Nasal Brushing Molecular Endotyping Distinguishes CRSwNP Patients with Better Response to Dupilumab.

BACKGROUND: There is evidence of pathophysiologic diversity in chronic rhinosinusitis with nasal polyps (CRSwNP), but data characterizing the molecular endotypes of CRSwNP and their association with treatment is lacking. OBJECTIVES: To identify gene signatures associated with CRSwNP endotypes, clinical features, and dupilumab treatment response. METHODS: Nasal brushing samples were collected from 89 patients randomized to dupilumab 300 mg every 2 weeks or placebo in the SINUS-52 trial (NCT02898454). Microarrays were used to identify transcriptional clusters and assess the relationship between gene expression and baseline clinical features and clinical response to dupilumab. Endotype signatures were determined using differential expression analysis. RESULTS: Two distinct transcriptional clusters (C1 and C2) were identified, both with elevated type 2 biomarkers. At baseline, C2 patients had higher mean Nasal Polyp Score and higher type 2 biomarker levels than C1 patients. At Week 24, significant improvements in clinical outcomes (dupilumab vs placebo) were observed in both clusters, although the magnitude of improvements was significantly greater in C2 than C1, and more C2 patients demonstrated clinically meaningful responses. Gene sets enrichment analyses supported the existence of two molecular endotypes: C2 was enriched in genes associated with type 2 inflammation (including periostin, cadherin-26, and type 2 cysteine protease inhibitors), while C1 was enriched in genes associated with T cell activation and interleukin-12 production. CONCLUSION: Two distinct gene signatures associated with CRSwNP clinical features were identified; the endotype signatures were associated with clinical outcome measures and magnitude of dupilumab response.

Differential modulation of allergic rhinitis nasal transcriptome by dupilumab and allergy immunotherapy.

BACKGROUND: Nasal epithelial cells are important regulators of barrier function and immune signaling; however, in allergic rhinitis (AR) these functions can be disrupted by inflammatory mediators. We aimed to better discern AR disease mechanisms using transcriptome data from nasal brushing samples from individuals with and without AR. METHODS: Data were drawn from a feasibility study of individuals with and without AR to Timothy grass and from a clinical trial evaluating 16 weeks of treatment with the following: dupilumab, a monoclonal antibody that binds interleukin (IL)-4Rα and inhibits type 2 inflammation by blocking signaling of both IL-4/IL-13; subcutaneous immunotherapy with Timothy grass (SCIT), which inhibits allergic responses through pleiotropic effects; SCIT + dupilumab; or placebo. Using nasal brushing samples from these studies, we defined distinct gene signatures in nasal tissue of AR disease and after nasal allergen challenge (NAC) and assessed how these signatures were modulated by study drug(s). RESULTS: Treatment with dupilumab (normalized enrichment score [NES] = -1.73, p = .002) or SCIT + dupilumab (NES = -2.55, p < .001), but not SCIT alone (NES = +1.16, p = .107), significantly repressed the AR disease signature. Dupilumab (NES = -2.55, p < .001), SCIT (NES = -2.99, p < .001), and SCIT + dupilumab (NES = -3.15, p < .001) all repressed the NAC gene signature. CONCLUSION: These results demonstrate type 2 inflammation is an important contributor to the pathophysiology of AR disease and that inhibition of the type 2 pathway with dupilumab may normalize nasal tissue gene expression.

IL-33 Expression Is Lower in Current Smokers at both Transcriptomic and Protein Levels.

