Relationship of Pneumocystis antibody responses to paediatric asthma severity

More than Just Protein Degradation: The Regulatory Roles and Moonlighting Functions of Extracellular Proteases Produced by Fungi Pathogenic for Humans

Extracellular proteases belong to the main virulence factors of pathogenic fungi. Their proteolytic activities plays a crucial role in the acquisition of nutrients from the external environment, destroying host barriers and defenses, and disrupting homeostasis in the human body, e.g., by affecting the functions of plasma proteolytic cascades, and playing sophisticated regulatory roles in various processes. Interestingly, some proteases belong to the group of moonlighting proteins, i.e., they have additional functions that contribute to successful host colonization and infection development, but they are not directly related to proteolysis. In this review, we describe examples of such multitasking of extracellular proteases that have been reported for medically important pathogenic fungi of the Candida, Aspergillus, Penicillium, Cryptococcus, Rhizopus, and Pneumocystis genera, as well as dermatophytes and selected endemic species. Additional functions of proteinases include supporting binding to host proteins, and adhesion to host cells. They also mediate self-aggregation and biofilm formation. In addition, fungal proteases affect the host immune cells and allergenicity, understood as the ability to stimulate a non-standard immune response. Finally, they play a role in the proper maintenance of cellular homeostasis. Knowledge about the multifunctionality of proteases, in addition to their canonical roles, greatly contributes to an understanding of the mechanisms of fungal pathogenicity.

A therapeutic vaccine strategy to prevent Pneumocystis pneumonia in an immunocompromised host in a non-human primate model of HIV and Pneumocystis co-infection

Introduction

Pneumocystis is a ubiquitous fungal pathogen that causes pneumonia (PCP) and pulmonary sequelae in HIV-infected individuals and other immunocompromised populations. With the success of anti-retroviral therapy for HIV-infected individuals the frequency of PCP in that population has decreased, however, PCP remains a significant cause of morbidity and mortality in individuals with hematologic and solid malignancies, and in individuals treated with immunosuppressive therapies for autoimmune diseases, and following bone marrow and solid organ transplantation. Despite the clinical need, there is no approved vaccine to prevent PCP in vulnerable populations. The ultimate goal of the field is to develop an effective vaccine that can overcome immune deficits in at risk populations and induce long-lasting protective immunity to Pneumocystis. Toward this goal, our laboratory has established a model of PCP co-infection in simian immunodeficiency virus (SIV)-infected non-human primates (NHP) and identified a recombinant protein sub-unit vaccine, KEX1, that induces robust anti-Pneumocystis immunity in immune-competent macaques that is durable and prevents PCP following simian immunodeficiency virus (SIV)-induced immunosuppression. Type I, or invariant natural killer T (iNKT) cells have the potential to provide B cell help under conditions of reduced CD4+ T cell help.

Methods

In the present study, we used the SIV model of HIV infection to address whether therapeutic vaccination with the iNKT cell-activating adjuvant α-galactosylceramide (α-GC) and KEX1 (α-GC+KEX1) can effectively boost anti-Pneumocystis humoral immunity following virus-induced immunosuppression.

Results

Immunization of antigen-experienced NHPs with α-GC+KEX1 during the early chronic phase of SIV-infection significantly boosted anti-Pneumocystis humoral immunity by increasing memory B cells and antibody titers, and enhanced titer durability during SIV-induced immunosuppression. This therapeutic vaccination strategy boosted anti-Pneumocystis immune responses during SIV-infection and contributed to protection against Pneumocystis co-infection in KEX1-vaccinated macaques.

Conclusion

These studies present a novel strategy for stimulating durable anti-Pneumocystis humoral immunity in the context of complex, chronic SIV-induced immunosuppression and may be further applied to immunization of other immunosuppressed populations, and toward other common recall antigens.

Immunogenicity and protective efficacy of a pan-fungal vaccine in preclinical models of aspergillosis, candidiasis, and pneumocystosis

Invasive fungal infections cause over 1.5 million deaths worldwide. Despite increases in fungal infections as well as the numbers of individuals at risk, there are no clinically approved fungal vaccines. We produced a "pan-fungal" peptide, NXT-2, based on a previously identified vaccine candidate and homologous sequences from Pneumocystis, Aspergillus,Candida, and Cryptococcus. We evaluated the immunogenicity and protective capacity of NXT-2 in murine and nonhuman primate models of invasive aspergillosis, systemic candidiasis, and pneumocystosis. NXT-2 was highly immunogenic and immunized animals had decreased mortality and morbidity compared to nonvaccinated animals following induction of immunosuppression and challenge with Aspergillus, Candida, or Pneumocystis. Data in multiple animal models support the concept that immunization with a pan-fungal vaccine prior to immunosuppression induces broad, cross-protective antifungal immunity in at-risk individuals.

