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Muscle & Nerve Mar 2022Pneumocystis jirovecii (PJ) is ubiquitously present in the environment and capable of causing an interstitial pneumonia in immunocompromised subjects. It has been...
Pneumocystis jirovecii (PJ) is ubiquitously present in the environment and capable of causing an interstitial pneumonia in immunocompromised subjects. It has been advocated that routine prophylaxis against PJ be given to patients with autoimmune neuromuscular conditions that require prolonged use of corticosteroid therapy and/or other immunosuppressive agents. Available data, however, suggest that the risk of PJ infection in patients with autoimmune neuromuscular diseases is extremely low and the widespread use of prophylactic therapy is likely unnecessary. Comorbidities, including intestinal lung disease, prolonged lymphopenia, low CD4 count, parenchymal organ failure, and active cancer status, appear to increase the risk for PJ infection, and it is our opinion that these risk factors should be considered to determine the risk of PJ infection and the requirement for prophylaxis.
Topics: Autoimmune Diseases; Humans; Immunocompromised Host; Neuromuscular Diseases; Pneumocystis carinii; Pneumonia, Pneumocystis
PubMed: 34952994
DOI: 10.1002/mus.27481 -
Medical Mycology Oct 2019The genus Pneumocystis comprises potential pathogens that reside normally in the lungs of a wide range of mammals. Although they generally behave as transient or...
The genus Pneumocystis comprises potential pathogens that reside normally in the lungs of a wide range of mammals. Although they generally behave as transient or permanent commensals, they can occasionally cause life-threatening pneumonia (Pneumocystis pneumonia; PCP) in immunosuppressed individuals. Several decades ago, the presence of Pneumocystis morphotypes (trophic forms and cysts) was described in the lungs of normal cats and cats with experimentally induced symptomatic PCP (after immunosuppression by corticosteroids); yet to date spontaneous or drug-induced PCP has not been described in the clinical feline literature, despite immunosuppression of cats by long-standing retrovirus infections or after kidney transplantation. In this study, we describe the presence of Pneumocystis DNA in the lungs of normal cats (that died of various unrelated causes; n = 84) using polymerase chain reactions (PCRs) targeting the mitochondrial small and large subunit ribosomal RNA gene (mtSSU rRNA and mtLSU rRNA). The presence of Pneumocystis DNA was confirmed by sequencing in 24/84 (29%) cats, with evidence of two different sequence types (or lineages). Phylogenetically, lineage1 (L1; 19 cats) and lineage 2 (L2; 5 cats) formed separate clades, clustering with Pneumocystis from domestic pigs (L1) and carnivores (L2), respectively. Results of the present study support the notion that cats can be colonized or subclinically infected by Pneumocystis, without histological evidence of damage to the pulmonary parenchyma referable to pneumocystosis. Pneumocystis seems most likely an innocuous pathogen of cats' lungs, but its possible role in the exacerbation of chronic pulmonary disorders or viral/bacterial coinfections should be considered further in a clinical setting.
Topics: Animals; Cat Diseases; Cats; DNA, Fungal; Female; Lung; Male; Phylogeny; Pneumocystis; Pneumonia, Pneumocystis; RNA, Mitochondrial; RNA, Ribosomal
PubMed: 30566653
DOI: 10.1093/mmy/myy139 -
Journal of Medical Microbiology Dec 2021Pathogen-associated molecular patterns' (PAMPs) are microbial signatures that are recognized by host myeloid C-type lectin receptors (CLRs). These CLRs interact with...
Pathogen-associated molecular patterns' (PAMPs) are microbial signatures that are recognized by host myeloid C-type lectin receptors (CLRs). These CLRs interact with micro-organisms via their carbohydrate recognition domains (CRDs) and engage signalling pathways within the cell resulting in pro-inflammatory and microbicidal responses. In this article, we extend our laboratory study of additional CLRs that recognize fungal ligands against and and their purified major surface glycoproteins (Msgs). To study the potential of newly synthesized hFc-CLR fusions on binding to and its Msg. A library of new synthesized hFc-CLR fusions was screened against and organisms and their purified major surface glycoproteins (Msgs) found on the respective fungi via modified ELISA. Immunofluorescence assay (IFA) was implemented and quantified to verify results. mRNA expression analysis by quantitative PCR (q-PCR) was employed to detect respective CLRs found to bind fungal organisms in the ELISA and determine their expression levels in the mouse immunosuppressed Pneumocystis pneumonia (PCP) model. We detected a number of the CLR hFc-fusions displayed significant binding with and organisms, and similarly to their respective Msgs. Significant organism and Msg binding was observed for CLR members C-type lectin domain family 12 member A (CLEC12A), Langerin, macrophage galactose-type lectin-1 (MGL-1), and specific intracellular adhesion molecule-3 grabbing non-integrin homologue-related 3 (SIGNR3). Immunofluorescence assay (IFA) with the respective CLR hFc-fusions against whole life forms corroborated these findings. Lastly, we surveyed the mRNA expression profiles of the respective CLRs tested above in the mouse immunosuppressed Pneumocystis pneumonia (PCP) model and determined that macrophage galactose type C-type lectin (), implicated in recognizing terminal N-acetylgalactosamine (GalNAc) found in the glycoproteins of microbial pathogens was significantly up-regulated during infection. The data herein add to the growing list of CLRs recognizing and provide insights for further study of organism/host immune cell interactions.
