Assuntos
Reação em Cadeia da Polimerase , Humanos , Reações Falso-Negativas , Pneumocystis/genética , Pneumocystis/isolamento & purificação , Pneumocystis/classificação , Pneumocystis carinii/genética , Pneumocystis carinii/isolamento & purificação , Pneumonia por Pneumocystis/diagnóstico , Pneumonia por Pneumocystis/microbiologia , Reação em Cadeia da Polimerase/métodosRESUMO
SUMMARYEvery human being is presumed to be infected by the fungus Pneumocystis jirovecii at least once in his or her lifetime. This fungus belongs to a large group of species that appear to exclusively infect mammals, with P. jirovecii being the only one known to cause disease in humans. The mystery of P. jirovecii origin and speciation is just beginning to unravel. Here, we provide a review of the major steps of P. jirovecii evolution. The Pneumocystis genus likely originated from soil or plant-associated organisms during the period of Cretaceous ~165 million years ago and successfully shifted to mammals. The transition coincided with a substantial loss of genes, many of which are related to the synthesis of nutrients that can be scavenged from hosts or cell wall components that could be targeted by the mammalian immune system. Following the transition, the Pneumocystis genus cospeciated with mammals. Each species specialized at infecting its own host. Host specialization is presumably built at least partially upon surface glycoproteins, whose protogene was acquired prior to the genus formation. P. jirovecii appeared at ~65 million years ago, overlapping with the emergence of the first primates. P. jirovecii and its sister species P. macacae, which infects macaques nowadays, may have had overlapping host ranges in the distant past. Clues from molecular clocks suggest that P. jirovecii did not cospeciate with humans. Molecular evidence suggests that Pneumocystis speciation involved chromosomal rearrangements and the mounting of genetic barriers that inhibit gene flow among species.
Assuntos
Filogenia , Pneumocystis carinii , Humanos , Animais , Pneumocystis carinii/genética , Pneumocystis carinii/classificação , Pneumocystis carinii/patogenicidade , Infecções por Pneumocystis/microbiologia , Pneumocystis/genética , Pneumocystis/classificação , Evolução Molecular , Especificidade de Hospedeiro , Pneumonia por Pneumocystis/microbiologia , Genoma Fúngico/genética , Mamíferos/microbiologia , Evolução BiológicaRESUMO
Twenty-years ago, considering the host specificity of Pneumocystis species, the human-derived Pneumocystis, Pneumocystis carinii formae specialis hominis, was renamed Pneumocystis jirovecii. Pneumocystis carinii formae specialis carinii was finally renamed Pneumocystis carinii and kept for the species derived from Rattus norvegicus. P. jirovecii is now widely used by most authors. The PCP acronym that initially referred to "Pneumocystis cariniipneumonia" was contemporaneously redefined to stand for Pneumocystispneumonia in order to avoid changing the acronym of the name of the disease that clinicians have used for several decades. Using analysis of multidata bases on PubMed, we have noted a recent acceleration in the use of PJP for Pneumocystis jiroveciipneumonia, which may be grammatically correct but not in accordance with retaining PCP, which was proposed in the early 2000s. Through this reminder, in order to standardize the literature on P. jirovecii, we plead for the use of only one acronym, PCP. LAY SUMMARY: Through this reminder on Pneumocystis nomenclature, we plead for the use of only one acronym, PCP, the retention of which was proposed in the early 2000s, and which currently stands for Pneumocystispneumonia.
