Autoimmune skin diseases and the metabolic syndrome

Pemphigus and pemphigoid are associated with Alzheimer's disease in older adults: evidence from the US Nationwide inpatient sample 2016-2018

BACKGROUND

Pemphigus and pemphigoid are rare autoimmune skin disorders caused by autoantibodies against structural proteins and characterized by blistering of the skin and/or mucous membranes. Associations have been noted between skin diseases and Alzheimer's dementia (AD). Dementia is a neurological disorder of progressive cognitive impairment with increasing incidence among older adults. This study aimed to assess the potential associations between pemphigus, pemphigoid and AD in a large, nationally representative US cohort.

METHODS

All data of hospitalized patients aged 60 years or older were extracted from the US Nationwide Inpatient Sample (NIS) database 2016-2018. Patients with a history of head trauma, diagnosis of vascular dementia, history of cerebrovascular disease, or malformation of cerebral vessels were excluded. The study population was divided into those with and without pemphigus (cohort 1) and with and without pemphigoid (cohort 2).

RESULTS

Pemphigus was independently associated with a 69% increased risk of AD. Adults ≥80 years old with pemphigus were 72% more likely to develop AD than adults without pemphigus. Women with pemphigus were 78% more likely to develop AD than women without pemphigus. On the other hand, pemphigoid was independently associated with a 39% increased risk for AD and subjects ≥80 years with pemphigoid were 40% more likely to have AD than those without pemphigoid. Females with pemphigoid were 63% more likely to have AD than those without pemphigoid. Moreover, Hispanic older adults with pemphigus were 3-times more likely to have AD than those without pemphigoid.

CONCLUSIONS

Pemphigus and pemphigoid were both independently associated with AD in older adults, especially among females and octogenarians. Further studies addressing the etiology and mechanisms underlying these associations are highly warranted.

LEP and LEPR are possibly a double-edged sword for wound healing

Wound healing is a complex and error-prone process. Wound healing in adults often leads to the formation of scars, a type of fibrotic tissue that lacks skin appendages. Hypertrophic scars and keloids can also form when the wound-healing process goes wrong. Leptin (Lep) and leptin receptors (LepRs) have recently been shown to affect multiple stages of wound healing. This effect, however, is paradoxical for scarless wound healing. On the one hand, Lep exerts pro-inflammatory and profibrotic effects; on the other hand, Lep can regulate hair follicle growth. This paper summarises the role of Lep and LepRs on cells in different stages of wound healing, briefly introduces the process of wound healing and Lep and LepRs, and examines the possibility of promoting scarless wound healing through spatiotemporal, systemic, and local regulation of Lep levels and the binding of Lep and LepRs.

Study of leptin gene polymorphism and leptin serum level in alopecia areata patients

Leptin, produced by adipocytes, regulates metabolism, hunger, and immune response. The inflammatory role of leptin has been linked to autoimmune diseases. To assess leptin gene polymorphism and serum level in alopecia areata and their relation to metabolic syndrome (MS). This case-control study was conducted on 100 alopecia areata patients (50 with MS and 50 without MS) and 50 age- and gender-matched controls. Leptin gene polymorphism and serum level were assessed through the use of PCR and ELISA, respectively. GG genotype was the highest in AA with MS (54%), lower in AA without MS (42%), and the lowest in controls (20%). G allele was more expressed in cases, than in controls (P < .001). The serum leptin level was the highest in AA with MS, lower in AA without MS, and the lowest in controls (P value = 0.001). Leptin level was significantly higher in GG polymorphism than AG and AA. Leptin gene polymorphism (GG genotype) and serum level appear to play a significant role in AA. Absent difference regarding leptin gene polymorphism and MS might indicate a separate inflammatory role of leptin or the future risk of MS development in AA patients.

Relationship between acanthosis nigricans, acrochordon and metabolic syndrome in patients with lichen planus

AIM

In the literature, there are no data examining the association with lichen planus with acanthosis nigricans and acrochordon, which are skin findings of metabolic syndrome (MS).

MATERIALS

A total of 108 lichen planus (LP) patients, age and sex-matched 109 controls, 217 patients in total were prospectively included in the study.

