Elevated level of the soluble receptor for advanced glycation end-products involved in sarcopenia: an observational study

Background The soluble receptor for advanced glycation end products (sRAGE) has been proposed to serve as a marker for disease severity, but its role in sarcopenia, an age-related progressive loss of muscle mass and function, remains elusive. This study examines the association between sRAGE and sarcopenia. Methods A total of 314 community-dwelling elderly adults who had their health examination at Tri-Service General Hospital from 2017 to 2019 underwent protein analysis with enzyme-linked immunosorbent assay. The relationship with sarcopenia and its detailed information, including components and diagnosis status, were examined using linear and logistic regressions. Results As for sarcopenia components, low muscle mass (β = 162.8, p = 0.012) and strength (β = 181.31, p = 0.011) were significantly correlated with sRAGE, but not low gait speed (p = 0.066). With regard to disease status, confirmed sarcopenia (β = 436.93, p < 0.001), but not probable (p = 0.448) or severe sarcopenia (p = 0.488), was significantly correlated with sRAGE. In addition, females revealed a stronger association with sRAGE level by showing significant correlations with low muscle mass (β = 221.72, p = 0.014) and low muscle strength (β = 208.68, p = 0.043). Conclusions sRAGE level showed a positive association with sarcopenia, illustrating its involvement in the evolution of sarcopenia. This association is more evident in female groups, which may be attributed to the loss of protection from estrogen in postmenopausal women. Utilizing sRAGE level as a prospective marker for sarcopenia deserves further investigation in future studies.

The amelioration of T2DM rat femoral bone achieved by anti-osteoporosis of caprine CSN1S2 protein through bone morphogenetic protein signaling pathway

We investigated the potential anti-glycation and anti-osteoporosis properties of Caprine milk CSN1S2 protein on the serum AGEs and sRAGE level, osteogenic factors expressions, femoral bone mesostructure, histomorphometry, and hydroxyapatite crystals changes in T2DM rats. Varying doses of Caprine milk CSN1S2 protein (0, 375, 750, and 1500mg/kg BW) were used to treat the control and T2DM rats. We measured AGEs and sRAGE level; RUNX2, OSX, BMP2, and Caspase-3 expressions in rats using ELISA and immunohistochemistry, respectively. The mesostructure and histomorphometry of femoral bone was analyzed using SEM Microscope and BoneJ software, then hydroxyapatite crystal size was determined using SEM-XRD. T2DM rats showed a high level of AGEs and a low level of sRAGE, the RUNX2, OSX, & BMP2 expression was down regulated, BV, BV.TV, Tb.Th, Tb.Sp, increased and SMI levels declined, respectively. Vice versa, after administration of the CSN1S2 protein to T2DM rats, improvement in all levels of molecular and cellular markers was achieved. In the CSN1S2 highest dose, AGEs level declined and sRAGE level elevated in T2DM rats. The 375 and 750 mg/kgBW of CSN1S2 protein was able to upregulate the RUNX2, OSX, and BMP2 expression in T2DM rats, thus improving the normalization of osteoclasts and osteoblasts number. The whole dose of CSN1S2 triggered the thickening of trabecular bone wall, granule formation, and normalized the trabecular thickness (Tb.Th) parameter of T2DM rats. The hydroxyapatite crystal size was increased in the highest dose of CSN1S2-treated T2DM rats. This study indicated that CSN1S2 protein had a protective effect against osteoporosis in the T2DM rat bones by means of glycation pathway inhibition, bone histomorphometry and mesostructure improvement via bone morphometric protein signaling.

Soluble receptor for advanced glycation end products (sRAGE) as a biomarker of COVID-19 disease severity and indicator of the need for mechanical ventilation, ARDS and mortality

