CAPD peritonitis induces the production of a novel peptide, daintain/allograft inflammatory factor-1.
OBJECTIVE
To study the occurrence of a novel macrophage-derived peptide, daintain/allograft inflammatory factor-1 (AIF-1), in dialysate from continuous ambulatory peritoneal dialysis (CAPD) patients at commencement and after a follow-up period of therapy and during peritonitis. In addition, we studied peptide production in response to bacterial stimulation of monocytes and macrophages.


METHODS
Peritoneal fluid and supernatants from cells stimulated with different bacteria were analyzed for daintain/AIF-1.


METHODS
Peritoneal fluid was obtained from 5 patients at commencement of CAPD therapy and during 8 weeks' follow-up, and from 14 patients (10 males, 4 females) during CAPD peritonitis and during the noninfected steady state. All patients were admitted to the Karolinska Hospital. A human monocyte cell-line, THP-1 was differentiated to macrophages, and both monocytes and macrophages were stimulated with live and heat-inactivated Escherichia coli, Staphylococcus aureus, and S. epidermidis. Cells were also stimulated with interleukin (IL)-1beta and interferon gamma (IFNgamma). Daintain/AIF-1 was analyzed with radioimmunoassay technique and IL-8 with enzyme immunoassay technique.


RESULTS
An increased production of daintain/AIF-1 was observed in the first spent dialysate in the newly started CAPD patients, with a decrease during the follow-up period (p < 0.05). During peritonitis, the first spent dialysate revealed significantly higher levels of daintain/AIF-1 (3.9 ng/mL) compared to the noninfected state (0.8 ng/mL), with production normalizing after 9-12 days. Bacterial stimulation with E. coli, S. aureus, or S. epidermidis induced higher daintain/AIF-1 response in monocytes compared to macrophages (p < 0.05). Live bacteria induced higher production of the peptide compared to heat-inactivated bacteria (p < 0.05). Interleukin-1beta and IFNgamma were used to stimulate monocytes and macrophages; however, no daintain/AIF-1 production was found, although increased IL-8 levels were detected.


CONCLUSIONS
CAPD peritonitis induces a high and prominent daintain/AIF-1 response. Bacteria are able to induce a response of the peptide from monocytes and macrophages, and it is likely that the virulent parts of the bacteria are heat-labile structures. The early rise in daintain/ AIF-1 might be used as a marker of CAPD peritonitis.
Brauner
Annelie
A
Department of Clinical Microbiology and MTC, Karolinska Hospital and Karolinska Institute, Stockholm, Sweden. annelie.brauner@ks.se
Hertting
Olof
O
Alkstrand
Eva
E
Sandberg
Elvi
E
Chromek
Milan
M
Chen
Zheng-Wang
ZW
Ostenson
Claes-Göran
CG
D000328:Adult; D000368:Aged; D001419:Bacteria / Q000276:immunology; D015415:Biomarkers / Q000032:analysis; D002135:Calcium-Binding Proteins / Q000096:biosynthesis* / Q000276:immunology*; D004268:DNA-Binding Proteins; D015314:Dialysis Solutions / Q000737:chemistry; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000276:immunology; D007375:Interleukin-1 / Q000276:immunology; D008262:Macrophage Activation / Q000276:immunology; D008264:Macrophages / Q000276:immunology; D008297:Male; D008840:Microfilament Proteins; D008875:Middle Aged; D009000:Monocytes / Q000276:immunology; D010531:Peritoneal Dialysis, Continuous Ambulatory / Q000009:adverse effects*; D010538:Peritonitis / Q000209:etiology* / Q000378:metabolism
C112986:AIF1 protein, human; D015415:Biomarkers; D002135:Calcium-Binding Proteins; D004268:DNA-Binding Proteins; D015314:Dialysis Solutions; D007375:Interleukin-1; D008840:Microfilament Proteins; D007371:Interferon-gamma