The Renal Resistive Index: A New Biomarker for the Follow-up of Vascular Modifications in Systemic Sclerosis

Role of kinurenic acid in the systemic sclerosis renal involvement

Systemic sclerosis (SSc) subclinical renal vasculopathy is characterized by progressive increase of intrarenal stiffness and reduction of parenchymal thickness due to post ischemic fibrosis secondary to the renal Raynaud phenomenon. Aims of this study were to evaluate kinurenic acid (KYNA) serum level in SSc patients and healthy controls (HC) and to assess the role of KYNA in SSc subclinical nephropathy. Serum level of KYNA was evaluated in 52 SSc patients and 20 HC, matched for sex and age. Renal function was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation to estimate glomerular filtration rate (eGFR) and renal doppler ultrasound was performed to evaluate kidneys' morphology and indices of intrarenal stiffness. The parameters registered were renal longitudinal length, atrophy index (AI), renal sinus, parenchymal thickness, renal resistive index (RRI), pulsatile index (PI) and systolic/diastolic ratio (S/D). SSc patients had lower median value of KYNA than HC [54.43 ng/ml (IQR 44.44-63.64) vs 61.94 ng/ml (IQR 55.23-88.75), p < 0.001]. SSc patients with AI ≥ 0.70 had lower KYNA than SSc patients with AI < 0.70 [47.85 ng/ml (IQR 41.16-59.91) vs 55.5 ng/ml (IQR 49.99-67.33), p < 0.05] and a slightly significant negative linear correlation was found between KYNA and AI (r =  - 0.249, p < 0.05). SSc patient with RRI ≥ 0.70 had higher KYNA than SSc patients with RRI < 0.70 [58.25 ng/ml (IQR 50.49-69.68) vs 50.07 ng/ml (IQR 42.70-56.31), p < 0.05] and a significant positive correlation was found between KYNA and RRI (r = 0.318, p < 0.05). KYNA may be used as a marker to evaluate the renal involvement in SSc patients.

Evaluation of hypertension in systemic sclerosis and systemic lupus erythematosus overlap

Patients with systemic sclerosis and systemic lupus erythematosus serologies present a unique challenge to the clinician when hypertension is detected in the outpatient setting. Treatment choices for non-renal crisis hypertension are different for systemic sclerosis versus systemic lupus erythematosus. Urgent laboratory studies and, in the presence of certain symptoms, imaging assessment are indicated in systemic sclerosis and systemic lupus erythematosus overlap patients with systemic hypertension. Long-term assessment of systemic hypertension may be enhanced by advances in non-contrast imaging that serve as valuable biomarkers for progressive vasculopathy. In this review, the diagnostic approach to systemic sclerosis and systemic lupus erythematosus overlap patients presenting with hypertension is discussed.

Latent trajectory modelling of pulmonary artery pressure in systemic sclerosis: a retrospective cohort study

OBJECTIVES

To visualise the trajectories of pulmonary arterial pressure (PAP) in systemic sclerosis (SSc) and identify the clinical phenotypes for each trajectory, by applying latent trajectory modelling for PAP repeatedly estimated by echocardiography.

METHODS

This was a multicentre, retrospective cohort study conducted at four referral hospitals in Kyoto, Japan. Patients with SSc who were treated at study sites between 2008 and 2021 and who had at least three echocardiographic measurements of systolic PAP (sPAP) were included. A group-based trajectory model was applied to the change in sPAP over time, and patients were classified into distinct subgroups that followed similar trajectories. Pulmonary hypertension (PH)-free survival was compared for each trajectory. Multinomial logistic regression analysis was performed for baseline clinical characteristics associated with trajectory assignment.

RESULTS

A total of 236 patients with 1097 sPAP measurements were included. We identified five trajectories: rapid progression (n=9, 3.8%), early elevation (n=30, 12.7%), middle elevation (n=54, 22.9%), late elevation (n=24, 10.2%) and low stable (n=119, 50.4%). The trajectories, in the listed order, showed progressively earlier elevation of sPAP and shorter PH-free survival. In the multinomial logistic regression analysis with the low stable as a reference, cardiac involvement was associated with rapid progression, diffuse cutaneous SSc was associated with early elevation and anti-centromere antibody was associated with middle elevation; older age of onset was associated with all three of these trajectories.

CONCLUSION

The pattern of changes in PAP over time in SSc can be classified into five trajectories with distinctly different clinical characteristics and outcomes.

