Dataset Information

Modulation of the pulmonary type 2 T-cell response to Cryptococcus neoformans by intratracheal delivery of a tumor necrosis factor alpha-expressing adenoviral vector.

ABSTRACT: C57BL/6 mice develop an allergic bronchopulmonary mycosis following intratracheal inoculation of Cryptococcus neoformans 24067. We determined that only low levels of tumor necrosis factor alpha (TNF-alpha) are produced in the lungs following infection. Thus, the objective of the present studies was to determine whether treatment with a TNF-alpha-expressing adenoviral vector (adenoviral vector with the murine TNF-alpha transgene under the control of the human cytomegalovirus promoter [AdTNFalpha]) could switch the type 2 (T2) T-cell response/T1 T-cell response balance toward the T1 T-cell response. AdTNFalpha induced an increase in TNF-alpha expression at days 3 and 7. At days 7 to 14, the number of cryptococcal lung CFU continued to increase in both untreated and control adenoviral vector (empty adenovirus type 5 backbone)-treated mice, but the number was ultimately 100-fold lower following AdTNFalpha treatment. AdTNFalpha markedly increased neutrophil and macrophage numbers, and pulmonary eosinophilia did not develop. CXCL1, CXCL2, and gamma interferon were also up-regulated, while eotaxin, interleukin-4 (IL-4), and IL-5 were down-regulated. AdTNFalpha treatment also increased the number of CD80(+) and CD40(+) cells and decreased the number of CD86(+) cells (CD11b(+) and CD11c(+)) in the lungs. Major histocompatibility complex class II levels on CD11b(+) cells were increased. Whole-lung expression of inducible nitric oxide synthase was increased, while YM2 expression and acidic mammalian chitinase expression were decreased. None of these effects were observed with the control (empty) adenoviral vector. Overall, these results support the hypothesis that early TNF-alpha expression promotes a shift in T-cell and macrophage polarization from T2/alternatively activated macrophages toward T1/classically activated macrophages, resulting in control of the fungal infection and prevention of the allergic response.

SUBMITTER: Milam JE

PROVIDER: S-EPMC2044519 | biostudies-literature | 2007 Oct

REPOSITORIES: biostudies-literature

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Modulation of the pulmonary type 2 T-cell response to Cryptococcus neoformans by intratracheal delivery of a tumor necrosis factor alpha-expressing adenoviral vector.

Milam Jami E JE Herring-Palmer Amy C AC Pandrangi Raj R McDonald Roderick A RA Huffnagle Gary B GB Toews Galen B GB

Infection and immunity 20070723 10

C57BL/6 mice develop an allergic bronchopulmonary mycosis following intratracheal inoculation of Cryptococcus neoformans 24067. We determined that only low levels of tumor necrosis factor alpha (TNF-alpha) are produced in the lungs following infection. Thus, the objective of the present studies was to determine whether treatment with a TNF-alpha-expressing adenoviral vector (adenoviral vector with the murine TNF-alpha transgene under the control of the human cytomegalovirus promoter [AdTNFalpha] ...[more]

PMID: 17646355

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Project description:The fungal pathogen, Cryptococcus neoformans, has been shown to undergo replicative aging. Old cells are characterized by advanced generational age and phenotypic changes that appear to mediate enhanced resistance to host and antifungal-based killing. As a consequence of this age-associated resilience, old cells accumulate during chronic infection. Based on these findings, we hypothesized that shifting the generational age of a pathogenic yeast population would alter its vulnerability to the host and affect its virulence. SIR2 is a well-conserved histone deacetylase, and a pivotal target for the development of anti-aging drugs. We tested its effect on C. neoformans' replicative lifespan (RLS). First, a mutant C. neoformans strain (sir2Δ) was generated, and confirmed a predicted shortened RLS in sir2Δ cells consistent with its known role in aging. Next, RLS analysis showed that treatment of C. neoformans with Sir2p-agonists resulted in a significantly prolonged RLS, whereas treatment with a Sir2p-antagonist shortened RLS. RLS modulating effects were dependent on SIR2 and not observed in sir2Δ cells. Because SIR2 loss resulted in a slightly impaired fitness, effects of genetic RLS modulation on virulence could not be compared with wild type cells. Instead we chose to chemically modulate RLS, and investigated the effect of Sir2p modulating drugs on C. neoformans cells in a Galleria mellonella infection model. Consistent with our hypothesis that shifts in the generational age of the infecting yeast population alters its vulnerability to host cells, we observed decreased virulence of C. neoformans in the Galleria host when RLS was prolonged by treatment with Sir2p agonists. In contrast, treatment with a Sir2p antagonist, which shortens RLS enhanced virulence in Galleria. In addition, combination of Sir2p agonists with antifungal therapy enhanced the antifungal's effect. Importantly, no difference in virulence was observed with drug treatment when sir2Δ cells were used for infection, which confirmed target specificity and ruled out non-specific effects of the drugs on the Galleria host. Thus, this study suggests that RLS modulating drugs, such as Sir2p agonists, shift lifespan and vulnerability of the fungal population, and should be further investigated as a potential class of novel antifungal drug targets that can enhance antifungal efficacy.

Dataset Information

Modulation of the pulmonary type 2 T-cell response to Cryptococcus neoformans by intratracheal delivery of a tumor necrosis factor alpha-expressing adenoviral vector.

Publications

Modulation of the pulmonary type 2 T-cell response to Cryptococcus neoformans by intratracheal delivery of a tumor necrosis factor alpha-expressing adenoviral vector.

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