Assuntos
Abreviaturas como Assunto , Pneumocystis/classificação , Pneumonia por Pneumocystis , Terminologia como AssuntoAssuntos
Pulmão , Pneumocystis , Pneumonia por Pneumocystis , Animais , Humanos , Pulmão/metabolismo , Pulmão/microbiologia , Pulmão/patologia , Pneumocystis/classificação , Pneumocystis/metabolismo , Pneumocystis/patogenicidade , Pneumonia por Pneumocystis/metabolismo , Pneumonia por Pneumocystis/microbiologia , Pneumonia por Pneumocystis/patologia , Especificidade da EspécieRESUMO
Fungal organisms of the genus Pneumocystis may cause Pneumocystis pneumonia (PCP) in humans, but also domestic and wild mammals. Almost every animal species hosts its own genetically distinct Pneumocystis species, however information is sparse. In this study, 62 red foxes (Vulpes vulpes) and 37 raccoon dogs (Nyctereutes procyonoides) were collected in North-East Germany. The lung tissues of the animals were analysed by a new designed specific pan-Pneumocystis mtLSU rRNA gene PCR and sequencing. With this PCR, detection and discrimination of all known Pneumocystis spp. in a single step should be possible. This first detection of Pneumocystis spp. in 29/62 (46.8%) red foxes and 29/37 (78.4%) raccoon dogs indicated, that they harbour two dissimilar strains, as seen by specific single nucleotide position changes (SNPs). Nevertheless, five samples with contrary SNPs showed a probable inter-species transmission.
Assuntos
Raposas , Pneumocystis/isolamento & purificação , Pneumonia por Pneumocystis/veterinária , Cães Guaxinins , Animais , DNA Fúngico/isolamento & purificação , Feminino , Pulmão/microbiologia , Masculino , Filogenia , Pneumocystis/classificação , Pneumocystis/genética , Pneumonia por Pneumocystis/diagnóstico , Pneumonia por Pneumocystis/epidemiologia , Reação em Cadeia da Polimerase/veterinária , Estudos RetrospectivosRESUMO
Pneumocystis, a major opportunistic pathogen in patients with a broad range of immunodeficiencies, contains abundant surface proteins encoded by a multicopy gene family, termed the major surface glycoprotein (Msg) gene superfamily. This superfamily has been identified in all Pneumocystis species characterized to date, highlighting its important role in Pneumocystis biology. In this report, through a comprehensive and in-depth characterization of 459 msg genes from 7 Pneumocystis species, we demonstrate, for the first time, the phylogeny and evolution of conserved domains in Msg proteins and provide a detailed description of the classification, unique characteristics, and phylogenetic relatedness of five Msg families. We further describe, for the first time, the relative expression levels of individual msg families in two rodent Pneumocystis species, the substantial variability of the msg repertoires in P. carinii from laboratory and wild rats, and the distinct features of the expression site for the classic msg genes in Pneumocystis from 8 mammalian host species. Our analysis suggests multiple functions for this superfamily rather than just conferring antigenic variation to allow immune evasion as previously believed. This study provides a rich source of information that lays the foundation for the continued experimental exploration of the functions of the Msg superfamily in Pneumocystis biology.IMPORTANCEPneumocystis continues to be a major cause of disease in humans with immunodeficiency, especially those with HIV/AIDS and organ transplants, and is being seen with increasing frequency worldwide in patients treated with immunodepleting monoclonal antibodies. Annual health care associated with Pneumocystis pneumonia costs â¼$475 million dollars in the United States alone. In addition to causing overt disease in immunodeficient individuals, Pneumocystis can cause subclinical infection or colonization in healthy individuals, which may play an important role in species preservation and disease transmission. Our work sheds new light on the diversity and complexity of the msg superfamily and strongly suggests that the versatility of this superfamily reflects multiple functions, including antigenic variation to allow immune evasion and optimal adaptation to host environmental conditions to promote efficient infection and transmission. These findings are essential to consider in developing new diagnostic and therapeutic strategies.
