid pleural mesothelioma represent the basis of this study. The patients are 51 men and 13 women between the ages of 42 and 79 years, who presented with symptoms of chest pain, cough, and weight loss. Diagnostic imaging showed the presence of diffuse pleural thickening with encasement of the lung parenchyma in all the cases. All patients had surgical resection via extrapleural pneumonectomy. By immunohistochemistry, all cases were positive for cytokeratin AE1/AE3; however, reactivity with other markers including keratin 5/6, calretinin, and D2-40 was seen in different proportions, whereas a few cases showed positive staining for GATA3, WT1, and p40. All tumors were negative for carcinomatous epitopes (carcinoembryonic antigen, CD15, and TTF1). Our findings show that even though the use of immunohistochemical stains plays an important role in the final interpretation, the best results are accomplished by a global interpretation of clinical, radiographical, and immunohistochemical findings. It is also important to highlight that it does not seem to be a single immunohistochemical stain that is pathognomonic of sarcomatoid mesothelioma and that some other stains that are commonly used for other tumors may also show positive staining in a small percentage of sarcomatoid mesotheliomas.

Bimodal fibrosis in a novel mouse model of bleomycin-induced usual interstitial pneumonia

Idiopathic pulmonary fibrosis (IPF) is pathologically classified by usual interstitial pneumonia (UIP). Conventional bleomycin models used to study pathogenic mechanisms of pulmonary fibrosis display transient inflammation and fibrosis so their relevance to UIP is limited. We developed a novel chronic induced-UIP (iUIP) model, inducing fibrosis in D1CC×D1BC transgenic mice by intra-tracheal instillation of bleomycin mixed with microbubbles followed by sonoporation (BMS). A bimodal fibrotic lung disease was observed over 14 weeks, with an acute phase similar to nonspecific interstitial pneumonia (NSIP), followed by partial remission and a chronic fibrotic phase with honeycombing similar to UIP. In this secondary phase, we observed poor vascularization despite elevated PDGFRβ expression. γ2PF- and MMP7-positive epithelial cells, consistent with an invasive phenotype, were predominantly adjacent to fibrotic areas. Most invasive cells were Scgb1a1 and/or keratin 5 positive. This iUIP mouse model displays key features of IPF and has identified potential mechanisms contributing to the onset of NSIP and progression to UIP. The model will provide a useful tool for the assessment of therapeutic interventions to oppose acute and chronic fibrosis.

The Developmental & Molecular Requirements for Ensuring that Human Pluripotent Stem Cell-Derived Hair Follicle Bulge Stem Cells Have Acquired Competence for Hair Follicle Generation Following Transplantation

When using human induced pluripotent stem cells (hiPSCs) to achieve hair follicle (HF) replacement, we found it best to emulate the earliest fundamental developmental processes of gastrulation, ectodermal lineage commitment, and dermogenesis. Viewing hiPSCs as a model of the epiblast, we exploited insights from mapping the dynamic up- and down-regulation of the developmental molecules that determine HF lineage in order to ascertain the precise differentiation stage and molecular requirements for grafting HF-generating progenitors. To yield an integrin-dependent lineage like the HF in vivo, we show that hiPSC derivatives should co-express, just prior to transplantation, the following combination of markers: integrins α6 and β1 and the glycoprotein CD200 on their surface; and, intracellularly, the epithelial marker keratin 18 and the hair follicle bulge stem cell (HFBSC)-defining molecules transcription factor P63 and the keratins 15 and 19. If the degree of trichogenic responsiveness indicated by the presence of these molecules is not achieved (they peak on Days 11-18 of the protocol), HF generation is not possible. Conversely, if differentiation of the cells is allowed to proceed beyond the transient intermediate progenitor state represented by the HFBSC, and instead cascades to their becoming keratin 14+ keratin 5+ CD200– keratinocytes (Day 25), HF generation is equally impossible. We make the developmental case for transplanting at Day 16-18 of differentiation—the point at which the hiPSCs have lost pluripotency, have attained optimal expression of HFBSC markers, have not yet experienced downregulation of key integrins and surface glycoproteins, have not yet started expressing keratinocyte-associated molecules, and have sufficient proliferative capacity to allow a well-populated graft. This panel of markers may be used for isolating (by cytometry) HF-generating derivatives away from cell types unsuited for this therapy as well as for identifying trichogenic drugs.

