Pneumocystis carinii pneumonia alters expression and distribution of lung collectins SP-A and SP-D

Elena Nikolaevna Atochina, James M. Beck, Seth T. Scanlon, Angela M. Preston, Michael F. Beers

Research output: Contribution to journalArticle

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Abstract

Surfactant proteins SP-A and SP-D, members of the collectin family, have been shown to play a significant role in lung host defense. Both proteins selectively bind Pneumocystis carinii (PC) organisms and modulate the interaction of this pathogen with alveolar macrophages. We hypothesized that the expression and distribution of lung collectins SP-A and SP-D is altered by PC lung infection. PC organisms (2 × 105) were inoculated intratracheally into C.B-17 scid/scid mice that do not require steroids for immunosuppression. Four weeks after inoculation, bronchoalveolar lavage (BAL) fluid was fractionated into three fractions - cell pellet, large aggregate (LA), and small aggregate (SA) surfactant - and each fraction was analyzed for the expression of surfactant components. In uninfected mice, the majority of SP-A (62% ± 10%) was found in association with lipids in the LA fraction, while 55% ± 14% of SP-D was distributed in the SA fraction. In contrast, both hydrophobic proteins SP-B and SP-C were associated exclusively with LA. PC infection resulted in major changes in the expression of all surfactant components. Total protein content of LA was unchanged by PC infection (115% ± 18% of control), whereas SA protein content markedly increased (240% ± 18% of control level, P <.001). In contrast, the phospholipid content of LA was significantly decreased (53% ± 5% of control level, P <.001), whereas the SA phospholipid content of infected mice was increased (172% ± 16% of control level, P <.001). By Western blotting, PC pneumonia (PCP) induced a 3-fold increase in the total alveolar SP-D protein that was reflected mainly in increases in SA SP-D (454% ± 135% of control, P <.05). The total alveolar SP-A protein content was also increased in PCP because of a large increase in SP-A in SA (720% ± 115% of control, P <.05); SP-A levels in LA were unchanged. The increases in lung collectin expression were selective, because PCP resulted in the down-regulation of both SP-B and SP-C in LA (5% ± 2% and 13% ± 2% of control, respectively, P <.001). We conclude that PCP induces marked elevations in alveolar collectin levels because of increased expression and accumulation of SP-A and SP-D protein in SA surfactant.

Original languageEnglish
Pages (from-to)429-439
Number of pages11
JournalJournal of Laboratory and Clinical Medicine
Volume137
Issue number6
DOIs
Publication statusPublished - Jun 2001
Externally publishedYes

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Collectins
Pulmonary Surfactant-Associated Protein D
Pneumocystis Pneumonia
Surface-Active Agents
Pneumocystis Infections
Pulmonary Surfactant-Associated Protein A
Lung
Pneumocystis carinii
Pneumonia
Phospholipids
Pulmonary Surfactant-Associated Protein B
Proteins
Bronchoalveolar Lavage Fluid
Alveolar Macrophages
Immunosuppression
Down-Regulation
Western Blotting
Steroids
Lipids

ASJC Scopus subject areas

  • Medicine(all)
  • Pathology and Forensic Medicine

Cite this

Pneumocystis carinii pneumonia alters expression and distribution of lung collectins SP-A and SP-D. / Atochina, Elena Nikolaevna; Beck, James M.; Scanlon, Seth T.; Preston, Angela M.; Beers, Michael F.

In: Journal of Laboratory and Clinical Medicine, Vol. 137, No. 6, 06.2001, p. 429-439.

Research output: Contribution to journalArticle

Atochina, Elena Nikolaevna ; Beck, James M. ; Scanlon, Seth T. ; Preston, Angela M. ; Beers, Michael F. / Pneumocystis carinii pneumonia alters expression and distribution of lung collectins SP-A and SP-D. In: Journal of Laboratory and Clinical Medicine. 2001 ; Vol. 137, No. 6. pp. 429-439.
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