The vascular microenvironment and systemic sclerosis

Chemical exposure-induced systemic fibrosing disorders: Novel insights into systemic sclerosis etiology and pathogenesis

Numerous drugs and chemical substances are capable of inducing exaggerated tissue fibrotic responses. The vast majority of these agents cause localized fibrotic tissue reactions or fibrosis confined to specific organs. Although much less frequent, chemically-induced systemic fibrotic disorders have been described, sometimes occurring as temporally confined outbreaks. These include the Toxic Oil Syndrome (TOS), the Eosinophilia-Myalgia Syndrome (EMS), and Nephrogenic Systemic Fibrosis (NSF). Although each of these disorders displays some unique characteristics, they all share crucial features with Systemic Sclerosis (SSc), the prototypic idiopathic systemic fibrotic disease, including vasculopathy, chronic inflammatory cell infiltration of affected tissues, and cutaneous and visceral tissue fibrosis. The study of the mechanisms and molecular alterations involved in the development of the chemically-induced systemic fibrotic disorders has provided valuable clues that may allow elucidation of SSc etiology and pathogenesis. Here, we review relevant aspects of the TOS, EMS, and NSF epidemic outbreaks of chemically-induced systemic fibrosing disorders that provide strong support to the hypothesis that SSc is caused by a toxic or biological agent that following its internalization by endothelial cells induces in genetically predisposed individuals a series of molecular alterations that result in the development of SSc clinical and pathological alterations.

Parental influence on systemic sclerosis

OBJECTIVE

To examine parental influence on the development of systemic sclerosis (SSc; scleroderma). We designed 3 studies: mitochondrial inheritance, birth order (a possible surrogate marker for microchimerism), and paternal age at conception (a possible surrogate for telomere erosion) to examine their association with development of SSc.

METHODS

SSc was defined by International Classification of Diseases, Ninth and Tenth Revision codes (ICD-9 710.1 and ICD 10 M34.0, M34.1, and M34.9) and identified from statewide discharge data, University of Utah Health Science Center Enterprise Data Warehouse (UUHSC), and death certificates that were linked to the Utah Population Database (UPDB) for analysis. Mitochondrial inheritance was evaluated by conditional logistic regression and population attributable risk using familial standardized incidence ratio as the covariate. Chi-square test and logistic regression were used to evaluate birth order and maternal/paternal age at conception of the SSc proband.

RESULTS

We found 1,947 unique SSc patients from UUHSC and UPDB. We selected 5 controls per case (n = 9,115), matched by birth year and sex. Mitochondrial inheritance analysis indicated no evidence to suggest SSc was associated with mitochondrial inheritance. Birth order and maternal/paternal age at conception analysis results show that they also do not significantly affect SSc development.

CONCLUSION

Results suggest that although heritable risk of SSc is observed, mitochondrial inheritance, birth order, and parental age are not likely responsible for pathogenesis.