Rationale: IL-33 is a proinflammatory cytokine thought to play a role in the pathogenesis of asthma and chronic obstructive pulmonary disease (COPD). A recent clinical trial using an anti-IL-33 antibody showed a reduction in exacerbation and improved lung function in ex-smokers but not current smokers with COPD. Objectives: This study aimed to understand the effects of smoking status on IL-33. Methods: We investigated the association of smoking status with the level of gene expression of IL-33 in the airways in eight independent transcriptomic studies of lung airways. Additionally, we performed Western blot analysis and immunohistochemistry for IL-33 in lung tissue to assess protein levels. Measurements and Main Results: Across the bulk RNA-sequencing datasets, IL-33 gene expression and its signaling pathway were significantly lower in current versus former or never-smokers and increased upon smoking cessation (P < 0.05). Single-cell sequencing showed that IL-33 is predominantly expressed in resting basal epithelial cells and decreases during the differentiation process triggered by smoke exposure. We also found a higher transitioning of this cellular subpopulation into a more differentiated cell type during chronic smoking, potentially driving the reduction of IL-33. Protein analysis demonstrated lower IL-33 levels in lung tissue from current versus former smokers with COPD and a lower proportion of IL-33-positive basal cells in current versus ex-smoking controls. Conclusions: We provide strong evidence that cigarette smoke leads to an overall reduction in IL-33 expression in transcriptomic and protein level, and this may be due to the decrease in resting basal cells. Together, these findings may explain the clinical observation that a recent antibody-based anti-IL-33 treatment is more effective in former than current smokers with COPD.

Dupilumab suppresses type 2 inflammatory biomarkers across multiple atopic, allergic diseases.

BACKGROUND: Type 2 inflammation is common in numerous atopic/allergic diseases and can be identified by elevated biomarker levels. Dupilumab, a fully human monoclonal antibody, blocks the shared receptor component for interleukin-4 and interleukin-13, key and central drivers of type 2 inflammation. OBJECTIVE: Assessment of dupilumab effect on type 2 inflammatory biomarkers in atopic dermatitis (AD), asthma, chronic rhinosinusitis with nasal polyps (CRSwNP) and eosinophilic esophagitis (EoE). METHODS: Data were extracted from three randomized placebo-controlled trials of dupilumab in AD (NCT02277743, N = 671; NCT02277769, N = 708; NCT02260986, N = 740); and one each in asthma (NCT02414854, N = 1902); CRSwNP (NCT02898454, N = 448); and EoE (NCT02379052, N = 47). Biomarkers assessed were serum thymus and activation-regulated chemokine (TARC), plasma eotaxin-3, serum total immunoglobulin E (IgE), serum periostin and blood eosinophil count. RESULTS: Dupilumab versus placebo significantly suppressed most type 2 inflammatory biomarker levels across all studies/indications where data were assessed. Reductions in serum TARC, plasma eotaxin-3 and serum periostin occurred rapidly, whereas reductions in serum total IgE were more gradual. Across diseases, at the end of treatment, median percentage change from baseline in TARC levels ranged from -24.8% to -88.6% (placebo +2.6% to -53.6%); -38.2% to -51.5% (placebo +8.3% to -0.16%) in eotaxin-3; -24.8% to -76.7% (placebo +8.3% to -4.4%) in total IgE; and -13.6% to -41.1% (placebo +10.1% to -6.94%) in periostin levels. Blood eosinophil responses to dupilumab varied by disease, with minimal changes in AD in the SOLO studies (median percentage change from baseline to end of treatment: 0% [95% CI: -15.8, 0]); transient increases followed by decreases to below-baseline levels in asthma (-14.6% [-20.0, -7.7]) and CRSwNP (-29.4% [-40.0, -16.3]); and significant decreases in EoE (-50.0% [-50.0, -33.3]). CONCLUSION AND CLINICAL RELEVANCE: Dupilumab reduced levels of type 2 biomarkers across clinical studies in patients with AD, asthma, CRSwNP and EoE.

Efficacy of dupilumab on clinical outcomes in patients with asthma and perennial allergic rhinitis.

