Characterizing viscoelastic properties of human melanoma tissue using Prony series.

Melanoma is the most invasive and deadly skin cancer, which causes most of the deaths from skin cancer. It has been demonstrated that the mechanical properties of tumor tissue are significantly altered. However, data about characterizing the mechanical properties of in vivo melanoma tissue are extremely scarce. In addition, the viscoelastic or viscous properties of melanoma tissue are rarely reported. In this study, we measured and quantitated the viscoelastic properties of human melanoma tissues based on the stress relaxation test, using the indentation-based mechanical analyzer that we developed previously. The melanoma tissues from eight patients of different ages (57-95), genders (male and female patients), races (White and Asian), and sites (nose, arm, shoulder, and chest) were excised and tested. The results showed that the elastic property (i.e., shear modulus) of melanoma tissue was elevated compared to normal tissue, while the viscous property (i.e., relaxation time) was reduced. Moreover, the tissue thickness had a significant impact on the viscoelastic properties, probably due to the amount of the adipose layer. Our findings provide new insights into the role of the viscous and elastic properties of melanoma cell mechanics, which may be implicated in the disease state and progression.

Sex-specific differences in oxidative stress markers and collagen expression in perioral skin wrinkling.

Wrinkling is the hallmark of skin ageing. We previously reported that perioral wrinkling is more severe in females; however, the molecular basis is unknown. This study assessed sex differences in the molecular expression of key ageing regulators in perioral skin. Twelve subjects (n = 6 male/female) were enrolled in this cross-sectional study and biopsies were taken from the perioral and periocular regions. RNA expression of collagen I, collagen III, cysteine-rich angiogenic inducer 61 (CYR61) and insulin-like growth factor 1 (IGF-1) was assessed by qPCR. There was no difference between females' and males' Griffith's grades (6 and 5.67, respectively, p = 0.092) or periocular wrinkling grades (3.2 and 2.6, p = 0.421), but females had more severe perioral wrinkling grades than males (6.2 and 2.8, p = 0.020). Females not only expressed significantly more CYR61 (p = 0.018) in the perioral region than malesm but also expressed more collagen III (p = 0.016). There was no difference in collagen I (p = 0.115) or IGF-1 (p = 0.124) expression in the perioral region between sexes. In the periocular region, there were no significant differences between sexes in the expression of all four markers. The significant molecular differences in the perioral region between the sexes may contribute to the greater perioral skin wrinkling seen clinically in females.

Associations between hidradenitis suppurativa and dermatological conditions in adults: a national cross-sectional study.

Hidradenitis suppurativa (HS) is a chronic, inflammatory condition associated with numerous comorbidities, but there has been no broad-spectrum investigation into the dermatological comorbidities that are associated with HS using nationally representative data. We therefore analysed the 2016-2018 National Inpatient Sample for adult patients with and without HS and used multivariable logistic regression to determine correlations between HS and 25 dermatological conditions, adjusting for age, ethnicity and race, sex and insurance type. As seen previously, HS is more likely to affect women and Black people. The prevalence of having any of the 25 dermatological conditions was higher in patients with HS than without (24.60% vs. 5.30%, P < 0.001) and HS was specifically associated with 18 of the 25 dermatological conditions. This research confirms anecdotal disease relationships and identifies novel correlations between HS and dermatological conditions using a national patient population.

Clinical and molecular change induced by repeated low-dose visible light exposure in both light-skinned and dark-skinned individuals.

