Accumulation Of Collagen In Skin Research Articles

The Pathogenesis of Systemic Sclerosis Revisited

Although infectiological stimuli, environmental factors and genotypic features are known to contribute to the initiation and perpetuation of systemic sclerosis (SSc), its etiology still remains to be enigmatic, and less elusive insights are to be achieved by ongoing and future investigations. Being characterized, however, as chronic autoimmune disease with excessive collagen accumulation in skin, synovia and visceral organs such as lung, heart, and digestive tract along with obliterating angiopathy, the pathophysiology of SSc can be summarized as being based on imbalances of the cellular and humoral immune system, vascular dysfunction and activation of resident connective tissue cells. A complex interplay between these major components manages to establish and maintain the inability of the vasculature to adequately react to the need for dilatation, constriction and growth of new vessels, to cause the increased deposition of extracellular matrix constituents as well as to facilitate immunological disarrangement. Despite parallels to the chicken and egg causality dilemma, all of these account for what later clinicians observe in patients suffering from Raynaud's phenomenon, digital ulcers, sclerodactyly, rigidity of the face, microstomia, sicca syndrome, dyspnea, dry cough, pulmonary hypertension, palpitations, syncopes, renal insufficiency, dysphagia, gastroesophageal reflux, dyspepsia, generalized arthralgias, but also dyspareunia, or erectile dysfunction.

Retracted] Fructose Diet‐Induced Skin Collagen Abnormalities Are Prevented by Lipoic Acid

Nonenzymatic glycation of proteins, leading to chemical modification and cross-linking are of importance in the pathology of diabetic complications.We studied the effect of α-lipoic acid (LA) on the content and characteristics of the protein collagen from skin of high-fructose fed rats. The rats were divided into 4 groups of 6 each. Two groups of rats were fed with a high fructose diet (60 g/100 g diet) and administered either LA (35 mg/kg b.w., i.p) (FRU+LA) or 0.2 ml vehicle (saline) (FRU) for 45 days. The other 2 groups were fed with control diet containing starch (60 g/100 g diet) and administered either saline (CON) or lipoic acid (CON+LA). The rats were maintained for 45 days and then sacrificed. Plasma glucose, insulin, fructosamine, protein glycation, and blood glycated hemoglobin (HbA1C) were measured. Collagen was isolated from skin and the physicochemical properties of collagen were studied. Fructose administration caused accumulation of collagen in skin. Extensive cross-linking was evidenced by enhanced glycation and AGE-linked fluorescence. Increased peroxidation and changes in physicochemical properties such as shrinkage temperature, aldehyde content, solubililty pattern, susceptibility to denaturing agents were observed in fructose-fed rats. SDS gel pattern of collagen from these rats showed elevated β component of type I collagen. These changes were alleviated by the simultaneous administration of LA. Administration of LA to fructose-fed rats had a positive influence on both quantitative and qualitative properties of collagen. The results suggest a mechanism for the ability of LA to delay diabetic complications.

Altered Procollagen mRNA Expression during the Progression of Avian Scleroderma

Spontaneous animal models of human autoimmune diseases provide the means to study the very first pathogenetic events, which is not possible in their human counterparts. This is particularly true for connective tissue diseases in which clinical symptoms become manifest only after a long and still obscure course of immunologic, inflammatory, and fibrotic processes. University of California at Davis line 200 chickens (UCD-200) develop a hereditary scleroderma-like disease resembling the entire spectrum of human systemic sclerosis, such as early endothelial cell damage, severe lymphocytic infiltration, and accumulation of collagen in skin and internal organs. In the present study, we investigated mRNA levels of alpha 1(I), alpha 2(I), alpha 1(II), alpha 1(III), alpha 1(VI), alpha 2(VI), and alpha 3(VI) procollagen and GAPDH using digoxigenin-labeled antisense probes in a nonradioactive ribonuclease protection assay (RPA). We analyzed tissue samples from comb, esophagus, heart, lung, and liver of UCD-200 chickens at different stages of the disease, and healthy UCD-058 chickens. During the early inflammatory stage of the disease, the ratios of procollagen types VI/I and types VI/III increased 7-fold in comb tissue, followed by a 3-fold elevation in type I procollagen transcripts in the late acute stage. In the chronic stage, alpha 1(III) procollagen message was increased 2-fold. Additionally, hybridization with the 180 bp alpha 2(I) antisense probe resulted in two bands of 180 bp and 115 bp, respectively, in the RPA. The ratio of these two previously undescribed bands changes in the early stage of the disease both in comb and esophagus. In an animal model with a spontaneous scleroderma-like disease we found a characteristic, sequential increase in type VI, type I, and type III procollagen transcripts, and we found evidence for the presence and altered ratio of two mRNA variants of alpha 2(I) procollagen, possibly caused by alternative splicing. Comparative analysis of alpha 2(I) procollagen variants in early stages of avian scleroderma and human SSc might provide answers to unresolved questions concerning the molecular basis for generalized fibrosis in scleroderma.

