Epidemiology and Treatment of Systemic Sclerosis in Korea

Characteristics of skin microbiome associated with disease severity in systemic sclerosis

Systemic sclerosis (SSc) is a chronic autoimmune disorder characterised by skin fibrosis and internal organ involvement. Disruptions in the microbial communities on the skin may contribute to the onset of autoimmune diseases that affect the skin. However, current research on the skin microbiome in SSc is lacking. This study aimed to investigate skin microbiome associated with disease severity in SSc. Skin swabs were collected from the upper limbs of 46 healthy controls (HCs) and 36 patients with SSc. Metagenomic analysis based on the 16S rRNA gene was conducted and stratified by cutaneous subtype and modified Rodnan skin score (mRSS) severity. Significant differences in skin bacterial communities were observed between the HCs and patients with SSc, with further significant variations based on subtype and mRSS severity. The identified biomarkers were Bacteroides and Faecalibacterium for patients with diffuse cutaneous SSc with high mRSS (≥ 10) and Mycobacterium and Parabacteroides for those with low mRSS (< 10). Gardnerella, Abies, Lactobacillus, and Roseburia were the biomarkers in patients with limited cutaneous SSc (lcSS) and high mRSS, whereas Coprococcus predominated in patients with lcSS and low mRSS. Cutaneous subtype analysis identified Pediococcus as a biomarker in the HCs, whereas mRSS analysis revealed the presence of Pseudomonas in conjunction with Pediococcus. In conclusion, patients with SSc exhibit distinct skin microbiota compared with healthy controls. Bacterial composition varies by systemic sclerosis cutaneous subtype and skin thickness.

Association between systemic sclerosis and venous thromboembolism, pulmonary embolism, and deep vein thrombosis: a meta-analysis

OBJECTIVE

This study aimed to analyze the published data pertaining to the correlation between venous thromboembolism (VTE) and systemic sclerosis (SSc).

METHODS

We conducted manual searches and explored MEDLINE, EMBASE, and Cochrane databases to review papers reporting the risk of VTE in patients with SSc. A meta-analysis was performed exploring the relative risks (RRs) of deep vein thrombosis (DVT), pulmonary embolism (PE), and VTE in these individuals.

RESULTS

Six trials that included 41,105 patients with SSc were eligible for inclusion. A meta-analysis of the six included studies revealed a statistically significant correlation (RR 2.372, 95% confidence interval [CI] = 1.608-3.500, p < 0.001) between the risk of VTE and SSc. Regional subgroup study revealed a strong correlation between SSc and VTE risk in Americans, Europeans, and Asians. Additionally, a significant correlation between SSc and PE risk was observed (RR 3.154, 95% CI = 1.320-7.539, p = 0.010). Finally, the meta-analysis revealed a substantial correlation (RR 5.190, 95% CI = 1.513-17.01, p = 0.009) between the risk of DVT and SSc.

CONCLUSION

This meta-analysis showed that SSc is linked to an increased risk of DVT, PE, and VTE. This finding underscores the importance of close monitoring for the emergence of these conditions in patients with SSc.

Bifidobacterium longum RAPO Attenuates Dermal and Pulmonary Fibrosis in a Mouse Model of Systemic Sclerosis through Macrophage Modulation and Growth of Short-Chain Fatty Acid Producers

Systemic sclerosis (SSc) is a complex autoimmune disease with an unclear etiology and no effective treatments. Recent research has suggested involvement of the microbiome in SSc pathogenesis. This study aimed to identify specific microbial species associated with SSc and explore their therapeutic potential. Serum Abs against 384 intestinal microbial species revealed a significant depletion in Abs against Bifidobacterium longum in patients with SSc compared to healthy controls. In a bleomycin-induced SSc mouse model, oral administration of B. longum strain RAPO attenuated skin and lung fibrosis, accompanied by reduced infiltration of inflammatory monocytes/macrophages and downregulation of pro-inflammatory cytokines and chemoattractant Ccl2 genes in lymph nodes and fibrotic tissues. B. longum RAPO treatment restored fecal microbial diversity and augmented short-chain fatty acid (SCFA)-producing bacteria in the gut, leading to increased fecal butyrate levels and upregulated SCFA receptor Gpr41 in the mesenteric lymph node. In vitro, B. longum RAPO and its culture supernatant suppressed the expressions of pro-inflammatory cytokine genes in macrophages and inhibited myofibroblast differentiation in fibroblasts. These findings highlight the probiotic potential of B. longum RAPO in preventing tissue fibrosis by modulating macrophage activity and promoting the growth of SCFA-producing bacteria, underscoring the therapeutic potential of microbial modulation in SSc.

