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Role of pili in Haemophilus influenzae adherence to, and internalization by, respiratory cells

J R Gilsdorf1, M Tucci, C F Marrs

  • 1Department of Pediatrics, University of Michigan Medical School, Ann Arbor 48109-0244, USA.

Pediatric Research
|February 1, 1996
PubMed

Insights

Haemophilus influenzae pili play a role in bacterial adherence to respiratory cells. However, nonpilus mechanisms are also crucial for both adherence and internalization by these cells.

Area of Science:

  • Microbiology
  • Cell Biology
  • Respiratory Medicine

Background:

  • Haemophilus influenzae is a significant respiratory pathogen.
  • Bacterial pili are known virulence factors involved in host cell adhesion.

Purpose of the Study:

  • To investigate the specific role of pili in Haemophilus influenzae adherence to various human respiratory cell types.
  • To differentiate between pilus-mediated and nonpilus-mediated adherence mechanisms.

Main Methods:

  • Testing piliated and nonpiliated strains of Haemophilus influenzae (type b and nontypeable) against cultured respiratory cells (HeLa, HEp-2, A549, tracheal, bronchial, buccal).
  • Utilizing nonpiliated mutants with inactivated pilin genes.
  • Employing GM1, a pilus receptor analog, to assess pilus-specific binding.

Main Results:

  • Both piliated and nonpiliated strains adhered to most tested respiratory cells.
  • Adherence varied by cell type: nonpiliated strains showed higher adherence to HEp-2 cells, while piliated strains were more adherent to bronchial and buccal cells.
  • GM1 inhibited pilus-mediated adherence but not nonpilus-mediated adherence.
  • Internalization by A549 cells was similar for both piliated and nonpiliated strains.

Conclusions:

  • Pili mediate adherence to specific respiratory cell types, but not all.
  • Nonpilus mechanisms significantly contribute to Haemophilus influenzae adherence and cellular internalization.
  • Understanding these mechanisms is vital for developing targeted therapeutic strategies against respiratory infections.

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