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Early murine cytomegalovirus (MCMV) infection induces liver natural killer (NK) cell inflammation and protection through macrophage inflammatory protein 1alpha (MIP-1alpha)-dependent pathways.

Salazar-Mather TP, Orange JS, Biron CA - J. Exp. Med. (1998)

Bottom Line: Our studies evaluated contributions of NK cells to early MCMV-induced liver inflammation and MIP-1alpha requirements for inflammation and delivery of antiviral defenses.NK cells were shown to be responsible for focal inflammation, and to be induced to migrate at high levels, in MCMV-infected livers.The results precisely define MIP-1alpha-dependent steps required to achieve NK cell inflammation during, and mechanisms promoting defense against, viral infections in tissues.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Microbiology and Immunology, Division of Biology and Medicine, Brown University, Providence, Rhode Island 02912, USA.

ABSTRACT
Natural killer (NK) cells mediate defense against early murine cytomegalovirus (MCMV) infections in liver. The chemokine, macrophage inflammatory protein 1alpha (MIP-1alpha), can promote inflammatory responses. Our studies evaluated contributions of NK cells to early MCMV-induced liver inflammation and MIP-1alpha requirements for inflammation and delivery of antiviral defenses. NK cells were shown to be responsible for focal inflammation, and to be induced to migrate at high levels, in MCMV-infected livers. MIP-1alpha gene expression was elevated at coinciding times, and mice deficient in MIP-1alpha function were dramatically inhibited in both inflammatory and protective liver responses. The results precisely define MIP-1alpha-dependent steps required to achieve NK cell inflammation during, and mechanisms promoting defense against, viral infections in tissues.

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Related in: MedlinePlus

Elevated MIP-1α expression in MCMV-infected livers. (A)  Liver RNA was isolated from uninfected and infected mice. Reverse  transcriptase PCR cDNA products were generated and amplified using  oligonucleotide primers specific to MIP-1α or the housekeeping gene,  GAPDH. Amplified DNA was detected by Southern blot analysis and hybridization with specific internal oligonucleotide probes as described in  Materials and Methods. Samples were from C57BL/6-MIP-1α−/− mice  infected with MCMV for 2 d (lane 1), or C57BL/6 mice that were uninfected (lane 2) or infected with MCMV for 1, 2, 3, and 5 d (respectively,  lanes 3–6). (B) Livers were harvested from day 2 MCMV-infected  C57BL/6 mice, and frozen tissue sections were prepared and used for immunohistochemical staining of MIP-1α protein as described in Materials  and Methods. The MIP-1α protein is identified by dark blue precipitates,  and tissues are counterstained with methyl green. Panel photograph was  taken at ×31.25. Inset photograph, showing higher power of an inflammatory focus, was taken at ×125. Bar, 100 μm.
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Figure 3: Elevated MIP-1α expression in MCMV-infected livers. (A) Liver RNA was isolated from uninfected and infected mice. Reverse transcriptase PCR cDNA products were generated and amplified using oligonucleotide primers specific to MIP-1α or the housekeeping gene, GAPDH. Amplified DNA was detected by Southern blot analysis and hybridization with specific internal oligonucleotide probes as described in Materials and Methods. Samples were from C57BL/6-MIP-1α−/− mice infected with MCMV for 2 d (lane 1), or C57BL/6 mice that were uninfected (lane 2) or infected with MCMV for 1, 2, 3, and 5 d (respectively, lanes 3–6). (B) Livers were harvested from day 2 MCMV-infected C57BL/6 mice, and frozen tissue sections were prepared and used for immunohistochemical staining of MIP-1α protein as described in Materials and Methods. The MIP-1α protein is identified by dark blue precipitates, and tissues are counterstained with methyl green. Panel photograph was taken at ×31.25. Inset photograph, showing higher power of an inflammatory focus, was taken at ×125. Bar, 100 μm.

Mentions: To evaluate MIP-1α induction, total RNA was prepared from livers of C57BL/6 mice infected with MCMV for 1, 2, 3, or 5 d. Control RNA was prepared from uninfected C57BL/6 and day 2 MCMV-infected C57BL/6-MIP-1α−/− mice. Northern blot analysis revealed induction of MIP-1α relative to GAPDH messenger RNA (mRNA) expression on day 2 after MCMV infection of normal C57BL/6 mice. The message was not detectable in samples from uninfected C57BL/6 normal or day 2 MCMV-infected C57BL/6-MIP-1α−/− mice, but was observed at marginally detectable levels with day 1, and >twofold induction levels with day 3, samples from infected normal mice. Densitometric analyses demonstrated that, compared to samples from uninfected C57BL/6 mice, MIP-1α induction was >50-fold on day 2 after infection (data not shown). To increase the signal, reverse transcription was used to generate cDNA from the mRNA, and expression was examined after PCR amplification of the cDNA and Southern blot analysis using specific internal sequences for hybridization. In contrast to GAPDH expression, MIP-1α was not detectable in RNA samples from infected C57BL/6-MIP-1α−/− (Fig. 3 A, lane 1) or uninfected C57BL/6 (Fig. 3 A, lane 2) mice. However, MIP-1α RNA expression was observed readily in samples from C57BL/6 mice on days 1, 2, 3, and 5 after MCMV infection (Fig. 3 A, lanes 3, 4, 5, and 6, respectively). Peak values were on day 2 after infection as evaluated by both Northern blot and PCR analyses.