Spreading of Isolated Ptch Mutant Basal Cell Carcinoma Precursors Is Physiologically Suppressed and Counteracts Tumor Formation in Mice

Basal cell carcinoma (BCC) originate from Hedgehog/Patched signaling-activated epidermal stem cells. However, the chemically induced tumorigenesis of mice with a CD4Cre-mediated biallelic loss of the Hedgehog signaling repressor Patched also induces BCC formation. Here, we identified the cellular origin of CD4Cre-targeted BCC progenitors as rare Keratin 5+ epidermal cells and show that wildtype Patched offspring of these cells spread over the hair follicle/skin complex with increasing mouse age. Intriguingly, Patched mutant counterparts are undetectable in age-matched untreated skin but are getting traceable upon applying the chemical tumorigenesis protocol. Together, our data show that biallelic Patched depletion in rare Keratin 5+ epidermal cells is not sufficient to drive BCC development, because the spread of these cells is physiologically suppressed. However, bypassing the repression of Patched mutant cells, e.g., by exogenous stimuli, leads to an accumulation of BCC precursor cells and, finally, to tumor development.

Metastatic Alveolar Soft Part Sarcoma to the Breast: A Case Report

Introduction/Objective Metastases to the breast are rare (less than 3% of all breast malignancies). In adults, malignant melanoma is the most common type of metastasis followed by carcinomas from various primary sites. Here, we describe a case of metastatic alveolar soft part sarcoma (ASPS) to the breast. Only a handful similar presentations are reported in the literature. Methods Here we describe the case of a 43-year-old female patient with a recent diagnosis of left base of tongue alveolar soft part sarcoma (in an outside hospital), presenting with a palpable mass in her left breast. Sonographic study of the left breast demonstrated a 1.4 cm oval hypoechoic mass with partially microlobulated margins at 1 o’clock. Results Histopathologic examination of the ultrasound guided core biopsy showed a “pink” neoplasm, composed of plump epithelioid tumor cells with an eosinophilic and granular cytoplasm, round to oval nuclei and conspicuous nucleoli. They are arranged in organoid nests separated by sinusoidal spaces. An immunohistochemical study shows the tumor cells to be negative for keratin AE1/AE3, keratin 7, keratin 5/6, GATA-3, Pax-8, estrogen receptor, HER2, p63, S100 and CD117. FISH test for TFE3 (Xp 11.23) is positive. PAS with diastase staining highlights the intracytoplasmic granules. Theses morphologic, clinical and molecular findings confirm the diagnosis of metastatic ASPS. Conclusion The differential diagnosis of “pink” tumors of the breast include primary tumors like secretory carcinoma and apocrine carcinoma and metastatic lesions of renal, thyroid, skin (melanoma), oral cavity and soft tissue. Although extremely rare, in the right clinical context, metastatic ASPS to the breast can occur and should be included in the differential diagnosis.

Molecular Modeling of Pathogenic Mutations in the Keratin 1B Domain

Keratin intermediate filaments constitute the primary cytoskeletal component of epithelial cells. Numerous human disease phenotypes related to keratin mutation remain mechanistically elusive. Our recent crystal structures of the helix 1B heterotetramer from keratin 1/10 enabled further investigation of the effect of pathologic 1B domain mutations on keratin structure. We used our highest resolution keratin 1B structure as a template for homology-modeling the 1B heterotetramers of keratin 5/14 (associated with blistering skin disorders), keratin 8/18 (associated with liver disease), and keratin 74/28 (associated with hair disorder). Each structure was examined for the molecular alterations caused by incorporating pathogenic 1B keratin mutations. Structural modeling indicated keratin 1B mutations can harm the heterodimer interface (R265PK5, L311RK5, R211PK14, I150VK18), the tetramer interface (F231LK1, F274SK74), or higher-order interactions needed for mature filament formation (S233LK1, L311RK5, Q169EK8, H128LK18). The biochemical changes included altered hydrophobic and electrostatic interactions, and altered surface charge, hydrophobicity or contour. Together, these findings advance the genotype-structurotype-phenotype correlation for keratin-based human diseases.