Serum uric acid as a marker of disease risk, severity, and survival in systemic sclerosis-related pulmonary arterial hypertension

Association of serum uric acid with right cardiac chamber remodeling assessed by cardiovascular magnetic resonance feature tracking in patients with connective tissue disease

Background

Right cardiac chamber remodeling is widespread in patients with connective tissue disease (CTD). Serum uric acid (SUA) is considered a potential independent risk factor for cardiovascular disease, and elevated SUA levels are often observed in patients with CTD. The correlation between SUA levels and right cardiac chamber remodeling remains unclear. This study investigated the association of SUA with right cardiac chamber remodeling as assessed by cardiac magnetic resonance feature-tracking (CMR-FT) in CTD patients.

Methods and results

In this cross-sectional study, a total of 104 CTD patients and 52 age- and sex-matched controls were consecutively recruited. All individuals underwent CMR imaging, and their SUA levels were recorded. The patients were divided into three subgroups based on the tertiles of SUA level in the present study. CMR-FT was used to evaluate the right atrial (RA) longitudinal strain and strain rate parameters as well as right ventricular (RV) global systolic peak strain and strain rate in longitudinal and circumferential directions for each subject. Univariable and multivariable linear regression analyses were used to explore the association of SUA with RV and RA strain parameters. Compared with the controls, the CTD patients showed significantly higher SUA levels but a lower RV global circumferential strain (GCS) and RA phasic strain parameters (all p < 0.05), except the RA booster strain rate. RV GCS remained impaired even in CTD patients with preserved RV ejection fraction. Among subgroups, the patients in the third tertile had significantly impaired RV longitudinal strain (GLS), RV GCS, and RA reservoir and conduit strain compared with those in the first tertile (all p < 0.05). The SUA levels were negatively correlated with RV GLS and RV GCS as well as with RA reservoir and conduit strain and strain rates (the absolute values of β were 0.250 to 0.293, all P < 0.05). In the multivariable linear regression analysis, the SUA level was still an independent determinant of RA conduit strain (β = -0.212, P = 0.035) and RV GCS (β = 0.207, P = 0.019).

Conclusion

SUA may be a potential risk factor of right cardiac chamber remodeling and is independently associated with impaired RA conduit strain and RV GCS in CTD patients.

Metabolic profiling of in vivo right ventricular function and exercise performance in pulmonary arterial hypertension

Right ventricular (RV) adaptation is the principal determinant of outcomes in pulmonary arterial hypertension (PAH), however, RV function is challenging to assess. RV responses to hemodynamic stressors are particularly difficult to interrogate without invasive testing. This study sought to identify metabolomic markers of in vivo right ventricular function and exercise performance in PAH. Consecutive subjects with PAH (n = 23) underwent rest and exercise right heart catheterization with multibeat pressure volume loop analysis. Pulmonary arterial blood was collected at rest and during exercise. Mass spectrometry-based targeted metabolomics were performed, and metabolic associations with hemodynamics and comprehensive measures of RV function were determined using sparse partial least squares regression. Metabolite profiles were compared with N-terminal prohormone of B-type natriuretic peptide (NT-proBNP) measurements for accuracy in modeling ventriculo-arterial parameters. Thirteen metabolites changed in abundance with exercise, including metabolites reflecting increased arginine bioavailability, precursors of catecholamine and nucleotide synthesis, and branched-chain amino acids. Higher resting arginine bioavailability predicted more favorable exercise hemodynamics and pressure-flow relationships. Subjects with more severe PAH augmented arginine bioavailability with exercise to a greater extent than subjects with less severe PAH. We identified relationships between kynurenine pathway metabolism and impaired ventriculo-arterial coupling, worse RV diastolic function, lower RV contractility, diminished RV contractility with exercise, and RV dilation with exercise. Metabolite profiles outperformed NT-proBNP in modeling RV contractility, diastolic function, and exercise performance. Specific metabolite profiles correspond to RV functional measurements only obtainable via invasive pressure-volume loop analysis and predict RV responses to exercise. Metabolic profiling may inform discovery of RV functional biomarkers.NEW & NOTEWORTHY In this cohort of patients with pulmonary arterial hypertension (PAH), we investigate metabolomic associations with comprehensive right ventricular (RV) functional measurements derived from multibeat RV pressure-volume loop analysis. Our results show that tryptophan metabolism, particularly the kynurenine pathway, is linked to intrinsic RV function and PAH pathobiology. Findings also highlight the importance of arginine bioavailability in the cardiopulmonary system's response to exercise stress. Metabolite profiles selected via unbiased analysis outperformed N-terminal prohormone of B-type natriuretic peptide (NT-proBNP) in predicting load-independent measures of RV function at rest and cardiopulmonary system performance under stress. Overall, this work suggests the potential for select metabolites to function as disease-specific biomarkers, offers insights into PAH pathobiology, and informs discovery of potentially targetable RV-centric pathways.

Association between serum uric acid/serum creatinine ratios and lung function in the general American population: National Health and Nutrition Examination Survey (NHANES), 2007-2012

BACKGROUND

Assessment of lung function is essential for the early screening chronic airway diseases (CADs). Nevertheless, it is still not widely used for early diagnosing CADs in epidemiological or primary care settings. Thus, we used data from the US National Health and Nutrition Examination Survey (NHANES) to discuss the relationship between the serum uric acid/serum creatinine (SUA/SCr) ratio and lung function in general adults to gain the role of SUA/SCr in early assessment of lung function abnormalities.

