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Stimulation of human polymorphonuclear leukocyte oxidative metabolism by type 1 pili from Escherichia coli
Abstract:
We compared the degree to which Escherichia coli phase variants which do (T1P+ E. coli) or do not (T1P- E. coli) express type 1 pili (T1P) stimulate human polymorphonuclear leukocyte (PMN) oxidative activity. Unopsonized T1P+ E. coli stimulated the release of 0.20 to 0.24 nmol of H2O2 per 10(6) PMN per min and the consumption of 1.4 to 4.0 nmol of O2 per 10(6) PMN per min; no measurable PMN oxidative activity was stimulated by unopsonized T1P- E. coli. In the presence of serum opsonins, T1P+ E. coli stimulated the release of 1.12 to 1.16 nmol of H2O2 per 10(6) PMN per min and the consumption of 5.0 to 6.0 nmol of O2 per 10(6) PMN per min, whereas T1P- E. coli stimulated the release of 0.42 to 0.43 nmol of H2O2 per 10(6) PMN per min and the consumption of 0.6 to 2.0 nmol of O2 per 10(6) PMN per min. Although unaggregated T1P did not stimulate PMN, latex beads coated with T1P (T1P-latex) stimulated alpha-methylmannoside-inhibitable, opsonin-independent PMN oxidative activity. The activity stimulated by either T1P+ E. coli or T1P-latex was susceptible to inhibition by cytochalasin B. Latex particles coated with bovine serum albumin or mannose-resistant pili did not stimulate PMN. These data indicate that T1P+ E. coli stimulate PMN oxidative metabolism more effectively than do T1P- E. coli and that a similar PMN oxidative response follows cellular stimulation by either unopsonized T1P+ or opsonized T1P- E. coli. Furthermore, T1P-latex faithfully mimics the ability of T1P+ E. coli to stimulate PMN oxidative metabolism. Such particles may be useful in further analyses of cellular responses to T1P+ E. coli.
Insights
Type 1 pili (T1P) on Escherichia coli (E. coli) significantly enhance stimulation of human polymorphonuclear leukocyte (PMN) oxidative activity. T1P-coated latex beads mimic this T1P+ E. coli effect, offering a tool for further research.
Area of Science:
- Immunology
- Microbiology
- Cellular Biology
Background:
- Escherichia coli (E. coli) exhibits phase variants differing in type 1 pili (T1P) expression.
- Polymorphonuclear leukocytes (PMNs) are key immune cells involved in oxidative responses against bacteria.
- The role of T1P in modulating PMN oxidative activity requires detailed investigation.
Purpose of the Study:
- To compare the capacity of T1P-expressing (T1P+) and non-expressing (T1P-) E. coli to stimulate PMN oxidative activity.
- To investigate the role of T1P and opsonins in PMN activation.
- To evaluate T1P-coated latex beads as a model for T1P-mediated PMN stimulation.
Main Methods:
- Quantification of hydrogen peroxide (H2O2) release and oxygen (O2) consumption by human PMNs stimulated with T1P+ and T1P- E. coli.
- Assessment of PMN oxidative activity in the presence and absence of serum opsonins.
- Stimulation of PMNs using T1P-coated latex beads and control particles (BSA or mannose-resistant pili coated).
Main Results:
- Unopsonized T1P+ E. coli significantly stimulated PMN oxidative activity, while T1P- E. coli did not.
- Opsonization increased PMN stimulation by both E. coli variants, but T1P+ remained more potent.
- T1P-coated latex beads induced alpha-methylmannoside-inhibitable, opsonin-independent PMN oxidative activity, mimicking T1P+ E. coli.
Conclusions:
- T1P expression on E. coli enhances PMN oxidative metabolism.
- T1P-coated latex beads serve as a reliable model for studying T1P-mediated PMN responses.
- This model facilitates further research into cellular interactions with T1P-expressing bacteria.