Environmental Health Perspectives 105, Supplement 5, September 1997

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Intratracheal Instillation versus Intratracheal Inhalation: Influence of Cytokines on Inflammatory Response

M. Osier, R.B. Baggs, and G. Oberdörster

Department of Environmental Medicine, University of Rochester School of Medicine, Rochester, New York

Abstract
Our laboratory has developed a method of particle exposure whereby anesthetized rats intratracheally inhale, at a regulated breathing rate and pressure, an aerosolized test material. This method is capable of delivering considerable doses in a short time period and, unlike the commonly used method of intratracheal instillation, does so with an even particle distribution throughout the lung. Early studies comparing the response of male Fischer 344 rats exposed to TiO 2 particles of two differing primary particle sizes showed that at similar particle doses animals exposed by the two methods showed differences in response, as measured by bronchoalveolar lavage (BAL) parameters. Building on this, we sought to study the roles that macrophage inflammatory protein-2 (MIP-2) and tumor necrosis factor alpha (TNF- alpha ), two cytokines thought to have proinflammatory roles in the lung, may play in the differences observed. Increases in MIP-2 protein levels in the lavaged cells, but not the supernatant, were observed in those groups where increased polymorphonuclear cells (PMN) in the lung lavage were found, but not in those where no increase in PMN levels was observed. BAL TNF- alpha levels, measured by enzyme-linked immunosorbent assay, showed no apparent correlation with cellular or biochemical BAL parameters for either particle size or dosing method. Increases in immunocytochemical staining for TNF- alpha , compared to unexposed controls, were observed in several particle-exposed groups. Thus, it appears that increased BAL MIP-2 protein levels, but not TNF- alpha , correlate well with the inflammatory response, as measured by PMN numbers in lavaged cells, for both exposure systems. -- Environ Health Perspect 105(Suppl 5):1265-1271 (1997)

Key words : intratracheal inhalation, MIP-2, TNF- alpha , particle, lavage

This paper is based on a presentation at The Sixth International Meeting on the Toxicology of Natural and Man-Made Fibrous and Non-Fibrous Particles held 15-18 September 1996 in Lake Placid, New York. Manuscript received at EHP 26 March 1997; accepted 3 July 1997.

The authors thank P. Wade-Mercer, N. Corson, Kiem Nguyen, Ro.Gelein, and L. Johnstone for technical advice and assistance. These studies were supported by NIEHS grants ES04872, ES01247, and HL07216.

Address correspondence to Dr. M. Osier, Department of Environmental Medicine, University of Rochester School of Medicine, 301 Elmwod Ave., Box EHSC, Rochester, NY 14642-0001. Telephone: (716) 275-8949. Fax: (716) 256- 2631. E-mail: osierm@envmed.rochester.edu

Abbreviations used: BAL, bronchoalveolar lavage; ELISA, enzyme-linked immunosorbent assay; ITIH, intratracheal inhalation; LPS, lipopolysaccharide; MIP-2, macrophage inflammatory protein-2; PBS, phosphate-buffered saline; PMN, polymorphonuclear cells; SDS-PAGE, sodium dodecyl sulfate-polyacrylamide gel electrophoresis; TNF- alpha , tumor necrosis factor alpha.

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Last Update: November 17, 1997