Genomic analysis of collagen and endogenous virus loci in the UCD-200 and 206 lines of chickens, animal models for scleroderma.

University of California at Davis (UCD) lines 200 and 206 chickens develop a hereditary systemic scleroderma-like connective tissue disease characterized by severe lymphocytic infiltration and excessive accumulation of collagen in skin and internal organs. The immune system seems to play an important role in the development and/or perpetuation of this condition. The main goal of our work with this strain is the investigation of interactions between endothelial cells, lymphocytes, macrophages and fibroblasts leading to the proliferation of the latter and to excessive collagen synthesis and/or deposition. One aim of the present study was to clarify whether UCD-200 and 206 chickens have a defect of collagen genes at the genomic level by means of restriction fragment length polymorphism (RFLP) analysis using non-radioactively labelled cDNA probes specific for chicken alpha 1(I), alpha 2(I), alpha 1(II), alpha 1(III), alpha 1(VI), alpha 2(VI), and alpha 3(VI) (pro) collagens. As in the human disease, no gross alteration at the genomic level of collagen genes has been found, thus providing the UCD-200/206 model to be appropriate for studying the altered collagen metabolism in systemic sclerosis (SSc). In addition to the RFLP analysis of procollagen genes, we investigated the endogenous avian leukosis virus loci (ev) of UCD-200 and 206 chickens by means of Southern blot analysis of Sac I and BamH I digested DNA samples using pRAV-2, a Rous sarcoma virus specific probe, for hybridization. Most UCD-200 and 206 chickens harbour evs 1, 3 and 10 similar to the healthy control UCD-058, but they also contain a novel ev characterized by a 4.2 kb Sac I fragment and a 6.1 kb BamH I fragment, which we would like to designate ev 23. So far, the role of ev 23 in the development of avian scleroderma is unclear; for further analysis classical crossbreeding experiments are necessary and are underway.

The Tight Skin (Tsk) Mutation in the Mouse, a Model for Human Fibrotic Diseases, Is Tightly Linked to the β2-Microglobulin (B2m) Gene on Chromosome 2

The Tsk mutation in the mouse is characterized by the excessive accumulation of collagen in skin and various internal organs, including the heart and lungs. These connective tissue abnormalities are similar to those present in human systemic sclerosis or scleroderma. The Tsk mutation provides an opportunity to investigate, at the molecular level, the pathogenesis of tissue fibrosis. As a first step to cloning the Tsk gene, we report the localization of the Tsk mutation with respect to known molecular markers on mouse chromosome 2. N2 progeny carrying the Tsk mutation were obtained from an intersubspecific backcross of [(C57BL/6-pa +/+ Tsk × Mus castaneus)F1 × M. castaneus ] mice. Genomic DNA from each N2 mouse was subjected to Southern and PCR analyses to identify restriction fragment length polymorphisms and simple sequence length polymorphisms, respectively. Our results refine the location of Tsk to a 3-cM region, eliminate several genes from consideration as the Tsk mutation, identify molecular probes tightly linked with Tsk, and suggest candidate genes responsible for the Tsk phenotype.