Assuntos
Evolução Molecular , Proteínas Fúngicas/genética , Variação Genética , Genoma Fúngico , Glicoproteínas de Membrana/genética , Filogenia , Pneumocystis/genética , Animais , Mamíferos/microbiologia , Pneumocystis/classificação , Ratos , Homologia de Sequência do Ácido NucleicoRESUMO
PCR inhibition is frequent in medical microbiology routine practice and may lead to false-negative results; however there is no consensus on how to detect it. Pathogen-specific and human gene amplifications are widely used to detect PCR inhibition. We aimed at comparing the value of PCR inhibitor detection using these two methods. We analysed Cp shifts (ΔCp) obtained from qPCRs targeting either the albumin gene or the pathogen-specific sequence used in two laboratory-developed microbiological qPCR assays. 3152 samples including various matrixes were included. Pathogen-specific amplification and albumin qPCR identified 62/3152 samples (2.0%), and 409/3152 (13.0%) samples, respectively, as inhibited. Only 16 samples were detected using both methods. In addition, the use of the Youden's index failed to determine adequate Cp thresholds for albumin qPCR, even when we distinguished among the different sample matrixes. qPCR targeting the albumin gene therefore appears not adequate to identify the presence of PCR inhibitors in microbiological PCR assays. Our data may be extrapolated to other heterologous targets and should discourage their use to assess the presence of PCR inhibition in microbiological PCR assays.
Assuntos
Amplificação de Genes , Técnicas Microbiológicas , Reação em Cadeia da Polimerase em Tempo Real , Humanos , Técnicas Microbiológicas/métodos , Técnicas Microbiológicas/normas , Pneumocystis/classificação , Pneumocystis/genética , Infecções por Pneumocystis/diagnóstico , Infecções por Pneumocystis/microbiologia , Reação em Cadeia da Polimerase em Tempo Real/métodos , Reação em Cadeia da Polimerase em Tempo Real/normas , Estudos Retrospectivos , Sensibilidade e Especificidade , Toxoplasma/classificação , Toxoplasma/genética , Toxoplasmose/diagnóstico , Toxoplasmose/microbiologiaRESUMO
Pneumocystis is a genus of parasitic fungi infecting lung tissues in a wide range of mammal species, displaying a strong host specificity and patterns of co-speciation with their hosts. However, a recent study on Asiatic murids challenged these patterns reporting several Pneumocystis lineages/species shared by different host species or even genera in the Rattini and Murini tribes. Here we screened lung samples of 27 species of African rodents from five families for the presence of Pneumocystis DNA. Using reconstructed multi-locus phylogenies of both hosts and parasites, we tested the hypothesis of their co-evolution. We found that Pneumocystis is widespread in African rodents, detected in all but seven screened host species, with species-level prevalence ranging from 5.9 to 100%. Several host species carry pairs of highly divergent Pneumocystis lineages/species. The retrieved co-phylogenetic signal was highly significant (pâ¯=â¯.0017). We found multiple co-speciations, sorting events and two host-shift events, which occurred between Murinae and Deomyinae hosts. Comparison of genetic distances suggests higher substitution rates for Pneumocystis relative to the rodent hosts on neutral loci and slower rates on selected ones. We discuss life-history traits and population dynamics factors which could explain the observed results.
Assuntos
Muridae/microbiologia , Pneumocystis/fisiologia , África , Animais , Evolução Biológica , Genes Fúngicos , Interações Hospedeiro-Patógeno , Pulmão/microbiologia , Filogenia , Pneumocystis/classificação , Pneumocystis/genéticaRESUMO
Pneumocystis jirovecii can cause severe potentially life-threatening pneumonia (PCP) in kidney transplant patients. Prophylaxis of patients against PCP in this setting is usually performed during 6 months after transplantation. The aim of this study is to describe the molecular epidemiology of a cluster of PCP in renal transplant recipients in Brazil. Renal transplant patients who developed PCP between May and December 2011 had their formalin-fixed paraffin-embedded (FFPE) lung biopsy samples analysed. Pneumocystis jirovecii 23S mitochondrial large subunit of ribosomal RNA (23S mtLSU-rRNA), 26S rRNA, and dihydropteroate synthase (DHPS) genes were amplified by polymerase chain reaction (PCR), sequenced, and analysed for genetic variation. During the study period, 17 patients developed PCP (only four infections were documented within the first year after transplantation) and six (35.3%) died. Thirty FFPE samples from 11 patients, including one external control HIV-infected patient, had fungal DNA successfully extracted for further amplification and sequencing for all three genes. A total of five genotypes were identified among the 10 infected patients. Of note, four patients were infected by more than one genotype and seven patients were infected by the same genotype. DNA extracted from FFPE samples can be used for genotyping; this approach allowed us to demonstrate that multiple P. jirovecii strains were responsible for this cluster, and one genotype was found infecting seven patients. The knowledge of the causative agents of PCP may help to develop new initiatives for control and prevention of PCP among patients undergoing renal transplant and improve routine PCP prophylaxis.