BACKGROUND: Visible light (VL) is known to induce pigmentation in dark-skinned individuals and immediate erythema in light-skinned individuals. However, the effects of accumulated low-dose VL exposure across skin types are not well established. METHODS: Thirty-one healthy subjects with light (Fitzpatrick skin types [FST] I-II, n = 13) and dark (FST V-VI, n = 18) skin types were enrolled. Subjects' buttocks were exposed daily to VL, wavelength 400-700 nm, with a dose of 120 J/cm2 at 50 mW/cm2 , for four consecutive days. Microarray using Affymetrix GeneChip (49,395 genes) was performed followed by qRT-PCR on skin samples. RESULTS: Repeated low-dose VL irradiation induced immediate pigment darkening and delayed tanning in dark-skinned individuals while no discernable pigmentation and erythema were observed in light-skinned individuals. Top ten upregulated genes by repeated VL exposure in microarray included melanogenic genes such as tyrosinase (TYR), tyrosinase-related protein-1 (TYRP1), dopachrome tautomerase (DCT), premelanosome protein (PMEL), melan-A (MLANA), and solute carrier family 24, member 5 (SLC24A5) and genes involved in inflammation/matrix remodeling/cell signaling including chemokine (C-C motif) ligand 18 (CCL18), BCL2-related protein A1 (BCL2A1), and cartilage oligomeric matrix protein (COMP). In qRT-PCR CCL18 was upregulated in light skin with a greater extent (mean fold change ± SD; 4.03 ± 3.28, p = .04) than in dark-skinned individuals (1.91 ± 1.32, p = .07) while TYR was not significantly upregulated in both skin types. CONCLUSION: This study highlights the genes upregulated by cumulative VL exposure involved in pigmentation, immune response, oxidation/reduction, and matrix remodeling across skin types providing relevant information on daily solar exposure.

Skin type specific photobiological response to visible light is mediated by constitutional melanin.

BACKGROUND: Visible light (VL) induces varying photobiological responses between skin types, likely influenced by inherent melanization. Individual typology angle (ITA) objectively measures skin types. We hypothesize that epidermal melanin content and distribution determine VL response. OBJECTIVES: This study describes clinical and histologic responses to VL and examines the potential role of melanin in the underlying mechanistic pathways. METHODS: We grouped enrolled participants by ITA (Light = 5, Intermediate = 4, Dark = 7) per colorimetry (CR-400, Konica Minolta). Photoprotected sites were exposed daily to 480 J/cm2 of VL (Fiber-Lite High Intensity Illuminator, Series 180, Dolan Jenner Industries Inc.) for 4 days (total = 1920 J/cm2 ), as tolerated. Treated and control sites were biopsied 96 h after first exposure. We used hematoxylin and eosin and Fontana-Mason to assess histological changes and melanin deposition, respectively. p53 and Ki67 immunohistochemical stains were done to assess DNA damage and proliferation. Matrix metalloproteinase (MMP)-1 expression was detected by immunohistochemical staining and immunofluorescence microscopy. RESULTS: Darker skin did not tolerate the full VL regimen with blistering occurring in most subjects at doses of 220-880 J/cm2 . Intermediate and Dark skin showed tanning. Light skin developed erythema. p53 counts were highest in Intermediate, followed by Light skin, although this was not statistically significant. VL treatment led to MMP-1 expression and nuclear localization in keratinocytes in Dark and Intermediate but not in Light skin, however differences between groups were not statistically significant. CONCLUSIONS: Skin types demonstrate unique biological responses to VL. The role of melanin in photoprotection is well-defined. However, given the pro-apoptotic function of nuclear MMPs, we suggest a potential mechanism by which melanin may mediate VL-induced phototoxicity.

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.

Cutaneous Toxicities Associated with Immune Checkpoint Inhibitors: An Observational, Pharmacovigilance Study.

Cutaneous immune-related adverse events (cirAEs) are the most prevalent complication to arise from immunotherapy and cause significant morbidity. We aimed to determine the spectrum, timing, clinical features, and outcomes of cirAEs by conducting an observational pharmacovigilance study using VigiBase, the World Health Organization's global database of individual case safety reports from over 130 member countries (ClinicalTrials.gov, number NCT04898751). We compared adverse event reporting in patients who received immune checkpoint inhibitors (91,323 adverse events) with those of the full reporting database (18,919,358 adverse events). There were 10,933 cases of cirAEs within 51 distinct dermatologic types, with 27 specific eruptions with disproportionate signal represented (information component [IC]025 > 0). Of these 27 eruptions, there were eight cirAEs with n > 100 reports, including vitiligo (IC025 = 4.87), bullous pemphigoid (IC025 = 4.08), lichenoid dermatitis (IC025 = 3.69), erythema multiforme (IC025 = 1.03), toxic epidermal necrolysis (IC025 = 0.95), Stevens‒Johnson syndrome (IC025 = 0.41), drug eruption (IC025 = 0.11), and eczematous dermatitis (IC025 = 0.11). There were differences in time to onset after immune checkpoint inhibitor initiation, with a median of approximately 1 month (erythema multiforme, Stevens‒Johnson syndrome, and toxic epidermal necrolysis), 2 months (drug eruption and eczematous dermatitis), 4 months (lichenoid dermatitis), and 5‒6 months (bullous pemphigoid and vitiligo). CirAEs are diverse, dependent on cancer type, and have distinct and different onset times that are linked to the cirAE subtype.

