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B Kreft

Publications and source records attributed to B Kreft.

113 records · Page 7Linked to original sources
PubMedDate not supplied

Virulence factors of Escherichia coli contribute to acute renal failure.

BACKGROUND: The development of acute renal failure (ARF) significantly enhances the mortality of patients with Gram-negative septic shock. The role of specific bacterial virulence factors different from lipopolysaccharides (LPS) in the deterioration of renal function in septic shock remains to be determined. METHODS: An Escherichia coli wild-type strain (536/21 WT, O6:K15:H31) was isolated from a patient suffering from a urinary tract infection. The strain expresses various virulence factors (e.g. hemolysin, fimbriae) genetically encoded by pathogenicity islands. The spontaneous deletion mutant 536/21 Del lacks the expression of these virulence factors. Isolated rat kidneys were perfused with a suspension (5 x 10(4)/ml) of the respective strain or control perfusion medium and the renal functional parameters were analyzed. Intrarenal deposition of E. coli was detected by immunohistology and Gram staining. RESULTS: The perfusion of the isolated perfused rat kidney with a uropathogenic E. coli wild-type strain (536/21 WT) caused an acute deterioration of renal function which was not observed in kidneys exposed to a deletion mutant of E. coli 536/21 lacking the expression of virulence factors. The glomerular filtration rate and the urine flow rate significantly decreased only in kidneys perfused with the E. coli wild-type strain, while there was no change versus controls in kidneys perfused with the deletion mutant. CONCLUSIONS: Distinctive bacterial virulence factors different from LPS such as hemolysin and the presence of different fimbriae may contribute to the development of ARF in sepsis induced by E. coli. Anti-LPS strategies may not be sufficient to reduce the risk of ARF in Gram-negative septic shock.

Acute Kidney Injury↗
PubMedDate not supplied

1,25-Dihydroxycholecalciferol stimulates the expression of intercellular adhesion molecule-1 in renal carcinoma cells.

1,25-Dihydroxycholecalciferol (1,25-D3) is a potent immunomodulatory vitamin modulating major histocompatibility complex class-II expression in monocytes and epithelial cells. However, the impact of 1,25-D3 on the expression of adhesion molecules in epithelial cells has not been investigated. Human renal tubular epithelial and renal carcinoma cells express intercellular adhesion molecule-1 (ICAM-1), a ligand of the leukocyte-function-associated antigen-1 (LFA-1). Therefore, we addressed the question whether 1,25-D3 modulates ICAM-1 expression by renal carcinoma cells. Using an enzyme-linked immunoassay we detected an increase in ICAM-1 expression by a renal carcinoma cell line (ACHN) cultured in the presence of 1,25-D3. Also, in ACHN cells stimulated with gamma-IFN a significant stimulatory effect of 1,25-D3 was evident. ICAM-1 is crucial for the adhesion of LFA-1-expressing lymphocytes and is involved in antigen presentation. In addition, ICAM-1 may be of significance in lymphocyte lysis of tumor cells. Therefore, the impact of 1,25-D3 on ICAM-1 expression by renal and non-renal and non-renal carcinoma cells and renal tubular epithelial cells may be of clinical importance.

Animals↗
PubMedDate not supplied

Tamm-Horsfall protein inhibits binding of S- and P-fimbriated Escherichia coli to human renal tubular epithelial cells.

Escherichia coli is the predominant pathogen in urinary tract infections. Fimbriae are one of the major virulence factors of these bacteria, since these protein appendices contribute towards bacterial adhesion to epithelial cells. In clinical E. coli isolates from urinary tract infections, P fimbriae are more frequently present than S fimbriae. However, these two types of fimbriae mediate adhesion to cultured tubular epithelial cells equally well. Tamm-Horsfall protein, which is the most abundant protein in normal human urine, inhibits hemagglutination by E. coli expressing S fimbriae, but does not interfere with hemagglutination by P-fimbriated E. coli. Therefore, it has been speculated that Tamm-Horsfall protein may serve as a clearance factor for S-fimbriated E. coli in human urine. In our experiments, adherence of purified S fimbriae and of S-fimbriated E. coli to tubular epithelial cells was inhibited by Tamm-Horsfall protein, but the protein also decreased binding of P-fimbriated E. coli to approximately the same degree. We found less adherence of both types of fimbriae to a Madin-Darby canine kidney cell line expressing soluble and membrane-bound Tamm-Horsfall protein as compared with the control cell line. In conclusion, our in vitro data suggest that urinary Tamm-Horsfall protein may serve as a clearance factor for E. coli expressing both S and P fimbriae. In the light of these findings, the low clinical relevance of S-fimbriated E. coli for urinary tract infections may be readily explained; however, the predominance of P fimbriae remains unresolved.

Adjuvants, Immunologic↗