Scleroderma therapy: clinical overview of current trends and future perspective

Raynaud's Phenomenon: A Current Update on Pathogenesis, Diagnostic Workup, and Treatment

Raynaud's phenomenon (RP) is a condition characterized by episodic, excessive vasoconstriction in the fingers and toes, triggered by cold or stress. This leads to a distinctive sequence of color changes in the digits. Pallor indicates reduced blood flow due to oxygen deprivation, while erythema appears as reperfusion. RP can be primary, with no identifiable underlying cause, or secondary, associated with other conditions. These conditions include autoimmune diseases, most commonly systemic sclerosis, vascular diseases; and neurological conditions. While the exact cause of RP remains unclear, genetic and hormonal (estrogen) factors are likely contributors. The pathogenesis of RP involves a complex interaction between the vascular wall, nerves, hormones, and humoral factors, disrupting the balance between vasoconstriction and vasodilation. In primary RP, the vascular abnormalities are primarily functional. However, in secondary RP, both functional and structural components occur in blood vessels. This explains why digital tissue damage frequently occurs in secondary RP but not primary RP. Diagnosis of RP is primarily clinical. Recent advancements in imaging techniques have aided in diagnosis and monitoring, but nail fold capillaroscopy remains the gold standard for distinguishing between primary and secondary RP. If there are signs of acute ischemic injury, vascular imaging, particularly preoperatively, is crucial to rule out other vaso-occlusive conditions. Management of RP focuses on alleviating symptoms and preventing tissue damage. Vasodilator medications are the first-line treatment when general measures like warmth and stress management are not sufficient. Dihydropyridine calcium channel blockers (CCBs), such as nifedipine, are commonly used for vasodilation. Phosphodiesterase-5 inhibitors and prostaglandin analogs are alternative options for patients who do not respond to CCBs or have ischemic tissue damage. Bosentan, an endothelin-1 receptor antagonist, has shown effectiveness in treating and preventing digital ulcers, especially in patients with multiple ulcers. For severe cases, botulinum toxin injections or sympathectomy surgery can be used to control RP symptoms. However, botulinum toxin injections require repeated administration, and sympathectomy's long-term effectiveness is uncertain. Fat grafting is a promising surgical therapy for promoting healing and preventing tissue injury.

Fat transplantation induces dermal adipose regeneration and reverses skin fibrosis through dedifferentiation and redifferentiation of adipocytes

Background

Localized scleroderma causes cosmetic disfigurement, joint contractures, and other functional impairment, but no currently available medications can reverse the resulting skin lesions. Fat grafting is beneficial for reversing skin fibrosis; however, the mechanism by which adipose tissue transplantation contributes to lesion improvement has not been fully clarified. The purpose of our study was to verify the therapeutic effect of fat grafts in reversing skin fibrosis.

Methods

Inguinal fat pads from AdipoqCreER+;mT/mG mice, which were treated with tamoxifen, were transplanted to the skin lesion in bleomycin-treated wild-type C57 mice. Tdtomato transgenic mice-derived adipocytes, adipose-derived stem cells (ASCs), dedifferentiated adipocytes (DAs) were embedded in matrigel and transplanted beneath the skin lesion of bleomycin-treated wild-type C57 mice. A transwell co‐culture system was used to verify the effect of ASCs, adipocytes or DAs on scleroderma fibroblasts or monocytes.

Results

Adipocytes from the fat grafts could undergo dedifferentiation and redifferentiation for dermal adipose tissue re-accumulation within the skin lesion. Moreover, compared with ASCs and adipocytes, DAs show greater potency of inducing adipogenesis. ASCs and DAs showed comparable effect on inducing angiogenesis and suppressing macrophage infiltration in fibrotic skin. Co-culture assay showed that DAs and ASCs were able to reduce fibrosis-related genes in human scleroderma fibroblasts and drive M2 macrophage polarization.

Conclusion

Our results indicated that adipocytes would transform into a more functional and dedifferentiated state and reverse dermal fibrosis, by promoting dermal adipose tissue regeneration, improving angiogenesis, suppressing macrophage-mediated inflammation and myofibroblast accumulation.