Transcriptomic analysis of atopic dermatitis in African Americans is characterized by Th2/Th17-centered cutaneous immune activation.

Atopic dermatitis (AD) often presents more severely in African Americans (AAs) and with greater involvement of extensor areas. To investigate immune signatures of AD in AAs with moderate to severe pruritus, lesional and non-lesional punch biopsies were taken from AA patients along with age-, race-, and sex-matched controls. Histology of lesional skin showed psoriasiform dermatitis and spongiotic dermatitis, suggesting both Th2 and Th17 activity. Gene Set Variation Analysis showed upregulation of Th2 and Th17 pathways in both lesional versus non-lesional and lesional versus control (p < 0.01), while Th1 and Th22 upregulation were observed in lesional versus control (p < 0.05). Evidence for a broad immune signature also was supported by upregulated Th1 and Th22 pathways, and clinically may represent greater severity of AD in AA. Furthermore, population-level analysis of data from TriNetX, a global federated health research network, revealed that AA AD patients had higher values for CRP, ferritin, and blood eosinophils compared to age-, sex-, and race-matched controls as well as white AD patients, suggesting broad systemic inflammation. Therefore, AA AD patients may feature broader immune activation than previously thought and may derive benefit from systemic immunomodulating therapies that modulate key drivers of multiple immune pathways.

Prurigo Nodularis Is Characterized by Systemic and Cutaneous T Helper 22 Immune Polarization.

Prurigo nodularis (PN) is an understudied, chronic inflammatory skin disease that disproportionately affects African Americans and presents with intensely pruritic nodules of unknown etiology. To better characterize the immune dysregulation in PN, PBMCs and skin biopsies were obtained from patients with PN and healthy subjects (majority African American) matched by age, race, and sex. Flow cytometric analysis of functional T-cell response comparing patients with PN with healthy subjects identified increased γδT cells (CD3+CD4-CD8-γδTCR+) and Vδ2+ γδT enrichment. Activated T cells demonstrated uniquely increased IL-22 cytokine expression in patients with PN compared with healthy controls. CD4+ and CD8+ T cells were identified as the source of increased circulating IL-22. Consistent with these findings, RNA sequencing of lesional PN skin compared with nonlesional PN skin and biopsy site‒matched control skin demonstrated robust upregulation of T helper (Th) 22‒related genes and signaling networks implicated in impaired epidermal differentiation. Th22‒related cytokine upregulation remained significant, with stratifications by race and biopsy site. Importantly, the expression of the IL-22 receptors IL22RA1 and IL22RA2 was significantly elevated in lesional PN skin. These results indicate that both systemic and cutaneous immune responses in patients with PN are skewed toward a Th22/IL-22 profile. PN may benefit from immunomodulatory therapies directed at Th22‒mediated inflammation.

Mixed-methods process evaluation of SafeTea: a multimedia campaign to prevent hot drink scalds in young children and promote burn first aid.

OBJECTIVES: SafeTea is a multifaceted intervention delivered by community practitioners to prevent hot drink scalds to young children and improve parents' knowledge of appropriate burn first aid. We adapted SafeTea for a national multimedia campaign, and present a mixed-methods process evaluation of the campaign. METHODS: We used social media, a website hosting downloadable materials and media publicity to disseminate key messages to parents/caregivers of young children and professionals working with these families across the UK. The SafeTea campaign was launched on National Burns Awareness Day (NBAD), October 2019, and ran for 3 months. Process evaluation measurements included social media metrics, Google Analytics, and quantitative and qualitative results from a survey of professionals who requested hard copies of the materials via the website. RESULTS: Findings were summarised under four themes: 'reach', 'engagement', 'acceptability' and 'impact/behavioural change'. The launch on NBAD generated widespread publicity. The campaign reached a greater number of the target audience than anticipated, with over 400 000 views of the SafeTea educational videos. Parents and professionals engaged with SafeTea and expressed positive opinions of the campaign and materials. SafeTea encouraged parents to consider how to change their behaviours to minimise the risks associated with hot drinks. Reach and engagement steadily declined after the first month due to reduced publicity and social media promotion. CONCLUSION: The SafeTea campaign was successful in terms of reach and engagement. The launch on NBAD was essential for generating media interest. Future campaigns could be shorter, with more funding for additional social media content and promotion.