METHODS

From 2007 to 2012 NHANES, a total of 9569 people were included in our study. Using the regression model, XGBoost algorithm model, generalised linear model and two-piecewise linear regression model, the link between the SUA/SCr ratio and lung function was investigated.

RESULTS

After correcting for confounding variables, the data revealed that forced vital capacity (FVC) declined by 47.630 and forced expiratory volume in one second (FEV1) decreased by 36.956 for each additional unit of SUA/SCr ratio. However, there was no association between SUA/SCr and FEV1/FVC. In the XGBoost model of FVC, the top five most important were glycohaemoglobin, total bilirubin, SUA/SCr, total cholesterol and aspartate aminotransferase, whereas in FEV1, were glycohaemoglobin, total bilirubin, total cholesterol, SUA/SCr and serum calcium. In addition, we determined the linear and inverse association between SUA/SCr ratio and FVC or FEV1 by constructing a smooth curve.

CONCLUSIONS

In the general American population, the SUA/SCr ratio is inversely linked with FVC and FEV1, but not with FEV1/FVC, according to our research. Future studies should investigate the impact of SUA/SCr on lung function and identify possible mechanisms of action.

Serum Biomarkers in Connective Tissue Disease-Associated Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a life-threatening complication of connective tissue diseases (CTDs) characterised by increased pulmonary arterial pressure and pulmonary vascular resistance. CTD-PAH is the result of a complex interplay among endothelial dysfunction and vascular remodelling, autoimmunity and inflammatory changes, ultimately leading to right heart dysfunction and failure. Due to the non-specific nature of the early symptoms and the lack of consensus on screening strategies-except for systemic sclerosis, with a yearly transthoracic echocardiography as recommended-CTD-PAH is often diagnosed at an advanced stage, when the pulmonary vessels are irreversibly damaged. According to the current guidelines, right heart catheterisation is the gold standard for the diagnosis of PAH; however, this technique is invasive, and may not be available in non-referral centres. Hence, there is a need for non-invasive tools to improve the early diagnosis and disease monitoring of CTD-PAH. Novel serum biomarkers may be an effective solution to this issue, as their detection is non-invasive, has a low cost and is reproducible. Our review aims to describe some of the most promising circulating biomarkers of CTD-PAH, classified according to their role in the pathophysiology of the disease.

Apelin-17 to diagnose idiopathic pulmonary arterial hypertension: A biomarker study

Background: NT-proBNP and GDF-15 are established blood-derived biomarkers for risk assessment in pulmonary hypertension (PH), despite limited sensitivity and specificity. Apelin has a crucial function in endothelial homeostasis, thus it might represent a new biomarker for PH. However, there are numerous circulating apelin isoforms, and their potential role in this setting is unknown. This study evaluated different apelin isoforms in PH patients and prospectively evaluated the role of apelin-17 in comparison with NT-proBNP and GDF-15 as diagnostic marker in idiopathic pulmonary arterial hypertension (IPAH). Methods: Based on our pilot study, we performed a power calculation for apelin-13, apelin-17, apelin-36, as predictor of IPAH vs healthy controls. Apelin-17 provided the best discriminatory power, and accordingly, we enrolled n = 31 patients with IPAH and n = 31 matched healthy controls in a prospective study. NT-proBNP and GDF-15 was determined in all patients. ROC curve analysis was performed to assess the diagnostic value of the markers and their combinations. Results: Apelin-17, NT-proBNP, and GDF-15 were significantly elevated in IPAH patients as compared to controls (p < .001). Apelin-17 detected IPAH with a sensitivity of 68% and a specificity of 93% at a cut-off value of >1,480 pg/ml (AUC 0.86, 95%CI:0.76-0.95) as compared to GDF-15 (sensitivity 86%; specificity 72%, AUC 0.81 (95%CI:0.7-0.92)) and NT-proBNP (sensitivity 86%; specificity 72% (AUC 0.85, 95%CI:0.75-0.95)). Combinations of these markers could be used to increase either specificity or sensitivity. Conclusion: Apelin-17 appears to be suitable blood derived diagnostic marker for idiopathic pulmonary arterial hypertension.

The role of tolvaptan in pulmonary hypertension: A retrospective study

Pulmonary hypertension (PH) is a severe form of pulmonary vascular disease that can lead to right heart failure (RHF). Nearly 2-thirds of patients with PH die within 5 years. Studies suggest that a new diuretic medication, called tolvaptan (TLV), can be used to treat PH. However, there is still insufficient evidence to confirm its effectiveness. Therefore, we investigated the role of TLV in patients with PH. This retrospective study included 73 patients with PH hospitalized in Shanghai Pulmonary Hospital between November 2019 and March 2022. All patients received 7.5 to 15.0 mg of TLV for 3 to 21 days starting at admission, in addition to targeted drugs and traditional diuretic therapy. The outcomes included the blood pressure, urine and water intake volumes, electrolyte concentrations, and renal, liver, and cardiac function indexes before and after TLV treatment. In addition, we assessed the clinical symptoms and adverse reactions during the treatment. After TLV treatment, the water intake and urine volumes significantly increased, and body weight, diastolic blood pressure (DBP) and mean arterial pressure significantly decreased. Total bilirubin, direct bilirubin, N-terminal pro-brain natriuretic peptide, and serum uric acid (UA) levels after TLV treatment were significantly lower than before treatment. After TLV treatment, dyspnea significantly improved in 71 of 73 patients, and lower limb edema disappeared in 42 of 53 patients. No obvious adverse reactions occurred during the TLV treatment period. These results suggest that adding TLV to targeted drug and traditional diuretic therapies is effective for patients with PH. However, more data are required to support these findings.

