Leptin induces secretion of pro-inflammatory cytokines by human keratinocytesin vitro- a possible reason for increased severity of psoriasis in patients with a high body mass index

Leptin induces altered differentiation of keratinocytes by inducing insulin resistance: implications for metabolic syndrome-induced resistance of psoriatic therapy

Background: Psoriatic patients tend to develop metabolic syndrome (MS). MS accelerates psoriasis, but the exact molecular mechanisms are poorly understood.Objectives: We aim to investigate the impact of leptin on keratinocyte insulin sensitivity and explore its underlying molecular mechanism, which might play a role in the pathogenesis of this disease.Methods: ELISA and immunohistochemistry were applied respectively to detect the level of leptin in serum and in lesion of psoriatic patients with and without MS. The HaCaT cell line was cultured and western-blot assay was performed to assess the change of insulin sensibility. q-PCR and western-blot assay were applied to detect the SOCS3 expressions. Knockdown of SOCS3 were generated in HaCaT cell line by siRNA. Leptin and insulin were treated for 6 days and K10 expression was evaluated by western-blot assay.Results: Patients with MS had higher level of leptin in serum and lesions than their counterparts without MS. Serum levels of leptin was negatively correlated to PASI decline index in psoriatic patients. Long-term treatment of leptin induced insulin resistance in HaCaT cell line, as indicated by elevated expression of p-IRS-1 (ser636) and lower p-PKB (ser473). Leptin treatment up-regulated the mRNA and protein expression of SOCS3. Knockdown of SOCS3 blocked the effect of leptin-induced insulin resistance. Leptin treatment attenuated insulin-elicited K10 expression.Conclusions: Leptin induces insulin resistance by upregulating SOCS3 and give rise to differentiation disorder of keratinocyte. Insulin resistance may serve as a target for anti-psoriatic therapies.

The Intersection of the Pathogenic Processes Underlying Psoriasis and the Comorbid Condition of Obesity

In the past decade, our understanding of psoriasis pathogenesis has made significant steps forward, leading to the development of multiple game-changing therapies. While psoriasis primarily affects the skin, it is increasingly recognized as a systemic disease that can have effects beyond the skin. Obesity is associated with more severe forms of psoriasis and can potentially worsen the systemic inflammation and metabolic dysfunction seen in psoriatic patients. The exact mechanisms underlying the link between these two conditions are not fully understood, but it is believed that chronic inflammation and immune dysregulation play a role. In this review, we examine the existing body of knowledge regarding the intersection of pathogenic processes responsible for psoriasis and obesity. The ability of biological therapies to reduce systemic and obesity-related inflammation in patients with psoriasis will be also discussed.

A quantitative systems pharmacology model for certolizumab pegol treatment in moderate-to-severe psoriasis

Background

Psoriasis is a chronic immune-mediated inflammatory systemic disease with skin manifestations characterized by erythematous, scaly, itchy and/or painful plaques resulting from hyperproliferation of keratinocytes. Certolizumab pegol [CZP], a PEGylated antigen binding fragment of a humanized monoclonal antibody against TNF-alpha, is approved for the treatment of moderate-to-severe plaque psoriasis. Patients with psoriasis present clinical and molecular variability, affecting response to treatment. Herein, we utilized an in silico approach to model the effects of CZP in a virtual population (vPop) with moderate-to-severe psoriasis. Our proof-of-concept study aims to assess the performance of our model in generating a vPop and defining CZP response variability based on patient profiles.

Methods

We built a quantitative systems pharmacology (QSP) model of a clinical trial-like vPop with moderate-to-severe psoriasis treated with two dosing schemes of CZP (200 mg and 400 mg, both every two weeks for 16 weeks, starting with a loading dose of CZP 400 mg at weeks 0, 2, and 4). We applied different modelling approaches: (i) an algorithm to generate vPop according to reference population values and comorbidity frequencies in real-world populations; (ii) physiologically based pharmacokinetic (PBPK) models of CZP dosing schemes in each virtual patient; and (iii) systems biology-based models of the mechanism of action (MoA) of the drug.

Results

The combination of our different modelling approaches yielded a vPop distribution and a PBPK model that aligned with existing literature. Our systems biology and QSP models reproduced known biological and clinical activity, presenting outcomes correlating with clinical efficacy measures. We identified distinct clusters of virtual patients based on their psoriasis-related protein predicted activity when treated with CZP, which could help unravel differences in drug efficacy in diverse subpopulations. Moreover, our models revealed clusters of MoA solutions irrespective of the dosing regimen employed.

Conclusion

Our study provided patient specific QSP models that reproduced clinical and molecular efficacy features, supporting the use of computational methods as modelling strategy to explore drug response variability. This might shed light on the differences in drug efficacy in diverse subpopulations, especially useful in complex diseases such as psoriasis, through the generation of mechanistically based hypotheses.

Psoriatic disease and non-alcoholic fatty liver disease shared pathogenesis review

Psoriatic disease (PD) and non-alcoholic fatty liver disease (NAFLD) potentially share disease pathways given the numerous inflammatory pathways involved in both diseases and a higher prevalence of NAFLD in PD patients.  Metabolic syndrome and obesity are a key link between the two diseases, but even when controlling for this, associations between both diseases are still seen. Therapeutics that impact metabolic or inflammatory pathways may be impactful in both PD and NAFLD. In this review, we describe common inflammatory pathways contributing to both PD and NAFLD and critically review the potential impact of treatments for and on both diseases.