Pathophysiology, diagnosis, and pharmacological treatment of prurigo nodularis.

Introduction: Prurigo nodularis (PN) is a chronic inflammatory skin disease characterized by intensely pruritic, hyperkeratotic nodules distributed on the trunk and extensor surfaces of the extremities. PN has a profoundly negative impact on sleep and quality of life in patients with PN. There are currently no U.S. Food and Drug Administration-approved agents and patients are often recalcitrant to current therapies, highlighting the importance of further research into this severely debilitating condition. Areas covered: A PubMed search was conducted to find available literature on the pathophysiology and clinical management of PN. In this review article, we discuss the current understanding of the pathophysiology, recommended diagnostic approach, and treatment options available for PN. Expert opinion/commentary: PN is an extremely difficult condition to treat, because there is a lack of effective therapies available due to our limited understanding of its pathophysiology. Currently, available treatment options are often multimodal due to the intersection of neuroimmune etiologic factors in the pathogenesis of PN. Fortunately, as our knowledge of PN expands, novel treatments targeting specific molecular biomarkers of PN are emerging, providing hope to this long-suffering patient population.

Fecal transplantation and butyrate improve neuropathic pain, modify immune cell profile, and gene expression in the PNS of obese mice.

Obesity affects over 2 billion people worldwide and is accompanied by peripheral neuropathy (PN) and an associated poorer quality of life. Despite high prevalence, the molecular mechanisms underlying the painful manifestations of PN are poorly understood, and therapies are restricted to use of painkillers or other drugs that do not address the underlying disease. Studies have demonstrated that the gut microbiome is linked to metabolic health and its alteration is associated with many diseases, including obesity. Pathologic changes to the gut microbiome have recently been linked to somatosensory pain, but any relationships between gut microbiome and PN in obesity have yet to be explored. Our data show that mice fed a Western diet developed indices of PN that were attenuated by concurrent fecal microbiome transplantation (FMT). In addition, we observed changes in expression of genes involved in lipid metabolism and calcium handling in cells of the peripheral nerve system (PNS). FMT also induced changes in the immune cell populations of the PNS. There was a correlation between an increase in the circulating short-chain fatty acid butyrate and pain improvement following FMT. Additionally, butyrate modulated gene expression and immune cells in the PNS. Circulating butyrate was also negatively correlated with distal pain in 29 participants with varied body mass index. Our data suggest that the metabolite butyrate, secreted by the gut microbiome, underlies some of the effects of FMT. Targeting the gut microbiome, butyrate, and its consequences may represent novel viable approaches to prevent or relieve obesity-associated neuropathies.

Robust signed-rank estimation and variable selection for semi-parametric additive partial linear models.

A fully nonparametric model may not perform well or when the researcher wants to use a parametric model but the functional form with respect to a subset of the regressors or the density of the errors is not known. This becomes even more challenging when the data contain gross outliers or unusual observations. However, in practice the true covariates are not known in advance, nor is the smoothness of the functional form. A robust model selection approach through which we can choose the relevant covariates components and estimate the smoothing function may represent an appealing tool to the solution. A weighted signed-rank estimation and variable selection under the adaptive lasso for semi-parametric partial additive models is considered in this paper. B-spline is used to estimate the unknown additive nonparametric function. It is shown that despite using B-spline to estimate the unknown additive nonparametric function, the proposed estimator has an oracle property. The robustness of the weighted signed-rank approach for data with heavy-tail, contaminated errors, and data containing high-leverage points are validated via finite sample simulations. A practical application to an economic study is provided using an updated Canadian household gasoline consumption data.

Development of a Staphylococcus aureus reporter strain with click beetle red luciferase for enhanced in vivo imaging of experimental bacteremia and mixed infections.