Early murine cytomegalovirus (MCMV) infection induces liver natural killer (NK) cell inflammation and protection through macrophage inflammatory protein 1alpha (MIP-1alpha)-dependent pathways.

Salazar-Mather TP, Orange JS, Biron CA - J. Exp. Med. (1998)

Elevated MIP-1α expression in MCMV-infected livers. (A)  Liver RNA was isolated from uninfected and infected mice. Reverse  transcriptase PCR cDNA products were generated and amplified using  oligonucleotide primers specific to MIP-1α or the housekeeping gene,  GAPDH. Amplified DNA was detected by Southern blot analysis and hybridization with specific internal oligonucleotide probes as described in  Materials and Methods. Samples were from C57BL/6-MIP-1α−/− mice  infected with MCMV for 2 d (lane 1), or C57BL/6 mice that were uninfected (lane 2) or infected with MCMV for 1, 2, 3, and 5 d (respectively,  lanes 3–6). (B) Livers were harvested from day 2 MCMV-infected  C57BL/6 mice, and frozen tissue sections were prepared and used for immunohistochemical staining of MIP-1α protein as described in Materials  and Methods. The MIP-1α protein is identified by dark blue precipitates,  and tissues are counterstained with methyl green. Panel photograph was  taken at ×31.25. Inset photograph, showing higher power of an inflammatory focus, was taken at ×125. Bar, 100 μm.
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Figure 3: Elevated MIP-1α expression in MCMV-infected livers. (A) Liver RNA was isolated from uninfected and infected mice. Reverse transcriptase PCR cDNA products were generated and amplified using oligonucleotide primers specific to MIP-1α or the housekeeping gene, GAPDH. Amplified DNA was detected by Southern blot analysis and hybridization with specific internal oligonucleotide probes as described in Materials and Methods. Samples were from C57BL/6-MIP-1α−/− mice infected with MCMV for 2 d (lane 1), or C57BL/6 mice that were uninfected (lane 2) or infected with MCMV for 1, 2, 3, and 5 d (respectively, lanes 3–6). (B) Livers were harvested from day 2 MCMV-infected C57BL/6 mice, and frozen tissue sections were prepared and used for immunohistochemical staining of MIP-1α protein as described in Materials and Methods. The MIP-1α protein is identified by dark blue precipitates, and tissues are counterstained with methyl green. Panel photograph was taken at ×31.25. Inset photograph, showing higher power of an inflammatory focus, was taken at ×125. Bar, 100 μm.
Mentions: To evaluate MIP-1α induction, total RNA was prepared from livers of C57BL/6 mice infected with MCMV for 1, 2, 3, or 5 d. Control RNA was prepared from uninfected C57BL/6 and day 2 MCMV-infected C57BL/6-MIP-1α−/− mice. Northern blot analysis revealed induction of MIP-1α relative to GAPDH messenger RNA (mRNA) expression on day 2 after MCMV infection of normal C57BL/6 mice. The message was not detectable in samples from uninfected C57BL/6 normal or day 2 MCMV-infected C57BL/6-MIP-1α−/− mice, but was observed at marginally detectable levels with day 1, and >twofold induction levels with day 3, samples from infected normal mice. Densitometric analyses demonstrated that, compared to samples from uninfected C57BL/6 mice, MIP-1α induction was >50-fold on day 2 after infection (data not shown). To increase the signal, reverse transcription was used to generate cDNA from the mRNA, and expression was examined after PCR amplification of the cDNA and Southern blot analysis using specific internal sequences for hybridization. In contrast to GAPDH expression, MIP-1α was not detectable in RNA samples from infected C57BL/6-MIP-1α−/− (Fig. 3 A, lane 1) or uninfected C57BL/6 (Fig. 3 A, lane 2) mice. However, MIP-1α RNA expression was observed readily in samples from C57BL/6 mice on days 1, 2, 3, and 5 after MCMV infection (Fig. 3 A, lanes 3, 4, 5, and 6, respectively). Peak values were on day 2 after infection as evaluated by both Northern blot and PCR analyses.

Bottom Line: Our studies evaluated contributions of NK cells to early MCMV-induced liver inflammation and MIP-1alpha requirements for inflammation and delivery of antiviral defenses.NK cells were shown to be responsible for focal inflammation, and to be induced to migrate at high levels, in MCMV-infected livers.The results precisely define MIP-1alpha-dependent steps required to achieve NK cell inflammation during, and mechanisms promoting defense against, viral infections in tissues.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Microbiology and Immunology, Division of Biology and Medicine, Brown University, Providence, Rhode Island 02912, USA.

ABSTRACT
Natural killer (NK) cells mediate defense against early murine cytomegalovirus (MCMV) infections in liver. The chemokine, macrophage inflammatory protein 1alpha (MIP-1alpha), can promote inflammatory responses. Our studies evaluated contributions of NK cells to early MCMV-induced liver inflammation and MIP-1alpha requirements for inflammation and delivery of antiviral defenses. NK cells were shown to be responsible for focal inflammation, and to be induced to migrate at high levels, in MCMV-infected livers. MIP-1alpha gene expression was elevated at coinciding times, and mice deficient in MIP-1alpha function were dramatically inhibited in both inflammatory and protective liver responses. The results precisely define MIP-1alpha-dependent steps required to achieve NK cell inflammation during, and mechanisms promoting defense against, viral infections in tissues.

Show MeSH
Related in: MedlinePlus