Genetic analysis of interleukin-1 receptor antagonist and interleukin-1β single-nucleotide polymorphisms C-511T and C+3953T in alopecia areata: susceptibility and severity association

Aberrant inflammasome activation as a driving force of human autoimmune skin disease

Autoimmune skin diseases are understood as conditions in which the adaptive immune system with autoantigen-specific T cells and autoantibody-producing B cells reacting against self-tissues plays a crucial pathogenic role. However, there is increasing evidence that inflammasomes, which are large multiprotein complexes that were first described 20 years ago, contribute to autoimmune disease progression. The inflammasome and its contribution to the bioactivation of interleukins IL-1β and IL-18 play an essential role in combating foreign pathogens or tissue damage, but may also act as a pathogenic driver of myriad chronic inflammatory diseases when dysfunctionally regulated. Inflammasomes containing the NOD-like receptor family members NLRP1 and NLRP3 as well as the AIM2-like receptor family member AIM2 have been increasingly investigated in inflammatory skin conditions. In addition to autoinflammatory diseases, which are often associated with skin involvement, the aberrant activation of the inflammasome has also been implied in autoimmune diseases that can either affect the skin besides other organs such as systemic lupus erythematosus and systemic sclerosis or are isolated to the skin in humans. The latter include, among others, the T-cell mediated disorders vitiligo, alopecia areata, lichen planus and cutaneous lupus erythematosus as well as the autoantibody-driven blistering skin disease bullous pemphigoid. Some diseases are characterized by both autoinflammatory and autoimmune responses such as the chronic inflammatory skin disease psoriasis. Further insights into inflammasome dysregulation and associated pathways as well as their role in forming adaptive immune responses in human autoimmune skin pathology could potentially offer a new field of therapeutic options in the future.

Bidirectional association between alopecia areata and irritable bowel syndrome: A nationwide population-based cohort study

BACKGROUND

Alopecia areata (AA) and irritable bowel syndrome (IBS) are two distinct diseases that share a similar pathophysiology; however, the relationship between these two diseases is unknown. This study aimed to investigate the bidirectional relationship between AA and IBS.

METHODS

Participants were recruited from the National Health Insurance Research Database in Taiwan. We included 5446 patients with AA and 21 784 matched controls to assess the risk of IBS, and 56 429 patients with IBS and 225 716 matched controls to assess the risk of AA. The Cox proportional-hazards regression model was used to calculate the adjusted hazard ratio (aHR).

RESULTS

After adjustment for potential confounders, patients with AA had an aHR of 5.20 [95% confidence interval (CI) 3.97-6.82] for IBS in comparison with the controls. Furthermore, compared with the controls, IBS patients had an aHR of 5.38 (95% CI 3.95-7.34) for AA.

CONCLUSION

AA is bidirectionally associated with IBS. Further investigation is needed to elucidate the shared pathogenesis underlying these two diseases.

Induction of IL-1β and antimicrobial peptides as a potential mechanism for topical dithranol

Topical dithranol is effective in autoimmune conditions like alopecia areata, inducing hair regrowth in a high percentage of cases. Exact mechanisms of dithranol in alopecia areata, with seemingly healthy epidermis besides altered hair follicles, are not well understood. To better understand dithranol's mechanisms on healthy skin, we analysed its effect on normal murine as well as xenografted human skin. We found a strong increase in mRNA expression of anti-microbial peptides (AMPs) (eg Lcn2, Defb1, Defb3, S100a8, S100a9), keratinocyte differentiation markers (eg Serpinb3a, Flg, Krt16, Lce3e) and inflammatory cytokines (eg Il1b and Il17) in healthy murine skin. This effect was paralleled by inflammation and disturbed skin barrier, as well as an injury response resulting in epidermal hyperproliferation, as observed in murine and xenografted adult human skin. This contact response and disturbed barrier induced by dithranol might lead via a vicious loop between AMPs such as S100a8/a9 (that led to skin swelling itself after topical application) and cytokines such as IL-1β to an immune suppressive environment in the skin. A better understanding of the skin's physiologic response to dithranol may open up new avenues for the establishment of novel therapeutics (including AMP-related/interfering molecules) for certain skin conditions, such as alopecia areata.

Cigarette Smoking, Alcohol Consumption, and Risk of Alopecia Areata: A Population-Based Cohort Study in Taiwan

BACKGROUND

The effects of cigarette smoking and alcohol consumption on the risk of alopecia areata (AA) are unclear.