Pathogenic Role of Adipose Tissue-Derived Mesenchymal Stem Cells in Obesity and Obesity-Related Inflammatory Diseases

Adipose tissue-derived mesenchymal stem cells (ASCs) are adult stem cells, endowed with self-renewal, multipotent capacities, and immunomodulatory properties, as mesenchymal stem cells (MSCs) from other origins. However, in a pathological context, ASCs like MSCs can exhibit pro-inflammatory properties and attract inflammatory immune cells at their neighborhood. Subsequently, this creates an inflammatory microenvironment leading to ASCs' or MSCs' dysfunctions. One such example is given by obesity where adipogenesis is impaired and insulin resistance is initiated. These opposite properties have led to the classification of MSCs into two categories defined as pro-inflammatory ASC1 or anti-inflammatory ASC2, in which plasticity depends on the micro-environmental stimuli. The aim of this review is to (i) highlight the pathogenic role of ASCs during obesity and obesity-related inflammatory diseases, such as rheumatoid arthritis, multiple sclerosis, psoriasis, inflammatory bowel disease, and cancer; and (ii) describe some of the mechanisms leading to ASCs dysfunctions. Thus, the role of soluble factors, adhesion molecules; TLRs, Th17, and Th22 cells; γδ T cells; and immune checkpoint overexpression will be addressed.

Adiponectin, Leptin and Resistin in Patients with Psoriasis

Psoriasis is a common chronic, inflammatory skin disease characterised by keratinocyte hyperproliferation, parakeratosis, and T-cell infiltration. Adipose tissue has an endocrine function, producing an abundance of cytokines and adipokines. It has also been described that the major adipokines, leptin, resistin, and adiponectin, may be involved in the pathogenesis of psoriasis. The aim of the study was to examine the plasma levels of adiponectin, leptin, and resistin in patients with psoriasis and their correlations with disease activity parameters: Psoriasis Activity Severity Index (PASI), Dermatology Life Quality Index (DLQI), and Body Surface Area (BSA) index, as well as selected clinical parameters. The study included 53 patients with the plaque type and 31 healthy controls. The plasma concentrations of adiponectin were significantly lower in patients with psoriasis (p < 0.001) than in the control group. The plasma concentrations of leptin were higher in patients with psoriasis, however, due to high intra-patient variability of leptin plasma concentrations these differences did not reach statistical significance (p = 0.2). The plasma concentrations of resistin were significantly increased in patients with psoriasis compared to healthy controls (p = 0.02). There were no statistically significant correlations between adiponectin and leptin plasma concentrations and values of PASI, DLQI, and BSA. The resistin plasma concentrations correlated significantly with DLQI values. Additionally, we examined the correlations between adiponectin, leptin, and resistin plasma concentrations, and selected clinical parameters. Plasma concentrations of adiponectin correlated significantly with CRP values and ALT values. Leptin plasma concentrations correlated significantly with creatinine values. The results of our study confirm the role of adiponectin, leptin, and resistin in the pathogenesis of psoriasis.

Mast cells as important regulators in the development of psoriasis

Psoriasis is a chronic inflammatory immune skin disease mediated by genetic and environmental factors. As a bridge between innate and adaptive immunity, mast cells are involved in the initiation, development, and maintenance of psoriasis by interactions and communication with a variety of cells. The current review describes interactions of mast cells with T cells, Tregs, keratinocytes, adipocytes, and sensory neurons in psoriasis to emphasize the important role of mast cell-centered cell networks in psoriasis.

Adipocyte-Derived CTRP3 Exhibits Anti-Inflammatory Effects via LAMP1-STAT3 Axis in Psoriasis

Psoriasis is a systemic disease that is associated with metabolic disorders, which may contribute to abnormal adipokine levels. However, the underlying mechanism is largely unknown. Here, we investigated the role of the adipokine CTRP3 in the pathogenesis of psoriasis and comorbidities. The circulating CTRP3 level in patients with psoriasis was significantly lower than that in healthy controls and negatively correlated with metabolic risk factors. Rescuing CTRP3 levels with the GLP-1 receptor agonist exendin-4 in diet-induced obese mice could alleviate its more severe psoriatic symptoms in an imiquimod-induced mouse model. Topical application of CTRP3 also exerted a protective effect on imiquimod-induced normal diet mice. Moreover, CTRP3 could directly inhibit the inflammatory responses of psoriatic keratinocytes by blocking phosphorylation of signal transducer and activator of transcription 3 via LAMP1 in vitro. We identified the critical psoriatic cytokines, including IL-17A and TNF-α, that impaired adipocyte differentiation and sufficient CTRP3 secretion. In sum, our study reveals that adipocyte dysfunction and low level of CTRP3 caused by IL-17A exacerbates psoriasis progression and related metabolic syndrome, implying a mechanism underlying the vicious cycle between psoriasis and metabolic disorders. Pharmacological agents that improve CTRP3 level in obese patients with psoriasis may be considered as a potential strategy for psoriasis treatment.

