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Peritoneal dialysis fluid (PDF) C++ and 1,25(OH)2D3 modulate peritoneal macrophage (PM0) antimicrobial activity in
S Carozzi1, M G Nasini, C Schelotto
1Nephrology and Dialysis Unit, St. Paul's Hospital, Savona, Italy.
Abstract:
Our previous in vitro studies have shown that Ca++ and 1,25(OH)2D3 modulate peritoneal macrophage (PMO) antimicrobial activity in CAPD patients. We thus evaluated in vivo in 24 CAPD patients (12 who had never had peritonitis and 12 with an overall peritonitis incidence of more than one episode per 8 patient/month), the effects of different peritoneal dialysis fluid (PDF) Ca++ concentrations (1.25, 1.75 and 2.25 mmol/L) on PMO: 1. cytoplasmic Ca++ concentration; 2. superoxide generation; 3. Leukotriene B4 (LTB4) release; 4. bacterial killing for staphylococcus epidermidis. The same parameters were also evaluated after adding 1,25(OH)2D3 (0.25 microgram/L) to the PDF. Results showed a direct correlation between the PDF Ca++ concentration and PMO Ca++ levels, superoxide and LTB4 generation, and bacterial killing, such that with 2.25 mmol/L of Ca++ these values were significantly higher than those seen with 1.75 mmol/L. The addition of 1,25(OH)2D3 potentiated the Ca++ - induced effects. On the contrary, with PDF Ca++ levels of 1.25 mmol/L, an inhibition of the aforementioned parameters was seen. However, this effect was reversed by the addition of 1,25(OH)2D3. These in vivo results confirm the importance of Ca++ and 1,25(OH)2D3 in PMO antibacterial functions in CAPD patients and may be useful in the prophylaxis and therapy of peritonitis.
Insights
Higher calcium (Ca++) in peritoneal dialysis fluid enhances macrophage antimicrobial activity in CAPD patients. Vitamin D (1,25(OH)2D3) further boosts this effect, aiding peritonitis prevention and treatment.
Area of Science:
- Nephrology
- Immunology
- Biochemistry
Background:
- Previous in vitro studies indicated calcium (Ca++) and 1,25(OH)2D3 influence peritoneal macrophage (PMO) antimicrobial activity in CAPD patients.
- Peritonitis remains a significant complication in continuous ambulatory peritoneal dialysis (CAPD).
Purpose of the Study:
- To investigate the in vivo effects of varying peritoneal dialysis fluid (PDF) Ca++ concentrations on PMO antimicrobial functions in CAPD patients.
- To assess the impact of adding 1,25(OH)2D3 to PDF on these PMO functions.
Main Methods:
- Evaluated 24 CAPD patients, divided into those with no peritonitis history and those with recurrent peritonitis.
- Measured PMO cytoplasmic Ca++ concentration, superoxide generation, Leukotriene B4 (LTB4) release, and bacterial killing of Staphylococcus epidermidis.
- Assessed these parameters using PDFs with Ca++ concentrations of 1.25, 1.75, and 2.25 mmol/L, both with and without added 1,25(OH)2D3.
Main Results:
- A direct correlation was observed between PDF Ca++ concentration and PMO Ca++ levels, superoxide generation, LTB4 release, and bacterial killing.
- The highest Ca++ concentration (2.25 mmol/L) showed significantly enhanced PMO functions compared to 1.75 mmol/L.
- 1,25(OH)2D3 addition potentiated Ca++-induced effects; lower Ca++ (1.25 mmol/L) showed inhibition, which was reversed by 1,25(OH)2D3.
Conclusions:
- In vivo results confirm the crucial role of Ca++ and 1,25(OH)2D3 in enhancing peritoneal macrophage antibacterial functions in CAPD patients.
- Optimizing PDF Ca++ levels and potentially incorporating 1,25(OH)2D3 may offer a strategy for peritonitis prophylaxis and therapy.