OBJECTIVE

The aim was to examine the association of cigarette smoking and alcohol consumption with AA.

METHODS

We collected participants from four rounds (2001, 2005, 2009, and 2013) of the Taiwan National Health Interview Survey. Incident AA cases were identified from the National Health Insurance database.

RESULTS

Of the 60,055 participants, 154 developed AA during the 647,902 person-years of follow-up. After controlling for confounders, current smokers had a higher risk of incident AA than never smokers [adjusted hazard ratio (aHR) 1.88; 95% confidence interval (CI) 1.22-2.88]. There was a trend toward an increased risk of AA with increasing numbers of years of smoking and cumulative pack-years of smoking among current smokers. The aHRs (95% CIs) of current smokers of > 5 and ≤ 15 cigarettes per day, > 10 and ≤ 20 years of smoking, ≤ 10, and > 10 and ≤ 20 pack-years of smoking were 2.03 (1.17-3.51), 2.25 (1.21-4.18), 1.86 (1.12-3.09), and 2.04 (1.04-4.01), respectively. Conversely, social and regular drinkers had significantly lower risks of AA than never drinkers [aHRs (95% CIs) 0.65 (0.43-0.98) and 0.49 (0.26-0.93), respectively].

CONCLUSION

Current smokers had an increased risk of developing AA, while alcohol consumption was associated with a decreased risk of AA.

Severe subtype of alopecia areata is highly associated with thyroid autoimmunity

Objectives:

To assess the significance of thyroid autoimmune screening in alopecia areata (AA) patients in Saudi population, and to determine whether there is a difference in thyroid autoimmune susceptibility between mild and severe AA.

Methods:

In a prospective case-control study, we included 50 alopecia totalis (AT) and alopecia universalis (AU) patients, 50 age- and gender-matched patients with localized AA, and 50 age- and gender- matched healthy subjects between March 2015 and August 2015. Patients with AA were consecutively recruited from the hair disorders out-patient clinic of King Khalid University Hospital, Riyadh, Kingdom of Saudi Arabia.

Results:

Thyroid autoantibodies (TAAs) were positive in AT/AU (40%), mild AA (14%), and healthy subjects (4%). The frequency of TAAs was significantly higher in patients with AT/AU than in mild AA (p=0.001) and healthy controls (p<0.001). The frequency of thyroid peroxidase antibody (TPO-Abs) was significantly higher in patients with AT/AU than in mild AA and healthy controls (p<0.001 for both). The frequency of TG-Abs was significantly higher in patients with AT/AU (p=0.003) and mild AA (p=0.043) than in healthy controls. Serum TSH level was significantly higher in AT/AU patients than in mild AA patients (p=0.006) and healthy controls (p=0.005).

Conclusion:

Severe subtype of AA is associated with a high risk of autoimmune thyroid disease. This highlights the significance of screening for thyroid abnormalities and TAAs in patients with AT/AU.

IL-1 Receptor-Knockout Mice Develop Epidermal Cysts and Show an Altered Innate Immune Response after Exposure to UVB Radiation

In this study, we observed that mice lacking the IL-1 receptor (IL-1R) (IL1r^-/-) or deficient in IL1-β developed multiple epidermal cysts after chronic UVB exposure. Cysts that developed in IL1r^-/- mice were characterized by the presence of the hair follicle marker Sox 9, keratins 10 and 14, and normal melanocyte distribution and retinoid X receptor-α expression. The increased incidence of cysts in IL1r^-/- mice was associated with less skin inflammation as characterized by decreased recruitment of macrophages, and their skin also maintained epidermal barrier function compared with wild-type mice. Transcriptional analysis of the skin of IL1r^-/- mice after UVB exposure showed decreased gene expression of proinflammatory cytokines such as tumor necrosis factor-α and IL-6. In vitro, primary keratinocytes derived from IL1r^-/- mice were more resistant to UVB-triggered cell death compared with wild-type cells, and tumor necrosis factor-α release was completely blocked in the absence of IL-1R. These observations illustrate an unexpected yet prominent phenotype associated with the lack of IL-1R signaling in mice and support further investigation into the role of IL-1 ligands in epidermal repair and innate immune response after damaging UVB exposure.