Obesity and Dyslipidemia Synergistically Exacerbate Psoriatic Skin Inflammation

Patients with psoriasis are frequently complicated with metabolic syndrome; however, it is not fully understood how obesity and dyslipidemia contribute to the pathogenesis of psoriasis. To investigate the mechanisms by which obesity and dyslipidemia exacerbate psoriasis using murine models and neonatal human epidermal keratinocytes (NHEKs), we used wild-type and Apoe-deficient dyslipidemic mice, and administered a high-fat diet for 10 weeks to induce obesity. Imiquimod was applied to the ear for 5 days to induce psoriatic dermatitis. To examine the innate immune responses of NHEKs, we cultured and stimulated NHEKs using IL-17A, TNF-α, palmitic acid, and leptin. We found that obesity and dyslipidemia synergistically aggravated psoriatic dermatitis associated with increased gene expression of pro-inflammatory cytokines and chemokines. Treatment of NHEKs with palmitic acid and leptin amplified pro-inflammatory responses in combination with TNF-α and IL-17A. Additionally, pretreatment with palmitic acid and leptin enhanced IL-17A-mediated c-Jun N-terminal kinase phosphorylation. These results revealed that obesity and dyslipidemia synergistically exacerbate psoriatic skin inflammation, and that metabolic-disorder-associated inflammatory factors, palmitic acid, and leptin augment the activation of epidermal keratinocytes. Our results emphasize that management of concomitant metabolic disorders is essential for preventing disease exacerbation in patients with psoriasis.

Are irisin levels associated with inflammation and insulin resistance in patients with moderate-to-severe psoriasis?

BACKGROUND

A wide variety of effects of irisin, as a myokine and adipokine, have been reported. Although there are some clues about its role in the modulation of immune response in the pathogenesis of immune-mediated diseases such as psoriasis, it has not yet been clearly elucidated. The aim of the present study is to investigate the relationship of irisin levels with inflammation and insulin resistance in patients with psoriasis.

METHODS

This study was conducted in patients with moderate-to-severe psoriasis and healthy subjects who were admitted to Haseki Training and Research Hospital. In addition to routine laboratory analyses, hs-CRP, insulin, irisin, adiponectin, and leptin levels were measured. The association between irisin levels and study variables was assessed using univariate and multivariate analyses.

RESULTS

A total of 42 non-diabetic patients with moderate-to-severe psoriasis and 43 healthy subjects were enrolled. The mean irisin, waist circumference, insulin, insulin resistance, and hs-CRP, and frequency of metabolic syndrome were significantly higher in psoriasis patients than healthy controls. Psoriasis and control groups were similar in terms of adiponectin, leptin, and Body Mass Index levels. Also, hs-CRP levels were positively and strongly correlated with irisin, adiponectin, and leptin levels. The median irisin level was 2.15 µg/mL. In the binary logistic regression analysis, CRP level (OR=1.14, 95% CI 1.005-1.29, P=0.042) and a BMI>30 kg/m2 (OR=5.9, 95% CI 1.02-34.4, P=0.048) were independent predictors of a higher irisin level.

CONCLUSIONS

This study demonstrates that serum irisin levels are higher in patients with moderate-to-severe psoriasis than in healthy subjects. Irisin seems to be associated with inflammation, as measured by hs-CRP. More comprehensive studies are needed to clarify the effect of irisin, on immune-modulate response in patients with psoriasis.

An Interleukin-4 and Interleukin-13 Induced Atopic Dermatitis Human Skin Equivalent Model by a Skin-On-A-Chip

Currently, the mechanism of progression of atopic dermatitis (AD) is not well understood because there is no physiologically appropriate disease model in terms of disease complexity and multifactoriality. Type 2 inflammation, mediated by interleukin (IL)-4 and IL-13, plays an important role in AD. In this study, full-thickness human skin equivalents consisting of human-derived cells were fabricated from pumpless microfluidic chips and stimulated with IL-4 and IL-13. The morphological properties, gene expression, cytokine secretion and protein expression of the stimulated human skin equivalent (HSE) epidermis were investigated. The results showed epidermal and spongy formations similar to those observed in lesions in AD, and decreased expression of barrier-related filaggrin, loricrin and involucrin genes and proteins induced by IL-4Rα signaling. In addition, we induced the expression of carbonic anhydrase II (CAII), a gene specifically expressed in the epidermis of patients with AD. Thus, AD human skin equivalents can be used to mimic the key pathological features of atopic dermatitis, overcoming the limitations of existing studies that rely solely on mouse models and have been unable to translate their effects to humans. Our results will be useful for future research on the development of therapeutic agents for atopic dermatitis.

Compositional Features of Distinct Microbiota Base on Serum Extracellular Vesicle Metagenomics Analysis in Moderate to Severe Psoriasis Patients

The bacterial microbiota in the skin and intestine of patients with psoriasis were different compared with that of healthy individuals. However, the presence of a distinct blood microbiome in patients with psoriasis is yet to be investigated. In this study, we investigated the differences in bacterial communities in plasma-derived extracellular vesicles (EVs) between patients with moderate to severe psoriasis (PSOs) and healthy controls (HCs). The plasma EVs from the PSO (PASI > 10) (n = 20) and HC (n = 8) groups were obtained via a series of centrifugations, and patterns were examined and confirmed using transmission electron microscopy (TEM) and EV-specific markers. The taxonomic composition of the microbiota was determined by using full-length 16S ribosomal RNA gene sequencing. The PSO group had lower bacterial diversity and richness compared with HC group. Principal coordinate analysis (PCoA)-based clustering was used to assess diversity and validated dysbiosis for both groups. Differences at the level of amplicon sequence variant (ASV) were observed, suggesting alterations in specific ASVs according to health conditions. The HC group had higher levels of the phylum Firmicutes and Fusobacteria than in the PSO group. The order Lactobacillales, family Brucellaceae, genera Streptococcus, and species Kingella oralis and Aquabacterium parvum were highly abundant in the HC group compared with the PSO group. Conversely, the order Bacillales and the genera Staphylococcus and Sphihgomonas, as well as Ralstonia insidiosa, were more abundant in the PSO group. We further predicted the microbiota functional capacities, which revealed significant differences between the PSO and HC groups. In addition to previous studies on microbiome changes in the skin and gut, we demonstrated compositional differences in the microbe-derived EVs in the plasma of PSO patients. Plasma EVs could be an indicator for assessing the composition of the microbiome of PSO patients.