Topics: Animals; Mice; Fungal Proteins; Galactose; Host-Pathogen Interactions; Lectins, C-Type; Membrane Glycoproteins; Pneumocystis; Pneumocystis carinii; Pneumonia, Pneumocystis; RNA, Messenger
PubMed: 34889727
DOI: 10.1099/jmm.0.001470 -
Mycopathologia May 2024Pneumocystis pneumonia is a serious lung infection caused by an original ubiquitous fungus with opportunistic behavior, referred to as Pneumocystis jirovecii. P....
Pneumocystis pneumonia is a serious lung infection caused by an original ubiquitous fungus with opportunistic behavior, referred to as Pneumocystis jirovecii. P. jirovecii is the second most common fungal agent among invasive fungal infections after Candida spp. Unfortunately, there is still an inability to culture P. jirovecii in vitro, and so a great impairment to improve knowledge on the pathogenesis of Pneumocystis pneumonia. In this context, animal models have a high value to address complex interplay between Pneumocystis and the components of the host immune system. Here, we propose a protocol for a murine model of Pneumocystis pneumonia. Animals become susceptible to Pneumocystis by acquiring an immunocompromised status induced by iterative administration of steroids within drinking water. Thereafter, the experimental infection is completed by an intranasal challenge with homogenates of mouse lungs containing Pneumocystis murina. The onset of clinical signs occurs within 5 weeks following the infectious challenge and immunosuppression can then be withdrawn. At termination, lungs and bronchoalveolar lavage (BAL) fluids from infected mice are analyzed for fungal load (qPCR) and immune response (flow cytometry and biochemical assays). The model is a useful tool in studies focusing on immune responses initiated after the establishment of Pneumocystis pneumonia.
Topics: Animals; Pneumonia, Pneumocystis; Disease Models, Animal; Bronchoalveolar Lavage Fluid; Lung; Mice; Pneumocystis; Colony Count, Microbial; Pneumocystis carinii; Immunocompromised Host
PubMed: 38709375
DOI: 10.1007/s11046-024-00846-1 -
Microbiology Spectrum Dec 2022The proposed life cycle of fungi in the genus Pneumocystis has typically included both an asexual cycle via binary fission and a sexual cycle. Until recently, the...
The proposed life cycle of fungi in the genus Pneumocystis has typically included both an asexual cycle via binary fission and a sexual cycle. Until recently, the strategy used for sexual replication was largely unknown, but genomic and functional assays now support a mode known as primary homothallism (self-fertilization). The question of whether an asexual cycle contributes to the growth of these fungi remains. Treatment of Pneumocystis pneumonia in immunosuppressed rodent models with the class of drugs known as echinocandins is challenging the historical concept of asexual replication. The echinocandins target 1,3-β-D-glucan (BG) synthesis resulting in death for most fungi. Because Pneumocystis species have both non-BG expressing life cycle stages (trophic forms) and BG-expressing asci, treatment with anidulafungin and caspofungin resulted in elimination of asci, with large numbers of non-BG expressing organisms remaining in the lungs. Transcriptional analyses of anidulafungin treated Pneumocystis murina-infected lungs indicated that these agents were blocking the sexual cycle. In the present study, we explored whether there was an asexual or alternative method of replication that could rescue P. murina survival and growth in the context of anidulafungin treatment. The effects of anidulafungin treatment on early events in the sexual cycle were investigated by RT-qPCR targeting specific mating genes, including , and . Results from the and gene expression studies clearly indicated there was no rescue by an asexual cycle, supporting these fungi's reliance on the sexual cycle for survival and growth. Dysregulation of mating-associated genes showed that anidulafungin induced effects early in the mating process. The concept of a sexually obligate fungus is unique among human fungal pathogens. This reliance can be exploited for drug development and here we show a proof of principle for this unusual target. Most human fungal pathogens eschew the mammalian environment with its battery of immune responses. Pneumocystis appear to have evolved to survive in such an environment, perhaps by using sexual replication to help in DNA repair and to introduce genetic variation in its major surface antigen family because the lung is the primary environment of these pathogens. The concept of primary homothallism fits well into its chosen ecosystem, with ready mating partners expressing both mating type receptors, and a sexual cycle that can introduce beneficial genetic variation without the need for outbreeding.
