Role of adipokines in systemic sclerosis pathogenesis

In the Pursuit of Metabolic Markers of Systemic Sclerosis-Plasma Adiponectin and Omentin-1 in Monitoring the Course of the Disease

Systemic sclerosis (SSc) is a connective tissue disease leading to cutaneous and visceral fibrosis. Pathological features of SSc include immune dysregulation, vasculopathy, and impaired angiogenesis. Adipokines act as cytokines and hormones and are involved in various pathological processes, including metabolic disorders, inflammation, vasculopathy, and fibrosis. This study aimed to determine the level of omentin-1 and adiponectin to evaluate their potential role in the pathogenesis of SSc. We assessed serum omentin-1 and adiponectin as well as metabolic parameters in 58 patients with SSc and 30 healthy controls. The follow-up was performed in SSc individuals. Omentin-1 levels were significantly higher in SSc individuals as compared to the controls. In post-hoc analysis, omentin-1 was higher in the group with disease duration ≥7 years than in the control group. A positive correlation was noted between disease duration and both adipokines and increased with longer disease duration. However, there were no correlations between selected adipokines and metabolic parameters. Enhanced omentin-1 levels and higher levels of omentin-1 in patients with longer disease duration may suggest that omentin-1 is involved in the pathomechanisms of SSc as its concentrations are not directly related to BMI, age, and insulin resistance.

Higher body mass index is associated with a lower iloprost infusion rate tolerance and higher iloprost-related adverse events in patients with systemic sclerosis

Background

Systemic sclerosis (SSc) is an autoimmune disease characterized by vasospasm and microvascular involvement. Iloprost (ILO), a prostaglandin analogous, is used for the treatment of SSc-related Raynaud's phenomenon and digital ulcers. The suggested dose is 0.5-2 ng/kg/min for 6-8 h, and the maximum dose is decided upon the patient's tolerance.

Objectives

This study aims to analyze ILO infusion tolerance and possible predictive factors in patients with SSc.

Design

This is a retrospective observational study.

Method

We evaluated 113 patients with SSc beginning ILO intravenous (IV) infusion treatment between 2004 and 2021. We assessed the maximum tolerated ILO IV infusion rate, the incidence of adverse events (AEs), and the need for symptomatic therapy during the dose-finding sessions. We collected relevant demographic and medical and employed generalized linear models to assess possible predictors of maximum tolerated ILO infusion rate and AEs and logistic regression to assess predictors of AEs.

Results

The median ILO infusion rate at the end of the dose-finding process was 0.88 ng/kg/min [interquartile range (IQR) = 0.37]. We found a significant inverse correlation between ILO infusion rate and body mass index (BMI) at the beginning of treatment. BMI was negatively associated with ILO infusion rate (β = -0.21, p = 0.02) after correction for relevant confounding factors. Overweight patients (BMI >26) presented a 13-fold increased risk of developing AEs during ILO titration [adjusted odds ratio = 13.979, 95% confidence interval (CI) = 2.359-82.845]. AEs during ILO titration occurred in 47.8% of patients, of whom 22.2% presented hypotension. Other AEs were headache, nausea, vomiting, diarrhea, and edema. Symptomatic therapy was needed in half of the patients at least once.

Conclusion

This study showed that higher BMI was statistically associated with lower ILO infusion rate tolerance and higher AEs rate, underlying a possible BMI-dependent endothelial dysfunction. Individual ILO regimens still need to be tailored to the patient.

Plain Language Summary

Introduction: Systemic sclerosis is a rare a rheumatic disease characterized by skin thickening, vasospasm, and digital ulcers (DUs), as well as other organs involvement. Iloprost, which is administered as intravenous infusion, is one of the main treatments for this disease, and it is effective in reducing vasospasm and the frequency of DUs. Even if there is a suggested dose range, the exact dose must be tailored on each patient, because the tolerance to the drug is variable. Tolerance is limited by dose-dependent unwanted effects, as headache, low blood pressure, dizziness, and sickness. This study aimed to identify possible predictors of such tolerance.Materials and Methods: We collected data from our patients with systemic sclerosis beginning the treatment with iloprost between January 2004 and November 2021 at our hospital facility in Verona, Italy, and analyzed different factors that could be associated with a better tolerance, as age, sex, disease duration, smoking habit, body mass index (a measure of body fatness), blood pressure, concomitant medications, and different patterns of the disease.Results: We found that a higher body mass index was associated with lower iloprost tolerance and higher adverse events rate in patients with systemic sclerosis, while we did not find a correlation with other factors. We believe overweight and obese patients (who have a higher body mass index) have a defect in the vasodilatation mechanism and can therefore be more susceptible to the effect of this medication.Conclusions: While preliminary, our results could provide a good starting point to develop a predictive tool to limit adverse events during this therapy.