Assuntos
Variação Genética , Transplante de Rim/efeitos adversos , Pneumocystis/isolamento & purificação , Pneumonia por Pneumocystis/microbiologia , Complicações Pós-Operatórias/microbiologia , Adulto , Brasil , Estudos Transversais , DNA Fúngico/genética , Feminino , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Filogenia , Pneumocystis/classificação , Pneumocystis/genética , Pneumonia por Pneumocystis/diagnóstico , Complicações Pós-Operatórias/diagnóstico , Estudos Retrospectivos , Subunidades Ribossômicas Maiores/genética , Adulto JovemRESUMO
Pneumocystis, a unique atypical fungus with an elusive lifestyle, has had an important medical history. It came to prominence as an opportunistic pathogen that not only can cause life-threatening pneumonia in patients with HIV infection and other immunodeficiencies but also can colonize the lungs of healthy individuals from a very early age. The genus Pneumocystis includes a group of closely related but heterogeneous organisms that have a worldwide distribution, have been detected in multiple mammalian species, are highly host species specific, inhabit the lungs almost exclusively, and have never convincingly been cultured in vitro, making Pneumocystis a fascinating but difficult-to-study organism. Improved molecular biologic methodologies have opened a new window into the biology and epidemiology of Pneumocystis. Advances include an improved taxonomic classification, identification of an extremely reduced genome and concomitant inability to metabolize and grow independent of the host lungs, insights into its transmission mode, recognition of its widespread colonization in both immunocompetent and immunodeficient hosts, and utilization of strain variation to study drug resistance, epidemiology, and outbreaks of infection among transplant patients. This review summarizes these advances and also identifies some major questions and challenges that need to be addressed to better understand Pneumocystis biology and its relevance to clinical care.
Assuntos
Infecções por Pneumocystis/epidemiologia , Infecções por Pneumocystis/microbiologia , Pneumocystis/fisiologia , Classificação , Surtos de Doenças , Farmacorresistência Fúngica , Especificidade de Hospedeiro , Pneumocystis/classificaçãoRESUMO
Pneumocystis species are opportunistic mammalian pathogens that cause severe pneumonia in immunocompromised individuals. These fungi are highly host specific and uncultivable in vitro Human Pneumocystis infections present major challenges because of a limited therapeutic arsenal and the rise of drug resistance. To investigate the diversity and demographic history of natural populations of Pneumocystis infecting humans, rats, and mice, we performed whole-genome and large-scale multilocus sequencing of infected tissues collected in various geographic locations. Here, we detected reduced levels of recombination and variations in historical demography, which shape the global population structures. We report estimates of evolutionary rates, levels of genetic diversity, and population sizes. Molecular clock estimates indicate that Pneumocystis species diverged before their hosts, while the asynchronous timing of population declines suggests host shifts. Our results have uncovered complex patterns of genetic variation influenced by multiple factors that shaped the adaptation of Pneumocystis populations during their spread across mammals.IMPORTANCE Understanding how natural pathogen populations evolve and identifying the determinants of genetic variation are central issues in evolutionary biology. Pneumocystis, a fungal pathogen which infects mammals exclusively, provides opportunities to explore these issues. In humans, Pneumocystis can cause a life-threatening pneumonia in immunosuppressed individuals. In analysis of different Pneumocystis species infecting humans, rats, and mice, we found that there are high infection rates and that natural populations maintain a high level of genetic variation despite low levels of recombination. We found no evidence of population structuring by geography. Our comparisons of the times of divergence of these species to their respective hosts suggest that Pneumocystis may have undergone recent host shifts. The results demonstrate that Pneumocystis strains are widely disseminated geographically and provide a new understanding of the evolution of these pathogens.