In vivo bioluminescence imaging has been used to monitor Staphylococcus aureus infections in preclinical models by employing bacterial reporter strains possessing a modified lux operon from Photorhabdus luminescens. However, the relatively short emission wavelength of lux (peak 490 nm) has limited tissue penetration. To overcome this limitation, the gene for the click beetle (Pyrophorus plagiophtalamus) red luciferase (luc) (with a longer >600 emission wavelength), was introduced singly and in combination with the lux operon into a methicillin-resistant S. aureus strain. After administration of the substrate D-luciferin, the luc bioluminescent signal was substantially greater than the lux signal in vitro. The luc signal had enhanced tissue penetration and improved anatomical co-registration with infected internal organs compared with the lux signal in a mouse model of S. aureus bacteremia with a sensitivity of approximately 3 × 104 CFU from the kidneys. Finally, in an in vivo mixed bacterial wound infection mouse model, S. aureus luc signals could be spectrally unmixed from Pseudomonas aeruginosa lux signals to noninvasively monitor the bacterial burden of both strains. Therefore, the S. aureus luc reporter may provide a technological advance for monitoring invasive organ dissemination during S. aureus bacteremia and for studying bacterial dynamics during mixed infections.

Clonal Vγ6+Vδ4+ T cells promote IL-17-mediated immunity against Staphylococcus aureus skin infection.

T cell cytokines contribute to immunity against Staphylococcus aureus, but the predominant T cell subsets involved are unclear. In an S. aureus skin infection mouse model, we found that the IL-17 response was mediated by γδ T cells, which trafficked from lymph nodes to the infected skin to induce neutrophil recruitment, proinflammatory cytokines IL-1α, IL-1ß, and TNF, and host defense peptides. RNA-seq for TRG and TRD sequences in lymph nodes and skin revealed a single clonotypic expansion of the encoded complementarity-determining region 3 amino acid sequence, which could be generated by canonical nucleotide sequences of TRGV5 or TRGV6 and TRDV4 However, only TRGV6 and TRDV4 but not TRGV5 sequences expanded. Finally, Vγ6+ T cells were a predominant γδ T cell subset that produced IL-17A as well as IL-22, TNF, and IFNγ, indicating a broad and substantial role for clonal Vγ6+Vδ4+ T cells in immunity against S. aureus skin infections.

In Vivo Bioluminescence Imaging in a Rabbit Model of Orthopaedic Implant-Associated Infection to Monitor Efficacy of an Antibiotic-Releasing Coating.

BACKGROUND: In vivo bioluminescence imaging (BLI) provides noninvasive monitoring of bacterial burden in animal models of orthopaedic implant-associated infection (OIAI). However, technical limitations have limited its use to mouse and rat models of OIAI. The goal of this study was to develop a larger, rabbit model of OIAI using in vivo BLI to evaluate the efficacy of an antibiotic-releasing implant coating. METHODS: A nanofiber coating loaded with or without linezolid-rifampin was electrospun onto a surgical-grade locking peg. To model OIAI in rabbits, a medial parapatellar arthrotomy was performed to ream the femoral canal, and a bright bioluminescent methicillin-resistant Staphylococcus aureus (MRSA) strain was inoculated into the canal, followed by retrograde insertion of the coated implant flush with the articular surface. In vivo BLI signals were confirmed by ex vivo colony-forming units (CFUs) from tissue, bone, and implant specimens. RESULTS: In this rabbit model of OIAI (n = 6 rabbits per group), implants coated without antibiotics were associated with significantly increased knee width and in vivo BLI signals compared with implants coated with linezolid-rifampin (p < 0.001 and p < 0.05, respectively). On day 7, the implants without antibiotics were associated with significantly increased CFUs from tissue (mean [and standard error of the mean], 1.4 × 10 ± 2.1 × 10 CFUs; p < 0.001), bone (6.9 × 10 ± 3.1 × 10 CFUs; p < 0.05), and implant (5.1 × 10 ± 2.2 × 10 CFUs; p < 0.05) specimens compared with implants with linezolid-rifampin, which demonstrated no detectable CFUs from any source. CONCLUSIONS: By combining a bright bioluminescent MRSA strain with modified techniques, in vivo BLI in a rabbit model of OIAI demonstrated the efficacy of an antibiotic-releasing coating. CLINICAL RELEVANCE: The new capability of in vivo BLI for noninvasive monitoring of bacterial burden in larger-animal models of OIAI may have important preclinical relevance.