The hair follicle-psoriasis axis: Shared regulatory mechanisms and therapeutic targets

An initial investigation of transcutaneous delivery of plasmid DNA encoding interleukin-10 for the treatment of psoriatic skin conditions

Psoriasis is a chronic immune-mediated skin disorder characterized by intense local inflammation, epidermal hyperplasia, and leukocyte infiltration. Current treatment approaches for psoriasis aim to alleviate symptoms and prevent disease progression, including systemically administered drugs with whole body side effects. Despite some advances in psoriasis treatment, success has been quite limited. To begin to address this challenge, we undertook an initial investigation of whether transcutaneous delivery of an endogenous anti-inflammatory cytokine could provide an effective, local treatment of psoriatic-like skin conditions. To do this, we utilized a previously documented rodent model of psoriasis, induced via a single topical application of Imiquimod (IMQ) to the shaved back of rats. The therapeutic approach used for this initial investigation was delivery of plasmid DNA encoding rat interleukin-10 (pDNA-rIL10), a non-viral gene therapy approach previously shown to be effective in suppressing neuroinflammatory disorders after localized delivery either intracerebrally or intrathecally. Translation of this CNS therapeutic for use in psoriatic-like skin disorders required reformulation to enable transcutaneous delivery. Toward that end, pDNA-rIL10 was topically applied in Lipoderm HMW, a base explicitly designed to deliver higher molecular weight compounds into skin. Here we show that a single topical application of pDNA-rIL10 in Lipoderm HMW was effective in decreasing mRNA levels of pro-inflammatory cytokines as well as reducing the recruitment of T-cells to IMQ-treated skin. Furthermore, this transcutaneous IL-10 gene therapy decreased signs of skin inflammation, reflected by reduced erythema. Moreover, the results provide an initial indication that IL10 may stimulate hair regrowth in psoriatic-like skin.

Psychological Stress-Induced Pathogenesis of Alopecia Areata: Autoimmune and Apoptotic Pathways

Alopecia areata (AA) is an autoimmune dermatological disease with multifactorial etiology and is characterized by reversible hair loss in patches. AA may be closely related to emotional stress and influenced by psychological factors as part of its pathophysiology; however, its etiology remains predominantly unknown. This review aimed to elucidate the association between AA occurrence and the neuropeptide substance P (SP) and corticotropin-releasing hormone (CRH), which are secreted during emotional stress, and have been understood to initiate and advance the etiopathogenesis of AA. Therefore, this review aimed to explain how SP and CRH initiate and contribute to the etiopathogenesis of AA. To assess the etiopathogenesis of AA, we conducted a literature search on PubMed and ClinicalTrials.gov. Overall, several authors described interactions between the hair follicles (HFs) and the stress-associated signaling substances, including SP and CRH, in the etiology of AA; this was attributed to the understanding in that AA can occur without the loss of HFs, similar to that observed in hereditary hair loss with age. Most studies demonstrated that the collapse of "immune privilege" plays a crucial role in the development and exacerbation of the AA; nonetheless, a few studies indicated that substances unrelated to autoimmunity may also cause apoptosis in keratocytes, leading to the development of AA. We investigated both the autoimmune and apoptotic pathways within the etiology of AA and assessed the potential interactions between the key substances of both pathways to evaluate potential therapeutic targets for the treatment of AA. Clinical trials of marketed/unreviewed intervention drugs for AA were also reviewed to determine their corresponding target pathways.

The PI3K-Akt-mTOR and Associated Signaling Pathways as Molecular Drivers of Immune-Mediated Inflammatory Skin Diseases: Update on Therapeutic Strategy Using Natural and Synthetic Compounds

The dysregulated phosphatidylinositol-3-kinase (PI3K)-Akt-mammalian target of rapamycin (mTOR) signaling pathway has been implicated in various immune-mediated inflammatory and hyperproliferative dermatoses such as acne, atopic dermatitis, alopecia, psoriasis, wounds, and vitiligo, and is associated with poor treatment outcomes. Improved comprehension of the consequences of the dysregulated PI3K/Akt/mTOR pathway in patients with inflammatory dermatoses has resulted in the development of novel therapeutic approaches. Nonetheless, more studies are necessary to validate the regulatory role of this pathway and to create more effective preventive and treatment methods for a wide range of inflammatory skin diseases. Several studies have revealed that certain natural products and synthetic compounds can obstruct the expression/activity of PI3K/Akt/mTOR, underscoring their potential in managing common and persistent skin inflammatory disorders. This review summarizes recent advances in understanding the role of the activated PI3K/Akt/mTOR pathway and associated components in immune-mediated inflammatory dermatoses and discusses the potential of bioactive natural products, synthetic scaffolds, and biologic agents in their prevention and treatment. However, further research is necessary to validate the regulatory role of this pathway and develop more effective therapies for inflammatory skin disorders.

Genome-wide association analysis of anti-TNF-α treatment response in Chinese patients with psoriasis

Background: TNF-α inhibitors are effective biological agents for treating psoriasis, but the treatment responses differ across patients. This study aimed to identify genetic biomarkers of anti-TNF-α response in Chinese psoriasis patients using a genome-wide association approach.

Methods: We recruited two independent cohorts of Chinese psoriasis patients administered etanercept biosimilar (with or without methotrexate). We identified 61 and 87 good responders (PASI improvement ≥75%), 19 and 10 poor responders (PASI improvement <50%) after 24 weeks treatment in the two cohorts, respectively. Then we performed genome-wide association studies (GWAS) on anti-TNF-α response in each cohort independently, followed by a fixed-effects inverse-variance meta-analysis in the 148 good and 29 poor responders.

Results: We tested genetic associations with >3 million genetic variants in either cohort. Meta-analysis identified significant associations within seven loci at p < 10⁻⁵, which also showed consistent association evidence in the two cohorts. These seven loci include rs2431355 (OR = 6.65, p = 4.46 × 10⁻⁷, IQGAP2-F2RL2 on 5q13.3), rs11801616 (OR = 0.11, p = 1.75 × 10⁻⁶, SDC3 on 1p35.2), rs3754679 (OR = 0.17, p = 7.71 × 10⁻⁶, CNOT11 on 2q11.2), rs13166823 (OR = 0.09, p = 3.71 × 10⁻⁶, IRF1-AS1 on 5q31.1), rs10220768 (OR = 5.49, p = 1.48 × 10⁻⁶, NPAP1 on 15q11.2), rs4796752 (OR = 5.56, p = 1.49 × 10⁻⁶, KRT31 on 17q21.2), and rs13045590 (OR = 0.08, p = 9.67 × 10⁻⁷, CTSZ on 20q13.3). Of the seven SNPs, six SNPs showed significant eQTL effect (p < 1 × 10⁻⁶) for several genes in multiple tissues.

Conclusion: These results suggest novel biological mechanisms and potential biomarkers for the response to anti-TNF therapies. These findings warrant further validation.