Plasma Cell-Free DNA Predicts Survival and Maps Specific Sources of Injury in Pulmonary Arterial Hypertension

BACKGROUND

Cell-free DNA (cfDNA) is a noninvasive marker of cellular injury. Its significance in pulmonary arterial hypertension (PAH) is unknown.

METHODS

Plasma cfDNA was measured in 2 PAH cohorts (A, n=48; B, n=161) and controls (n=48). Data were collected for REVEAL 2.0 (Registry to Evaluate Early and Long-Term PAH Disease Management) scores and outcome determinations. Patients were divided into the following REVEAL risk groups: low (≤6), medium (7-8), and high (≥9). Total cfDNA concentrations were compared among controls and PAH risk groups by 1-way analysis of variance. Log-rank tests compared survival between cfDNA tertiles and REVEAL risk groups. Areas under the receiver operating characteristic curve were estimated from logistic regression models. A sample subset from cohort B (n=96) and controls (n=16) underwent bisulfite sequencing followed by a deconvolution algorithm to map cell-specific cfDNA methylation patterns, with concentrations compared using t tests.

RESULTS

In cohort A, median (interquartile range) age was 62 years (47-71), with 75% female, and median (interquartile range) REVEAL 2.0 was 6 (4-9). In cohort B, median (interquartile range) age was 59 years (49-71), with 69% female, and median (interquartile range) REVEAL 2.0 was 7 (6-9). In both cohorts, cfDNA concentrations differed among patients with PAH of varying REVEAL risk and controls (analysis of variance P≤0.002) and were greater in the high-risk compared with the low-risk category (P≤0.002). In cohort B, death or lung transplant occurred in 14 of 54, 23 of 53, and 35 of 54 patients in the lowest, middle, and highest cfDNA tertiles, respectively. cfDNA levels stratified as tertiles (log-rank: P=0.0001) and REVEAL risk groups (log-rank: P<0.0001) each predicted transplant-free survival. The addition of cfDNA to REVEAL improved discrimination (area under the receiver operating characteristic curve, 0.72-0.78; P=0.02). Compared with controls, methylation analysis in patients with PAH revealed increased cfDNA originating from erythrocyte progenitors, neutrophils, monocytes, adipocytes, natural killer cells, vascular endothelium, and cardiac myocytes (Bonferroni adjusted P<0.05). cfDNA concentrations derived from erythrocyte progenitor cells, cardiac myocytes, and vascular endothelium were greater in patients with PAH with high-risk versus low-risk REVEAL scores (P≤0.02).

CONCLUSIONS

Circulating cfDNA is elevated in patients with PAH, correlates with disease severity, and predicts worse survival. Results from cfDNA methylation analyses in patients with PAH are consistent with prevailing paradigms of disease pathogenesis.

Association between Routine Laboratory Parameters and the Severity and Progression of Systemic Sclerosis

(1) Background: Systemic sclerosis (SSc) is a heterogeneous connective tissue disease with a high mortality and morbidity rate. Identification of biomarkers that can predict the evolution of SSc is a key factor in the management of patients. The aim of this study was to assess the association of routine laboratory parameters, widely used in practice and easily available, with the severity and progression of SSc. (2) Methods: In this retrospective monocentric cohort study, 372 SSc patients were included. We gathered clinical and laboratory data including routine laboratory parameters: C-reactive-protein (CRP), erythrocyte sedimentation rate (ESR), complete blood count, serum sodium and potassium levels, creatinin, urea, ferritin, albumin, uric acid, N-terminal pro-brain natriuretic peptide (NTproBNP), serum protein electrophoresis, and liver enzymes. Associations between these routine laboratory parameters and clinical presentation and outcome were assessed. (3) Results: Median (interquartile range) age was 59.0 (50.0; 68.0) years. White blood cell, monocyte, and neutrophil absolute counts were significantly higher in patients with diffuse cutaneous SSc and with interstitial lung disease (ILD) (p < 0.001). CRP was significantly higher in patients with ILD (p < 0.001). Hemoglobin and ferritin were significantly lower in patients with pulmonary hypertension (PH) including pulmonary arterial hypertension and ILD associated PH (p = 0.016 and 0.046, respectively). Uric acid and NT pro BNP were significantly higher in patients with PH (<0.001). Monocyte count was associated with ILD progression over time. (4) Conclusions: Overall, our study highlights the association of routine laboratory parameters used in current practice with the severity and progression of SSc.

Artificial Intelligence-Enabled Electrocardiogram Improves the Diagnosis and Prediction of Mortality in Patients With Pulmonary Hypertension

BACKGROUND

Pulmonary hypertension is a disabling and life-threatening cardiovascular disease. Early detection of elevated pulmonary artery pressure (ePAP) is needed for prompt diagnosis and treatment to avoid detrimental consequences of pulmonary hypertension.