Standardized mortality ratios in systemic sclerosis: a meta-analysis assessing overall and sex- and disease subtype-specific differences

OBJECTIVE

This study aims to evaluate the overall and sex- and illness subtype-specific standardized mortality ratios (SMRs) in patients with systemic sclerosis (SSc).

METHODS

We searched and examined studies that compared the overall and sex- and illness subtype-specific SMRs in patients with SSc to those in the general population using MEDLINE, EMBASE, and Cochrane databases (until May 2023). We then conducted a meta-analysis of the overall and sex- and illness subtype-specific SMRs in patients with SSc.

RESULTS

Overall, 29 studies including 30,673 patients with SSc and 5582 deaths met the inclusion criteria. Patients with SSc had a higher overall SMR than that in the general population (SMR: 2.742, 95% confidence interval [CI]: 2.224-3.38091, p < 0.001). The SMR significantly increased in populations from Europe, North America, Asia, and Oceania according to regional stratification. A sex-specific meta-analysis revealed a substantial increase in the SMR in both men and women (SMR: 3.598, 95% CI: 3.097-4.180, p < 0.001; SMR: 2.833, 95% CI: 2.4384-3.292, p < 0.001, respectively) and the mortality rate was higher in men compared to women. A substantial increase in the SMR in diffuse cutaneous SSc (dcSSc) and limited cutaneous SSc (lcSSc) was observed in a disease subtype-specific meta-analysis. In addition, the SMR in the dcSSc group was higher than that in the lcSSc group (SMR: 4.726, 95% CI: 3.795-5.885, p < 0.001; SMR: 1.987, 95% CI: 1.586-2.489, p < 0.001, respectively).

CONCLUSION

Our findings demonstrated that the mortality rate in patients with SSc was 2.74-times greater than that in the general population. The mortality rate was higher in men compared to women. Additionally, compared to patients with lcSSc, those with dcSSc showed much higher fatality rates.

Systemic sclerosis is a risk factor of incident psoriasis: results from a nationwide cohort study

Objective

Although the co-existence of systemic sclerosis (SSc) and psoriasis (PsO) has been reported, the risk relationship between the two diseases remains unclear. We aimed to assess whether SSc is associated with the risk of incident PsO.

Methods

From the Korean National Health Insurance Service database, 4,933 patients with SSc and 24,665 age- and sex-matched controls were selected. Hazard ratios (HRs) and 95% confidence intervals (CIs) for incident PsO were estimated using multivariable Cox proportional hazard models adjusted for known risk factors of PsO. Further, we selected individuals whose health check-up data were available (2,355 patients with SSc and 11,775 age- and sex-matched controls). In this population, we further adjusted for additional risk factors of PsO using the health check-up data.

Results

In the analysis of 4,933 patients with SSc and 24,665 age- and sex-matched controls, incidence rates of PsO in patients with SSc and controls were 10.26 and 3.20 per 1,000 person-years, respectively. After adjusting for risk factors of PsO, patients with SSc had a significantly higher risk of incident PsO (adjusted HR: 3.055 [95% CI: 2.597, 3.594]). Moreover, in the analysis of individuals who had health check-up data, additional risk factors of PsO were further adjusted; the result also showed that patients with SSc have a significantly higher risk of incident PsO (adjusted HR: 2.820 [95% CI: 2.207, 3.603]).

Conclusion

Patients with SSc had a 3-fold higher risk of developing incident PsO than controls, independent of known risk factors of PsO.