BACKGROUND: Comorbid perennial allergic rhinitis (PAR) or year-round aeroallergen sensitivity substantially contributes to disease burden in patients with asthma. Dupilumab blocks the shared receptor for interleukin (IL) 4 and IL-13, key drivers of type 2 inflammation that play important roles in asthma and PAR. In the LIBERTY ASTHMA QUEST trial (NCT02414854), dupilumab reduced severe asthma exacerbations and improved forced expiratory volume in 1 second (FEV1) in patients with uncontrolled, moderate-to-severe asthma, with greater efficacy observed in patients with elevated type 2 inflammatory biomarkers at baseline (blood eosinophils and fractional exhaled nitric oxide). OBJECTIVE: To assess dupilumab efficacy in LIBERTY ASTHMA QUEST patients with comorbid PAR. METHODS: Severe asthma exacerbation rates, FEV1, asthma control (5-item Asthma Control Questionnaire), rhinoconjunctivitis-specific health-related quality of life (Standardized Rhinoconjunctivitis Quality of Life Questionnaire +12 scores), and type 2 inflammatory biomarkers during the 52-week treatment period were assessed. RESULTS: A total of 814 of the 1902 patients (42.8%) had comorbid PAR (defined as an allergic rhinitis history and ≥1 perennial aeroallergen specific immunoglobulin E (IgE) level ≥0.35 kU/L at baseline). Dupilumab, 200 and 300 mg every 2 weeks, vs placebo reduced severe exacerbations rates by 32.2% and 34.6% (P < .05 for both) and improved FEV1 at week 12 by 0.14 L and 0.18 L (P < .01 for both); greater efficacy was observed in patients with elevated baseline blood eosinophil counts (≥300 cells/µL) and fractional exhaled nitric oxide. Dupilumab treatment also numerically improved the 5-item Asthma Control Questionnaire and Standardized Rhinoconjunctivitis Quality of Life Questionnaire +12 scores and suppressed type 2 inflammatory biomarkers. CONCLUSION: Dupilumab improved key asthma-related outcomes, asthma control, and rhinoconjunctivitis-specific health-related quality of life while suppressing type 2 inflammatory biomarkers and perennial allergen-specific IgE in patients with moderate-to-severe asthma and comorbid PAR, highlighting its dual inhibitory effects on IL-4 and IL-13 and its role in managing asthma and PAR.

FGF5 is a crucial regulator of hair length in humans.

Mechanisms that regulate the growth of eyelashes have remained obscure. We ascertained two families from Pakistan who presented with familial trichomegaly, or extreme eyelash growth. Using a combination of whole exome sequencing and homozygosity mapping, we identified distinct pathogenic mutations within fibroblast growth factor 5 (FGF5) that underlie the disorder. Subsequent sequencing of this gene in several additional trichomegaly families identified an additional mutation in FGF5. We further demonstrated that hair fibers from forearms of these patients were significantly longer than hairs from control individuals, with an increased proportion in the growth phase, anagen. Using hair follicle organ cultures, we show that FGF5 induces regression of the human hair follicle. We have identified FGF5 as a crucial regulator of hair growth in humans for the first time, to our knowledge, and uncovered a therapeutic target to selectively regulate eyelash growth.

Reduced Toxicity Conditioning and Allogeneic Hematopoietic Progenitor Cell Transplantation for Recessive Dystrophic Epidermolysis Bullosa.

Recessive dystrophic epidermolysis bullosa is a severe, incurable, inherited blistering disease caused by COL7A1 mutations. Emerging evidence suggests hematopoietic progenitor cells (HPCs) can be reprogrammed into skin; HPC-derived cells can restore COL7 expression in COL7-deficient mice. We report two children with recessive dystrophic epidermolysis bullosa treated with reduced-toxicity conditioning and HLA-matched HPC transplantation.

Baseline FeNO Independently Predicts the Dupilumab Response in Patients With Moderate-to-Severe Asthma.