OBJECTIVES

This study sought to develop an artificial intelligence (AI)-enabled electrocardiogram (ECG) model to identify patients with ePAP and related prognostic implications.

METHODS

From a hospital-based ECG database, the authors extracted the first pairs of ECG and transthoracic echocardiography taken within 2 weeks of each other from 41,097 patients to develop an AI model for detecting ePAP (PAP > 50 mm Hg by transthoracic echocardiography). The model was evaluated on independent data sets, including an external cohort of patients from Japan.

RESULTS

Tests of 10-fold cross-validation neural-network deep learning showed that the area under the receiver-operating characteristic curve of the AI model was 0.88 (sensitivity 81.0%; specificity 79.6%) for detecting ePAP. The diagnostic performance was consistent across age, sex, and various comorbidities (diagnostic odds ratio >8 for most factors examined). At 6-year follow-up, the patients predicted by the AI model to have ePAP were independently associated with higher cardiovascular mortality (HR: 3.69). Similar diagnostic performance and prediction for cardiovascular mortality could be replicated in the external cohort.

CONCLUSIONS

The ECG-based AI model identified patients with ePAP and predicted their future risk for cardiovascular mortality. This model could serve as a useful clinical test to identify patients with pulmonary hypertension so that treatment can be initiated early to improve their survival prognosis.

Exercise-induced pulmonary hypertension in HFpEF and HFrEF: Different pathophysiologic mechanism behind similar functional impairment

AIMS

Pathophysiological mechanisms behind cardio-pulmonary impairment in heart failure (HF) with reduced (HFrEF) and preserved (HFpEF) ejection fraction are likely different. We analysed them using combined cardiopulmonary-exercise stress echocardiography (CPET-ESE).

METHODS

We matched 1:1 subjects with HFrEF (n = 90) and HFpEF (n = 90) for age, sex, body mass index (BMI), peak oxygen consumption, and minute ventilation/carbon dioxide production slope. All patients underwent a symptom-limited graded ramp bicycle CPET-ESE compared with 40 age-, sex- and BMI-matched healthy controls.

RESULTS

During a median follow-up of 25 months, we observed 22 deaths and 80 HF hospitalisations, with similar distribution between HFpEF and HFrEF. Compared with HFrEF, HFpEF had a higher prevalence of metabolic syndrome (p = 0.02) with higher levels of high-sensitivity C-reactive protein and uric acid (p < 0.01). The multipoint mean pulmonary artery pressure/cardiac output (mPAP/CO) slope showed equally increased values in HFrEF and HFpEF (3.5 ± 1.8 and 3.7 ± 1.5 mmHg/L/min) compared with controls (1.8 ± 1.1 mmHg/L/min; p < 0.0001). During exercise, HFpEF displayed more adverse interaction of right ventricle-pulmonary artery (RV-PA; tricuspid annular plane systolic excursion/systolic pulmonary artery pressure: 0.40 ± 0.2 vs 0.47 ± 0.2 mm/mmHg in HFrEF; p < 0.01) and left atrium-left ventricle (LA-LV; LA reservoir strain/LV global longitudinal strain: 1.5 ± 0.8 vs 2.2 ± 1.1 in HFrEF; p < 0.01). The latter were independent predictors of mPAP/CO slope, along with hs-CRP (adjusted R2: 0.21; p < 0.0001).

CONCLUSION

Despite similar disease severity, HFpEF and HFrEF show different pathophysiological mechanisms. HFpEF is characterised by a worse LA-LV and RV-PA interaction than HFrEF, with more prevalent low-grade systemic inflammation. In HFpEF, these features may have a role in exercise-induced pulmonary hypertension.

The Prognostic Impact of Serum Uric Acid on Disease Severity and 5-Year Mortality in Patients With Idiopathic Pulmonary Artery Hypertension

Background

Serum uric acid (UA) has long been identified as a prognostic factor of adverse outcomes in pulmonary hypertension. However, there remains a paucity of evidence on patients with idiopathic pulmonary artery hypertension (IPAH) in the era of targeted drug therapy. This study aims to explore the impact of serum UA levels on the disease severity and mortality in patients with IPAH.

Methods

Consecutive patients diagnosed with IPAH were enrolled, from which UA levels at baseline and the first follow-up were collected. Patients were divided into groups of “hyperuricemia,” which is defined as serum UA level ≥357 μmol/L in women and ≥420 μmol/L in men, and otherwise “normouricemia.” The potential relationship between UA and hemodynamics at right heart catheterization was investigated. Associations between UA and survival were evaluated by Kaplan-Meier analysis and Cox proportional hazard modeling.

Results

Of 207 patients with IPAH, 121 (58.5%) had hyperuricemia. Higher serum UA levels were associated with lower cardiac index (r = 0.47, p < 0.001) and higher pulmonary vascular resistance (r = 0.36, p < 0.001). During a median follow-up of 34 months, there were 32 deaths recorded, accounting for a 15.5% mortality rate. Patients with hyperuricemia had a significantly lower survival rate than those with normouricemia (log-rank test, p = 0.002). Hyperuricemia at baseline was independently associated with a 2.6-fold increased risk of 5-year death, which was consistent across different subgroups, especially in females and those aged ≥30 years (each p < 0.05). Individuals with higher variability in UA had a higher mortality than those with stable UA (log-rank test, p = 0.024).

