Circulating type I collagen degradation products: a new serum marker for clinical severity in patients with scleroderma?

Impaired LAIR-1-mediated immune control due to collagen degradation in fibrosis

Tissue repair is disturbed in fibrotic diseases like systemic sclerosis (SSc), where the deposition of large amounts of extracellular matrix components such as collagen interferes with organ function. LAIR-1 is an inhibitory collagen receptor highly expressed on tissue immune cells. We questioned whether in SSc, impaired LAIR-1-collagen interaction is contributing to the ongoing inflammation and fibrosis. We found that SSc patients do not have an intrinsic defect in LAIR-1 expression or function. Instead, fibroblasts from healthy controls and SSc patients stimulated by soluble factors that drive inflammation and fibrosis in SSc deposit disorganized collagen products in vitro, which are dysfunctional LAIR-1 ligands. This is dependent of matrix metalloproteinases and platelet-derived growth factor receptor signaling. In support of a non-redundant role of LAIR-1 in the control of fibrosis, we found that LAIR-1-deficient mice have increased skin fibrosis in response to repeated injury and in the bleomycin mouse model for SSc. Thus, LAIR-1 represents an essential control mechanism for tissue repair. In fibrotic disease, excessive collagen degradation may lead to a disturbed feedback loop. The presence of functional LAIR-1 in patients provides a therapeutic opportunity to reactivate this intrinsic negative feedback mechanism in fibrotic diseases.

Dental implants in patients suffering from systemic sclerosis: a retrospective analysis of clinical outcomes in a case series with 24 patients

PURPOSE

Patients with systemic sclerosis (SSc) often suffer from premature tooth loss. This is a retrospective case series of patients with systemic sclerosis who were treated with dental implants.

METHODS

SSc patients treated with at least one dental implant between 5 August 1998 and 31 December 2018 were included in this long-term retrospective study. The primary study variables were the plaque index (PLI), sulcus bleeding index (SBI), peri-implant pocket depth (PPD) and interincisal distance (ID). The test for marginal homogeneity analysed whether the SBI and PLI values changed between examination and follow-up. A linear regression was performed for the PPD measurement. The rank correlation coefficient compared the SBI with the PLI and the PPD with the PLI. The survival rate data for the implants were analysed by the Kaplan-Meier procedure. P < .05 was considered significant.

RESULTS

Twenty-four patients [(age: mean 59.6 years (SD ± 13.08)] received a total of 72 implants. ID resulted in a mean value of 29.54 mm (SD ± 6.4 mm). The mean value of the PPD was between 2.4 mm and 2.8 mm. A comparison of the SBI with the PLI and the PPD with the PLI showed a significantly positive correlation between the SBI and the PLI and between the PPD and the PLI. The correlation between the PPD and the PLI (Spearman rho: 0.36, p < 0.001) was less pronounced than that between the SBI and the PLI (Spearman rho: 0.61, p < 0.001). Kaplan-Meier analysis showed a post-10-year implant survival rate of 87.6% (95%-KI: 75.5-94.0).

CONCLUSION

Implant-supported oral rehabilitation can be carried out and maintained successfully in SSc patients.

Potential Biomarkers in Systemic Sclerosis: A Literature Review and Update

Systemic sclerosis (SSc) is a chronic autoimmune disease characterized by dysregulation of the immune system, vascular damage, and fibrosis of the skin and internal organs. Patients with SSc show a heterogeneous phenotype and a range of clinical courses. Therefore, biomarkers that are helpful for precise diagnosis, prediction of clinical course, and evaluation of the therapeutic responsiveness of disease are required in clinical practice. SSc-specific autoantibodies are currently used for diagnosis and prediction of clinical features, as other biomarkers have not yet been fully vetted. Krebs von den Lungen-6 (KL-6), surfactant protein-D (SP-D), and CCL18 have been considered as serum biomarkers of SSc-related interstitial lung disease. Moreover, levels of circulating brain natriuretic peptide (BNP) and N-terminal pro-brain natriuretic peptide (NT-proBNP) can provide diagnostic information and indicate the severity of pulmonary arterial hypertension. Assessment of several serum/plasma cytokines, chemokines, growth factors, adhesion molecules, and other molecules may also reflect the activity or progression of fibrosis and vascular involvement in affected organs. Recently, microRNAs have also been implicated as possible circulating indicators of SSc. In this review, we focus on several potential SSc biomarkers and discuss their clinical utility.

Results of the 4th scientific workshop of the ECCO (Group II): markers of intestinal fibrosis in inflammatory bowel disease

The fourth scientific workshop of the European Crohn's and Colitis Organization (ECCO) focused on intestinal fibrosis in inflammatory bowel disease (IBD). The objective was to better understand basic mechanisms and markers of intestinal fibrosis as well as to suggest new therapeutic targets to prevent or treat fibrosis. The results of this workshop are presented in three separate manuscripts. This section describes markers of fibrosis in IBD, identifies unanswered questions in the field and provides a framework for future studies addressing the unmet needs in the field of intestinal fibrosis.

