In vitro and in vivo models for peritonitis demonstrate unchanged neutrophil migration after exposure to dialysis fluids.
BACKGROUND
Recurrent infections in peritoneal dialysis (PD) patients may alter the abdominal wall resulting in an impairment of its dialysis capacity. In this study we investigated both in vitro and in vivo the effects of mesothelial exposure to dialysis fluids on the migration of neutrophils and their capacity to clear a bacterial infection.


METHODS
First, we evaluated neutrophil migration in an in vitro transwell model for the peritoneal membrane with monolayers of primary human mesothelial cells (MC) on the lower side and primary human endothelial cells (EC) on top of the same transwell membrane, upon exposure of MC to PD fluid (PDF)-derived components. In addition to this in vitro model, we combined chronic peritoneal exposure to PDF with a peritoneal infection model in the rat. We investigated the kinetics of the chemokine response, neutrophil recruitment and bacterial clearance.


RESULTS
Known chemoattractants, such as fMLP and IL-8, strongly increased neutrophil migration across both cell layers in the in vitro model of the peritoneal membrane. Pre-incubation of the MC layer for 48 h with 55 mM glucose, a combination of two glucose degradation products, methylglyoxal and 3-deoxyglucosone, or conventional dialysis fluid (1:4 dilution), however, did not change the IL-8-induced migration of neutrophils. In concert with this finding we demonstrated an unchanged MC expression of ICAM-1 and VCAM-1 after these pre-treatments. Unexpectedly, chronic i.p. exposure to conventional PDF or a recently developed lactate/bicarbonate-buffered PDF in a rat peritoneal exposure model strongly hampered the chemokine response upon bacterial challenge. Nevertheless, neutrophil recruitment and bacterial clearance were effective and did not differ from rats not pre-exposed to PDF.


CONCLUSIONS
We conclude that exposure of MC to PDF does not hamper the recruitment of functional neutrophils upon challenge.
Welten
Angelique G A
AG
Department of Molecular Cell Biology and Immunology, VU University Medical Center, FdG, Postbus 7057, 1007 MB Amsterdam, The Netherlands. j.vandenborn@vumc.nl
Zareie
Mohammad
M
van den Born
Jacob
J
ter Wee
Piet M
PM
Schalkwijk
Casper G
CG
Driesprong
Bas A J
BA
Mul
Frederik P J
FP
Hordijk
Peter L
PL
Beelen
Robert H J
RH
Hekking
Liesbeth H P
LH
D001826:Body Fluids; D002465:Cell Movement; D002478:Cells, Cultured; D004195:Disease Models, Animal; D004847:Epithelial Cells; D004927:Escherichia coli Infections / Q000382:microbiology; D006801:Humans; D009504:Neutrophils / Q000502:physiology*; D010530:Peritoneal Dialysis; D010537:Peritoneum / Q000166:cytology / Q000382:microbiology; D010538:Peritonitis / Q000276:immunology* / Q000382:microbiology*; D013203:Staphylococcal Infections / Q000382:microbiology