Conclusions

Baseline hyperuricemia and high variability in serum UA at first follow-up were related to a higher rate of 5-year mortality in patients with IPAH. Closely detecting the UA levels may aid in the early recognition of IPAH patients at higher mortality risk.

Association Between Uric Acid and Worsening Peripheral Microangiopathy in Systemic Sclerosis

Objective: The key element in the pathogenesis of systemic sclerosis (SSc) is microcirculatory changes in several vascular beds. Uric acid is associated with endothelial dysfunction and therefore, microvascular damage. The aim of this study was to examine the association between uric acid (UA) and peripheral microvascular involvement in patients with SSc. Methods: We included consecutive, consenting patients with SSc. Serum UA, urea and creatinine were measured, and glomerular filtration rate (GFR) was calculated with CKD-EPI. All participants underwent nailfold video-capillaroscopy (NVC) to evaluate the microcirculation. Results: A total of 64 patients (95.3% women) were included in the study. UA levels were significantly associated with the number of avascular areas (r = 0.290; p = 0.020), whereas no correlation was shown for the GFR (r = -0.065; p = 0.609). A significant trend of UA in the three capillaroscopic patterns was shown (3.90 ± 1.52 vs. 4.15 ± 0.98 vs. 5.38 ± 2.26; for early, active, and late patterns respectively, p = 0.028). Multivariate analysis showed that male gender (β = 3.049; 95% CI = 0.997-5.101) and UA (β = 0.352; 95% CI = 0.117-0.588) were independently associated with the number of avascular areas. Conclusion: These data suggest that UA levels are significantly associated with the capillaroscopic patterns, reflecting a progressive microvasculopathy.

Ventricular mass discriminates pulmonary arterial hypertension as redefined at the Sixth World Symposium on Pulmonary Hypertension

Cardiac magnetic resonance (CMR) measures of right ventricular (RV) mass, volumes, and function have diagnostic and prognostic value in pulmonary arterial hypertension (PAH). We hypothesized that RV mass-based metrics would discriminate incident PAH as redefined by the lower mean pulmonary arterial pressure (mPAP) threshold of >20 mmHg at the Sixth World Symposium on Pulmonary Hypertension (6th WSPH). Eighty-nine subjects with suspected PAH underwent CMR imaging, including 64 subjects with systemic sclerosis (SSc). CMR metrics, including RV and left ventricular (LV) mass, were measured. All subjects underwent right heart catheterization (RHC) for assessment of hemodynamics within 48 h of CMR. Using generalized linear models, associations between CMR metrics and PAH were assessed, the best subset of CMR variables for predicting PAH were identified, and relationships between mass-based metrics, hemodynamics, and other predictive CMR metrics were examined. Fifty-nine subjects met 6th WSPH criteria for PAH. RV mass metrics, including ventricular mass index (VMI), demonstrated the greatest magnitude difference between subjects with versus without PAH. Overall and in SSc, VMI and RV mass measured by CMR were among the most predictive variables discriminating PAH at RHC, with areas under the receiver operating characteristic curve 0.86 and 0.83. respectively. VMI increased linearly with pulmonary vascular resistance and with mPAP in PAH, including in lower ranges of mPAP associated with mild PAH. VMI ≥ 0.37 yielded a positive predictive value of 90% for discriminating PAH. RV mass metrics measured by CMR, including VMI, discriminate incident, treatment-naïve PAH as defined by 6th WSPH criteria.

The expression profiling of microRNA in systemic sclerosis-associated pulmonary arterial hypertension

Background

The role of microRNAs (miRNAs) in the pathogenesis of systemic sclerosis-associated pulmonary arterial hypertension (SSc-PAH) remains to be fully elucidated. This study evaluated the expression profile of miRNAs in the lung tissue of patients with SSc-PAH.

Methods

Lung tissue samples were collected from 3 SSc-PAH patients and 4 healthy controls. A small RNA high throughput sequence approach was used for screening the differentially expressed miRNAs in the lung tissue samples. Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to validate 4 highly significant differentially expressed miRNAs. Gene Ontology and KEGG (Kyoto Encyclopedia of Genes and Genomes) enrichment analysis for mRNAs were performed using the R package clusterProfiler software.

Results

A total of 82 upregulated miRNAs and 35 downregulated miRNAs were detected in the lung tissues of patients with SSc-PAH compared with healthy controls. GO enrichment analysis demonstrated that the upregulated target genes were closely involved in biological processes such as nervous system development, anatomical structure morphogenesis, system development, cellular macromolecule metabolic processes, and cellular processes. The downregulated target genes were involved in the plasma membrane bound cell projection morphogenesis and the regulation of macromolecule metabolic processes. The KEGG enrichment analysis showed that the upregulated genes were associated with important pathways involved in cancer biology, and the target genes of the downregulated miRNAs were involved in axon guidance. High throughput sequencing and qRT-PCR revealed that hsa-miR-205-5p and hsa-miR-539-3p were differentially expressed in SSc-PAH tissue. The target genes of hsa-miR-205-5p and hsa-miR-539-3p, IRF1and ADCYAP1, respectively, were verified using the high throughput dataset GSE48149.

