Single-Cell RNA Sequencing Reveals Dysregulated POSTN+WNT5A+ Fibroblast Subclusters in Prurigo Nodularis.

Prurigo nodularis (PN) is an intensely pruritic, inflammatory skin disease with a poorly understood pathogenesis. We performed single-cell transcriptomic profiling of 28,695 lesional and nonlesional PN cells. Lesional PN has increased dysregulated fibroblasts (FBs) and myofibroblasts. FBs in lesional PN were shifted toward a cancer-associated FB-like phenotype, with POSTN+WNT5A+ cancer-associated FBs increased in PN and similarly so in squamous cell carcinoma. A multicenter cohort study revealed an increased risk of squamous cell carcinoma and cancer-associated FB-associated malignancies (breast and colorectal) in patients with PN. Systemic fibroproliferative diseases (renal sclerosis and idiopathic pulmonary fibrosis) were upregulated in patients with PN. Ligand-receptor analyses demonstrated an FB neuronal axis with FB-derived WNT5A and periostin interactions with neuronal receptors melanoma cell adhesion molecule and ITGAV. These findings identify a pathogenic and targetable POSTN+WNT5A+ FB subpopulation that may predispose cancer-associated FB-associated malignancies in patients with PN.

Somatic mutations reveal hyperactive Notch signaling and racial disparities in prurigo nodularis.

Prurigo nodularis (PN) is a chronic inflammatory skin disease that disproportionately affects African Americans and is characterized by pruritic skin nodules of unknown etiology. Little is known about genetic alterations in PN pathogenesis, especially relating to somatic events which are often implicated in inflammatory conditions. We thus performed whole-exome sequencing on 54 lesional and nonlesional skin biopsies from 17 PN patients and 10 atopic dermatitis (AD) patients for comparison. Somatic mutational analysis revealed that PN lesional skin harbors pervasive somatic mutations in fibrotic, neurotropic, and cancer-associated genes. Nonsynonymous mutations were most frequent in NOTCH1 and the Notch signaling pathway, a regulator of cellular proliferation and tissue fibrosis, and NOTCH1 mutations were absent in AD. Somatic copy-number analysis, combined with expression data, showed that recurrently deleted and downregulated genes in PN lesional skin are associated with axonal guidance and extension. Follow-up immunofluorescence validation demonstrated increased NOTCH1 expression in PN lesional skin fibroblasts and increased Notch signaling in PN lesional dermis. Finally, multi-center data revealed a significantly increased risk of NOTCH1-associated diseases in PN patients. In characterizing the somatic landscape of PN, we uncover novel insights into its pathophysiology and identify a role for dysregulated Notch signaling in PN.

Topical GZ21T Inhibits the Growth of Actinic Keratoses in a UVB-Induced Model of Skin Carcinogenesis.

Actinic keratoses (AKs) are premalignant intraepidermal neoplasms that occur as a result of cumulative sun damage. AKs commonly relapse, and up to 16% undergo malignant transformation into cutaneous squamous cell carcinoma. There is a need for novel therapies that reduce the quantity and surface area of AKs as well as prevent malignant transformation to cutaneous squamous cell carcinomas. We recently showed that GZ17-6.02, an anticancer agent composed of curcumin, haramine, and isovanillin, inhibited the growth of H297.T cells. This study evaluated the efficacy of a topical formulation of GZ17-6.02, known as GZ21T, in a murine model of AK generated by exposing SKH1 mice to UVR. Treatment of mice with topical GZ21T inhibited the growth of AKs by decreasing both lesion count (P = 0.012) and surface area occupied by tumor (P = 0.002). GZ21T also suppressed the progression of AKs to cutaneous squamous cell carcinoma by decreasing the count (P = 0.047) and surface area (P = 0.049) of lesions more likely to represent cutaneous squamous cell carcinoma. RNA sequencing and proteomic analyses revealed that GZ21T suppressed several pathways, including MAPK (P = 0.025), phosphoinositide 3-kinase-protein kinase B (P = 0.04), HIF-1α (P = 0.016), Wnt (P = 0.025), insulin (P = 0.018), and ERBB (P = 0.016) signaling. GZ21T also upregulated the autophagy-promoting protein AMPK while suppressing proteins such as PD-L1, glutaminase, pAkt1 S473, and eEF2K.

