Human newborn polymorphonuclear neutrophils exhibit decreased levels of MyD88 and attenuated p38 phosphorylation in response to lipopolysaccharide

PURPOSE: Human newborn infants have increased susceptibility to gram-negative bacterial infection. Since lipopolysaccharide (LPS) primes polymorphonuclear neutrophils (PMN) to enhance host defense functions, we investigated its effect on adult and newborn PMN in vitro.

METHODS: PMN were isolated from blood of healthy adults and umbilical cords of full term newborns using dextran and Ficoll-Paque gradient sedimentation. Gel electrophoresis and Western blotting of membranes were used to probe for Mitogen-Activated Protein (MAP) kinase p38 phosphorylation, Toll-like Receptor-4 (TLR-4) and Myeloid Differentiation Factor 88 (MyD88) on isolated PMN membranes using specific antibodies. LPS induced degranulation was assessed using CD66 expression on PMN measured by flow cytometry.

RESULTS: We show that p38 phosphorylation in newborn PMN is attenuated in response to LPS stimulation even though adult and newborn PMN have similar amounts of p38 protein. The degree of attenuation in newborn PMN is dependent on the osmolarity of the medium. In addition, LPS-induced degranulation, a process that is p38 dependent, was also absent in newborn PMN. Although the LPS receptor TLR-4 is present at similar levels on newborn and adult PMN, its downstream adaptor protein MyD88 was significantly diminished in newborn PMN compared to adult cells.

CONCLUSIONS: Although the mechanism of PMN priming by LPS is not fully understood, our results suggest that MyD88 and p38 phosphorylation are important pathways in the process and contribute to attenuated response of newborn PMN to LPS in vitro.

Medienart:

E-Artikel

Erscheinungsjahr:

2007

Erschienen:

2007

Enthalten in:

Zur Gesamtaufnahme - volume:30

Enthalten in:

Clinical and investigative medicine. Medecine clinique et experimentale - 30(2007), 2 vom: 23., Seite E44-53

Sprache:

Englisch

Beteiligte Personen:

Al-Hertani, Walla [VerfasserIn]
Yan, Sen Rong [VerfasserIn]
Byers, David M [VerfasserIn]
Bortolussi, Robert [VerfasserIn]

Themen:

Antigens, CD
CD66 antigens
Cell Adhesion Molecules
EC 2.7.11.24
Journal Article
Lipopolysaccharides
Myeloid Differentiation Factor 88
P38 Mitogen-Activated Protein Kinases
Research Support, Non-U.S. Gov't
TLR4 protein, human
Toll-Like Receptor 4

Anmerkungen:

Date Completed 11.10.2007

Date Revised 10.11.2019

published: Print

Citation Status MEDLINE

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM172288525