BACKGROUND: FeNO may have a role as both a prognostic and predictive biomarker in combination with eosinophils for assessing responsiveness to some biological therapies. OBJECTIVE: We evaluated the value of baseline FeNO, adjusted for baseline blood eosinophil levels and other clinical characteristics, as an independent predictor of treatment response to dupilumab in patients with uncontrolled moderate-to-severe asthma. METHODS: We performed a post hoc analysis of LIBERTY ASTHMA QUEST (NCT02414854), a phase 3, double-blind study in patients aged 12 years and older with uncontrolled moderate-to-severe asthma, who received dupilumab 200 or 300 mg, or placebo every 2 weeks up to 52 weeks. We assessed the annualized event rate of severe exacerbations and least-squares mean change from baseline in prebronchodilator FEV1 at weeks 12 and 52 in relationship to baseline FeNO, adjusted for eosinophils and other clinical characteristics. RESULTS: The annualized event rate increased with increasing baseline FeNO in placebo and decreased in dupilumab groups. The relative risk of severe exacerbations was 22·7%, 58·3%, and 69·3% lower for dupilumab versus placebo for the FeNO less than 25, 25 to less than 50, and 50 and greater parts per billion subgroups. The magnitude of FEV1 improvement increased with higher baseline FeNO for dupilumab and was consistent across the continuum of FeNO levels in placebo. Both findings were independent of blood eosinophil levels. Significant differences were observed between FeNO subgroups. CONCLUSIONS: Increased baseline FeNO was associated with greater clinical effects in dupilumab versus placebo independently of eosinophil levels and other clinical characteristics.

Effect of Dupilumab on Type 2 Biomarkers in Chronic Rhinosinusitis With Nasal Polyps: SINUS-52 Study Results.

OBJECTIVES: Chronic rhinosinusitis with nasal polyps (CRSwNP), asthma, and non-steroidal anti-inflammatory drug-exacerbated respiratory disease (NSAID-ERD) are frequent coexisting conditions and share type 2 inflammatory pathophysiology, with interleukin (IL)-4 and IL-13 as key cytokines. Dupilumab is a monoclonal antibody that blocks the shared receptor for IL-4 and IL-13. The objective of this analysis was to evaluate dupilumab's effect on type 2 inflammation biomarkers in patients with CRSwNP with/without coexisting asthma or NSAID-ERD from the SINUS-52 (NCT02898454) study. METHODS: Patients received treatment with dupilumab or placebo for 52 weeks. Blood and urinary biomarkers were evaluated through 52 weeks, and nasal secretions and mucosa brushings through 24 weeks. RESULTS: Of 447 patients, 60% had coexisting asthma and 27% had coexisting NSAID-ERD. At baseline, blood eotaxin-3, eosinophils, and periostin, nasal secretion eotaxin-3, and urinary leukotriene E4 were significantly higher in patients with coexisting NSAID-ERD than without. Dupilumab reduced eotaxin-3, thymus and activation-regulated chemokine, periostin, and total immunoglobulin E in blood, eotaxin-3, periostin, IL-5, and eosinophil cationic protein in nasal secretions, and leukotriene E4 in urine. Reductions were generally similar or greater in the subgroups with asthma and NSAID-ERD than without. Dupilumab also reduced MUC5AC and mast cell counts in nasal mucosa brushings. CONCLUSION: Dupilumab reduced local and systemic type 2 inflammatory biomarkers in patients with CRSwNP, including mast cells in nasal mucosa and cysteinyl leukotrienes in urine. These findings provide insight into the processes driving CRSwNP and the mechanisms of dupilumab's therapeutic effects. CLINICAL TRIAL REGISTRY NAME: SINUS-52 https://www.clinicaltrials.gov/ct2/show/NCT02898454. CLINICALTRIALS.GOV IDENTIFIER: NCT02898454.

Pharmacokinetics and pharmacodynamics of itepekimab in healthy adults and patients with asthma: Phase I first-in-human and first-in-patient trials.