Mesenchymal Stem Cell-Based Therapy as a New Approach for the Treatment of Systemic Sclerosis

Systemic sclerosis (SSc) is an intractable autoimmune disease with unmet medical needs. Conventional immunosuppressive therapies have modest efficacy and obvious side effects. Targeted therapies with small molecules and antibodies remain under investigation in small pilot studies. The major breakthrough was the development of autologous haematopoietic stem cell transplantation (AHSCT) to treat refractory SSc with rapidly progressive internal organ involvement. However, AHSCT is contraindicated in patients with advanced visceral involvement. Mesenchymal stem cells (MSCs) which are characterized by immunosuppressive, antifibrotic and proangiogenic capabilities may be a promising alternative option for the treatment of SSc. Multiple preclinical and clinical studies on the use of MSCs to treat SSc are underway. However, there are several unresolved limitations and safety concerns of MSC transplantation, such as immune rejections and risks of tumour formation, respectively. Since the major therapeutic potential of MSCs has been ascribed to their paracrine signalling, the use of MSC-derived extracellular vesicles (EVs)/secretomes/exosomes as a "cell-free" therapy might be an alternative option to circumvent the limitations of MSC-based therapies. In the present review, we overview the current knowledge regarding the therapeutic efficacy of MSCs in SSc, focusing on progresses reported in preclinical and clinical studies using MSCs, as well as challenges and future directions of MSC transplantation as a treatment option for patients with SSc.

Life after Autologous Hematopoietic Stem Cell Transplantation for Systemic Sclerosis

Stem cell transplantation has been investigated as treatment for severe and progressive systemic sclerosis (SSc) for the past 25 years. To date, more than 1000 SSc patients have been transplanted worldwide. Overall and event-free survival have increased over the years, reflecting stricter patient selection criteria and better clinical management strategies. This review addresses long-term outcomes of transplanted SSc patients, considering phase I/II and randomized clinical trials, as well as observational studies and those assessing specific aspects of the disease. Clinical outcomes are discussed comparatively between studies, highlighting advances, drawbacks and controversies in the field. Areas for future development are also discussed.

[Expression of pituitary tumor-transforming gene-1 and its pathogenic role in systemic sclerosis]

OBJECTIVE

To investigate the expression of tumor-transforming gene-1 (PTTG1) in systemic sclerosis (SSc) and its role in fibrosis.

METHODS

Skin biopsy samples were collected from 21 patients with SSc and 22 patients with healthy skin for detecting the mRNA and protein expressions of PTTG1 using real-time PCR (RT-PCR) and immunohistochemistry, respectively. In cultured primary human dermal fibroblasts, PTTG1 expression was knocked down via RNA interference (siRNA), and the mRNA expression levels of PTTG1 and the fibrosis-related genes α-SMA, COL1A1, COL1A2, and COL3A1 were detected using RT-PCR; the proliferation of the cells was assessed using a real-time cell proliferation detection system.

RESULTS

Compared with those in normal skin samples, the mRNA and protein expressions of PTTG1 increased significantly in the skin tissue of patients with SSc (P < 0.05). In cultured primary skin fibroblasts, the expression of PTTG1 mRNA was positively correlated with those of α-SMA (R²=0.8192, P < 0.05), COL1A1 (R²=0.6398, P < 0.05), COL1A2 (R²=0.316, P < 0.05) and COL3A1 mRNAs (R²=0.3727, P < 0.05). Interference of PTTG1 expression significantly inhibited the cell proliferation, obviously lowered the expressions of fibrosis-related genes, and down-regulated the expression of collagen in the fibroblasts.

CONCLUSIONS

PTTG1 is highly expressed in skin tissues of patients with SSc, and PTTG1 knockdown can reduce the activity of the dermal fibroblasts, suggesting a close correlation of PTTG1 with fibrosis in SSc.

[Expression of calponin-1 and its pathogenic role in systemic sclerosis]

OBJECTIVE

To investigate the expression of calponin-1 (CNN1) in systemic sclerosis (SSc) and its pathogenic role in fibrosis.

METHODS

Skin biopsy samples were collected from 19 patients with SSc and 21 healthy subjects. Real-time PCR was used to detect the expression of CNN1 and α-SMA mRNAs in the samples, and the protein expression of CNN1 was detected using immunohistochemistry. In cultured primary human dermal fibroblasts, CNN1 expression was knocked down via RNA interference, and the mRNA expression levels of CNN1 and the fibrosis-related genes α-SMA, CTGF, COL1A1, COL1A2, and COL3A1 were detected using real-time PCR; the proliferation of the cells was assessed using a real-time cell proliferation detection system.