Assuntos
Pneumocystis/genética , Pneumocystis/isolamento & purificação , Pneumonia por Pneumocystis/microbiologia , Pneumonia por Pneumocystis/veterinária , Doenças dos Roedores/microbiologia , Animais , Variação Genética , Genômica , Humanos , Camundongos , Filogenia , Pneumocystis/classificação , Ratos , Ratos Sprague-Dawley , Recombinação GenéticaRESUMO
Lung specimens (n = 216) from six wildlife species were examined for occurrence of Pneumocystis species in pulmonary tissues. Among small mammals the shrew Sorex antinorii (80 %) were most frequently colonized. In contrast, foxes and badgers did not yield positive amplification. Host-specificity was noted, at least at the level of the host genus. Phylogenetic trees based on partial mtLSU and mtSSU showed high diversity of species corresponding to animal host diversity. Nuclear rDNA ITS data confirmed unambiguous separation of species. In conclusion, ITS is an excellent marker to distinguish species of the genus Pneumocystis.
Assuntos
Animais Selvagens/microbiologia , Pneumocystis/isolamento & purificação , Pneumonia por Pneumocystis/veterinária , Animais , Código de Barras de DNA Taxonômico , Pulmão/microbiologia , Dados de Sequência Molecular , Filogenia , Pneumocystis/classificação , Pneumocystis/genética , Pneumonia por Pneumocystis/microbiologiaRESUMO
Pneumocystis sequences can be downloaded from GenBank for purposes as primer/probe design or phylogenetic studies. Due to changes in nomenclature and assignment, available sequences are presented with a variety of inhomogeneous information, which renders practical utilization difficult. The aim of this study was the descriptive evaluation of different parameters of 532 Pneumocystis sequences of mitochondrial and ribosomal origin downloaded from GenBank with regard to completeness and information content. Pneumocystis sequences were characterized by up to four different names. Official changes in nomenclature have only been partly implemented and the usage of the "forma specialis", a special feature of Pneumocystis, has only been established fragmentary in the database. Hints for a mitochondrial or ribosomal genomic origin could be found, but can easily be overlooked, which renders the download of wrong reference material possible. The specification of the host was either not available or variable regarding the used language and the localization of this information in the title or several subtitles, which limits their applicability in phylogenetic studies. Declaration of products and geographic origin was incomplete. The print version of this manuscript is completed by an online database which contains detailed information to every accession number included in the meta-analysis.
Assuntos
Bases de Dados de Ácidos Nucleicos , Pneumocystis/genética , Sequência de Bases , DNA Fúngico/química , DNA Fúngico/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Dados de Sequência Molecular , Pneumocystis/química , Pneumocystis/classificação , Alinhamento de SequênciaRESUMO
Pneumocystis jirovecii is an important opportunistic pathogen associated with AIDS and other immunodeficient conditions. Currently, very little is known about its nuclear and mitochondrial genomes. In this study, we sequenced the complete mitochondrial genome (mtDNA) of this organism and its closely related species Pneumocystis carinii and Pneumocystis murina by a combination of sequencing technologies. Our study shows that P. carinii and P. murina mtDNA share a nearly identical number and order of genes in a linear configuration, whereas P. jirovecii has a circular mtDNA containing nearly the same set of genes but in a different order. Detailed studies of the mtDNA terminal structures of P. murina and P. carinii suggest a unique replication mechanism for linear mtDNA. Phylogenetic analysis supports a close association of Pneumocystis species with Taphrina, Saitoella, and Schizosaccharomyces, and divergence within Pneumocystis species, with P. murina and P. carinii being more closely related to each other than either is to P. jirovecii. Comparative analysis of four complete P. jirovecii mtDNA sequences in this study and previously reported mtDNA sequences for diagnosing and genotyping suggests that the current diagnostic and typing methods can be improved using the complete mtDNA data. The availability of the complete P. jirovecii mtDNA also opens the possibility of identifying new therapeutic targets.