Insights into interplay of immunopathophysiological events and molecular mechanistic cascades in psoriasis and its associated comorbidities

Psoriasis is an inflammatory skin disease with complex pathogenesis and multiple etiological factors. Besides the essential role of autoreactive T cells and constellation of cytokines, the discovery of IL-23/Th17 axis as a central signaling pathway has unraveled the mechanism of accelerated inflammation in psoriasis. This has provided insights into psoriasis pathogenesis and revolutionized the development of effective biological therapies. Moreover, genome-wide association studies have identified several candidate genes and susceptibility loci associated with this disease. Although involvement of cellular innate and adaptive immune responses and dysregulation of immune cells have been implicated in psoriasis initiation and maintenance, there is still a lack of unifying mechanism for understanding the pathogenesis of this disease. Emerging evidence suggests that psoriasis is a high-mortality disease with additional burden of comorbidities, which adversely affects the treatment response and overall quality of life of patients. Furthermore, changing trends of psoriasis-associated comorbidities and shared patterns of genetic susceptibility, risk factors and pathophysiological mechanisms manifest psoriasis as a multifactorial systemic disease. This review highlights the recent progress in understanding the crucial role of different immune cells, proinflammatory cytokines and microRNAs in psoriasis pathogenesis. In addition, we comprehensively discuss the involvement of various complex signaling pathways and their interplay with immune cell markers to comprehend the underlying pathophysiological mechanism, which may lead to exploration of new therapeutic targets and development of novel treatment strategies to reduce the disastrous nature of psoriasis and associated comorbidities.

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.

The influence of body weight of patients with chronic plaque psoriasis on biological treatment response

Psoriasis is a chronic inflammatory disease of the skin. The new era of biological therapies initiated a shift in the definition of the disease therapeutic success, however, recent reports in the literature draw attention to the treatment-induced weight gain in psoriatic patients. Therefore, it is worth considering the body mass index influence on the biological treatment of chronic plaque psoriasis, seeing that it has manifold associations with the disease and may play an important role in clinical practice management.

Comorbidities associated with psoriatic arthritis: Review and update

Psoriatic arthritis is an inflammatory arthropathy frequently associated with psoriasis and several other comorbidities. The goal of this review is to summarize the available evidence on the epidemiology, clinical implications, pathological mechanisms proposed, and screening and management recommendations for the comorbidities related with PsA. Reported comorbidities include cardiovascular disease, metabolic syndrome, obesity, diabetes mellitus, dyslipidemia, inflammatory bowel disease, fatty liver disease, uveitis, kidney disease, infections, osteoporosis, depression, central sensitization syndrome, and gout. Given that these comorbidities may affect both clinical outcomes and the management for these patients, their recognition and monitoring by all health-care providers caring for patients with psoriatic arthritis is of utmost importance.

Epicardial Adipose Tissue Inflammation Can Cause the Distinctive Pattern of Cardiovascular Disorders Seen in Psoriasis

Psoriasis is a systemic inflammatory disorder that can target adipose tissue; the resulting adipocyte dysfunction is manifest clinically as the metabolic syndrome, which is present in ≈20%-40% of patients. Epicardial adipose tissue inflammation is likely responsible for a distinctive pattern of cardiovascular disorders consisting of 1) accelerated coronary atherosclerosis leading to myocardial infarction, 2) atrial myopathy leading to atrial fibrillation and thromboembolic stroke, and 3) ventricular myopathy leading to heart failure with a preserved ejection fraction. If cardiovascular inflammation drives these risks, then treatments that focus on blood pressure, lipids, and glucose will not ameliorate the burden of cardiovascular disease in patients with psoriasis, especially in those who are young and have severe inflammation. Instead, interventions that alleviate systemic and adipose tissue inflammation may not only minimize the risks of atrial fibrillation and heart failure but may also have favorable effects on the severity of psoriasis. Viewed from this perspective, the known link between psoriasis and cardiovascular disease is not related to the influence of the individual diagnostic components of the metabolic syndrome.

New insights into different adipokines in linking the pathophysiology of obesity and psoriasis

Psoriasis is a chronic, systemic, hyper-proliferative immune-mediated inflammatory skin disease. The results of epidemiological investigations have shown that psoriasis affects around 2% of the general population worldwide, and the total number of psoriasis patients is more than 6 million in China. Apart from the skin manifestations, psoriasis has been verified to associate with several metabolic comorbidities, such as insulin resistance, diabetes and obesity. However, the underlying mechanism is still not elucidated. Adipocytes, considered as the active endocrine cells, are dysfunctional in obesity which displays increased synthesis and secretion of adipokines with other modified metabolic properties. Currently, growing evidence has pointed to the central role of adipokines in adipose tissue and the immune system, providing new insights into the effect of adipokines in linking the pathophysiology of obesity and psoriasis. In this review, we summarize the current understanding of the pathological role of adipokines and the potential mechanisms whereby different adipokines link obesity and psoriasis. Furthermore, we also provide evidence which identifies a potential therapeutic target aiming at adipokines for the management of these two diseases.