RESULTS

Metabolic Syndrome was found in 55 (50.9%) of 108 patients with lichen planus and 36.7% in the control group. The frequency of MS in the lichen planus group was found to be significantly higher than that in the control group (P = .03). The incidence of acanthosis nigricans (AN) was statistically higher in the LP group (P = .009). In addition, while 38 of 47 AN patients in the LP group had MS, 17 of 61 patients without AN had MS, and the presence of MS was found significantly higher in LP patients with AN (p˂0.001). The incidence of acrochordon was statistically higher in the LP group (P = .03). In addition, while 43 of 62 patients with acrochordon in the LP group had MS, 12 of 46 patients without acrochordon had MS, and the presence of MS was found significantly higher in patients with LP with acrochordon (P ˂ .001).

CONCLUSION

In our study, it was found that skin findings such as AN and acrochordon increased in patients with lichen planus. This increase was also observed in lichen planus patients with metabolic syndrome. Therefore, the association of acanthosis nigricans and acrochordon may be a predictive of metabolic syndrome in patients with lichen planus admitted to the dermatology outpatient clinic.

Increased risk of subclinical atherosclerosis and metabolic syndrome in patients with vitiligo: a real association or a coincidence?

Inflammatory and autoimmune skin diseases such as vitiligo may be associated with systemic disorders, including endocrine and cardiovascular diseases, due to some similarities in the pathogenesis. It was aimed to evaluate metabolic syndrome and subclinical atherosclerosis in patients with vitiligo. Seventy patients with nonsegmental vitiligo and 70 age-matched and gender-matched healthy controls participated in the study. These participants were investigated for metabolic syndrome criteria. The mean intima-media thickness of the common carotid artery (MIMT-CCA) of the subjects was measured for assessment of subclinical atherosclerosis. Metabolic syndrome and subclinical atherosclerosis were significantly more frequent in vitiligo patients compared with the controls (P = .006 and P = .002, respectively). In addition, metabolic syndrome and subclinical atherosclerosis had positive, significant correlations with the severity and duration of vitiligo (P = .031 and r = .482; P < .01, respectively). Our study suggested that patients with vitiligo, especially those with more chronic and severe disease or concomitant metabolic syndrome, are at a higher risk of developing cardiovascular diseases. Therefore, early diagnosis and treatment of metabolic syndrome in patients with vitiligo to prevent cardiovascular complications were recommended.

The Important Role of Leptin in Modulating the Risk of Dermatological Diseases

It is an indisputable fact that obesity is associated with a series of health problems. One important hallmark of obesity is excessive accumulation of lipids in the adipocyte, especially triglyceride (TG). Currently, the adipocyte has been considered not only as a huge repository of excess energy in the form of fat but also as an important source of multiple hormones and cytokines called adipokines. In obesity, the adipocyte is dysfunctional with excessive production and secretion of pro-inflammatory adipokines, such as tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), and leptin. On the other hand, accumulating evidence has shown that leptin plays a vital role in stimulating angiogenesis, controlling lipid metabolism, and modulating the production of pro-inflammatory cytokines. Furthermore, the various activities of leptin are related to the wide distribution of leptin receptors. Notably, it has been reported that enhanced leptin levels and dysfunction of the leptin signaling pathway can influence diverse skin diseases. Recently, several studies revealed the roles of leptin in wound healing, the hair cycle, and the pathogenic development of skin diseases, such as psoriasis, lupus erythematosus, and dermatological cancers. However, the exact mechanisms of leptin in modulating the dermatological diseases are still under investigation. Therefore, in the present review, we summarized the regulatory roles of leptin in the pathological progression of diverse diseases of skin and skin appendages. Furthermore, we also provided evidence to elucidate the complicated relationship between leptin and different dermatological diseases, such as systemic lupus erythematosus (SLE), psoriasis, hidradenitis suppurativa, and some skin tumors.