Renal Disease and Systemic Sclerosis: an Update on Scleroderma Renal Crisis

Scleroderma renal crisis (SRC) is a life-threatening complication of systemic sclerosis (SSc) with a mortality of 20% at 6 months. Once the leading cause of mortality in scleroderma (SSc), it remains a serious complication, often necessitating level three care for patients affected. Whilst renal outcomes have significantly improved following the advent of angiotensin-converting enzyme inhibitor (ACEi) therapy, SRC remains a precarious challenge for clinicians, due to lack of preventative measures and the fact that patients can rapidly decline despite best medical management. Large cohort studies spanning decades have allowed clear identification of phenotypes particularly at risk of developing SRC thus allowing enhanced monitoring and early identification in those individuals. Novel urinary biomarkers for renal disease in SSc may offer a new window for early identification of SRC patients and response to treatment. Multiple studies have demonstrated increased activity of complement pathways in SRC with some anecdotal cases exhibiting serological response to treatment with eculizumab where ACEi and therapeutic plasma exchange (TPE) were not successful. Endothelin-1 blockade, a therapeutic strategy in other SSc vasculopathies, has shown potential as a target but clinical trials are yet to show a clear treatment benefit. Clear guidelines for the management of SRC are in place to standardise care and facilitate early collaboration between rheumatology and renal physicians. Outcomes following renal transplant have improved but the mortality of SRC remains high, indicating the need for continued exploration of the mechanisms precipitating and exacerbating SRC in order to develop novel therapies.

Estimated glomerular filtration rate is a marker of mortality in the European Scleroderma Trials and Research Group (EUSTAR) database

OBJECTIVES

Study aim was to evaluate estimated glomerular filtration rate (eGFR), its association with clinical disease and its predictive ability with mortality in systemic sclerosis (SSc) patients from the European Scleroderma Trials and Research Group (EUSTAR) database.

METHODS

SSc patients from the EUSTAR database with available items for calculation of eGFR at baseline visit and with a second follow-up visit were included. A cut-off of 60 ml/min was chosen for all SSc patients and 30 ml/min for scleroderma renal crisis (SRC). Cox regression and competing risk analysis were performed to evaluate the role of eGFR as predictive factor of mortality.

RESULTS

3650 SSc patients were included. Mean serum level of creatinine and eGFR were 0.8 mg/dl (IQR 0.6-0.9) and 86.6 ± 23.7 ml/min. The eGFR was significantly lower in patients with pulmonary hypertension. Overall survival (OS) was significantly reduced in SSc patients with eGFR <60 ml/min respect to patients with eGFR ≥ 60 ml/min [OS at five years 0.763 (CI 95%: 0.700-0.814) vs 0.903 (CI 95%: 0.883-0.919 p< 0.001)]. In multivariable analysis, OS was associate with male gender (p< 0.01), systolic pulmonary arterial pressure (sPAP) (p< 0.001) and eGFR (p< 0.001). Cumulative incidence of deaths due to SSc was associate with increased sPAP (p< 0.001) and reduced eGFR (p< 0.05). OS at five years of 53 SRC patients was not significantly different in SSc patients with eGFR > 30 ml/min or eGFR < 30 ml/min.

CONCLUSION

eGFR represents a predictive risk factor of overall survival in SSc. The eGFR is not a risk factor for death in SRC.

Renal resistive index in IgA nephropathy and renal scleroderma vasculopathy

BACKGROUND

Renal Ultra-Sound (US) and Doppler US provide measurements which reflect changes in renal and systemic haemodynamic. The renal resistive index (RRI), obtained through the Doppler spectrum analysis of renal small arteries, is altered in several pathologic conditions. Glomerulonephritis cause minor RRI changes, while renal scleroderma vasculopathy (RSV) leads to significant RRI modifications. The aim of our study was to assess RRI in IgA nephropathy (IgAN) and RSV in a retrospective observational study and to investigate determinants of the RRI in these groups of patients.

METHODS

We enrolled 61 IgAN patients [23 female, median age 41 (33-58) years] and 80 SSc patients [71 female, median age 52 (43-60) years]. RRI was evaluated in all patients at the time of enrolment. Laboratory tests and clinical assessment were evaluated in all patients.

RESULTS

IgAN patients showed lower RRI values than RSV patients [0.70 (0.65-0.73) vs 0.66 (0.62-0.72), p < 0.01], while no significant difference in longitudinal length was observed. Median age was significantly lower in IgAN patients than in RSV patients [41 (33-58) vs 52 (43-60), p < 0.05] while IgAN patients showed a higher prevalence of high blood pressure than RSV patients (39.3% vs 13.8%, p < 0.01). The multiple regression analysis, weighted for age, showed that RRI inversely correlates with estimated glomerular filtration rate (β coefficient = -0.524, p < 0.0001).

CONCLUSION

Higher RRI were found in RSV patients than IgAN patients. IgAN is characterized mainly by glomerular injury, not leading to major RRI changes.