Introduction and Aims: Elevated pulse wave velocity (PWV) and central aortic blood pressures are independent predictors of increased cardiovascular morbidity and mortality in hemodialysis (HD) patients. Oxalic acid is a uremic retention molecule that is extensively studied in the pathogenesis of calcium-oxalate stones. Oxalobacter formigenes, a member of colon microbiota, has important roles in oxalate homeostasis. Data regarding the colonization and the exact role of the Oxalobacter formigenes in the pathogenesis of oxalic acid metabolism in HD patients are scant. Hence, we aimed to determine the relationship between colo-reno-cardiac axis in terms of faecal Oxalobacter formigenes colonization, serum oxalic acid and hemodinamic parameters in HD patients.
Methods: Fifty HD patients were enrolled in this study. PWV and central aortic systolic (cASBP) and diastolic blood pressure (cADBP) were measured by Mobil-O-Graph (GmbH, Germany). Serum oxalic acid levels were measured with ELISA and faecal Oxalobacter formigenes DNA levels were isolated and measured with real-time PCR.
Demographic, clinic and central hemodinamic features of Hemodialysis Patients
| Parameters | Hemodialysis patients (n=50) |
|---|---|
| Age (years) | 62.0±14.9 |
| Female/Male | 23/27 |
| BMI (kg/m2) | 26.5±5.6 |
| Disease Duration(Months) | 62±54 |
| SBP (mmHg) | 139±36 |
| DBP (mmHg) | 82±21 |
| Central Aortic SBP (mmHg) | 126±32 |
| Central Aortic DBP (mmHg) | 84±22 |
| Pulse Pressure (mmHg) | 56±21 |
| Pulse Wave Velocity (m/s) | 9.4±2.5 |
| Parameters | Hemodialysis patients (n=50) |
|---|---|
| Age (years) | 62.0±14.9 |
| Female/Male | 23/27 |
| BMI (kg/m2) | 26.5±5.6 |
| Disease Duration(Months) | 62±54 |
| SBP (mmHg) | 139±36 |
| DBP (mmHg) | 82±21 |
| Central Aortic SBP (mmHg) | 126±32 |
| Central Aortic DBP (mmHg) | 84±22 |
| Pulse Pressure (mmHg) | 56±21 |
| Pulse Wave Velocity (m/s) | 9.4±2.5 |
Demographic, clinic and central hemodinamic features of Hemodialysis Patients
| Parameters | Hemodialysis patients (n=50) |
|---|---|
| Age (years) | 62.0±14.9 |
| Female/Male | 23/27 |
| BMI (kg/m2) | 26.5±5.6 |
| Disease Duration(Months) | 62±54 |
| SBP (mmHg) | 139±36 |
| DBP (mmHg) | 82±21 |
| Central Aortic SBP (mmHg) | 126±32 |
| Central Aortic DBP (mmHg) | 84±22 |
| Pulse Pressure (mmHg) | 56±21 |
| Pulse Wave Velocity (m/s) | 9.4±2.5 |
| Parameters | Hemodialysis patients (n=50) |
|---|---|
| Age (years) | 62.0±14.9 |
| Female/Male | 23/27 |
| BMI (kg/m2) | 26.5±5.6 |
| Disease Duration(Months) | 62±54 |
| SBP (mmHg) | 139±36 |
| DBP (mmHg) | 82±21 |
| Central Aortic SBP (mmHg) | 126±32 |
| Central Aortic DBP (mmHg) | 84±22 |
| Pulse Pressure (mmHg) | 56±21 |
| Pulse Wave Velocity (m/s) | 9.4±2.5 |
Laboratory features of Hemodialysis Patients
| Parameters | Hemodialysis patients (n=50) |
|---|---|
| Glucose (mg/dL) | 126±57 |
| Urea (mg/dL) | 138±32 |
| Creatinine (mg/dL) | 8.9±2.1 |
| Calcium (mg/dL) | 8.5±0.85 |
| Phosphorus (mg/dL) | 4.6±1.2 |
| Albumin (g/dL) | 3.7±0.4 |
| Triglyceride (mg/dL) | 200±113 |
| Uric Acid (mg/dL) | 6.0±1.3 |
| Oxalic Acid (µg/mL) | 3.6±3.1 |
| CRP (mg/dL) | 3.5±3.8 |
| NLR | 3.5±3.2 |
| Parameters | Hemodialysis patients (n=50) |
|---|---|
| Glucose (mg/dL) | 126±57 |
| Urea (mg/dL) | 138±32 |
| Creatinine (mg/dL) | 8.9±2.1 |
| Calcium (mg/dL) | 8.5±0.85 |
| Phosphorus (mg/dL) | 4.6±1.2 |
| Albumin (g/dL) | 3.7±0.4 |
| Triglyceride (mg/dL) | 200±113 |
| Uric Acid (mg/dL) | 6.0±1.3 |
| Oxalic Acid (µg/mL) | 3.6±3.1 |
| CRP (mg/dL) | 3.5±3.8 |
| NLR | 3.5±3.2 |
Laboratory features of Hemodialysis Patients
| Parameters | Hemodialysis patients (n=50) |
|---|---|
| Glucose (mg/dL) | 126±57 |
| Urea (mg/dL) | 138±32 |
| Creatinine (mg/dL) | 8.9±2.1 |
| Calcium (mg/dL) | 8.5±0.85 |
| Phosphorus (mg/dL) | 4.6±1.2 |
| Albumin (g/dL) | 3.7±0.4 |
| Triglyceride (mg/dL) | 200±113 |
| Uric Acid (mg/dL) | 6.0±1.3 |
| Oxalic Acid (µg/mL) | 3.6±3.1 |
| CRP (mg/dL) | 3.5±3.8 |
| NLR | 3.5±3.2 |
| Parameters | Hemodialysis patients (n=50) |
|---|---|
| Glucose (mg/dL) | 126±57 |
| Urea (mg/dL) | 138±32 |
| Creatinine (mg/dL) | 8.9±2.1 |
| Calcium (mg/dL) | 8.5±0.85 |
| Phosphorus (mg/dL) | 4.6±1.2 |
| Albumin (g/dL) | 3.7±0.4 |
| Triglyceride (mg/dL) | 200±113 |
| Uric Acid (mg/dL) | 6.0±1.3 |
| Oxalic Acid (µg/mL) | 3.6±3.1 |
| CRP (mg/dL) | 3.5±3.8 |
| NLR | 3.5±3.2 |
Results: Demographic features were demonstrated in Table 1. Isolation of faecal Oxalobacter formigenes were found in only two HD patients. One of these patients had 113.609 copy/mL, the other one had 1.056 copy/mL of faecal Oxalobacter Formigenes. These patients had also lower levels of serum oxalic acid levels (1.4 µg/mL and 2.7 µg/mL,respectively) when compared with HD patients who did not have Oxalobacter Formigenes colonization. Laboratory results were shown in Table 2. Serum oxalic acid levels were found to be positively correlated with PWV (r:0.29,p:0.03)(Figure 1), CaSBP (r:0.33,p:0.001), CaDBP (r:0.42,p:0.002) and negatively correlated with low density lipoprotein (r:-0.30, p:0.03). In multivariate linear regression analysis, PWV was independently predicted by oxalic acid, glucose and triglyceride.
Conclusions: This is the first study that demonstrate the absance of Oxalobacter formigenes and the relation between serum oxalic acid CaSBP, CaDBP and PWV in HD patients in the literature. Replacement of Oxalobacter formigenes with prebiotics and probiotics might decrease serum oxalic acid and improve cardiovascular outcomes in HD patients.
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