Double-stranded RNA induces inflammation via the NF-κB pathway and inflammasome activation in the outer root sheath cells of hair follicles

Alopecia areata (AA), a chronic, relapsing, hair-loss disorder, is considered to be a T cell-mediated autoimmune disease. It affects approximately 1.7% of the population, but its precise pathogenesis remains to be elucidated. Despite the recent attention focused on the roles of inflammasomes in the pathogenesis of autoinflammatory diseases, little is known about inflammasome activation in AA. Thus, in this study, we investigated the pattern of NLRP3 inflammasome activation in the outer root sheath (ORS) cells of hair follicles. We found that interleukin (IL)-1β and caspase-1 expression was increased in hair follicle remnants and inflammatory cells of AA tissue specimens. After stimulation of ORS cells with the double-stranded (ds)RNA mimic polyinosinic:polycytidylic acid (poly[I:C]), the activation of caspase-1 and secretion of IL-1β were enhanced. Moreover, NLRP3 knockdown decreased this poly(I:C)-induced IL-1β production. Finally, we found that high-mobility group box 1 (HMGB1) translocated from the nucleus to the cytosol and was secreted into the extracellular space by inflammasome activation. Taken together, these findings suggest that ORS cells are important immunocompetent cells that induce NLRP3 inflammasomes. In addition, dsRNA-induced IL-1β and HMGB1 secretion from ORS cells may contribute to clarifying the pathogenesis and therapeutic targets of AA.

Extreme Phenotype of Epidermal Growth Factor Receptor Inhibitor-induced Destructive Folliculitis

Due to the increasingly widespread use and side effect profile of epidermal growth factor receptor inhibitors (EGFRIs), cutaneous side effects of these drugs are frequently encountered. The EGFR is expressed on keratinocytes and fibroblasts. Inhibition of EGFR can produce a range of cutaneous adverse effects, the most frequent being a characteristic acneiform skin eruption. As the latter is associated with good anti-neoplastic responses, the onset of EGFRI-induced acneiform skin eruption is typically viewed as a positive sign by patients and physicians. It can usually be treated well with standard acne drugs, but in rare cases, the skin eruption can be so severe that systemic therapy and/or interruption of EGFRI treatment are required. One of the severest forms of EGFRI-induced skin eruption occurring on the head and neck area resembles folliculitis decalvans. Here, we discuss the management of such a case seen in our department. In addition, we present an analysis of tumor necrosis factor-α, interleukin-1β (IL-1β), and IL-17A expression based on immunohistochemical stains and qPCR.

The association between three promoter polymorphisms of IL-1 and stroke: a meta-analysis

AIM

The association between Interleukin-1 (IL-1) gene polymorphism and stroke remains controversial. The present study was designed to clarify this relationship through a pooled analysis of the numerous epidemiological studies focusing on this association.

METHODS

Published data addressing the association between polymorphism of the IL-1 gene and stroke were selected from electronic databases. A total of 21 studies from 19 publications including 5280 stroke patients and 5699 controls were included in this meta-analysis which detect whether IL-1α-889C/T, IL-1β-511C/T and IL-1 RN polymorphism were associated with stroke susceptibility.

RESULT

The combined results of overall analysis revealed that there was a significant association between IL-1α-889C/T polymorphism and stroke (allele model: OR = 1.39, 95% CI = 1.14-1.68, P < 0.001; recessive model: OR = 1.56, 95% CI = 1.27-1.90, P < 0.001; dominant model: OR = 1.45, 95% CI = 1.13-1.87, P = 0.004; additive model: OR = 1.70, 95% CI = 1.37-2.10, P < 0.001). On a subgroup analysis by ethnicity of study population, significant association was found in Asians (allele model: OR = 1.25 95% CI = 1.12-1.39, P < 0.001; recessive model: OR = 1.36, 95% CI = 1.09-1.69, P = 0.007; dominant model: OR = 1.29, 95% CI = 1.12-1.48, P < 0.001; additive model: OR = 1.42, 95% CI = 1.13-1.80, P = 0.003). There are no associations of IL-1β-511C/T and IL-RN polymorphisms on stroke risk were identified.

CONCLUSION

In conclusion, our results suggested that IL-1α-889C/T polymorphism is associated with stroke risk, especially in Asians. However, no associations of IL-1β-511C/T and IL-RN polymorphisms on stroke risk in overall analysis or subgroup analysis.