Increased collagen synthesis and increased content of type VI collagen in myocardium of tight skin mice

The tight skin mouse (TSK) is a mutant strain characterised by excessive collagen accumulation in skin and some internal organs such as the heart. The aims of this study were (1) to examine in vitro collagen synthesis in TSK myocardium; (2) to determine myocardial content of type VI collagen in the same model; and (3) to examine the expression of one of the genes for type VI collagen in cultured TSK myocardial fibroblasts. Individual hearts from 8 month old heterozygous male TSK and normal sex and age matched mice were incubated with 14C proline. Total 14C protein and 14C collagen synthesis by myocardial tissues were determined with collagenase digestion and SDS gel electrophoresis. For determination of type VI collagen, hearts from 10 month old male TSK and normal mice were subjected to guanidine extraction followed by pepsin digestion, salt fractionation, and western blotting. Expression of the alpha 2(VI) collagen gene was determined in myocardial fibroblasts cultured from TSK and normal mice, employing northern and dot blot hybridizations with a murine specific cDNA. TSK hearts had up to twofold greater protein and collagen biosynthesis and 2.5-fold greater type VI collagen content (400 micrograms v 156 micrograms). Fibroblasts cultured from TSK mice hearts displayed up to threefold higher steady state concentrations of alpha 2(VI) collagen mRNA than normal myocardial fibroblasts. Hearts from TSK mice showed increased protein and collagen biosynthesis and increased myocardial content of type VI collagen compared with hearts from age matched normal mice. Also, fibroblast cultures from TSK mice myocardium showed increased expression of the alpha 2(VI) collagen gene, indicating that increased transcription of type VI collagen genes may be responsible for the accumulation of this collagen in myocardium from TSK mice.

Serum levels of aminoterminal type III procollagen peptide and hyaluronan predict mortality in systemic sclerosis.

Systemic sclerosis (SSc) is characterized by an excessive accumulation of collagen in skin and internal organs and increased serum concentrations of different connective tissue metabolites have been reported. In this study of 82 patients with SSc, serum concentrations of aminoterminal type III procollagen peptide (PIIINP), smaller PIIINP-related antigens (Fab PIIINP) and hyaluronan (HA) were increased as compared to healthy controls matched for age and sex. Patients with a shorter disease duration (less than 3 years) had higher serum levels of PIIINP and Fab PIIINP than patients with a longer disease duration. The highest serum concentrations of PIIINP and HA were seen in seven patients who died within 2 years.

Increased collagen biosynthesis and increased expression of type I and type III procollagen genes in tight skin (TSK) mouse fibroblasts.

The Tight Skin (TSK) mouse is a mutant strain that displays connective tissue abnormalities characterized by excessive accumulation of collagen in skin, subcutaneous tissues, and some internal organs such as the heart. Increased collagen biosynthesis by skin organ cultures from affected mice has been previously demonstrated, but the mechanisms responsible have not been identified. In order to examine the molecular alterations responsible for the increased production of this protein, normal and TSK mouse dermal fibroblast cell lines were established, and studies of collagen biosynthesis and expression of Types I and III procollagen genes were performed. Secondary cultures of 5 normal and 5 TSK mice dermal fibroblasts were incubated in media containing 10% fetal calf serum and 50 micrograms/ml ascorbic acid and after labeling with [14C]proline for 72 h the amount of [14C]hydroxyproline synthesized was determined. The results showed that TSK mice dermal fibroblasts produced significantly greater amounts of [14C]hydroxyproline than their normal counterparts (118 +/- 28.3 X 10(-2) versus 53.7 +/- 21.9 X 10(-2) dpm/micrograms of DNA; p less than 0.004). Subsequently, the expression of three procollagen genes in normal and TSK mice fibroblasts was analyzed by Northern blot hybridization of polyadenylated RNA to the human cDNA clones alpha 12, Hf 32, and RJ 5 which are specific probes for transcripts of alpha 1(I), alpha 2(I), and alpha 1(III) procollagen chains, respectively. It was found that TSK mice fibroblasts consistently displayed increased levels (up to 5-fold) of all three collagen transcripts while beta-actin mRNA levels were unchanged. The results demonstrate that TSK mice dermal fibroblasts produce excessive amounts of collagen in culture concomitant with a dramatic increase in the expression of Types I and III procollagen genes.