Conclusions

miRNAs may play an important role in the pathogenesis of SSc-PAH, and hsa-miR-205-5p and hsa-miR-539-3p may be potential therapeutic targets in patients with SSc-PAH.

Serum and pulmonary uric acid in pulmonary arterial hypertension

Previous studies have suggested an association between uric acid (UA) and the severity of pulmonary arterial hypertension (PAH), but it is unknown whether UA contributes to disease pathogenesis.The aim of this study was to determine the prognostic value of circulating UA in the era of current management of PAH and to investigate the role of UA in pulmonary vascular remodelling.Serum UA levels were determined in idiopathic, heritable or anorexigen PAH at baseline and first re-evaluation in the French Pulmonary Hypertension Network. We studied protein levels of xanthine oxidase (XO) and the voltage-driven urate transporter 1 (URATv1) in lungs of control and PAH patients and of monocrotaline (MCT) and Sugen/hypoxia (SuHx) rats. Functional studies were performed using human pulmonary artery smooth muscle cells (PA-SMCs) and two animal models of pulmonary hypertension (PH).High serum UA levels at first follow-up, but not at baseline, were associated with a poor prognosis. Both the generating enzyme XO and URATv1 were upregulated in the wall of remodelled pulmonary arteries in idiopathic PAH patients and MCT and SuHx rats. High UA concentrations promoted a mild increase in cell growth in idiopathic PAH PA-SMCs, but not in control PA-SMCs. Consistent with these observations, oxonic acid-induced hyperuricaemia did not aggravate MCT-induced PH in rats. Finally, chronic treatment of MCT and SuHx rats with benzbromarone mildly attenuated pulmonary vascular remodelling.UA levels in idiopathic PAH patients were associated with an impaired clinical and haemodynamic profile and might be used as a non-invasive indicator of clinical prognosis during follow-up. Our findings also indicate that UA metabolism is disturbed in remodelled pulmonary vascular walls in both experimental and human PAH.

Pulmonary hypertension in systemic sclerosis: diagnosis by systematic screening and prognosis after three years follow-up

Background

Systemic sclerosis (SSc) is a rare disease, and the presence of pulmonary hypertension can be a determining factor in prognosis. The aim of this study was to evaluate the diagnosis, profile, and prognosis of systemic sclerosis pulmonary hypertension (SSc-PH) diagnosed by systematic screening in a Brazilian population.

Methods

A cohort of SSc patients underwent systematic screening for SSc-PH. Patients were referred for right heart catheterization (RHC) according to transthoracic echocardiogram or a combination of diagnostic tools. The clinical, immunological, and hemodynamic features and prognosis after 3 years were evaluated.

Results

Twenty patients underwent RHC. SSc pulmonary arterial hypertension (SSc-PAH) was the most common group of SSc-PH. These patients had long disease duration, high urate levels and highly elevated mean pulmonary arterial pressure (mPAP) and peripheral vascular resistance (PVR) on hemodynamics. Patients with mPAP > 20– < 25 mmHg had hemodynamic features of intermediate disease. Patients with SSc-PH associated to interstitial lung disease (SSc-ILD-PH) had signs of vasculopathy on hemodynamics. In patients with no-SSc-PH, the survival at 1, 2, and 3 years was 96%, 92% and 92%, respectively and in patients with SSc-PH it was 86.7%, 60% and 53.3%, respectively.

Conclusions

Patients identified with SSc-PAH and SSc-ILD-PH in our screening had severe clinical and hemodynamic features. Mortality remains high in SSc-PH but was more related to Bo-PAH and SSc-ILD-PH, while in SSc-PAH, the prognosis was better. Trial registration: Current Controlled Trials ISRCTN 72968188, July 8th, 2021. Retrospectively registered.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01618-z.

Candidate Genes Identified in Systemic Sclerosis-Related Pulmonary Arterial Hypertension Were Associated with Immunity, Inflammation, and Cytokines

Background

Pulmonary complications of systemic sclerosis (SSc), including pulmonary arterial hypertension (PAH), are the leading causes of patient death. However, the precise molecular mechanisms of its etiology are unclear. This study's objective was to identify the candidate genes involved in the progression of SSc-PAH and investigate the genes' function.

Methods

The gene expression profiles of GSE33463 were obtained from the Gene Expression Omnibus (GEO) database. A free-scale gene coexpression network was constructed using the weighted gene coexpression network analysis (WGCNA) to explore the association between gene sets and clinical features and identify candidate biomarkers. Then, gene ontology analysis was performed. A second dataset was used, GSE19617, to validate the hub genes. The verified hub genes' potential function was further explored using gene set enrichment analysis (GSEA).

Results

Through average link-level clustering, a total of seven modules were classified. A total of 938 hub genes were identified in the key module, and the key module's function mainly enriched was related to chemokine activities. Subsequently, four candidate genes, BTG3, CCR2, RAB10, and TMEM60, were filtered. The expression levels of these four hub genes were consistent in the GSE19617 and GSE33463 datasets. We plotted the ROC curve of the hub genes (all AUC > 0.70). Furthermore, the results of the GSEA for hub genes were correlated with complement and inflammatory responses.

Conclusions

The hub genes (BTG3, CCR2, RAB10, and TMEM60) performed well in distinguishing the SSc-PAH patients from controls, and some biological functions, related to immunity, inflammation, and cytokines, might pave the way for follow-up studies on the diagnosis and treatment of SSc-PAH.

