Microbial Pathogenesis 1991 ; 11 : 171-178
Phagocytosis of Escherichia coil mediated by man nose resistant non-fimbrial haemagglutinin (NFA-1) Janina Goldhar, Miri Yavzori, Yona Keisari and Itzhak Ofek Department of Human Microbiology, Sackler School of Medicine, Tel-Aviv University, Ramat Aviv, Tel-A viv 69978, Israel (Received December 28,1990; accepted in revised form May 2, 1991)
Goldhar, J . (Dept of Human Microbiology, Sackler School of Medicine, Tel-Aviv University, Ramat Aviv, Tel-Aviv 69978, Israel), M . Yavzori, Y . Keisari and I . Ofek . Phagocytosis of Escherichia co/imediated by mannose resistant non-fimbrial haemagglutinin (NFA-1) . Microbial Pathogenesis 1991 ; 11 : 171-178 . We examined the interaction between a urinary isolate of E. co/i carrying non-fimbrial MR adhesin (NFA-1) and human polymorphonuclear leukocytes (PMN) . We found that the organisms attach to PMN and the attachment was dose dependent and saturable . It was inhibited by isolated NFA-1, but not by mannoside . Recombinant plasmid encoding NFA-1 adhesin conferred binding capacity on a non-adhesive strain . The attachment of the bacteria carrying NFA-1 to PMN was associated with oxidative burst and inhibited by isolated NFA-1 . The data taken together suggest that NFA-1 mediates the attachment of the bacteria to PMN . The attachment is followed by ingestion and killing of the organisms, but at a slower rate than with bacteria bound via type 1 fimbriae . Key words : phagocytosis ; non-fimbrial adhesins ; E. co/i haemagglutinin .
Introduction Evidence obtained during the last decade indicates that phagocytes recognize specific structures expressed on bacterial surfaces . The molecular basis of this non-opsonic recognition has been characterized in a number of systems . In one system (termed lectinophagocytosis) the phagocytes bind and subsequently ingest the bacteria by lectin-sugar interactions .' Lectinophagocytosis mediated by the mannose-specific (or man nose-sensitive, MS) type 1 fimbrial lectin of E. coli, has been studied extensively . The MS-mediated binding of the bacteria to phagocytic cells results in stimulation of antimicrobial mechanisms exhibited as internalization and killing of the bacteria .' Most pathogenic E. coli carry genetic information encoding the expression of mannose resistant (MR) adhesins, in addition to type 1 fimbriae . The MR adhesins are best expressed in agar-grown bacteria at 37°C, while the MS adhesins are best expressed in broth-grown bacteria under static conditions, either at 18 or 37°C .2 Structurally, MR adhesins may be in fimbrial, fibrillar or non-fimbrial forms ." Functionally, the adhesins are responsible for the binding of the organisms to receptors 5-7 present on the surface of various types of eukaryotic cells . Recently several studies have been undertaken to determine whether any of the fimbrial MR haemagglutinins mediate binding of the bacteria to phagocytic cells . Among the fimbrial MR adhesins, the P and S fimbriae were found to bind poorly or not at all to polymorphonuclear leukocytes (PMNs) 810 suggesting that phagocytes 0882-4010/91 /090171 +08 $03 .00/0
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either lack receptors for these haemagglutinins or that the receptors are inaccessible to mediate binding of the MR-fimbriated bacteria . In addition, a poor association was observed between enterotoxigenic E. coli carrying the MR fimbrial adhesins CFA/I and CFA/II, and PMN ." A number of MR non-fimbrial (or fibrillar) adhesins expressed by various E. coli isolates have been described recently . a-6,12-16 In some cases the non-fimbrial adhesins were found to be organized in a capsule-like form on bacterial surfaces ."' Non-fimbrial adhesins (NFA-1 and NFA-2) mediate the adherence of bacteria to human epithelial cells in tissue culture .' It is not known, however, whether any of these NFAs mediate the binding of the bacteria to phagocytic cells . In the present study we show that NFA-1 expressed by a urinary isolate of E. coli mediates the binding of the bacteria to human PMNs . The association of NFA-1 carrying bacteria with PMNs triggered an oxidative burst in the phagocytic cells . The rate of ingestion and killing of E. coli bound via NFA-1 was found to be considerably slower, compared with E. coli bound to phagocytic cells via MS type 1 fimbrial adhesins . Results Microscopic examination showed that attachment of the NFA-1 -carrying E. coil 827 bacteria to PMNs was optimal (c . 90% of PMNs bound bacteria, 1-9 bacteria per PMN) in monolayers incubated for 60 min at 37°C with bacteria suspended in D-PBS (see Materials and methods section) . The binding was Mg t +- and Ca 21 -dependent and it was abolished by glutaraldehyde treatment or drying of the PMN monolayer before adding the bacteria (