Demographic and Socioeconomic Factors Associated with Fungal Infection Risk, United States, 2019

Diagnosis disproportionately affected minority and low-income populations, underscoring the need for broad public health interventions.

Fungal infections cause substantial rates of illness and death. Interest in the association between demographic factors and fungal infections is increasing. We analyzed 2019 US hospital discharge data to assess factors associated with fungal infection diagnosis, including race and ethnicity and socioeconomic status. We found male patients were 1.5–3.5 times more likely to have invasive fungal infections diagnosed than were female patients. Compared with hospitalizations of non-Hispanic White patients, Black, Hispanic, and Native American patients had 1.4–5.9 times the rates of cryptococcosis, pneumocystosis, and coccidioidomycosis. Hospitalizations associated with lower-income areas had increased rates of all fungal infections, except aspergillosis. Compared with younger patients, fungal infection diagnosis rates, particularly for candidiasis, were elevated among persons >65 years of age. Our findings suggest that differences in fungal infection diagnostic rates are associated with demographic and socioeconomic factors and highlight an ongoing need for increased physician evaluation of risk for fungal infections.

Refractory flare-up of severe bronchial asthma controlled with mepolizumab due to Pneumocystis pneumonia: a case report

Background

Biologics dramatically improve symptoms of severe asthma; however, various exacerbating factors may induce flare-up. Pneumocystis spp. have not been reported as a cause of asthma exacerbation during biologic use, although patients with severe asthma have high levels of antibodies against Pneumocystis spp.

Case presentation

An 87-year-old female with severe asthma that was well-controlled with mepolizumab, who developed a steroid-resistant refractory flare-up. Chest computed tomography showed bilateral ground glass opacities, and results of polymerase chain reaction tests on induced sputum were positive for Pneumocystis DNA. Therefore, a diagnosis of Pneumocystis pneumonia was made. The clinical symptoms improved after treatment with sulfamethoxazole–trimethoprim.

Conclusion

Clinicians should be aware of Pneumocystis pneumonia as a cause of refractory exacerbation of bronchial asthma during use of interleukin-5 inhibitors.

Detection of Pneumocystis jirovecii in Hospitalized Children Less Than 3 Years of Age

Few data are available in the literature regarding Pneumocystis jirovecii infection in children under 3 years old. This retrospective cohort study aimed to describe medically relevant information among them. All children under 3 years old treated in the same medical units from April 2014 to August 2020 and in whom a P. jirovecii evaluation was undertaken were enrolled in the study. A positive case was defined as a child presenting at least one positive PCR for P. jirovecii in a respiratory sample. Medically relevant information such as demographical characteristics, clinical presentation, microbiological co-infections, and treatments were collected. The objectives were to describe the characteristics of these children with P. jirovecii colonization/infection to determine the key underlying diseases and risk factors, and to identify viral respiratory pathogens associated. The PCR was positive for P. jirovecii in 32 children. Cardiopulmonary pathologies (21.9%) were the most common underlying disease in them, followed by severe combined immunodeficiency (SCID) (18.8%), hyaline membrane disease (15.6%), asthma (9.4%) and acute leukaemia (6.3%). All SCID children were diagnosed with pneumocystis pneumonia. Co-infection with Pj/Rhinovirus (34.4%) was not significant. Overall mortality was 18.8%. Paediatric pneumocystis is not restricted to patients with HIV or SCID and should be considered in pneumonia in children under 3 years old.

Mortality Trends in Risk Conditions and Invasive Mycotic Disease in the United States, 1999-2018

BACKGROUND

Invasive fungal infections (IFIs) in the United States are chronically underdiagnosed and a lack of coordinated surveillance makes the true burden of disease difficult to determine. The purpose of this analysis was to capture mortality-associated burden of risk conditions and fungal infections.

METHODS

We analyzed data from the National Vital Statistics System from 1999-2018 to estimate the mortality attributed to risk conditions and related fungal disease.

RESULTS

The number of risk conditions associated with fungal disease is steadily rising in the United States with 1,047,422 diagnoses at time of death in 2018. While fungal disease decreased substantially from 1999 to 2010, primarily due to the control of HIV infection, the number deaths with fungal diagnosis has increased in the non-HIV cohort, with significant increases in patients with diabetes, cancer, immunosuppressive disorders, or sepsis.

CONCLUSION

The landscape of individuals at risk for serious fungal diseases is changing, with a continued decline in HIV-associated incidence, but increased diagnoses in patients with cancer, sepsis, immunosuppressive disorders, and influenza. Additionally, there is an overall increase in the number of fungal infections in recent years, indicating a failure to control fungal disease mortality in these new immunocompromised cohorts. Improvement in prevention and management of fungal diseases is needed to control morbidity and mortality in the rising number of immunocompromised and at-risk patients in the United States.