Leptin in skin disease modulation

In obesity, adipocytes are dysfunctional with excessive production and secretion of pro-inflammatory hormones and cytokines, ie, adipokines, such as tumor necrosis factor α (TNF-α), interleukin 6 (IL-6) and leptin. Accumulating evidence has shown that leptin possesses pleiotropic functions including stimulation of angiogenesis and production of pro-inflammatory cytokines. Furthermore, various leptin associated activities involve a wide distribution of leptin receptors. For example, increased serum leptin was associated with tissue receptor resistance in metabolic syndrome. Although increased serum leptin, receptor and signaling impairment are involved in wound healing, hair cycle and the pathogenesis of many skin diseases such as psoriasis and lupus erythematosus as well as skin cancer, its exact role remains unclear. In the present article, we discuss the biochemistry of leptin action and its potential role in the pathophysiology of diverse skin diseases.

The role of leptin in selected skin diseases

Leptin is an adipokine, adipocyte-derived compound, which acts both as a hormone and cytokine. It is mainly synthesized by adipocytes of white adipose tissue. Leptin possesses pleiotropic functions including, among others, stimulation of angiogenesis and production of proinflammatory cytokines. The various types of leptin activity are related to the wide distribution of leptin receptors. This adipokine acts by activating intracellular signaling cascades such as JAKs (Janus kinases), STATs (signal transducers and activators of transcription), and others.In a course of obesity, an increased serum level of leptin coexists with tissue receptor resistance. It has been reported that enhanced leptin levels, leptin receptor impairment, and dysfunction of leptin signaling can influence skin and hair. The previous studies revealed the role of leptin in wound healing, hair cycle, and pathogenesis of skin diseases like psoriasis, lupus erythematosus, and skin cancers. However, the exact mechanism of leptin's impact on the skin is still under investigation. Herein, we present the current knowledge concerning the role of leptin in psoriasis and selected skin diseases.

IFN-γ enhances cell-mediated cytotoxicity against keratinocytes via JAK2/STAT1 in lichen planus

Lichen planus (LP) is a chronic debilitating inflammatory disease of unknown etiology affecting the skin, nails, and mucosa with no current FDA-approved treatments. It is histologically characterized by dense infiltration of T cells and epidermal keratinocyte apoptosis. Using global transcriptomic profiling of patient skin samples, we demonstrate that LP is characterized by a type II interferon (IFN) inflammatory response. The type II IFN, IFN-γ, is demonstrated to prime keratinocytes and increase their susceptibility to CD8⁺ T cell-mediated cytotoxic responses through MHC class I induction in a coculture model. We show that this process is dependent on Janus kinase 2 (JAK2) and signal transducer and activator of transcription 1 (STAT1), but not JAK1 or STAT2 signaling. Last, using drug prediction algorithms, we identify JAK inhibitors as promising therapeutic agents in LP and demonstrate that the JAK1/2 inhibitor baricitinib fully protects keratinocytes against cell-mediated cytotoxic responses in vitro. In summary, this work elucidates the role and mechanisms of IFN-γ in LP pathogenesis and provides evidence for the therapeutic use of JAK inhibitors to limit cell-mediated cytotoxicity in patients with LP.

Metabolic syndrome and inflammatory skin conditions

PURPOSE OF REVIEW

Several chronic inflammatory skin disorders have been linked to metabolic syndrome (MetS) and an increased risk for cardiovascular disease. In this review, we will summarize the recent evidence on the association between psoriasis, hidradenitis suppurativa (HS), and atopic dermatitis (AD) and metabolic syndrome with careful attention to this association among the pediatric population.

RECENT FINDINGS

Historically, psoriasis has exhibited the most robust association with MetS in the literature. Recent studies show that the prevalence of MetS appears to be higher among patients with HS and can be associated with MetS even in mild disease. A relationship between AD and MetS is still under debate, but research has shown a clear link between pediatric AD and being overweight or obese.

SUMMARY

There are no current consensus guidelines for metabolic syndrome in the pediatric population, and its clinical implications in children are still unclear. Nevertheless, providers should be aware of the shared underlying inflammatory state and link between several cutaneous disorders and metabolic syndrome. Early diagnosis and proper disease management of these at risk populations has the potential to assist in disease control and mitigate future cardiovascular disease.