Cancer antigen-125 is a predictor of mortality in patients with pulmonary arterial hypertension

BACKGROUND

Carbohydrate antigen 125 (CA 125), known as a tumor marker for ovarian cancer, has been reported to increase and be associated with severity in heart failure and chronic obstructive pulmonary disease. Patients with pulmonary arterial hypertension may also die due to developing right heart failure. The aim of this study is to evaluate the prognostic role of CA-125 in PAH patients.

METHODS

A total of 40 consecutive patients with PAH were evaluated prospectively. The mean age of patients was 52 ± 11 years (12% males, 88% females) with a median follow-up period of 16 months.

RESULTS

After follow-up period, 12 out of 40 patients (30%) died. CA-125 levels were higher among those who died compared to those who survived [78.5 (11.0-292) vs. 27.5 (2.10-138) U/ml, p = 0.001]. The optimal cut-off value of CA-125 to predict mortality was found as 35.29 U/ml, with 85.7% specificity and 75% sensitivity. In multivariable Cox proportional-hazards model with forward stepwise method; CA-125 > 35.32 U/ml on admission (HR = 7.645, 95% CI: 1.356-43.121, p = 0.021), age (HR = 1.132, 95% CI: 1.040-1.233, p = 0.004), TAPSE (HR = 0.740, 95% CI: 0.549-0.998, p = 0.048) and uric acid (HR = 1.444, 95% CI: 1.022-2.042, p = 0.037) remained associated with an increased risk of death.

CONCLUSION

In this study, we showed for the first time that serum CA-125 values were an independent predictor for the long-term mortality in PAH patients.

Association between serum uric acid and spirometric pulmonary function in Korean adults: The 2016 Korea National Health and Nutrition Examination Survey

BACKGROUND

A limited number of epidemiological studies have investigated the association between serum uric acid and pulmonary function in the general population. However, the results have been inconclusive.

OBJECTIVES

This study was performed to investigate the association between serum uric acid and spirometric pulmonary function in general population.

METHODS

Among the 8,150 participants who participated in the 2016 Korea National Health and Nutrition Examination Survey, 2,901 participants were analyzed in this study. Subjects were divided into four groups according to forced vital capacity (FVC)% predicted or forced expiratory volume in 1 second (FEV1) % predicted quartiles. Participants in the lowest quartile of FVC % predicted and FEV1% predicted were compared to those in the remaining quartiles according to age, education level, household income, smoking status, alcohol consumption, aerobic exercise, obesity, hypertension, diabetes, renal impairment, serum uric acid, and hyperuricemia. Multivariable logistic regression analyses were used to calculate the odds ratio (OR) of hyperuricemia for participants in the lowest quartile of FVC% and FEV1 predicted, with above covariates.

RESULTS

In women, hyperuricemia was associated with lowest quartile of FVC% predicted (OR 1.71, 95% CI 1.06-2.75, p = 0.027) and FEV1 predicted (OR 1.70, 95% CI 1.06-2.74, p = 0.028) respectively, serving as above confounding variables. In men, hyperuricemia (OR 1.54, 95% CI 1.07-2.22, p = 0.021) was associated with the lowest quartile of FEV1% predicted, not FVC% predicted. According to median age, in women, age ≥ 56 years old with hyperuricemia was associated with lowest quartile of FVC% predicted (OR 1.85, 95% CI 1.04-3.28, p = 0.037) and FEV1% predicted (OR 1.99, 95% CI 1.11-3.75, p = 0.021), respectively. In men, age ≥ 56 years old with hyperuricemia was associated with lowest quartile of FEV1% predicted (OR 1.75, 95% CI 1.05-2.94, p = 0.033), not FCV% predicted.

CONCLUSIONS

Hyperuricemia was associated with lowest quartile of FEV1% or FVC% predicted in Korean general population. This correlation between hyperuricemia and low pulmonary function was more pronounced in women and older age.

Serum uric acid is associated with disease severity and may predict clinical outcome in patients of pulmonary arterial hypertension secondary to connective tissue disease in Chinese: a single-center retrospective study

Background

Previous studies have shown that serum uric acid (UA) levels are correlated with the severity of idiopathic pulmonary arterial hypertension (IPAH) and are predictors of disease prognosis. Still, few studies have explored the value of serum UA in pulmonary arterial hypertension secondary to connective tissue disease (CTD-PAH). This retrospective study aimed to investigate the clinical value of serum UA levels in patients with CTD-PAH.

Methods

Fifty CTD-PAH patients were enrolled in our study, from which baseline UA levels, respective variations, and additional clinical data were collected. The potential association between baseline UA level and severity of CTD-PAH was investigated. Furthermore, the relationship between baseline UA and survival rate of CTD-PAH patients, as well as between UA variations and survival rate of pulmonary hypertension secondary to connective tissue disease (CTD-PH) patients was discussed.

Results

Baseline serum UA levels were positively correlated with pulmonary vascular resistance (PVR). During the follow-up period, 3 CTD-PAH and 12 CTD-PH patients died. Kaplan-Meier survival curves showed lower survival rate in patients with hyperuricemia than in patients with normouricemia, in both groups (CTD-PAH group p = 0.041, CTD-PH group p = 0.013). Concerning serum UA variations, patients with persistent hyperuricemia showed the lowest survival rate when compared with patients with steady normouricemia (p = 0.01) or patients with decresing serum UA levels, i.e. undergoing from a status of hyperuricemia to a status of normouricemia (p = 0.023).