Assuntos
DNA Mitocondrial/genética , Genoma Mitocondrial/genética , Pneumocystis/genética , Sequência de Aminoácidos , Animais , Códon , Replicação do DNA , Humanos , Modelos Biológicos , Dados de Sequência Molecular , Filogenia , Pneumocystis/classificação , Pneumocystis carinii/genética , Roedores/microbiologia , Análise de Sequência de DNARESUMO
Pneumocystis spp. are yeast-like fungi that cause pneumocystis pneumonia (PcP) in immunocompromised individuals and exacerbate chronic lung diseases in immunocompetent individuals. The Pneumocystis life cycle includes trophic forms and asci (cyst forms). The cell walls of Pneumocystis asci contain ß-1,3-D-glucan, and treatment of PcP with ß-1,3-D-glucan synthase inhibitors, such as anidulafungin, results in depletion of asci, but not trophic forms. The pulmonary host response during immune reconstitution (IR)-mediated clearance of PcP in anidulafungin-treated and untreated mice was characterized to identify ascus-specific responses. During IR, similar numbers of trophic forms were present in the anidulafungin-treated and untreated mice; however, asci were only present in the untreated mice. IR resulted in a significant reduction of trophic forms from the lungs in both groups and asci in the untreated group. The presence of asci in untreated mice correlated with increased ß-glucan content in the lungs. The untreated mice mounted immune responses associated with a deleterious host inflammatory response, including increased CD8(+) T cell influx and expression of macrophage inflammatory response markers. A more robust cellular response was also observed in the untreated mice, with increased numbers of macrophages and neutrophils that were associated with greater lung damage. Markers of a Th17 response were also elevated in the untreated mice. These results suggest that the host mounts unique responses to asci and trophic forms. That these 2 life cycle stages provoked distinct host response profiles has significant implications for clearance and interpretation of the host immune responses to PcP.
Assuntos
Pneumocystis/classificação , Pneumocystis/imunologia , Pneumonia por Pneumocystis/imunologia , Pneumonia por Pneumocystis/microbiologia , Albuminas/metabolismo , Anidulafungina , Animais , Antifúngicos/uso terapêutico , Líquido da Lavagem Broncoalveolar/citologia , Parede Celular/química , Parede Celular/metabolismo , Equinocandinas/uso terapêutico , Feminino , Citometria de Fluxo , Inflamação/metabolismo , Pulmão/citologia , Camundongos , Camundongos Endogâmicos C3H , Pneumonia por Pneumocystis/tratamento farmacológico , Pneumonia por Pneumocystis/patologiaRESUMO
Bats belong to a wide variety of species and occupy diversified habitats, from cities to the countryside. Their different diets (i.e., nectarivore, frugivore, insectivore, hematophage) lead Chiroptera to colonize a range of ecological niches. These flying mammals exert an undisputable impact on both ecosystems and circulation of pathogens that they harbor. Pneumocystis species are recognized as major opportunistic fungal pathogens which cause life-threatening pneumonia in severely immunocompromised or weakened mammals. Pneumocystis consists of a heterogeneous group of highly adapted host-specific fungal parasites that colonize a wide range of mammalian hosts. In the present study, 216 lungs of 19 bat species, sampled from diverse biotopes in the New and Old Worlds, were examined. Each bat species may be harboring a specific Pneumocystis species. We report 32.9% of Pneumocystis carriage in wild bats (41.9% in Microchiroptera). Ecological and behavioral factors (elevation, crowding, migration) seemed to influence the Pneumocystis carriage. This study suggests that Pneumocystis-host association may yield much information on Pneumocystis transmission, phylogeny, and biology in mammals. Moreover, the link between genetic variability of Pneumocystis isolated from populations of the same bat species and their geographic area could be exploited in terms of phylogeography.