Single-cell RNA sequencing reveals dysregulated fibroblast subclusters in prurigo nodularis.

Prurigo nodularis (PN) is an intensely pruritic, chronic inflammatory skin disease that disproportionately affects black patients. However, the pathogenesis of PN is poorly understood. We performed single-cell transcriptomic profiling, ligand receptor analysis and cell trajectory analysis of 28,695 lesional and non-lesional PN skin cells to uncover disease-identifying cell compositions and genetic characteristics. We uncovered a dysregulated role for fibroblasts (FBs) and myofibroblasts as a key pathogenic element in PN, which were significantly increased in PN lesional skin. We defined seven unique subclusters of FBs in PN skin and observed a shift of PN lesional FBs towards a cancer-associated fibroblast (CAF)-like phenotype, with WNT5A+ CAFs increased in the skin of PN patients and similarly so in squamous cell carcinoma (SCC). A multicenter PN cohort study subsequently revealed an increased risk of SCC as well as additional CAF-associated malignancies in PN patients, including breast and colorectal cancers. Systemic fibroproliferative diseases were also upregulated in PN patients, including renal sclerosis and idiopathic pulmonary fibrosis. Ligand receptor analyses demonstrated increased FB1-derived WNT5A and periostin interactions with neuronal receptors MCAM and ITGAV, suggesting a fibroblast-neuronal axis in PN. Type I IFN responses in immune cells and increased angiogenesis/permeability in endothelial cells were also observed. As compared to atopic dermatitis (AD) and psoriasis (PSO) patients, increased mesenchymal dysregulation is unique to PN with an intermediate Th2/Th17 phenotype between atopic dermatitis and psoriasis. These findings identify a pathogenic role for CAFs in PN, including a novel targetable WNT5A+ fibroblast subpopulation and CAF-associated malignancies in PN patients.

A Review on the Safety of Using JAK Inhibitors in Dermatology: Clinical and Laboratory Monitoring.

Janus kinase (JAK) inhibitors are disease-modifying agents with efficacy in treating a spectrum of burdensome dermatologic conditions. The US Food and Drug Administration (FDA) recently placed a black box warning on this class of medications due to safety concerns based on data from studies investigating tofacitinib in patients with rheumatoid arthritis. Here we provide an overview of the timeline of FDA approval of JAK inhibitors in dermatology. We also discuss the available safety profiles of approved oral JAK1 inhibitors, namely abrocitinib and upadacitinib, oral baricitinib, a JAK1/2 inhibitor, deucravacitinib, a Tyk2 inhibitor, and the topical JAK1/2 inhibitor ruxolitinib in dermatology patients. Additionally, we offer suggestions for initial screening and laboratory monitoring for patients receiving JAK inhibitors. We found that the rates of venous thromboembolism reported in trials ranged from no events to 0.1-0.5% in dermatology-specific phase 3 clinical trials compared with no events in the placebo. The rates of cardiovascular events ranged from no events to 0.4-1.2% compared with no events to 0.5-1.2% in the placebo. The rates of serious infections were 0.4-4.8% compared with no events to 0.5-1.3% in the placebo. The rates of nonmelanoma skin cancer (NMSC) ranged from no event to 0.6-0.9% compared with no events in the placebo. The rates of non-NMSC ranged from no event to 0.2-0.7% compared with no event to 0.6% in the placebo. Most patients who developed these adverse events had risk factors for the specific event. The most common adverse events of oral JAK inhibitors included upper respiratory infections, nasopharyngitis, nausea, headache, and acne. Dermatologists should consider patients' baseline risk factors for developing serious complications when prescribing oral JAK inhibitors.

Construction of a Secondary Enclosure for UVB Irradiation of Mice.