Conclusion

Baseline serum UA levels might predict severity of CTD-PAH. Together with baseline values, changes of uric acid level may predict the clinical prognosis of the disease.

Diagnostic and prognostic markers and treatment of connective tissue disease-associated pulmonary arterial hypertension: current recommendations and recent advances

INTRODUCTION

Pulmonary arterial hypertension (PAH), also referred to as group 1 pulmonary hypertension, occurs either primarily or in association with other diseases such as connective tissue diseases (CTD). Of CTD, systemic sclerosis (SSc), systemic lupus erythematosus and mixed connective tissue disease are commonly accompanied with PAH. It is of note that SSc-PAH is associated with distinctive histopathology, an unfavorable outcome, and a blunted responsiveness to modern PAH therapies.

AREAS COVERED

The data in articles published until May 2020 in peer-reviewed journals, covered by PubMed databank, are discussed. The current review introduces recent advances over the past years which have moved our understanding of CTD-PAH forward and discusses what we are currently able to do and what will be necessary in the future to overcome the yet unsatisfactory situation in the management of CTD-PAH, particularly in that of SSc-PAH.

EXPERT OPINION

A multifaceted and integrated approach would be crucial to improve the outcome of patients with SSc-PAH. The authors also propose a possible algorithm to classify and treat SSc patients with suspicion of pulmonary vascular disease.

Interleukin-32 in systemic sclerosis, a potential new biomarker for pulmonary arterial hypertension

Background

Pulmonary arterial hypertension (PAH) is a severe complication of systemic sclerosis (SSc), associated with a progressive elevation in pulmonary vascular resistance and subsequent right heart failure and death. Due to unspecific symptoms, the diagnosis of PAH is often delayed. On this basis, it is of great value to improve current diagnostic methods and develop new strategies for evaluating patients with suspected PAH. Interleukin-32 (IL-32) is a proinflammatory cytokine expressed in damaged vascular cells, and the present study aimed to assess if this cytokine could be a new biomarker of PAH during SSc.

Methods

The IL-32 expression was evaluated in the sera and skin samples of 18 SSc-PAH patients, 21 SSc patients without PAH, 15 patients with idiopathic PAH (iPAH) and 14 healthy controls (HCs), by enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry (IHC). Receiver-operating characteristic (ROC) curves were performed to evaluate the cut-off of IL-32 in identifying patients with PAH. Furthermore, in SSc patients, correlation analyses were performed between IL-32 sera levels and mean pulmonary artery pressure (mPAP) evaluated by right heart catheterization (RHC) and systolic pulmonary artery pressure (sPAP), obtained by echocardiography. Additionally, the number of skin IL-32+ cells was correlated with modified Rodnan skin score (mRSS).

Results

In SSc-PAH patients, IL-32 sera levels were significantly higher when compared with SSc patients without PAH and patients affected by iPAH. The analysis of ROC curve showed that IL-32 sera levels above 11.12 pg/ml were able to predict patients with PAH (sensitivity = 90%, specificity = 100%). Furthermore, the IL-32 sera levels of patients with SSc correlated with both mPAP and sPAP. In the skin derived from SSc-PAH patients, the number of IL-32+ cells was significantly increased when compared with the skin derived from SSc patients without PAH, correlating with the mRSS.

Conclusion

Our study suggested that sera determination of IL-32 may be a promising approach to evaluate the presence of PAH in SSc patients and together with longitudinal future studies could help to increase the understanding how these biomarkers mirror the vascular changes and the inflammatory process during SSc.

Novel Molecular Mechanisms of Pulmonary Hypertension: A Search for Biomarkers and Novel Drug Targets-From Bench to Bed Site

Pulmonary hypertension (PH) is defined as increased mean pulmonary artery pressure (mPAP) above 25 mmHg, measured at rest by right heart catheterization. The exact global prevalence of PH is difficult to estimate, mainly due to the complex aetiology, and its spread may be underestimated. To date, numerous studies on the aetiology and pathophysiology of PH at molecular level were conducted. Simultaneously, some clinical studies have shown potential usefulness of well-known and widely recognized cardiovascular biomarkers, but their potential clinical usefulness in diagnosis and management of PH is poor due to their low specificity accompanied with numerous other cardiovascular comorbidities of PH subjects. On the other hand, a large body of basic research-based studies provides us with novel molecular pathomechanisms, biomarkers, and drug targets, according to the evidence-based medicine principles. Unfortunately, the simple implementation of these results to clinical practice is impossible due to a large heterogeneity of the PH pathophysiology, where the clinical symptoms constitute only a common denominator and a final result of numerous crosstalking metabolic pathways. Therefore, future studies, based mostly on translational medicine, are needed in order to both organize better the pathophysiological classification of various forms of PH and define precisely the optimal diagnostic markers and therapeutic targets in particular forms of PH. This review paper summarizes the current state of the art regarding the molecular background of PH with respect to its current classification. Novel therapeutic strategies and potential biomarkers are discussed with respect to their limitations in use in common clinical practice.