Itepekimab is a monoclonal antibody that targets interleukin (IL-33) and has been shown to reduce airway inflammation and associated tissue damage in preclinical studies. We assessed the safety, tolerability, pharmacokinetics (PKs), and pharmacodynamic profiles of single-ascending and multiple-ascending doses of itepekimab in two randomized, double-blind, placebo-controlled phase I studies. Healthy adults (N = 40) were randomized to the single-dose study and patients with moderate asthma (N = 23) to the multiple-dose study. Itepekimab was administered intravenously (0.3, 1, 3, or 10 mg/kg infusion) or subcutaneously (150 mg) in the single-dose study and subcutaneously (75 or 150 mg weekly for 4 weeks) in the multiple-dose study. Itepekimab exhibited linear PKs across studies and dose-proportional increases in mean maximum concentration in serum and area under the concentration-time curve following single intravenous or multiple subcutaneous doses. Itepekimab demonstrated mean subcutaneous bioavailability of 59-73% and a long terminal half-life (30.0-31.6 days). IL-33 concentrations in most healthy participants and patients with asthma were undetectable at baseline. Following administration of itepekimab in both studies, total IL-33 concentrations increased and blood eosinophils decreased, both with durable effect. Itepekimab was well-tolerated in both studies with no detection of treatment-emergent anti-drug antibody responses.

Baseline FeNO as a prognostic biomarker for subsequent severe asthma exacerbations in patients with uncontrolled, moderate-to-severe asthma receiving placebo in the LIBERTY ASTHMA QUEST study: a post-hoc analysis.

BACKGROUND: Fractional exhaled nitric oxide (FeNO) has potential as a prognostic biomarker in asthma, but its prognostic value among other recognised indicators is unclear. We assessed the added prognostic value of baseline FeNO to blood eosinophil count and prior severe asthma exacerbations for subsequent exacerbations. METHODS: In this post-hoc analysis of the 52-week, double-blind, phase 3 LIBERTY ASTHMA QUEST study, we identified 620 patients with moderate-to-severe asthma who were randomly assigned to placebo; had uncontrolled asthma with inhaled glucocorticoids plus up to two controllers; one or more exacerbations in the previous year; FEV1 percent predicted 40-80%; FEV1 reversibility of 12% or higher and 200 mL; Asthma Control Questionnaire (ACQ-5) score of 1·5 or higher; and complete data on baseline type 2 biomarkers (FeNO, eosinophils, and total IgE) with no baseline minimum requirement. Annualised severe exacerbation rate was assessed by baseline FeNO (<25 ppb, ≥25 to <50 ppb, ≥50 ppb; negative binomial model) and cross-classified by baseline blood eosinophils (<150 cells per µL, ≥150 to <300 cells per µL, ≥300 cells per µL) and prior exacerbations (one, two or more), all adjusted for baseline ACQ-5, postbronchodilator FEV1, and other clinical characteristics. Post-hoc analyses were done in the intention-to-treat population. The LIBERTY ASTHMA QUEST STUDY is registered on ClinicalTrials.gov, NCT02414854, and is complete. FINDINGS: Patients with baseline FeNO of 50 ppb or higher (n=144) had a 1·54-times higher exacerbation rate than patients with FeNO of less than 25 ppb (n=291; relative risk 1·54 [95% CI 1·11-2·14]; p=0·0097). Patients with baseline FeNO of 25 to <50 ppb (n=185) had a 1·33-times higher exacerbation rate than patients with FeNO of less than 25 ppb (1·33 [0·99-1·78]; p=0·0572). Patients with baseline FeNO of 25 ppb or higher, a blood eosinophil count of 150 cells per µL or higher, and two or more prior exacerbations (n=157) had an exacerbation rate 3·62-times higher than patients with FeNO of less than 25 ppb, a blood eosinophil count of less than 150 cells per µL, and one prior exacerbation (n=116; 3·62 [1·67-7·81]; p=0·0011). INTERPRETATION: In uncontrolled, moderate-to-severe asthma, higher baseline FeNO levels were associated with greater risk of severe asthma exacerbations, particularly in combination with elevated eosinophil count and prior exacerbations, supporting the added value of FeNO as a prognostic biomarker. Further research is needed to confirm FeNO as an independent predictor for asthma exacerbations. FUNDING: Sanofi and Regeneron Pharmaceuticals.