Background COVID-19 pneumonia and subsequent respiratory failure is causing an immense strain on intensive care units globally. Early prediction of severe disease enables clinicians to avoid acute respiratory distress syndrome (ARDS) development and improve management of critically ill patients. The soluble receptor of advanced glycation endproducts (sRAGE) is a biomarker shown to predict ARDS. Although sRAGE level varies depending on the type of disease, there is limited information available on changes in sRAGE levels in COVID-19. Therefore, sRAGE was measured in COVID-19 patients to determine sRAGE level variation in COVID-19 severity and to examine its ability to predict the need for mechanical ventilation (MV) and mortality in COVID-19. Methods In this single-centre observational cohort study in Germany, serum sRAGE during acute COVID-19, 20 weeks after the start of COVID-19 symptoms, as well as in control groups of non-COVID-19 pneumonia patients and healthy controls were measured using ELISA. The primary endpoint was severe disease (high-flow nasal oxygen therapy (HFNO)/MV and need of organ support). The secondary endpoints were respiratory failure with need of MV and 30-day mortality. The area under the curve (AUC), cut-off based on Youden’s index and odds ratio with 95% CI for sRAGE were calculated with regard to prediction of MV need and mortality. Results Serum sRAGE in 164 COVID-19 patients, 101 matched COVID-19 convalescent patients, 23 non-COVID-19 pneumonia patients and 15 healthy volunteers were measured. sRAGE level increased with COVID-19 severity, need for oxygen therapy, HFNO/MV, ARDS severity, need of dialysis and catecholamine support, 30-day mortality, sequential organ failure assessment (SOFA) and quick SOFA (qSOFA) score. sRAGE was found to be a good predictor of MV need in COVID-19 inpatients and mortality with an AUC of 0.871 (0.770–0.973) and 0.903 (0.817–0.990), respectively. When adjusted for male gender, age, comorbidity and SOFA score ≥ 3, sRAGE was independently associated with risk of need for HFNO/MV. When adjusted for SOFA score ≥ 3, sRAGE was independently associated with risk of need for MV. Conclusions Serum sRAGE concentrations are elevated in COVID-19 patients as disease severity increases. sRAGE should be considered as a biomarker for predicting the need for MV and mortality in COVID-19.

Distinct Time Courses and Pathogenic Contributions of Alveolar Epithelial and Endothelial Injury in Acute Respiratory Distress Syndrome With COVID-19: Evidence From Circulating Biomarkers

Background: In severe cases of coronavirus disease (COVID-19), acute respiratory distress syndrome (ARDS) with alveolar tissue injury occurs. However, the time course and specific contributions of alveolar epithelial and endothelial injury to the pathogenesis of COVID-19 ARDS remain unclear.Methods: We evaluated the levels of a circulating alveolar epithelial injury marker (soluble receptor for advanced glycation end-products: sRAGE) and an endothelial injury marker (angiopoietin-2: ANG-2), along with an alveolar permeability indicator (surfactant protein D: SP-D) in 107 serum samples from nine patients with ARDS and eight without ARDS, all with COVID-19, admitted to Yokohama City University Hospital from January to July 2020. We compared the initial levels of these markers between ARDS and non-ARDS patients, and analysed the temporal changes of these markers in ARDS patients. Results: All the initial levels of sRAGE (median: 2680 pg/mL, IQR:1522–5076 vs. median 701 pg/mL, IQR:344–1148.0, p=0.0152), ANG-2 (median: 699 pg/mL, IQR: 410-2501 vs. median: 231 pg/mL, IQR: 64-584, p=0.0464), and SP-D (median: 17542 pg/mL, IQR: 7423-22979 vs. 1771 pg/mL, IQR: 458-204, p=0.0274) were significantly higher in the ARDS patients than in the non-ARDS patients. The peak sRAGE level in the ARDS patients was observed at the very early phase of disease progression (median: day 1, IQR: day 1–3.5). However, the peaks of ANG-2 (median: day 4, IQR: day 2.5–6) and SPD (median: day 5, IQR: day 3–7.5) were observed at a later phase. Moreover, the ANG-2 level was significantly correlated with the arterial oxygenation (p=0.030) and the SPD level (p=0.002), but the sRAGE level was not. Conclusion: Evaluation of circulating markers confirms that COVID-19 ARDS is characterised by severe alveolar tissue injury. Our data indicate that the endothelial injury, which continues for a longer period than the epithelial injury, seems to be the main contributor to alveolar barrier disruption. Targeting the endothelial injury may, thus, be a promising approach to overcome ARDS with COVID-19.

