[Chronic renal failure and guanidino compounds]

In vitro study of the potential role of guanidines in leukocyte functions related to atherogenesis and infection

BACKGROUND

The blunted immune response upon stimulation in chronic renal failure (CRF) is often coupled to a baseline inflammatory status which has been related to atherogenesis. Uremic biologic fluids and several specific uremic retention solutes alter cell-mediated immune responses, as well as the interaction of calcitriol with the immune system.

METHODS

The present study evaluated the influence of different guanidino compounds on DNA synthesis, chemiluminescence production, and CD14 expression of undifferentiated and calcitriol-differentiated HL-60 cells. In a second setup, these guanidino compounds were evaluated for their specific effect on normal human leukocyte oxidative burst activity and tumor necrosis factor-alpha (TNF-alpha) expression.

RESULTS

First, several guanidino compounds elicited proinflammatory effects on leukocytes. Methylguanidine and guanidine stimulated the proliferation of undifferentiated HL-60 cells and the antiproliferative effect of calcitriol (P < 0.05) was neutralized in the presence of methylguanidine (P < 0.05) and guanidinosuccinic acid (P < 0.05). The phorbol-myristate-acetate (PMA)-stimulated chemiluminescence production of the calcitriol differentiated HL-60 cells was enhanced in the presence of guanidine (P < 0.05). Methylguanidine and guanidinoacetic acid enhanced the lipopolysaccharide (LPS)-stimulated intracellular production of TNF-alpha by normal human monocytes (P < 0.05). Second, several guanidino compounds inhibited the function of leukocytes if they were activated. The PMA-stimulated chemiluminescence production of the calcitriol differentiated HL-60 cells was inhibited by the presence of methylguanidine (P < 0.05), guanidinoacetic acid (P < 0.05) and guanidinosuccinic acid (P < 0.05). After incubation of whole blood in the presence of methylguanidine, the Escherichia coli stimulated oxidative burst activity of the granulocyte population was significantly inhibited (P < 0.05). In addition, guanidinosuccinic acid had an inhibitory effect on the LPS-stimulated intracellular production of TNF-alpha by human monocytes (P < 0.01).

CONCLUSION

Guanidino compounds exert proinflammatory as well as anti-inflammatory effects on monocyte/macrophage function. This could contribute to the altered prevalence of cardiovascular disease and propensity to infection in patients with CRF.

Erythrocyte transketolase activity and guanidino compounds in hemodialysis patients

BACKGROUND

The toxic effects of guanidino compounds on enzymatic activity in uremic patients are known. Thus, we determined the hemodialysis (HD) impact on this toxicity.

METHODS

The erythrocyte transketolase activity (ETKA), total guanidino compounds (TGCs), and guanidinosuccinic acid (GSA) levels in plasma were compared before, after 5 hours of HD, and at 12 and 24 hours from the end of HD. Thirty-seven HD patients (28 to 49 years old) with primary glomerulopathies participated in this study. Thirty healthy volunteers (HVs) served as controls.

RESULTS

At the beginning of this study, ETKA was lower in uremics (1.94 +/- 0.45) than in HVs (2.59 +/- 0.26). The TGC and GSA plasma levels were higher (26.07 +/- 5.34 and 4.5 +/- 1.22) than in HVs (10.41 +/- 1.42 and 0.76 +/- 0.09, P < 0.001), respectively. After five hours of HD, the ETKA increased to 2.49 +/- 0.62 (P < 0.001). The plasma levels TGC decreased to 12.56 +/- 2.02 (P < 0.001) and the GSA to 2.12 +/- 0.68 (P < 0.001). After 12 and 24 hours from the end of HD, the ETKA decreased to 2.25 +/- 0.56 and 2.09 +/- 0.49 (P < 0.001), respectively. The plasma levels for TGC and GSA both increased: TGC to 19.39 +/- 3.67 and 25.68 +/- 4.61 (P < 0.001), respectively; GSA to 3.49 +/- 1.11 and 4.53 +/- 1.12 (P < 0.001), respectively.

CONCLUSION

There was no significant correlation between ETKA and the plasma levels of the examined toxins. By removing the guanidino compounds, HD temporarily decreases the inhibition of ETKA, diminishing other metabolic disturbances connected with pentose phosphate cycle.