Dupilumab Efficacy in Patients with Uncontrolled, Moderate-to-Severe Allergic Asthma.

BACKGROUND: Dupilumab blocks the shared receptor component for IL-4 and IL-13, key drivers of type 2 inflammation, including IgE-mediated allergic inflammation in asthma. In the LIBERTY ASTHMA QUEST (NCT02414854) study, dupilumab reduced severe asthma exacerbations and improved forced expiratory volume in 1 second (FEV1) in patients with uncontrolled, moderate-to-severe asthma with greater efficacy observed in patients with elevated type 2 inflammatory biomarkers (blood eosinophils and fractional exhaled nitric oxide) at baseline. OBJECTIVE: We assessed dupilumab's effect on key asthma outcomes in QUEST patients with/without evidence of allergic asthma (total serum IgE ≥30 IU/mL and ≥1 perennial aeroallergen-specific IgE ≥0.35 kU/L at baseline). METHODS: Severe exacerbation rates and change from baseline in FEV1, asthma control, and markers of type 2 inflammation during the 52-week treatment period were assessed. RESULTS: In the allergic asthma subgroup (n = 1083), dupilumab 200/300 mg every 2 weeks versus placebo reduced severe asthma exacerbation rates (-36.9%/-45.5%; both P < .01), improved FEV1 at week 12 (0.13 L/0.16 L; both P < .001; improvements were evident by the first evaluation at week 2) with greater efficacy observed in patients with elevated type 2 inflammatory biomarkers at baseline, and improved asthma control. Dupilumab treatment also resulted in rapid and sustained reductions in type 2 inflammatory biomarkers. Comparable results were observed in patients without evidence of allergic asthma (n = 819). CONCLUSION: Dupilumab reduced severe exacerbation rates, improved FEV1 and asthma control, and suppressed type 2 inflammatory biomarkers in patients with uncontrolled, moderate-to-severe asthma with or without evidence of allergic asthma, highlighting the key role of IL-4 and IL-13 in airway inflammation.

Dupilumab Efficacy in Uncontrolled, Moderate-to-Severe Asthma with Self-Reported Chronic Rhinosinusitis.

BACKGROUND: Dupilumab, a fully human monoclonal antibody, blocks the shared receptor component for IL-4 and IL-13 signaling, key drivers of type 2 inflammation. In the phase 3 study (NCT02414854), add-on dupilumab 200 mg/300 mg every 2 weeks, versus placebo, significantly reduced severe asthma exacerbations and improved pre-bronchodilator forced expiratory volume in 1 second (FEV1) and quality-of-life measures in patients with uncontrolled, moderate-to-severe asthma, with greater efficacy observed in those with a high baseline type 2 phenotype. OBJECTIVE: To assess the efficacy and safety of dupilumab in patients with uncontrolled, moderate-to-severe asthma with or without self-reported comorbid chronic rhinosinusitis (CRS or non-CRS). METHODS: Comorbid CRS was self-reported by patients using an e-diary. Annualized severe exacerbation rates, changes from baseline in pre- and post-bronchodilator FEV1, patient-reported outcomes, type 2 biomarkers, and safety were assessed. RESULTS: CRS was self-reported by 382 of 1902 (20.1%) patients. Dupilumab 200 mg/300 mg reduced annualized severe exacerbation rates by 63%/61%, respectively, in patients with CRS, and by 42%/40% in patients without CRS (all P < .001 vs placebo). Dupilumab also improved lung function and patient-reported asthma control and quality of life, and suppressed type 2 biomarkers versus placebo in both subgroups. Clinical responses were rapid, with near-maximal responses observed at the earliest measured time points and sustained at week 52. Improvements observed in the CRS subgroup were similar to or numerically greater than those in the non-CRS subgroup. CONCLUSION: Dupilumab showed efficacy and was generally well tolerated in patients with uncontrolled, moderate-to-severe asthma with or without CRS.