Application of biomarkers to clinical trials in systemic sclerosis

Important clinical advances in the treatment of systemic sclerosis have been made, yet fibrotic disease remains largely untreatable. Optimal design of clinical trials to test new therapeutics for fibrotic disease features has suffered from dual difficulties in patient selection and patient evaluation. Patient selection for entry into trials for treatment of interstitial lung disease and/or skin fibrosis is challenged by the natural history of the disease, which stabilizes in some patients while relentlessly progressing in others, and our lack of good clinical markers to distinguish between these trajectories. Patient evaluation is made difficult, particularly in skin disease, by the inherent difficulty in quantifying the extent of disease. Biomarkers hold the potential to solve many of these problems as surrogate outcome measures and as markers for disease progression. Identified biomarkers may have the potential to graduate to surrogate outcome singly or, more likely, in combination. Predictive biomarkers are still largely unknown.

Fibrosis in endstage human heart failure: severe changes in collagen metabolism and MMP/TIMP profiles

OBJECTIVES

We studied fibrosis, collagen metabolism, MMPs/TIMPs and cytokine expression in various forms of human heart failure (HF) by quantitative immunofluorescent microscopy, Western blot, zymography, RT-PCR and in situ hybridization. In explanted human hearts with HF due to either dilated (DCM, n=6) or ischemic (ICM-BZ-borderzone, ICM-RZ-remote zone, n=7) or inflammatory (myocarditis, MYO, n=6) cardiomyopathy and 8 controls MMP2, 8, 9, 19, and TIMP1, 2, 3, 4 as well as procollagens I and III (PINP, PIIINP), mature collagen III (IIINTP) and the cross-linked collagen I degradation product (ICTP) were measured.

RESULTS

In comparison with controls, MMPs and TIMPs were significantly upregulated ranging (from highest to lowest) from ICM-BZ, DCM, ICM-RZ, MYO for all MMPs with the exception of MMP9 (highest in DCM), and for TIMPs from ICM-BZ, ICM-RZ, DCM and MYO. MMP2 and 9 were activated in all groups. The TIMP/MMP ratio was 1.3 for control, 1.9 in ICM-BZ (TIMP>MMP) and lowered to 1.0 in the other groups. Collagen I/collagen III ratio correlated significantly with the decrease in LVEDP. PINP was higher than ICTP in all groups. PIIINP elevation was present in DCM and ICM-RZ and IIINTP was up to 4-fold augmented in all groups. Fibrosin mRNA was upregulated in ICM-BZ, activin A in MYO but FGF1 and FGF2 remained unchanged. ANP mRNA was increased in all groups.

CONCLUSIONS

Although different degrees of severity of collagen metabolism, MMP/TIMP imbalance and cytokine expression in diverse forms of HF are present, the end product is collagen deposition. These findings suggest multiple mechanisms acting alone or in concert in fibrosis development in HF.

Scleroderma: from pathophysiology to novel therapeutic approaches

Systemic scleroderma may serve as a paradigm for orphan diseases where the rarity, different subsets and fluctuating disease activity constitute major obstacles of research into mechanisms and therapeutic development. Recently, significant advances in the detailed understanding of the functioning of growth factors, their receptors and of the physiology of the connective tissue have been achieved. In particular, an improved concept was developed for the pathophysiology of scleroderma, highlighting the role of hypoxia, cellular stress and a concert of interacting cytokines. Tyrosine kinases have been shown to regulate the activity of a number of cytokines and growth factors, e.g. transforming growth factor-beta and platelet-derived growth factor, which play a central role in the pathophysiology of SSc. Novel pharmacological compounds interacting with signalling cascades induced by hypoxia and intracellular signal transduction pathways of mesenchymal cells, e.g. tyrosine kinase inhibitors, are currently being investigated for the treatment of this life-threatening disease.

Biomarkers in systemic sclerosis

Systemic sclerosis is an autoimmune inflammatory disorder of unknown etiologycharacterized b y pronounced fibroproliferative alterations in the microvasculature, and frequent cellular and humoral immunity abnormalities, culminating in a severe and often progressive fibrotic process. Numerous biomarkers reflecting the three main pathogenetic mechanisms in systemic sclerosis have been described; however, aside from several disease-specific autoantibodies, other biomarkers have not been thoroughly validated and require further study. Thus, there is an unmet need for validated biomarkers for diagnosis, disease classification, and evaluation of organ involvement and therapeutic response in systemic sclerosis.

