Dataset Information

Impact of surfactant protein D, interleukin-5, and eosinophilia on Cryptococcosis.

ABSTRACT: Cryptococcus neoformans is an opportunistic fungal pathogen that initiates infection following inhalation. As a result, the pulmonary immune response provides a first line of defense against C. neoformans. Surfactant protein D (SP-D) is an important regulator of pulmonary immune responses and is typically host protective against bacterial and viral respiratory infections. However, SP-D is not protective against C. neoformans. This is evidenced by previous work from our laboratory demonstrating that SP-D-deficient mice infected with C. neoformans have a lower fungal burden and live longer than wild-type (WT) control animals. We hypothesized that SP-D alters susceptibility to C. neoformans by dysregulating the innate pulmonary immune response following infection. Thus, inflammatory cells and cytokines were compared in the bronchoalveolar lavage fluid from WT and SP-D(-/-) mice after C. neoformans infection. Postinfection, mice lacking SP-D have reduced eosinophil infiltration and interleukin-5 (IL-5) in lung lavage fluid. To further explore the interplay of SP-D, eosinophils, and IL-5, mice expressing altered levels of eosinophils and/or IL-5 were infected with C. neoformans to assess the role of these innate immune mediators. IL-5-overexpressing mice have increased pulmonary eosinophilia and are more susceptible to C. neoformans infection than WT mice. Furthermore, susceptibility of SP-D(-/-) mice to C. neoformans infection could be restored to the level of WT mice by increasing IL-5 and eosinophils by crossing the IL-5-overexpressing mice with SP-D(-/-) mice. Together, these studies support the conclusion that SP-D increases susceptibility to C. neoformans infection by promoting C. neoformans-driven pulmonary IL-5 and eosinophil infiltration.

SUBMITTER: Holmer SM

PROVIDER: S-EPMC3911392 | biostudies-other | 2014 Feb

REPOSITORIES: biostudies-other

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Impact of surfactant protein D, interleukin-5, and eosinophilia on Cryptococcosis.

Holmer Stephanie M SM Evans Kathy S KS Asfaw Yohannes G YG Saini Divey D Schell Wiley A WA Ledford Julie G JG Frothingham Richard R Wright Jo Rae JR Sempowski Gregory D GD Perfect John R JR

Infection and immunity 20131125 2

Cryptococcus neoformans is an opportunistic fungal pathogen that initiates infection following inhalation. As a result, the pulmonary immune response provides a first line of defense against C. neoformans. Surfactant protein D (SP-D) is an important regulator of pulmonary immune responses and is typically host protective against bacterial and viral respiratory infections. However, SP-D is not protective against C. neoformans. This is evidenced by previous work from our laboratory demonstrating t ...[more]

PMID: 24478083

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Project description:UnlabelledCryptococcus neoformans is a human opportunistic fungal pathogen causing severe disseminated meningoencephalitis, mostly in patients with cellular immune defects. This species is divided into three serotypes: A, D, and the AD hybrid. Our objectives were to compare population structures of serotype A and D clinical isolates and to assess whether infections with AD hybrids differ from infections with the other serotypes. For this purpose, we analyzed 483 isolates and the corresponding clinical data from 234 patients enrolled during the CryptoA/D study or the nationwide survey on cryptococcosis in France. Isolates were characterized in terms of ploidy, serotype, mating type, and genotype, utilizing flow cytometry, serotype- and mating type-specific PCR amplifications, and multilocus sequence typing (MLST) methods. Our results suggest that C. neoformans serotypes A and D have different routes of multiplication (primarily clonal expansion versus recombination events for serotype A and serotype D, respectively) and important genomic differences. Cryptococcosis includes a high proportion of proven or probable infections (21.5%) due to a mixture of genotypes, serotypes, and/or ploidies. Multivariate analysis showed that parameters independently associated with failure to achieve cerebrospinal fluid (CSF) sterilization by week 2 were a high serum antigen titer, the lack of flucytosine during induction therapy, and the occurrence of mixed infection, while infections caused by AD hybrids were more likely to be associated with CSF sterilization. Our study provides additional evidence for the possible speciation of C. neoformans var. neoformans and grubii and highlights the importance of careful characterization of causative isolates.ImportanceCryptococcus neoformans is an environmental fungus causing severe disease, estimated to be responsible for 600,000 deaths per year worldwide. This species is divided into serotypes A and D and an AD hybrid, and these could be considered two different species and an interspecies hybrid. The objectives of our study were to compare population structures of serotype A and serotype D and to assess whether infections with AD hybrids differ from infections with serotype A or D isolates in terms of clinical presentation and outcome. For this purpose, we used clinical data and strains from patients diagnosed with cryptococcosis in France. Our results suggest that, according to the serotype, isolates have different routes of multiplication and high genomic differences, confirming the possible speciation of serotypes A and D. Furthermore, we observed a better prognosis for infections caused by AD hybrid than those caused by serotype A or D, at least for those diagnosed in France.

Project description:BackgroundPatients with human immunodeficiency virus/AIDS-associated cryptococcal meningitis (CM) frequently experience clinical deterioration, known as cryptococcosis-associated immune reconstitution inflammatory syndrome (C-IRIS), upon initiation of antiretroviral therapy (ART). The immunological mechanisms underlying C-IRIS are incompletely defined and no reliable predictive biomarkers exist. We investigated whether plasma or cerebrospinal fluid (CSF) levels of cytokines and chemokines predicted C-IRIS and are potential predictive biomarkers.MethodsPatients with CM who experienced C-IRIS (N = 27) upon ART initiation were compared to CD4+ T-cell count-matched patients without C-IRIS (N = 27). Plasma and CSF collected pre-ART were assayed for cytokines and chemokines using a 17-plex Luminex kit or enzyme-linked immunosorbent assay. Cox proportional hazards regression and principal component analyses were also performed.ResultsPlasma interleukin (IL) 2, IL-4, IL-5, IL-7, IL-17, interferon-?, and tumor necrosis factor-? levels were higher in C-IRIS patients compared to controls (all P < .05), with IL-5 and IL-7 significant after Bonferroni-Holm correction. In multivariate Cox proportional hazards regression, high IL-5 (hazard ratio [HR], 5.76 [95% confidence interval {CI}, .77-43.0]; P = .088) and IL-7 (HR, 9.30 [95% CI, 1.96-44.0]; P = .005) were predictive of C-IRIS. Plasma IL-5 (P = .0008) and IL-10 (P = .0089) were lower in those who achieved CSF cryptococcal culture negativity compared to those with positive cultures pre-ART. There were no significant differences in CSF cytokine or chemokine levels between cases and controls.ConclusionsHigh plasma IL-5 and IL-7 levels pre-ART were associated with increased risk of developing C-IRIS. High IL-5 levels may reflect a Th2 environment associated with impaired clearance of cryptococci while high IL-7 levels may reflect IL-7/IL-7R pathway dysfunction in T cells, both of which could be associated with C-IRIS immunopathogenesis.

Dataset Information

Impact of surfactant protein D, interleukin-5, and eosinophilia on Cryptococcosis.

Publications

Impact of surfactant protein D, interleukin-5, and eosinophilia on Cryptococcosis.

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