Topics: Animals; Anidulafungin; Echinocandins; Ecosystem; Pneumocystis; Pneumonia, Pneumocystis
PubMed: 36287071
DOI: 10.1128/spectrum.02906-22 -
Frontiers in Public Health 2021We performed a meta-analysis to systematically review the risk factors of mortality from non-HIV-related pneumonia (PcP) and provide the theoretical basis for managing... (Meta-Analysis)
Meta-Analysis
We performed a meta-analysis to systematically review the risk factors of mortality from non-HIV-related pneumonia (PcP) and provide the theoretical basis for managing non-HIV-related PcP. PubMed, Embase, Web of Science, the Cochrane Library and CNKI databases were searched. A meta-analysis of the risk factors of mortality from non-HIV-related PcP was conducted. A total of 19 studies and 1,310 subjects were retrieved and included in the meta-analysis, including 485 and 825 patients in the non-survivor and survivor groups, respectively. In the primary analysis, age, concomitant with other pulmonary diseases at diagnosis of PcP, solid tumors, cytomegalovirus(CMV) co-infection, lactate dehydrogenase (LDH), lymphocyte count, invasive ventilation during hospitalization, and pneumothorax were associated with mortality from non-HIV-related PcP, whereas sex, albumin, PcP prophylaxis, use of corticosteroids after admission, and time from onset of symptoms to treatment were not associated with mortality from non-HIV-related PcP. The mortality rate of non-HIV-infected patients with PcP was still high. Age, concomitant with other pulmonary diseases at diagnosis of PcP, solid tumors, CMV co-infection, LDH, lymphocyte count, invasive ventilation during hospitalization, and pneumothorax were risk factors of mortality from non-HIV-related PcP. Improved knowledge of prognostic factors is crucial to guide early treatment.
Topics: Coinfection; Cytomegalovirus Infections; Humans; Pneumocystis; Pneumonia, Pneumocystis; Risk Factors
PubMed: 34222179
DOI: 10.3389/fpubh.2021.680108 -
Clinical Rheumatology Sep 2021To compare Pneumocystis jirovecii pneumonia (PJP) risk between patients with autoimmune rheumatic diseases (ARD) and the general population METHODS: We identified...
OBJECTIVE
To compare Pneumocystis jirovecii pneumonia (PJP) risk between patients with autoimmune rheumatic diseases (ARD) and the general population METHODS: We identified patients with ARD recorded in the National Health Insurance Research Database of Taiwan from 2002 to 2015 and randomly selected a comparison cohort from the general population matched for age and sex. We analyzed PJP risk stratified by sex, age, comorbidities, and medications using Cox proportional hazard model.
RESULTS
We enrolled 103,117 patients with ARD. PJP risk significantly increased in patients with any ARD and with each individual ARD like rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), Sjogren's syndrome (SjS), polymyositis and dermatomyositis (PM/DM), systemic sclerosis (SSc), and systemic vasculitis. Patients with PM/DM showed prominent risk with incidence rate of 12.47/100,000 patient year (95% confidence interval (CI), 32.16-86.70). In a time-dependent Cox proportional hazard model with comorbidities and medications as covariates, PM/DM, SSc, SLE, and SjS significantly increased adjusted hazard ratios (aHR) of 5.40, 5.12, 4.09, and 3.64, respectively (95% CI of 2.82-10.35, 2.16-12.13, 2.41-6.95, and 2.06-6.42, respectively). AHR after adjusting for male sex, cancer, human immunodeficiency virus infection (HIV), and interstitial lung disease also significantly increased. Use of daily oral steroid dose of >10 mg conferred the highest risk followed by mycophenolate. Use of injected steroids, cyclophosphamide, biological agents, methotrexate, and cyclosporine conferred a significantly higher risk.
