Regulation of PDGF and its receptors in fibrotic diseases.

Of 397 systemic sclerosis (scleroderma) patients from the University of Pittsburgh, who had serum determinations of both anti-Scl-70 and anticentromere antibody (ACA), 26% had anti-Scl-70 and 22% had ACA. No patient had both autoantibodies. Weak associations with HLA-DR5 and HLA-DR1 were detected with anti-Scl-70 and ACA, respectively. ACA was found almost exclusively (96%) in patients with limited cutaneous scleroderma (the CREST syndrome variant), but the majority (57%) of patients with limited scleroderma did not have this antibody. Among patients with limited scleroderma, those with ACA more often had calcinosis and telangiectasias and less often had pulmonary interstitial fibrosis and restrictive lung disease. However, the frequency of pulmonary hypertension and the survival rates were similar in the ACA+ and ACA- limited scleroderma patients. Two-thirds of patients with anti-Scl-70 had diffuse scleroderma, but only 33% of all diffuse scleroderma patients had this antibody. Within the subset of diffuse scleroderma, anti-Scl-70 was associated with peripheral vascular disease (digital pitting scars) and pulmonary interstitial fibrosis, but was not predictive of cardiac or renal involvement or survival. ACA and anti-Scl-70 are useful in diagnosing and classifying systemic sclerosis variants and in predicting the natural course of the disease. Their mutually exclusive occurrence suggests either 2 separate clinical entities or important host factors determining their production.

Clinical correlations and prognosis based on serum autoantibodies in patients with systemic sclerosis.

Mononuclear cells (MNC) present in the dermis of the forearm and in the blood of patients with progressive systemic sclerosis (PSS) were quantified and analyzed for subsets using monoclonal antibodies. The findings were correlated with cutaneous and systemic features of the disease. Total T lymphocytes and their subsets, B cells, and macrophages were enumerated in the skin samples of 21 patients with PSS. The dermal MNC infiltrates consisted mostly of activated T lymphocytes with a mean T helper/T suppressor (T4/T8) ratio of 2.4 +/- 1.3 SD. Few B1-positive or T6-positive cells (macrophages) were observed. There was no correlation between the skin or blood T4/T8 ratios and the degree of skin thickening. On histologic examination, 58 of 115 (50%) untreated patients with PSS had prominent dermal MNC infiltration. Significant correlations between the degree of MNC infiltration and both the degree (P less than 0.05) and progression (P less than 0.05) of skin thickening were observed. No correlations with other systemic disease features of PSS were noted. These results suggest that cutaneous T lymphocytes may play a role in mediating dermal sclerosis in PSS.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/art.1780270607

Lymphocytes in the skin of patients with progressive systemic sclerosis. Quantification, subtyping, and clinical correlations.

Regulation of angiogenesis: wound healing as a model.

Injuries to tissue, whether due to mechanical, chemical, immunological, or thermal insults, initiate an orderly but complex series of cellular and biochemical interactions that lead to the formation of new tissue and the eventual repair of the wound. The cellular components of this pathway include hematopoietic cells such as platelets, polymorphonuclear leukocytes, lymphocytes, and monocytes, and mesenchymal cells such as fibroblasts and endothelial cells. These cells migrate to the site of tissue damage in a sequence determined by soluble factors that are released at the site of injury through a wide variety of mechanisms. Among these are tissue breakdown, blood coagulation, and cellular release. Each cell type has a specific function to perform such as degradation and resorption of damaged tissue, protection against infection, or deposition of new extracellular matrix.

Inflammation and Repair

Increased collagen accumulation in dermal fibroblast cultures from patients with progressive systemic sclerosis (scleroderma).

Progressive systemic sclerosis (PSS, scleroderma) dermal fibroblasts synthesize increased amounts of glycosaminoglycan.

Fibroblast cultures were established by explant culture from upper and lower dermis of 7 normal donors and 10 patients with early progressive systemic sclerosis (PSS). Antibodies against collagens containing the A and B chains, collagens which occur largely in vascular structures, were isolated and used for immunofluorescence studies. Cultures from lower PSS dermis accumulated significantly more of these collagens than fibroblast cultures from upper PSS dermis or cultures from upper or lower dermis of normal skin. These data indicate that the collagens containing the A and B chains in early PSS lesions are produced by cells of vascular origin and support the concept that alterations in vascular tissue play a prominent role in the pathogenesis of PSS.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/art.1780230209

Collagen types synthesized in dermal fibroblast cultures from patients with early progressive systemic sclerosis.