Adipose tissue and adipose secretome in systemic sclerosis

PURPOSE OF REVIEW

Adipose tissue is closely associated with systemic sclerosis (SSc)-pathology, both anatomically and functionally. This review focuses on local effects of adipocytes in the context of adipose to mesenchymal transdifferentiation (AMT), effects of the adipose stromal vascular fraction on SSc pathogenesis and systemic effects of adipose tissue secretome.

RECENT FINDINGS

Novel populations of fibroblasts evolving from adipose tissue were identified- for example COL11+ cancer-associated fibroblasts differentiated from adipose-derived stromal cells. Lipofibroblasts in human lungs were described using nonconventional markers that allow more effective population identification. These findings could make an important contribution to further clarification of adipocyte involvement in SSc.Recent studies confirmed that lipolysis contributes to fibrogenesis through AMT differentiation and release of fatty acids (FA). Unbalanced metabolism of FA has been reported in several studies in SSc. Other adipose tissue secretome molecules (e.g. lysophosphatidic acid), novel adipokines and extracellular vesicles from adipose mesenchymal stem cells make important contributions to the pro-/antifibrotic balance.

SUMMARY

There is a growing evidence of important contribution of adipose tissue and its secretome to SSc pathogenesis. Novel techniques such as single-cell RNA sequencing (scRNAseq) and metabolomics, albeit challenging to use in adipose tissue, will provide further evidence.

Adiponectin: a pleiotropic hormone with multifaceted roles

Adipose tissue mostly composed of different types of fat is one of the largest endocrine organs in the body playing multiple intricate roles including but not limited to energy storage, metabolic homeostasis, generation of heat, participation in immune functions and secretion of a number of biologically active factors known as adipokines. The most abundant of them is adiponectin. This adipocite-derived hormone exerts pleiotropic actions and exhibits insulin-sensitizing, antidiabetic, anti-obesogenic, anti-inflammatory, antiatherogenic, cardio- and neuroprotective properties. Contrariwise to its protective effects against various pathological events in different cell types, adiponectin may have links to several systemic diseases and malignances. Reduction in adiponectin levels has an implication in COVID-19-associated respiratory failure, which is attributed mainly to a phenomenon called 'adiponectin paradox'. Ample evidence about multiple functions of adiponectin in the body was obtained from animal, mostly rodent studies. Our succinct review is entirely about multifaceted roles of adiponectin and mechanisms of its action in different physiological and pathological states.

Serum resistin is predictive marker of development of new digital ulcers in systemic sclerosis

Systemic sclerosis (SSc) is autoimmune disease characterized by endothelial dysfunction and microvascular damage. Resistin has been implied in microvascular dysfunction. Objective of this study is to evaluate the association between baseline resistin and development of new digital ulcers (DUs) in SSc patients. At baseline, serum resistin has been assessed in 70 female SSc patients and 26 healthy controls (HC). In SSc patients, clinical assessment was performed at baseline and after a 52-weeks follow-up. Serum resistin level was increased in SSc patients compared to HC [5.89 ng/ml (2.5 ng/ml–8.1 ng/ml) vs 2.3 ng/ml (0.4 ng/ml–2.4 ng/ml), p = 0.0004)]. Resistin was lower (p = 0.005) in SSc patients with early capillaroscopic pattern than patients with active or late capillaroscopic pattern [2.49 ng/ml (0.89 ng/ml–5.81 ng/ml) vs 7.11 ng/ml (3.48 ng/ml–11.35 ng/ml) and 6.49 ng/ml (3.35 ng/ml–8.87 ng/ml), respectively]. After a 52-weeks follow-up, 34 (48.6%) patients developed new DUs. Median serum resistin was significantly higher in patients with new DUs than in patients without new DUs [6.54 ng/ml (3.35 ng/ml–11.02 ng/ml) vs 4.78 ng/ml (1.06 ng/ml–7.6 ng/ml), p = 0.019]. Kaplan–Meier curves show a significantly reduced free survival from DUs in patients with increased resistin (p = 0.002). In multivariate analysis, resistin is associated with the development of new DUs. Increased serum resistin level is a predictive marker of new DUs in SSc.