JAK-STAT Signaling Jump Starts the Hair Cycle.

Legrand et al show that JAK/STAT5 signaling in the dermal papilla is required for anagen onset in the murine hair cycle. Interestingly, others have shown that JAK-inhibition is able to induce telogen-to-anagen transition in wild-type mice. This apparent contradiction highlights the complexity of interactions within the hair follicle, and encourages further discussion on the role of JAK-STAT signaling in the various stem cell niches of the hair follicle.

Highly efficient small interfering RNA delivery to primary mammalian neurons induces MicroRNA-like effects before mRNA degradation.

The study of protein function in neurons has been hindered by the lack of highly efficient, nontoxic methods of inducing RNA interference in such cells. Here we show that application of synthetic small interfering RNA (siRNA) linked to the vector peptide Penetratin1 results in rapid, highly efficient uptake of siRNA by entire populations of cultured primary mammalian hippocampal and sympathetic neurons. This treatment leads to specific knock-down of targeted proteins within hours without the toxicity associated with transfection. In contrast to current methods, our technique permits study of protein function across entire populations with minimal disturbance of complex cellular networks. Using this technique, we found that protein knock-down (evident after 6 hr) precedes any decrease in targeted message (evident after 24 hr), suggesting an early, translational repression by perfectly targeted siRNAs.

Pharmacologic inhibition of JAK-STAT signaling promotes hair growth.

Several forms of hair loss in humans are characterized by the inability of hair follicles to enter the growth phase (anagen) of the hair cycle after being arrested in the resting phase (telogen). Current pharmacologic therapies have been largely unsuccessful in targeting pathways that can be selectively modulated to induce entry into anagen. We show that topical treatment of mouse and human skin with small-molecule inhibitors of the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway results in rapid onset of anagen and subsequent hair growth. We show that JAK inhibition regulates the activation of key hair follicle populations such as the hair germ and improves the inductivity of cultured human dermal papilla cells by controlling a molecular signature enriched in intact, fully inductive dermal papillae. Our findings open new avenues for exploration of JAK-STAT inhibition for promotion of hair growth and highlight the role of this pathway in regulating the activation of hair follicle stem cells.

Alopecia areata is driven by cytotoxic T lymphocytes and is reversed by JAK inhibition.

Alopecia areata (AA) is a common autoimmune disease resulting from damage of the hair follicle by T cells. The immune pathways required for autoreactive T cell activation in AA are not defined limiting clinical development of rational targeted therapies. Genome-wide association studies (GWAS) implicated ligands for the NKG2D receptor (product of the KLRK1 gene) in disease pathogenesis. Here, we show that cytotoxic CD8(+)NKG2D(+) T cells are both necessary and sufficient for the induction of AA in mouse models of disease. Global transcriptional profiling of mouse and human AA skin revealed gene expression signatures indicative of cytotoxic T cell infiltration, an interferon-γ (IFN-γ) response and upregulation of several γ-chain (γc) cytokines known to promote the activation and survival of IFN-γ-producing CD8(+)NKG2D(+) effector T cells. Therapeutically, antibody-mediated blockade of IFN-γ, interleukin-2 (IL-2) or interleukin-15 receptor ß (IL-15Rß) prevented disease development, reducing the accumulation of CD8(+)NKG2D(+) T cells in the skin and the dermal IFN response in a mouse model of AA. Systemically administered pharmacological inhibitors of Janus kinase (JAK) family protein tyrosine kinases, downstream effectors of the IFN-γ and γc cytokine receptors, eliminated the IFN signature and prevented the development of AA, while topical administration promoted hair regrowth and reversed established disease. Notably, three patients treated with oral ruxolitinib, an inhibitor of JAK1 and JAK2, achieved near-complete hair regrowth within 5 months of treatment, suggesting the potential clinical utility of JAK inhibition in human AA.