Labordiagnostik bei systemischer Sklerose

For systemic sclerosis, laboratory tests can play a supplementary role to clinical investigations, imaging techniques and functional tests. Typical autoantibodies support early diagnosis and help in assigning patients to subgroups of the disease; negative results for antinuclear antibodies suggest exclusion of the diagnosis. To detect organ involvement and comorbidity, the laboratory contributes by clinical chemistry, in certain cases by histopathological findings and by the cytological assessment of broncho-alveolar lavage fluid. Inflammatory parameters are of minor importance. Multiple autoantibody determinations in the course of the disease are not yet helpful. Numerous additional laboratory parameters are of value for investigating pathogenesis, but have not yet been generally introduced into the routine diagnostics of systemic sclerosis.

[Current pathophysiological aspects of systemic sclerosis]

Systemic scleroderma is characterized by a chronic inflammatory process of unknown etiology resulting in an increased deposition of connective tissue proteins in the involved organs. Involvement of the vascular system and the resulting fibrosis lead to atrophy and malfunction of the involved internal organs and the skin. Due to the development of new therapeutic concepts in particular with regard to the vascular involvement, the interaction between the vascular system and the connective tissue moves increasingly into focus. This review describes the major advancemades during recent years for the understanding of the pathophysiology of systemic scleroderma.

Comparison of biochemical markers of bone metabolism in serum and femur aspirates

In 27 patients undergoing arthroscopy of the knee for treatment of meniscal diseases, biochemical markers of bone metabolism were measured in cancellous bone, and levels were compared with concentrations obtained from peripheral blood. Bone-specific alkaline phosphatase, osteocalcin, and collagen Type I metabolites (procollagen Type I N-terminal peptide and carboxy-terminal cross-linked telopeptide) were studied simultaneously in serum and in the distal femur using a radioimmunoassay. Although levels of bone-specific alkaline phosphatase and osteocalcin did not differ between serum and cancellous bone, concentrations of collagen Type I metabolites were elevated significantly in healthy cancellous bone. The close correlations between bone and serum concentrations confirmed accuracy of results obtained from cancellous bone. The mean bone-to-serum ratio for alkaline phosphatase and osteocalcin was 1.1 and 1.2, respectively. Collagen Type I metabolite ratios of 2.2 (for carboxy-terminal cross-linked telopeptide) and 2.3 (for procollagen Type I N-terminal peptide) indicate that these markers are formed locally and then released into the circulation. Bone seems to be a major contributor of collagen Type I metabolites to the serum pool.

Different pattern of collagen cross-links in two sclerotic skin diseases: lipodermatosclerosis and circumscribed scleroderma

Changes in the process of cross-linking of collagen molecules are associated with defects in the biomechanical stability of the extracellular matrix. Fibrosis of skin is characterized by an increase in pyridinolines, which are hydroxylysine aldehyde derived cross-links usually absent in healthy skin. In this study, we analyzed cross-links in lipodermatosclerosis and localized scleroderma to address the question whether all the mature cross-links currently characterized are increased in fibrosis in addition to the increase in pyridinolines. As psoralen plus ultraviolet A treatment leads to clinical improvement of fibrotic plaques in localized scleroderma we analyzed the cross-link content in lesional skin after bath psoralen plus ultraviolet A therapy. In skin from patients with localized scleroderma an increase in the total number of mature cross-links was found to be due to an increase in both pyridinolines and dehydro-histidinohydroxymerodesmosine. The concentration of histidinohydroxylysinonorleucine was unchanged. By contrast, the total number of mature cross-links was decreased in lipodermatosclerosis. This decrease was caused by a decrease of lysine aldehyde derived cross-links (dehydro-histidinohydroxymerodesmosine and histidinohydroxylysinonorleucine), whereas the concentration of pyridinolines increased. A decrease in the content of pyridinolines after bath psoralen plus ultraviolet A treatment was found in six out of nine patients with localized scleroderma, which might reflect a remodeling of the extracellular matrix. Our data provide evidence that sclerosis of skin is associated with either an increase in the number of cross-links per molecule of collagen or a change in the molecular nature of the cross-links formed.

Increased urinary pyridinoline cross-link compounds of collagen in patients with systemic sclerosis and Raynaud's phenomenon

OBJECTIVE

To study concentration changes in collagen degradation markers in patients with diffuse and limited cutaneous systemic sclerosis and patients with scleroderma-related diseases.

METHODS

Pyridinoline cross-link compounds were analysed in urine samples using high-performance liquid chromatography. Samples were analysed for pyridinoline (Pyr), deoxypyridinoline (Dpyr) and soft-tissue pyridinoline (stPyr) in patients with diffuse cutaneous systemic sclerosis (dcSSc, n=23) and limited cutaneous systemic sclerosis (lcSSc, n=48) and in patients with scleroderma-related diseases such as primary Raynaud's phenomenon (pRP, n=16) and secondary Raynaud's phenomenon (sRP, n=14). Healthy controls (n=18) and patients with post-menopausal osteoporosis (OP, n=35) were also investigated.