Assuntos
Portador Sadio/veterinária , Variação Genética , Pulmão/microbiologia , Pneumocystis/classificação , Pneumocystis/genética , Pneumonia por Pneumocystis/veterinária , Animais , Portador Sadio/microbiologia , Quirópteros , Análise por Conglomerados , DNA Fúngico/química , DNA Fúngico/genética , DNA Mitocondrial/química , DNA Mitocondrial/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Dados de Sequência Molecular , Filogenia , Pneumocystis/isolamento & purificação , Pneumonia por Pneumocystis/microbiologia , Análise de Sequência de DNARESUMO
Is Pneumocystis pneumonia (PcP) a transmissible fungal disease? Does nosocomial PcP occur? Is there Pneumocystis transmission in the community? These questions, which could not be tackled before the 2000s, may at present be approached using either noninvasive detection methods or experimental transmission models. Represented by a unique entity (P. carinii) for almost one century, the Pneumocystis genus was shown to contain several species, being P. jirovecii the sole species identified in humans hitherto. Molecular methods combined with cross infection experiments revealed strong host specificity that precludes Pneumocystis inter-species transmission. In contrast, respiratory transmission between mammals of a same species is usually highly active, even between immunocompetent hosts. Other transmission ways could also exist. New data show that human being is the unique P. jirovecii reservoir; it would constitute the sole infection source in both hospital and community.
Assuntos
Infecções por Pneumocystis/transmissão , Pneumonia por Pneumocystis/transmissão , Animais , Infecção Hospitalar/epidemiologia , Infecção Hospitalar/microbiologia , Infecção Hospitalar/transmissão , Humanos , Transmissão Vertical de Doenças Infecciosas/estatística & dados numéricos , Modelos Biológicos , Pneumocystis/classificação , Infecções por Pneumocystis/epidemiologia , Infecções por Pneumocystis/microbiologia , Pneumonia por Pneumocystis/epidemiologia , Pneumonia por Pneumocystis/microbiologiaRESUMO
Pneumocystis pneumonia was first diagnosed in malnourished children and has more recently been found in children with upper respiratory symptoms. We previously reported that there is a significant delay in the immune response in newborn mice infected with Pneumocystis compared to adults (Garvy BA, Harmsen AG, Infect. Immun. 64:3987-3992, 1996, and Garvy BA, Qureshi M, J. Immunol. 165:6480-6486, 2000). This delay is characterized by the failure of neonatal lungs to upregulate proinflammatory cytokines and attract T cells into the alveoli. Here, we report that regardless of the age at which we infected the mice, they failed to mount an inflammatory response in the alveolar spaces until they were 21 days of age or older. Anti-inflammatory cytokines had some role in dampening inflammation, since interleukin-10 (IL-10)-deficient pups cleared Pneumocystis faster than wild-type pups and the neutralization of transforming growth factor beta (TGF-ß) with specific antibody enhanced T cell migration into the lungs at later time points. However, the clearance kinetics were similar to those of control pups, suggesting that there is an intrinsic deficiency in the ability of innate immunity to control Pneumocystis. We found, using an adoptive transfer strategy, that the lung environment contributes to association of Pneumocystis organisms with alveolar macrophages, implying no intrinsic deficiency in the binding of Pneumocystis by neonatal macrophages. Using both in vivo and in vitro assays, we found that Pneumocystis organisms were less able to stimulate translocation of NF-κB to the nucleus of alveolar macrophages from neonatal mice. These data indicate that there is an early unresponsiveness of neonatal alveolar macrophages to Pneumocystis infection that is both intrinsic and related to the immunosuppressive environment found in neonatal lungs.