NAFLD and Extra-Hepatic Comorbidities: Current Evidence on a Multi-Organ Metabolic Syndrome

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease worldwide and its incidence is definitely increasing. NAFLD is a metabolic disease with extensive multi-organ involvement, whose extra-hepatic manifestations include type 2 diabetes mellitus, cardiovascular disease, obstructive sleep apnea, chronic kidney disease, osteoporosis, and polycystic ovarian syndrome. Recently, further evidence has given attention to pathological correlations not strictly related to metabolic disease, also incorporating in this broad spectrum of systemic involvement hypothyroidism, psoriasis, male sexual dysfunction, periodontitis, and urolithiasis. The most common cause of mortality in NAFLD is represented by cardiovascular disease, followed by liver-related complications. Therefore, clinicians should learn to screen and initiate treatment for these extra-hepatic manifestations, in order to provide appropriate multidisciplinary assessments and rigorous surveillance. This review evaluates the current evidence regarding extra-hepatic associations of NAFLD, focusing on the pathogenic hypothesis and the clinical implications.

An Update on the Role of Adipose Tissues in Psoriasis

Psoriasis is a common chronic inflammatory skin disease that is increasingly being recognized as a disease that not only affects the skin but also has multi-systemic implications. The pathophysiological link between psoriasis and obesity is becoming increasingly elucidated by recent studies. The cross-talk between adipocytes and the immune system via various mediators such as adipokines could explain how obesity contributes to psoriasis. The effects of obesity on adipocytes include upregulation of pro-inflammatory adipokines such as leptin and resistin, downregulation of anti-inflammatory adipokine, and also the stimulation of pro-inflammatory cytokine production by macrophages. This article provides an update on the role of adipose tissues in psoriasis.

Alterations in IL-4, IL-10 and IFN-γ levels synergistically decrease lipid content and protein expression of FAS and mature SREBP-1 in human sebocytes

When anti-acne alternatives from dietary and plant sources are ingested, systemic alterations of interleukin (IL)-4, IL-10, IL-12 and interferon (IFN)-γ, individually or simultaneously, are induced at a 0.1-10.0-fold (×) range of normal physiological concentrations (1×). However, little is known about the effects of these cytokines on excess sebum, a pathophysiological factor of acne development. In this study, human sebocytes were treated with 0.1-10.0× of IL-4, IL-10, IL-12 and IFN-γ for 3 or 5 days to elucidate the effects on lipid content. Treatment with individual cytokines decreased the lipid content at specific concentrations rather than in a concentration-dependent manner. Specifically, 5.0× of IL-4, 5.0× of IFN-γ (5.0IFN), and 0.5×, 5.0× and 10.0× of IL-10 for 3 days, and 0.5× of IL-4 (0.5IL4) for 5 days decreased lipid content to 87.6-93.0% of the control. Treatment with other concentrations of IL-4, IL-10 and IFN-γ, and 0.1-10.0× of IL-12 did not alter lipid content. Combined treatment with 0.5IL4, 5.0IFN and 0.5× of IL-10 for 3 or 5 days decreased the lipid content more than each individual treatment. However, this effect was more evident after 3 days, in parallel with decreased levels of triglycerides, cholesterol esters and free fatty acids, the major lipid compositions of sebocytes, and decreased protein expression of fatty acid synthase (FAS) and mature sterol response element-binding protein-1 (SREBP-1), the lipogenesis-related factors, without altered cell proliferation. We demonstrated that suppressed IL-4 and IL-10 with enhanced IFN-γ synergistically decreased lipid content and protein expression of FAS and mature SREBP-1 in human sebocytes.

Psoriasis in obesity: comparison of serum levels of leptin and adiponectin in obese subjects - cases and controls

BACKGROUND

Psoriasis and obesity are somewhat related to a low-grade systemic inflammatory response.

OBJECTIVES

To determine leptin and adiponectin levels in psoriasis patients compared to control patients matched for weight.

METHODS

A case-control study was performed, evaluating 113 psoriasis patients and 41 controls with other dermatologic diseases.

RESULTS

The prevalence of obesity was 33% in cases and 21.9% in controls. All evaluated comorbidities were more prevalent among cases. When stratified by weight, the comorbidities were more frequent in overweight patients. We found no correlation between being overweight (p=0.25), leptin (p=0.18) or adiponectin (p=0.762) levels and psoriasis severity. When overweight cases and controls were compared, we found differences in the adiponectin values (p= 0.04). The overweight cases had lower adiponectin levels than the overweight controls. We found no differences in the leptin dosage between cases and controls. The overweight cases had higher leptin values than the normal weight cases (p<0.001).

STUDY LIMITATIONS

Several patients used systemic anti-inflammatory medication.

CONCLUSIONS

The prevalence of obesity among psoriasis cases (33%) was higher than in the general population (17.4%). We did not find any correlation between severity of psoriasis and inflammatory cytokines and the condition of being overweight. The overweight cases had lower values of adiponectin than the overweight controls. It seems, therefore, that there is a relationship between adiponectin and psoriasis, but this relationship depends on the presence of obesity.

The role of adipokines in systemic sclerosis: a missing link?