RESULTS

Urinary Pyr, Dpyr and stPyr concentrations were significantly higher in patients with Raynaud's phenomenon and systemic sclerosis than in healthy controls. The highest concentrations (two to three times greater than in healthy controls) were found in patients with dcSSc. The stPyr concentration was significantly higher in patients with dcSSc than in those with lcSSc, sRP and pRP. No significant difference in stPyr concentration was found between the healthy controls and the OP group, suggesting that stPyr is derived from soft tissues rather than bone. The extent and severity of skin involvement, measured as a skin score, significantly correlated with the concentrations of stPyr and Pyr, whereas no such correlation was found for Dpyr.

CONCLUSIONS

Increased urinary concentrations of piridinoline cross-links reflect alterations in collagen turnover in both Raynaud's phenomenon and systemic sclerosis. The close correlation between stPyr concentration and the extent of skin involvement in systemic sclerosis suggests that this parameter may be useful in monitoring ongoing fibrosis in this disease.

Circulating collagen metabolites in systemic sclerosis. Differences between limited and diffuse form and relationship with pulmonary involvement

OBJECTIVE

To study collagen metabolites in systemic sclerosis (SSc) and their relationship with clinical manifestations of the disease.

METHODS

Forty-eight SSc patients, 13 with a diffuse form (dcSSc), 23 with a limited form (lcSSc) and 12 with suspected SSc not fulfilling the ACR criteria, and 31 healthy controls were examined. Serum concentrations of aminoterminal type III procollagen peptide (PIIINP), aminoterminal and carboxyterminal type I procollagen peptides (PINP and PICP) and cross-linked carboxyterminal telopeptide of collagen I (ICTP) were determined by radioimmunoassay.

RESULTS

Increased serum concentrations of ICTP were found in SSc patients compared with controls. Distinctly higher levels of ICTP were observed in dcSSc than in lcSSc. High serum ICTP was correlated with skin score and acute phase reactants, and with reduced pulmonary function. Serum PIIINP concentration was elevated in both lcSSc and dcSSc.

CONCLUSION

Augmented collagen catabolism accompanies the increased collagen synthesis in SSc. Serum ICTP concentration is a marker of this feature and also reflects clinical severity.

Scleroderma and related disorders: therapeutic aspects

Improvements in management of systemic sclerosis have occurred through a growing understanding of pathogenic events accompanied by advances in diagnosis and assessment, as well as developments in organ-based therapeutics. Unfortunately, disease-modifying therapies of proven efficacy remain elusive and several agents in current use have been shown in well-controlled clinical trials to be of questionable benefit. More positively, there have been advances in the treatment of major visceral complications such as renal crisis, pulmonary fibrosis, pulmonary hypertension, gastrointestinal involvement and in the management of scleroderma-associated Raynaud's phenomenon. Current approaches are reviewed, evidence supporting or refuting the use of putative disease-modifying agents is discussed, and new strategies are described that are currently being considered for this fascinating but complex multisystem connective tissue disease.

Losartan therapy for Raynaud's phenomenon and scleroderma: clinical and biochemical findings in a fifteen-week, randomized, parallel-group, controlled trial

OBJECTIVE

To compare the efficacy and tolerability of losartan, an antagonist of angiotensin II receptor type 1, with nifedipine for the treatment of primary and secondary Raynaud's phenomenon (RP) in a pilot study.

METHODS

In a randomized, parallel-group, controlled trial, patients with primary RP (n = 25) or RP secondary to systemic sclerosis (SSc [scleroderma]; n = 27) were allocated to receive 12 weeks' treatment with either losartan (50 mg/day) or nifedipine (40 mg/day). Primary outcome variables were the severity and frequency of RP episodes and findings on vascular measurements, including thermography and laser Doppler flowmetry. Serum levels of soluble adhesion molecules, endothelin 1, fibrinogen, von Willebrand factor, and procollagen type I N-terminal propeptide (PINP) were also measured.

RESULTS

There was a reduction in the severity of RP episodes following treatment with losartan and with nifedipine, but this effect was greater in the losartan arm of the study (P<0.05): episode frequency was reduced only in the losartan group (P<0.01 versus baseline). Symptomatic improvement was associated with a significant reduction in soluble vascular cell adhesion molecule 1 and PINP (P<0.01). Subgroup analysis suggested that although these biochemical changes occurred mainly in SSc patients, the clinical benefit was greater in the primary RP group.

CONCLUSION

This study confirms the tolerability of short-term treatment of RP with losartan, and our data suggest its clinical benefit. Further evaluation of this drug as a long-term treatment for SSc-associated RP should be considered, since it may have additional disease-modifying potential.