Phagocytosis of Escherichia coil mediated by man nose resistant non-fimbrial haemagglutinin (NFA-1) Janina Goldhar, Miri Yavzori, Yona Keisari and Itzhak Ofek Department of Human Microbiology, Sackler School of Medicine, Tel-Aviv University, Ramat Aviv, Tel-A viv 69978, Israel (Received December 28,1990; accepted in revised form May 2, 1991)
Goldhar, J . (Dept of Human Microbiology, Sackler School of Medicine, Tel-Aviv University, Ramat Aviv, Tel-Aviv 69978, Israel), M . Yavzori, Y . Keisari and I . Ofek . Phagocytosis of Escherichia co/imediated by mannose resistant non-fimbrial haemagglutinin (NFA-1) . Microbial Pathogenesis 1991 ; 11 : 171-178 . We examined the interaction between a urinary isolate of E. co/i carrying non-fimbrial MR adhesin (NFA-1) and human polymorphonuclear leukocytes (PMN) . We found that the organisms attach to PMN and the attachment was dose dependent and saturable . It was inhibited by isolated NFA-1, but not by mannoside . Recombinant plasmid encoding NFA-1 adhesin conferred binding capacity on a non-adhesive strain . The attachment of the bacteria carrying NFA-1 to PMN was associated with oxidative burst and inhibited by isolated NFA-1 . The data taken together suggest that NFA-1 mediates the attachment of the bacteria to PMN . The attachment is followed by ingestion and killing of the organisms, but at a slower rate than with bacteria bound via type 1 fimbriae . Key words : phagocytosis ; non-fimbrial adhesins ; E. co/i haemagglutinin .
Introduction Evidence obtained during the last decade indicates that phagocytes recognize specific structures expressed on bacterial surfaces . The molecular basis of this non-opsonic recognition has been characterized in a number of systems . In one system (termed lectinophagocytosis) the phagocytes bind and subsequently ingest the bacteria by lectin-sugar interactions .' Lectinophagocytosis mediated by the mannose-specific (or man nose-sensitive, MS) type 1 fimbrial lectin of E. coli, has been studied extensively . The MS-mediated binding of the bacteria to phagocytic cells results in stimulation of antimicrobial mechanisms exhibited as internalization and killing of the bacteria .' Most pathogenic E. coli carry genetic information encoding the expression of mannose resistant (MR) adhesins, in addition to type 1 fimbriae . The MR adhesins are best expressed in agar-grown bacteria at 37°C, while the MS adhesins are best expressed in broth-grown bacteria under static conditions, either at 18 or 37°C .2 Structurally, MR adhesins may be in fimbrial, fibrillar or non-fimbrial forms ." Functionally, the adhesins are responsible for the binding of the organisms to receptors 5-7 present on the surface of various types of eukaryotic cells . Recently several studies have been undertaken to determine whether any of the fimbrial MR haemagglutinins mediate binding of the bacteria to phagocytic cells . Among the fimbrial MR adhesins, the P and S fimbriae were found to bind poorly or not at all to polymorphonuclear leukocytes (PMNs) 810 suggesting that phagocytes 0882-4010/91 /090171 +08 $03 .00/0
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either lack receptors for these haemagglutinins or that the receptors are inaccessible to mediate binding of the MR-fimbriated bacteria . In addition, a poor association was observed between enterotoxigenic E. coli carrying the MR fimbrial adhesins CFA/I and CFA/II, and PMN ." A number of MR non-fimbrial (or fibrillar) adhesins expressed by various E. coli isolates have been described recently . a-6,12-16 In some cases the non-fimbrial adhesins were found to be organized in a capsule-like form on bacterial surfaces ."' Non-fimbrial adhesins (NFA-1 and NFA-2) mediate the adherence of bacteria to human epithelial cells in tissue culture .' It is not known, however, whether any of these NFAs mediate the binding of the bacteria to phagocytic cells . In the present study we show that NFA-1 expressed by a urinary isolate of E. coli mediates the binding of the bacteria to human PMNs . The association of NFA-1 carrying bacteria with PMNs triggered an oxidative burst in the phagocytic cells . The rate of ingestion and killing of E. coli bound via NFA-1 was found to be considerably slower, compared with E. coli bound to phagocytic cells via MS type 1 fimbrial adhesins . Results Microscopic examination showed that attachment of the NFA-1 -carrying E. coil 827 bacteria to PMNs was optimal (c . 90% of PMNs bound bacteria, 1-9 bacteria per PMN) in monolayers incubated for 60 min at 37°C with bacteria suspended in D-PBS (see Materials and methods section) . The binding was Mg t +- and Ca 21 -dependent and it was abolished by glutaraldehyde treatment or drying of the PMN monolayer before adding the bacteria (