Systemic sclerosis is a multiorgan autoimmune disease characterized by vasculopathy and tissue fibrosis of unknown etiology. Recently, adipokines (cell signaling proteins secreted by adipose tissue) have attracted much attention as a cytokine family contributing to the various pathological processes of systemic sclerosis. Adipokines, such as leptin, adiponectin, resistin, adipsin, visfatin or chemerin are a heterogenic group of molecules. Adiponectin exhibits anti-fibrotic features and affects inflammatory reactions. Leptin promotes fibrosis and inflammation. Resistin was linked to vascular involvement in systemic sclerosis. Visfatin was associated with regression of skin lesions in late-stage systemic sclerosis. Chemerin appears as a marker of increased risk of impaired renal function and development of skin sclerosis in the early stage of systemic sclerosis. Vaspin was indicated to have a protective role in digital ulcers development. Novel adipokines-adipsin, apelin, omentin and CTRP-3-are emerging as molecules potentially involved in SSc pathogenesis. Serum adipokine levels may be used as predictive and diagnostic factors in systemic sclerosis. However, further investigations are required to establish firm correlations between distinct adipokines and systemic sclerosis.

Bidirectional Association Between Psoriasis and Obesity: Benefits and Risks

Psoriasis is a chronic, immune-mediated inflammatory skin disease that is associated with several comorbidities such as obesity. This study was designed to estimate the possibility of utilizing psoriasin, nestin, keratin-16 (Krt16), and interleukin-21 (IL-21) as biochemical markers of psoriasis, to correlate these candidate psoriatic markers with biomarkers of obesity [body mass index (BMI), leptin, and resistin], and to elucidate the bidirectional association between obesity and psoriasis. Blood samples were collected from all participants (n = 108) who were classified according to their BMI into 4 groups: healthy control, obese, psoriatic, and obese psoriatic group. Plasma psoriasin, nestin, Krt16, IL-21, leptin, and resistin were estimated for all subjects. Psoriasin, nestin, Krt16, IL-21, leptin, and resistin were significantly elevated in psoriatic and obese psoriatic groups. However, only leptin, resistin, IL-21, and Krt16 were significantly increased in the obese group compared with the control group. Leptin and resistin showed significant positive correlations with psoriasis area and severity index score, psoriasin, nestin, Krt16, and IL-21. Cutoff values for psoriasin, nestin, Krt16, and IL-21 were 187.5 ng/mL, 1825 pg/mL, 33.1 ng/mL, and 128.6 ng/L, respectively. In conclusion, psoriasin, nestin, Krt16, and IL-21 can be utilized as biochemical markers of psoriasis; these psoriatic markers are significantly positively correlated with obesity biomarkers, and obesity can be considered a risk factor and/or consequence of psoriasis.

Leptin deficiency in mice counteracts imiquimod (IMQ)-induced psoriasis-like skin inflammation while leptin stimulation induces inflammation in human keratinocytes

Leptin is an adipocyte-derived cytokine secreted mostly by adipose tissue. Serum leptin levels are elevated in obese individuals and correlate positively with body mass index (BMI). Interestingly, serum leptin levels are also elevated in patients with psoriasis and correlate positively with disease severity. Psoriasis is associated with obesity; patients with psoriasis have a higher incidence of obesity, and obese individuals have a higher risk of developing psoriasis. Additionally, obese patients with psoriasis experience a more severe degree of psoriasis. In this study, we hypothesised that leptin may link psoriasis and obesity and plays an aggravating role in psoriasis. To investigate leptin's role in psoriasis, we applied the widely accepted imiquimod (IMQ)-induced psoriasis-like skin inflammation mouse model on leptin-deficient (ob/ob) mice and evaluated psoriasis severity. Moreover, we stimulated human keratinocytes with leptin and investigated the effect on proliferation and expression of pro-inflammatory proteins. In ob/ob mice, clinical signs of erythema, infiltration and scales in dorsal skin and inflammation in ear skin, as measured by ear thickness, were attenuated and compared with wt mice. Moreover, IL-17A and IL-22 mRNA expression levels, as well as increased epidermal thickness, were significantly less induced. In vitro, the effect of leptin stimulation on human keratinocytes demonstrated increased proliferation and induced secretion of several pro-inflammatory proteins; two hallmarks of psoriasis. In conclusion, leptin deficiency attenuated IMQ-induced psoriasis-like skin inflammation in a mouse model, and leptin stimulation induced a pro-inflammatory phenotype in human keratinocytes, thus, supporting an aggravating role of leptin in psoriasis.

Crosstalk between skin inflammation and adipose tissue-derived products: pathogenic evidence linking psoriasis to increased adiposity

INTRODUCTION

Psoriasis is a chronic skin disorder associated with several comorbid conditions. In psoriasis pathogenesis, the role of some cytokines, including TNF-α and IL-17, has been elucidated. Beside their pro-inflammatory activity, they may also affect glucose and lipid metabolism, possibly promoting insulin resistance and obesity. On the other hand, adipose tissue, secreting adipokines such as chemerin, visfatin, leptin, and adiponectin, not only regulates glucose and lipid metabolism, and endothelial cell function regulation, but it may contribute to inflammation. Areas covered: This review provides an updated 'state-of-the-art' about the reciprocal contribution of a small subset of conventional cytokines and adipokines involved in chronic inflammatory pathways, upregulated in both psoriasis and increased adiposity. A systematic search was conducted using the PubMed Medline database for primary articles. Expert commentary: Because psoriasis is associated with increased adiposity, it would be important to define the contribution of chronic skin inflammation to the onset of obesity and vice versa. Clarifying the pathogenic mechanism underlying this association, a therapeutic strategy having favorable effects on both psoriasis and increased adiposity could be identified.