RESULTS

Compared with that in samples from normal subjects, the expression of CNN1 mRNA was significantly increased in the skin tissue of patients with SSc (P < 0.05) with a positive correlation with α-SMA (r=0.7219, P < 0.0001); the protein expression of CNN1 was also significantly increased in the skin tissue of patients with SSc. In cultured primary skin fibroblasts, the expression of CNN1 mRNA was positively correlated with α-SMA and COL1A1 mRNA expressions (r=0.6547, P < 0.05; r=0.6438, P < 0.05). CNN1 knockdown in the fibroblasts significantly inhibited the cell proliferation, obviously lowered the expressions of fibrosis-related genes, and reduced the protein expression of collagen.

CONCLUSIONS

The expression of CNN1 is increased in the skin tissues of patients with SSc, and CNN1 knockdown can reduce the activity of dermal fibroblasts, suggesting the close correlation of CNN1 with fibrosis in SSc.

SIRT3 is attenuated in systemic sclerosis skin and lungs, and its pharmacologic activation mitigates organ fibrosis

Constitutive fibroblast activation is responsible for organ fibrosis in fibrotic disorders including systemic sclerosis (SSc), but the underlying mechanisms are not fully understood, and effective therapies are lacking. We investigated the expression of the mitochondrial deacetylase sirtuin 3 (SIRT3) and its modulation by hexafluoro, a novel fluorinated synthetic honokiol analogue, in the context of fibrosis. We find that augmenting cellular SIRT3 by forced expression in normal lung and skin fibroblasts, or by hexafluoro treatment, blocked intracellular TGF-ß signaling and fibrotic responses, and mitigated the activated phenotype of SSc fibroblasts. Moreover, hexafluoro attenuated mitochondrial and cytosolic reactive oxygen species (ROS) accumulation in TGF-β-treated fibroblasts. Remarkably, we found that the expression of SIRT3 was significantly reduced in SSc skin biopsies and explanted fibroblasts, and was suppressed by TGF-β treatment in normal fibroblasts. Moreover, tissue levels of acetylated MnSOD, a sensitive marker of reduced SIRT3 activity, were dramatically enhanced in lesional skin and lung biopsies from SSc patients. Mice treated with hexafluoro showed substantial attenuation of bleomycin-induced fibrosis in the lung and skin. Our findings reveal a cell-autonomous function for SIRT3 in modulating fibrotic responses, and demonstrate the ability of a novel pharmacological SIRT3 agonist to attenuate fibrosis in vitro and in vivo. In light of the impaired expression and activity of SIRT3 associated with organ fibrosis in SSc, pharmacological approaches for augmenting SIRT3 might have therapeutic potential.

Assessment of Central Corneal Thickness in Different Subtypes of Systemic Sclerosis

PURPOSE

To compare central corneal thickness between patients with diffuse cutaneous systemic sclerosis and limited cutaneous systemic sclerosis.

METHODS

A total of 53 consecutive patients with systemic sclerosis were enrolled in this study. All subjects were screened for age, gender, classification of disease subtype, autoantibody profile, duration of disease, organ involvement, current treatment, tear break-up time, Schirmer test, and measurement of the central corneal thickness with an ultrasonic pachymeter.

RESULTS

No statistically significant differences were found in terms of age, sex, and duration of the disease, and dry eye evaluation between systemic sclerosis subsets. The mean central corneal thickness was 535.3 ± 37.6 µm (range, 471-619 µm) in diffuse cutaneous systemic sclerosis patients, and 539.3 ± 37.1 µm (range, 484-651 µm) in limited cutaneous systemic sclerosis (p = 0.71).

CONCLUSIONS

Central corneal thickness in patients with diffuse cutaneous systemic sclerosis is not different from the one in limited cutaneous systemic sclerosis.

Update on juvenile systemic sclerosis

Juvenile systemic sclerosis is an orphan disease of the macro- and microvasculature with an unknown etiology. Although pediatric and adult classification systems have been developed, neither has been validated yet. Recent publications have shown a shift in the subset pattern in juvenile-onset adult patients, with a better outcome in these patients as compared with young adult patients. As a first step in assessing activity, damage, and severity, a pediatric severity score--a modification of the adult Medsger scale--was proposed but has not been validated. An activity score also has been developed but has not yet been published. Currently, treatment approaches are based only on adult data, and problems exist in extrapolating these data to a pediatric population.