UV irradiation is commonly used in murine models of skin cancers. Despite the popularity of using UVB rays to model photocarcinogenesis in animals, there is a lack of standardization in the secondary enclosures used to administer radiation. An appraisal of the literature also shows a general lack of details regarding the materials and procedures utilized in the fabrication of such enclosures. We present in this study a detailed overview of the construction of a UVB exposure chamber that successfully induces lesions in hairless mice. A standardized protocol for producing a UVB enclosure may reduce methodological variation in future studies seeking to investigate photocarcinogenesis in animals.

Risk of Hematologic Cancer in Patients With Undifferentiated Pruritus.

Importance: Although pruritus is common in patients with hematologic cancers, it is unknown whether patients with undifferentiated pruritus have higher risk of developing hematologic cancer. Furthermore, it is unclear whether serum lactate dehydrogenase (LDH) level, commonly ordered for cancer workup, has diagnostic utility in patients with pruritus. Objective: To assess the risk of hematologic cancer and the diagnostic utility of LDH level in patients with undifferentiated pruritus. Design, Setting, and Participants: This retrospective population-level cohort analysis was conducted using the TriNetX Research Network, a global health records database encompassing more than 69 million patients, from 2002 to 2020. The study included 327 502 eligible patients diagnosed with unspecified pruritus, excluding those with existing chronic pruritic dermatoses or systemic diseases known to cause pruritus, along with 327 502 matched controls. Exposures: Development of hematologic cancer within 1 year, 5 years, and 10 years following unspecified pruritus diagnosis. Main Outcomes and Measures: Primary study outcomes were 1-year, 5-year, and 10-year relative risks (RRs) for development of 9 hematologic cancers in patients with pruritus compared with control patients. Secondary outcomes were 1-year, 5-year, and 10-year RRs for any hematologic cancer at different LDH cutoffs (250 U/L and 500 U/L). Results: After matching, the pruritus and control cohorts each had 327 502 patients (68.1% female patients; 0.4% American Indian or Alaska Native patients; 3.5% Asian patients; 22.2% Black patients; 0.1% Native Hawaiian or Pacific Islander patients; 59.3% White patients; mean [SD] age, 42.2 [22] years). Patients with pruritus had increased 1-year risk of Hodgkin lymphoma (RR, 4.42; 95% CI, 2.83-6.88), myeloid leukemia (RR, 2.56; 95% CI, 1.79-3.67), multiple myeloma (RR, 2.38; 95% CI, 1.66-3.41), non-Hodgkin lymphoma (RR, 2.35; 95% CI, 1.96-2.82), monoclonal gammopathy (RR, 1.90; 95% CI, 1.55-2.32), myelodysplastic syndrome (RR, 1.74; 95% CI, 1.14-2.64), and lymphocytic leukemia (RR, 1.47; 95% CI, 1.07-2.02). After 12 months, the cancer risk was comparable with that of controls. Patients with pruritus had increased LDH levels, which were not associated with increased hematologic cancer risk. Conclusions and Relevance: In this cohort study, the RR of hematologic cancer in patients with undifferentiated pruritus was highest in the first 12 months, and LDH level had limited diagnostic utility in these patients. Clinicians should consider a thorough review of symptoms and assessment of cancer risk factors when deciding on workup for patients presenting with undifferentiated pruritus.

Identification of potential modulators of osteosarcoma metastasis by high-throughput cellular screening of natural products.

A high-throughput screening assay was developed and applied to a large library of natural product extract samples, in order to identify compounds which preferentially inhibited the in vitro 2D growth of a highly metastatic osteosarcoma cell line (MG63.3) compared to a cognate parental cell line (MG63) with low metastatic potential. Evaluation of differentially active natural product extracts with bioassay-guided fractionation led to the identification of lovastatin (IC50  = 11 µm) and the limonoid toosendanin (IC50  = 26 nm). Other statins and limonoids were then tested, and cerivastatin was identified as a particularly potent (IC50  < 0.1 µm) and selective agent. These compounds potently and selectively induced apoptosis in MG63.3 cells, but not MG63. Assays with other cell pairs were used to examine the generality of these results. Statins and limonoids may represent unexplored opportunities for development of modulators of osteosarcoma metastasis. As cerivastatin was previously approved for clinical use, it could be considered for repurposing in osteosarcoma, pending validation in further models.