Dermal fibroblast cultures from patients with progressive systemic sclerosis (PSS) synthesize up to 5 times more glycosaminoglycan (GAG) than normal cultures. In an in vitro model of fibroblast-lymphocyte interactions, we show that the supernatants of activated mononuclear cells (MNC) modulate GAG synthesis, as measured by the incorporation of 3H-glucosamine into GAG following incubation of the confluent fibroblast monolayers with active supernatant preparations. GAG accumulation was selectively increased up to 18 times in normal dermal fibroblast cultures. Cell viability was not affected, and 3H-thymidine uptake and cell numbers were depressed in cultures treated with the supernatants. In contrast to normal dermal fibroblast cultures, PSS fibroblasts responded to MNC supernatants by only a 1-2-fold increase in GAG. Supernatants of concanavalin A-activated PSS MNC had higher stimulatory activity than those of normal MNC. Supernatants made with MNC that had been depleted of monocytes on Sephadex G-10 columns were only minimally stimulatory. The GAG-stimulatory supernatants modulated the synthesis, but not the degradation of GAG. Gel filtration on a calibrated Sephadex G-100 column indicated the presence of stimulatory activity in both the 50,000 and 15,000 molecular weight fractions. These activities were trypsin-sensitive, but had different susceptibilities to heat. The active column fractions also contained interleukin-1 activity, as shown in an assay measuring proliferation of mouse thymocytes. Like our factors, interleukin-1 preparations increased GAG in normal and PSS dermal fibroblasts. Products of activated MNC may modulate normal and pathologic processes in human skin.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/art.1780280214

Soluble mediators from mononuclear cells increase the synthesis of glycosaminoglycan by dermal fibroblast cultures derived from normal subjects and progressive systemic sclerosis patients.

Supernatants of mononuclear cells (MNC-SN) were shown to increase synthesis of glycosaminoglycan (GAG) by cultured normal dermal fibroblasts. Fibroblasts from the skin of patients with progressive systemic sclerosis (PSS, scleroderma) were hyporesponsive. We exposed fibroblasts outgrowing from explants of normal adult skin to MNC-SN for up to 30 generations in culture. MNC-SN were obtained by incubating normal MNC with concanavalin A. Four experimental, 4 normal control, and 3 PSS control lines were passaged by trypsinizing and splitting the cultures 1:2 every 7 days. At the third and fifth passages, portions of the experimental fibroblasts were removed from MNC-SN, then passaged in medium alone. Cell counts, assays for GAG, and electron microscopy were performed and increases in GAG after brief reexposure to MNC-SN were determined at the third, fifth, and eighth passages. In normal dermal fibroblasts, baseline GAG production, measured by 3H-glucosamine uptake, was low and increased as much as 15 times after reexposure to MNC-SN. In contrast, production was high in both experimental and PSS lines, and increases after reexposure to MNC-SN were consistently small. This PSS-like behavior persisted in experimental fibroblasts removed from MNC-SN at the third and fifth passages. Growth of experimental and scleroderma fibroblasts was slower than that of control fibroblasts. Ultrastructurally, both scleroderma and experimental dermal fibroblasts differed from normal fibroblasts by their oval cellular shape, indentations in nuclear membrane, numerous organelles and bundles of microfilaments, prominent Golgi, and intranuclear inclusions. These experiments indicate that normal adult dermal fibroblasts subjected to MNC-SN in vitro acquire a scleroderma-like phenotype that persists for many generations.

Robert K. Prince

Papers

Increased collagen accumulation in dermal fibroblast cultures from patients with progressive systemic sclerosis (scleroderma).

Progressive systemic sclerosis (PSS, scleroderma) dermal fibroblasts synthesize increased amounts of glycosaminoglycan.

Collagen types synthesized in dermal fibroblast cultures from patients with early progressive systemic sclerosis.

Soluble mediators from mononuclear cells increase the synthesis of glycosaminoglycan by dermal fibroblast cultures derived from normal subjects and progressive systemic sclerosis patients.

Persistence of scleroderma-like phenotype in normal fibroblasts after prolonged exposure to soluble mediators from mononuclear cells.