Distinct time courses and pathogenic contributions of alveolar epithelial and endothelial injury in acute respiratory distress syndrome with COVID-19: evidence from circulating biomarkers

BackgroundIn severe cases of coronavirus disease (COVID-19), acute respiratory distress syndrome (ARDS) with alveolar tissue injury occurs. However, the time course and specific contributions of alveolar epithelial and endothelial injury to the pathogenesis of COVID-19 ARDS remain unclear.MethodsWe evaluated the levels of a circulating alveolar epithelial injury marker (soluble receptor for advanced glycation end-products: sRAGE) and an endothelial injury marker (angiopoietin-2: ANG-2), along with an alveolar permeability indicator (surfactant protein D: SP-D) in 107 serum samples from nine patients with ARDS and eight without ARDS, all with COVID-19. We compared the initial levels of these markers between ARDS and non-ARDS patients, and analysed the temporal changes of these markers in ARDS patients.FindingsAll the initial levels of sRAGE, ANG-2, and SP-D were significantly higher in the ARDS patients than in the non-ARDS patients. The peak sRAGE level in the ARDS patients was observed at the very early phase of disease progression. However, the peaks of ANG-2 and SPD were observed at a later phase. Moreover, the ANG-2 level was significantly correlated with the arterial oxygenation and the SPD level, but the sRAGE level was not.InterpretationEvaluation of circulating markers confirms that COVID-19 ARDS is characterised by severe alveolar tissue injury. Our data indicate that the endothelial injury, which continues for a longer period than the epithelial injury, seems to be the main contributor to alveolar barrier disruption. Targeting the endothelial injury may, thus, be a promising approach to overcome ARDS with COVID-19.FundingNone

Serum Soluble Receptor for Advanced Glycation End Products in Infants With Bronchiolitis: Associations With Acute Severity and Recurrent Wheeze

Background Although bronchiolitis contributes to substantial acute (eg, intensive care use) and chronic (eg, recurrent wheeze) morbidities in young children, the pathobiology remains uncertain. We examined the associations of serum soluble receptor for advanced glycation end products (sRAGE) with acute and chronic morbidities of bronchiolitis including recurrent wheeze. Methods A multicenter, multiyear, cohort study of infants hospitalized for bronchiolitis was analyzed. We measured the serum sRAGE level at hospitalization and its association with intensive care use (use of mechanical ventilation and/or admission to the intensive care unit) and development of recurrent wheeze by age 3 years. We performed causal mediation analysis to estimate indirect (mediation) and direct effects of sRAGE on recurrent wheeze. Results In 886 infants with bronchiolitis, the median age was 2.9 months. Overall, 15% underwent intensive care and 32% developed recurrent wheeze. In multivariable modeling adjusting for 11 confounders, a higher presenting sRAGE level was associated with lower risk of intensive care (odds ratio for each 1-log increment, 0.39; 95% confidence interval [CI], .16 -.91; P = .03) and significantly lower rate of recurrent wheeze (hazard ratio [HR], 0.58; 95% CI, .36 -.94; P = .03). In mediation analysis, the direct effect was significant (HR, 0.60; 95% CI, .37 -.97; P = .04), while the indirect effect was not (P = .30). Conclusions Serum sRAGE levels were inversely associated with acute and chronic morbidities of bronchiolitis. The effect of sRAGE on development of recurrent wheeze is potentially driven through pathways other than acute severity of bronchiolitis.

Circulating soluble RAGE and cell surface RAGE on peripheral blood mononuclear cells in healthy children

Background: The receptor for advanced glycation end products (RAGE) has a critical role in the pathogenesis of inflammation. In healthy children, its basal expression on the peripheral blood mononuclear cell (PBMC) and the basal circulating soluble RAGE (sRAGE) levels are unknown. The aim of this study was to describe both. Methods: This is a monocentric, observational and descriptive study of samples obtained from healthy children. The RAGE expression on PBMC was analyzed using flow cytometry. The sRAGE values were determined with a specific sandwich enzyme-linked immunosorbent assay (ELISA) kit, later the relation between cellular RAGE and sRAGE was described. Results: Forty-three children were included. The median sRAGE level was 849.0±579.0 pg/mL. The RAGE mean fluorescence intensity (MFI) was 1382±506 in monocytes and 792±506 in lymphocytes. There were no differences between genders. A negative correlation was found between sRAGE and RAGE MFI in lymphocytes (r=−0.3; p=0.04). Conclusions: We describe for the first time the RAGE surface levels on PBMC in children. It showed a negative correlation with sRAGE. The sRAGE circulating level is lower than the sRAGE level described in adult population or non-healthy children. Our findings should be confirmed in order to apply them as reference values for future investigations.