Differential expression of sheep beta-defensin-1 and -2 and interleukin 8 during acute Mannheimia haemolytica pneumonia.
Beta-defensins are antimicrobial peptides produced by several cell types, including respiratory epithelia and leukocytes. Expression of some beta-defensins is increased by bacterial-induced inflammatory responses whereas expression of other beta-defensins is constitutive. Two beta-defensins are expressed in lungs of sheep (sheep beta-defensin-1 and -2; SBD-1/-2) and expression of SBD-1 is increased during parainfluenza virus type 3 (PI-3) infection. The effect of Mannheimia haemolytica, a Gram-negative bacteria known to induce expression of bovine beta-defensins and NF-kappa B in lung, has not been determined for SBD-1/-2. In this study, different concentrations of M. haemolytica were inoculated into pulmonary bronchi of lambs. SBD-1 and SBD-2 mRNA levels detected by real time reverse transcriptase polymerase chain reaction in lung homogenates did not increase. In fact, SBD-1 mRNA levels were significantly decreased with the highest administered inoculum concentration (10(9)). In contrast, mRNA levels of interleukin-8 (IL-8) were significantly increased over controls and progressively increased with M. haemolytica concentrations. Co-inoculation of M. haemolytica with xylitol, an osmotic agent, did not alter mRNA levels of SBD-1, SBD-2 or IL-8. SBD-1 mRNA expression was detected in lung epithelia, but not in leukocytes. This study suggests that SDB-1 expression occurs in epithelia and decreases during severe bacterial pneumonia, which is in contrast to the increase that occurs with PI-3 infection.
Ackermann
Mark R
MR
Department of Veterinary Pathology, College of Veterinary Medicine, 2738 Veterinary Medicine, Iowa State University, Ames, IA 50011-1250, USA. mackerma@iastate.edu
Gallup
Jack M
JM
Zabner
Joseph
J
Evans
Richard B
RB
Brockus
Charles W
CW
Meyerholz
David K
DK
Grubor
Branka
B
Brogden
Kim A
KA
D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000382:microbiology; D015870:Gene Expression; D016209:Interleukin-8 / Q000096:biosynthesis* / Q000235:genetics; D007962:Leukocytes / Q000276:immunology / Q000378:metabolism; D008168:Lung / Q000276:immunology; D016978:Mannheimia haemolytica / Q000276:immunology* / Q000302:isolation & purification; D016871:Pasteurellaceae Infections / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D018410:Pneumonia, Bacterial / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D020545:Respiratory Mucosa / Q000276:immunology; D012756:Sheep; D012757:Sheep Diseases / Q000276:immunology* / Q000382:microbiology; D014158:Transcription, Genetic; D023083:beta-Defensins / Q000096:biosynthesis* / Q000235:genetics
D016209:Interleukin-8; D012333:RNA, Messenger; D023083:beta-Defensins