The triad psoriasis-obesity-adipokine profile

Psoriasis is a chronic inflammatory skin disease, often associated with overweight/obesity. The adipose tissue is a complex organ that secretes several adipokines, involved in the regulation of some metabolic processes, such as lipid metabolism, glucose homeostasis, angiogenesis, blood pressure and inflammation. In obesity, the distribution and function of adipose tissue, and the adipokine profile are altered. The unbalanced production of pro- and anti-inflammatory adipokines in obesity, contributes to the development of a chronic low-grade inflammation state, which seems to favour worsening of psoriasis lesion and a poorer response to treatment. In this review, we will debate published data concerning the current knowledge about the triad psoriasis-obesity-adipokine profile.

The role of hormones in the pathogenesis of psoriasis vulgaris

Psoriasis vulgaris is a chronic, common skin disease, which affects the patient’s quality of life to the highest degree. Several exogenous factors and endogenous hormonal changes may act as triggers for psoriasis.

The skin possesses a true endocrine system, which is very important in multiple systemic diseases. A number of conditions are associated with psoriasis, and its severity can also be influenced by hormones. Even though the sex hormones and prolactin have a major role in psoriasis pathogenicity, there are a lot of other hormones which can influence the psoriasis clinical manifestations: glucocorticoids, epinephrine, thyroid hormones, and insulin.

Psoriasis: classical and emerging comorbidities

Psoriasis is a chronic inflammatory systemic disease. Evidence shows an association of psoriasis with arthritis, depression, inflammatory bowel disease and cardiovascular diseases. Recently, several other comorbid conditions have been proposed as related to the chronic inflammatory status of psoriasis. The understanding of these conditions and their treatments will certainly lead to better management of the disease. The present article aims to synthesize the knowledge in the literature about the classical and emerging comorbidities related to psoriasis.

Cytokine and Adipokine Levels in Patients with Premalignant Oral Lesions or in Patients with Oral Cancer Who Did or Did Not Receive 1α,25-Dihydroxyvitamin D3 Treatment upon Cancer Diagnosis

Differences in levels of inflammation-modulating cytokines and adipokines in patients with premalignant oral lesions versus in patients that develop squamous cell carcinoma of the head and neck (HNSCC) were assessed. Also assessed was the impact of treating HNSCC patients with the immune regulatory mediator, 1α,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃], on modulators of inflammation. Compared to healthy controls, patients with premalignant oral lesions had increases in their systemic levels of the inflammatory cytokines IL-6 and IL-17, and increases in the adipokine, leptin. However, levels of these pro-inflammatory cytokines and adipokine were reduced in patients with HNSCC. Treatment of HNSCC patients with 1,25(OH)₂D₃ increased levels of each of the measured immune mediators. Levels of the anti-inflammatory adipokine, adiponectin, were shifted inversely with the levels of the pro-inflammatory cytokines and with leptin. These studies demonstrate heightened immune reactivity in patients with premalignant lesions, which wanes in patients with HNSCC, but which is restored by treatment with 1,25(OH)₂D₃.

Obesity exacerbates imiquimod-induced psoriasis-like epidermal hyperplasia and interleukin-17 and interleukin-22 production in mice

Psoriasis is a chronic inflammatory skin disorder that is accompanied by an imbalance between the proliferation and differentiation of keratinocytes. A number of studies have suggested an association between obesity and severe psoriasis; however, it remains to be clarified whether obesity exacerbates psoriasis. To address this unsolved question, we induced psoriasiform dermatitis in mouse models for obesity. We found that obesity exaggerated the severity of psoriasiform dermatitis induced by topical application of the Toll-like receptor (TLR) 7 agonist, imiquimod. Ear swelling and epidermal hyperplasia were more prominent in the obese mice than in the control mice. When compared to imiquimod-treated control mice, imiquimod-treated obese mice expressed higher levels of psoriasis mediators, interleukin-17A (IL-17A) and IL-22 in the skin. Food intake restriction partially abrogated enhanced ear swelling and cytokine overproduction in obese mice. Furthermore, the obesity environment and imiquimod treatment synergistically induced an IL-17A downstream molecule, regenerating islet-derived 3γ (Reg3γ), which is a critical molecule for psoriatic epidermal hyperplasia. Palmitic acid, one of the fatty acids released by subcutaneous adipocytes, increased the expression of REG3A (a human homologue of mouse Reg3γ) in both the HaCaT keratinocyte cell line and normal human keratinocytes. Taken together, these results strongly suggest that obesity exacerbates psoriasiform dermatitis in mice by upregulating IL-17A, IL-22 and Reg3γ.

The Relationship of Obesity With the Severity of Psoriasis: A Systematic Review

BACKGROUND

Psoriasis is a chronic inflammatory disease associated with obesity. The increased production of adipocytokines in central adiposity contributes to the systemic inflammation of obesity and perhaps to psoriasis.

OBJECTIVE

The objective of this systematic review is to determine the association of obesity with psoriasis severity.

METHODS

We searched PubMed, EMBASE, and Cochrane Database for English-language papers involving human subjects for all years. We extracted data on age, sex, body mass index (BMI), proportion obese, and psoriasis severity index score (PASI).

RESULTS

We identified 254 articles in our search and included 9. The sample size was 134 823 psoriasis patients. Seven of the 9 studies found a statistically significant association of increased psoriasis severity with higher BMI.