CONCLUSION
Underlying ARD significantly predisposes patients to PJP, with PM/DM posing the highest threat. In addition to underlying disease, comorbidities and concomitant immunosuppressants are major risks. The strongest risk is recent daily steroid dose of >10 mg. Mycophenolate seems to be a more prominent risk factor than cyclophosphamide. Key Points • Autoimmune rheumatic diseases (ARD) significantly increased the overall risk of PJP, and so did each individual ARD. • Use of steroids, mycophenolate, cyclophosphamide, biological agents, methotrexate, and cyclosporine all significantly increased risk of PJP. • Male, elderly, malignancy, HIV, and interstitial lung disease are also related to increased risk of PJP. • Underlying ARD, comorbidities, and use of immunosuppressant should all be considered in determining the overall risk of PJP.
Topics: Aged; Arthritis, Rheumatoid; Autoimmune Diseases; Humans; Lupus Erythematosus, Systemic; Male; Pneumocystis carinii; Pneumonia, Pneumocystis; Rheumatic Diseases
PubMed: 33646447
DOI: 10.1007/s10067-021-05660-4 -
Diagnostic Cytopathology Jan 2021
Topics: Aged; Biopsy, Fine-Needle; Female; Granuloma; Histocytochemistry; Humans; Immunocompromised Host; Immunohistochemistry; Lung; Male; Middle Aged; Pneumocystis carinii; Pneumonia, Pneumocystis; Spores, Fungal
PubMed: 32621323
DOI: 10.1002/dc.24537 -
MBio Mar 2020Environmental exposure has a significant impact on human health. While some airborne fungi can cause life-threatening infections, the impact of environment on fungal...
Environmental exposure has a significant impact on human health. While some airborne fungi can cause life-threatening infections, the impact of environment on fungal spore dispersal and transmission is poorly understood. The democratization of shotgun metagenomics allows us to explore important questions about fungal propagation. We focus on , a genus of host-specific fungi that infect mammals via airborne particles. In humans, causes lethal infections in immunocompromised patients if untreated, although its environmental reservoir and transmission route remain unclear. Here, we attempt to clarify, by analyzing human exposome metagenomic data sets, whether humans are exposed to different species present in the air but only cells are able to replicate or whether they are selectively exposed to Our analysis supports the latter hypothesis, which is consistent with a local transmission model. These data also suggest that healthy carriers are a major driver for the transmission.
Topics: Air Microbiology; DNA, Fungal; Environmental Exposure; Humans; Immunocompromised Host; Metagenomics; Pneumocystis carinii; Pneumonia, Pneumocystis
PubMed: 32156824
DOI: 10.1128/mBio.03138-19 -
Infection Aug 2022In the era of effective prophylaxis, the objective of this study was to describe pneumocystis pneumonia (PCP) patients' profile and evaluate the consistency of clinical...
PURPOSE
In the era of effective prophylaxis, the objective of this study was to describe pneumocystis pneumonia (PCP) patients' profile and evaluate the consistency of clinical situations encountered with the recommended indications for prophylaxis.
METHODS
This was a single-centre, retrospective study. All adults (> 18 years) with a definitive diagnosis of PCP were included. Data were collected from patients' electronic medical files.
RESULTS
The study examined the medical files of 225 patients diagnosed with PCP and treated between 1 January, 2015, and 30 June, 2020. More than 95% of the patients were not on anti-PCP prophylaxis at the time of PCP diagnosis. There were 32 (14%) deaths before the end of PCP treatment, mainly in auto-immune disease (30%) and solid tumours (38%) groups unlike the solid-organ transplants group, among whom deaths were infrequent. Indeed, 48% of our cohort (n = 107) had both corticosteroid (CS) therapy, immunosuppressive or immunomodulatory treatment, and lymphopaenia and could have been considered at high risk for PCP. Trimethoprim/sulfamethoxazole was administered as first-line PCP curative treatment in 95% of the patients. Toxicities of this drug led to treatment interruption in 25% of the patients (except death).
CONCLUSIONS
This study found a high number of PCP cases over 5 years. Unsurprisingly, most of the patients were immunosuppressed, with risk factors for PCP already described in the literature. This large number of PCP cases should be avoidable and, consequently, questions arise. Faced with these data, prophylaxis should be common sense for immunocompromised patients with risk factors, even if formalised recommendations do not exist.
Topics: Adult; Humans; Pneumocystis; Pneumocystis carinii; Pneumonia, Pneumocystis; Retrospective Studies; Trimethoprim, Sulfamethoxazole Drug Combination
PubMed: 35274281
DOI: 10.1007/s15010-022-01790-2