CONCLUSION

Increased severity of psoriasis appears to be associated with increased BMI. Most studies were cross-sectional or case-control, making it difficult to determine temporality. Dermatologists should consider recording BMI for psoriasis patients and offering them lifestyle counseling.

Risk of non-alcoholic fatty liver disease in patients with psoriasis: a systematic review and meta-analysis

BACKGROUND

Psoriasis has been linked to an increased risk of metabolic syndrome (MetS). Non-alcoholic fatty liver disease (NAFLD), the hepatic manifestation of MetS, is now the commonest liver disease worldwide and can evolve into cirrhosis in a subgroup of patients. Psoriasis has been reported to be associated to NAFLD.

AIM

The aim of this study was to evaluate the strength of the association between psoriasis and NAFLD.

METHODS

A systematic review of the literature was conducted in six databases (Medline, CINAHL, Scopus, LILACS, Cochrane Library and EMBASE). Data from studies assessing frequency of NAFLD in psoriatic and non-psoriatic patients were extracted and meta-analysed using the Mantel-Haenszel method. Subgroups analysis of patients with psoriatic arthritis and moderate to severe psoriasis was also performed.

RESULTS

Seven case-control studies were included, all of them of low or moderate quality. Psoriatic patients exhibited an increased risk of NAFLD compared to non-psoriatic controls (six studies; n = 267,761 patients; odds ratio (OR): 2.15, 95% CI: 1.57-2.94). The association remained significant (OR: 2.07, 95% CI: 1.62-2.64) when only high/moderate quality studies were analysed (three studies; n = 3345 patients). The risk of NAFLD was significantly greater in patients with psoriatic arthritis (three studies; n = 505 patients; OR: 2.25, 95% IC: 1.37-3.71) and in patients with moderate to severe psoriasis compared to those with mild psoriasis (two studies; 51,930 patients, OR: 2.07, 95% CI: 1.59-2.71).

LIMITATIONS

Data quality and heterogeneity may restrict the interpretation of the pooled risk estimates.

CONCLUSION

Case-control studies support an association between psoriasis and NAFLD. Screening of NAFLD in this group of patients may be warranted.

Psoriasis: in between the skin and the fat

Substantial epidemiological evidence indicates that psoriasis associates with a predisposition to develop metabolic dysregulation leading to obesity and insulin resistance. However, the nature of this association and the potential underlying mechanisms remain unclear. In a recent report, Gerdes et al. explored the hypothesis that wingless-type MMTV integration site, Wnt5a, which has been linked to aberrant fat cell metabolism, may be driving this process. In this study, the authors compare circulating serum levels of Wnt5a in individuals with psoriasis and compare with healthy controls matched for age, gender and BMI. The bottom-line results show higher levels of Wnt5a in psoriasis patients irrespective of BMI compared to the matched non-psoriatic controls, indicating that psoriasis per se may result in increased secretion of Wnt5a into the circulation. In addition, there was a significant difference among patients with higher levels of Wnt5a in the obese psoriasis population. The study, even though being purely descriptive, may serve to inspire a more mechanistic approach exploring not only Wnt5a, but other inflammatory pathways in between the skin and the fat.

Serum levels of leptin receptor in patients with malignant melanoma as a new tumor marker

Leptin is known to be abnormally expressed in a variety of cancers, and leptin receptors have been reported to be expressed on human melanoma cells. In this study, we evaluated the possibility that the serum levels of leptin receptor could be a tumor marker of malignant melanoma (MM). Serum samples were obtained from 71 patients with MM, and the serum levels of leptin receptor were measured by double-determinant ELISA. Interestingly, serum levels of leptin receptor decreased gradually with the stages of MM, being highest at in situ and lowest at stage IV. There was also a trend of reverse correlation between tumor thickness and serum levels of leptin receptor. To our knowledge, this is the first report investigating the serum levels of leptin receptor in MM, and serum leptin receptor levels may be used as a useful tumor marker of MM.

Hair cycle control by leptin as a new anagen inducer

Our purpose is to clarify the physiological role of leptin in hair cycle as leptin reportedly causes activation of Stat3, which is indispensable for hair cycling. While hair follicles in dorsal skin of 5-week-old C57/BL6 mice had progressed to late anagen phase, those in dorsal skin of 5-week-old leptin receptor deficient db/db mice remained in the first telogen and later entered the anagen at postnatal day 40, indicating that deficiency in leptin receptor signalling delayed the second hair cycle progression. Next, we shaved dorsal hairs on wild-type mice at postnatal 7 weeks and injected skin with mouse leptin or a mock. After 20 days, although mock injection showed no effect, hair growth occurred around leptin injection area. Human leptin fragment (aa22-56) had similar effects. Although the hair cycle of ob/ob mice was similar to that of wild-type mice, injection of mouse leptin on ob/ob mice at postnatal 7 weeks induced anagen transition. Immunohistochemically, leptin is expressed in hair follicles from catagen to early anagen in wild-type mice, suggesting that leptin is an anagen inducer in vivo. Phosphorylation of Erk, Jak2 and Stat3 in human keratinocytes was stimulated by leptin and leptin fragment. In addition, RT-PCR and ELISA showed that the production of leptin by human dermal papilla cells increased under hypoxic condition, suggesting that hypoxia in catagen/telogen phase promotes leptin production, preparing for entry into the next anagen. In conclusion, leptin, a well-known adipokine, acts as an anagen inducer and represents a new player in hair biology.