Fungal Respiratory Disease Research Articles

Influence of Zinc on Histoplasma capsulatum Planktonic and Biofilm Cells.

Histoplasma capsulatum causes a fungal respiratory disease. Some studies suggest that the fungus requires zinc to consolidate the infection. This study aimed to investigate the influence of zinc and the metal chelator TPEN on the growth of Histoplasma in planktonic and biofilm forms. The results showed that zinc increased the metabolic activity, cell density, and cell viability of planktonic growth. Similarly, there was an increase in biofilm metabolic activity but no increase in biomass or extracellular matrix production. N'-N,N,N,N-tetrakis-2-pyridylmethylethane-1,2 diamine (TPEN) dramatically reduced the same parameters in the planktonic form and resulted in a decrease in metabolic activity, biomass, and extracellular matrix production for the biofilm form. Therefore, the unprecedented observations in this study highlight the importance of zinc ions for the growth, development, and proliferation of H. capsulatum cells and provide new insights into the role of metal ions for biofilm formation in the dimorphic fungus Histoplasma, which could be a potential therapeutic strategy.

Aspergillus fumigatus Drives Tissue Damage via Iterative Assaults upon Mucosal Integrity and Immune Homeostasis.

The human lung is constantly exposed to Aspergillus fumigatus spores, the most prevalent worldwide cause of fungal respiratory disease. Pulmonary tissue damage is a unifying feature of Aspergillus-related diseases; however, the mechanistic basis of damage is not understood. In the lungs of susceptible hosts, A. fumigatus undergoes an obligatory morphological switch involving spore germination and hyphal growth. We modeled A. fumigatus infection in cultured A549 human pneumocytes, capturing the phosphoactivation status of five host signaling pathways, nuclear translocation and DNA binding of eight host transcription factors, and expression of nine host response proteins over six time points encompassing exposures to live fungus and the secretome thereof. The resulting data set, comprised of more than 1,000 data points, reveals that pneumocytes mount differential responses to A. fumigatus spores, hyphae, and soluble secreted products via the NF-κB, JNK, and JNK + p38 pathways, respectively. Importantly, via selective degradation of host proinflammatory (IL-6 and IL-8) cytokines and growth factors (FGF-2), fungal secreted products reorchestrate the host response to fungal challenge as well as driving multiparameter epithelial damage, culminating in cytolysis. Dysregulation of NF-κB signaling, involving sequential stimulation of canonical and noncanonical signaling, was identified as a significant feature of host damage both in vitro and in a mouse model of invasive aspergillosis. Our data demonstrate that composite tissue damage results from iterative (repeated) exposures to different fungal morphotypes and secreted products and suggest that modulation of host responses to fungal challenge might represent a unified strategy for therapeutic control of pathologically distinct types of Aspergillus-related disease.

Causes of mortality of kiwi (Apteryx spp.) in New Zealand: a retrospective analysis of post-mortem records, 2010–2020

ABSTRACT Aims To examine and assess causes of mortality of kiwi (Apteryx spp.) submitted to Massey University between 2010 and 2020 across the five recognised species according to location, age group and captivity status in New Zealand. Methods Post-mortem reports were obtained from the Massey University/Te Kunenga ki Pūrehuroa School of Veterinary Science/Wildbase Pathology Register. Inclusion criteria were all species of kiwi with a date of post-mortem examination between August 2010 and August 2020. Data from each report was exported, categorised and compared using Microsoft Excel. Results Of a total of 1,005 post-mortem reports, there were 766 North Island brown kiwi (NIBK; A. mantelli), 83 tokoeka (A. australis), 73 rowi (A. rowi), 49 great spotted kiwi (A. haastii), and 34 little spotted kiwi (A. owenii). This comprised 19 eggs/embryos, 125 neonatal, 473 juvenile, 153 subadult, and 235 adult kiwi. There were 615 kiwi from wild populations, 148 from sanctuary populations, 238 from captivity, and four from unspecified locations. The leading cause of death was trauma, affecting 322 (32.0 (95% CI = 29.2–35.0)%) kiwi including 289 (37.3 (95% CI = 26.0–31.7)%) NIBK. Nearly half of these died from predation by mustelids, with losses recorded from neonates to adults and clustered in the central to southern North Island. Predation by dogs was the second most common cause of death, killing 84 (8.4 (95% CI = 6.7–10.2)%) kiwi, of which 65.5% came from the northern districts of the North Island. Non-infectious disease killed 214 (21 (95% CI = 18.8–24.0)%) kiwi, and included developmental deformities, gastrointestinal foreign bodies and predator trap injuries. Infectious disease killed 181 (18.0 (95% CI = 15.7–20.5)%) kiwi and the proportion decreased with age, with common diagnoses including coccidiosis, bacterial septicaemia, avian malaria, and fungal respiratory disease. Starvation affected 42 (4.2 (95% CI = 3.0–5.6)%) kiwi, comprised of mainly neonatal or juvenile individuals from wild or sanctuary populations, with a higher percentage seen in tokoeka (11/83; 13.3%) compared to other species (min 0%, max 5.9%). The cause of death was undetermined in 246 (24.5 (95% CI = 21.8–27.3)%) cases, which was most often due to poor preservation of remains. This included 33/73 (46%) rowi and 32/83 (39%) tokoeka, and affected mainly birds from sanctuary and wild populations. Conclusions This study enhances our understanding of causes of mortality in captive, wild and sanctuary populations of all kiwi species and age groups within contemporary New Zealand.

Clinical neglect of aspergillosis in pulmonary tuberculosis coinfection: a case report of avoidable mortality in a resourceconstrained setting

Background: Pulmonary aspergillosis (PA) is common among patients with tuberculosis (TB). With both infections presenting with similar clinical and radiologic features, diagnosis of PA is often made too late or missed completely due to lack of clinical suspicion and poor diagnostic laboratory capacity for mycotic infections prevalent in our settings. We present a case of preventable mortality caused by delayed diagnosis and treatment of PA in a patient with pulmonary TB (PTB).
 Case presentation: A 13-year-old female was diagnosed and treated for PTB, having received anti-TB regimen for 8 months in a mission hospital from where she was referred due to worsening cough, chest pain and progressive breathlessness. The patient was re-assessed and investigated, with GeneXpert detecting Mycobacterium tuberculosis, susceptible to rifampicin. Diagnosis of pulmonary tuberculosis complicated by right pneumothorax was made indicating an emergency thoracotomy and chest tube insertion and continuation of the first line anti-TB regimen. At about 2 weeks into admission, patients had features of superimposed acute bacterial sepsis with fever becoming high grade, marked neutrophilia with toxic granulation and elevated sepsis biomarker, and this necessitated empiric antibiotic treatment with parenteral meropenem and vancomycin. However, the patient only had mild clinical improvement following which there was progressively worsening respiratory symptoms and massive haemoptysis. Result of sputum fungal study was available on admission day 20 and revealed a growth of Aspergillus flavus. Treatment with intravenous voriconazole was however commenced rather late when the fungal respiratory disease could no longer be remedied. The patient died on admission day 23.
 Conclusion: Diagnosis of PA in patients with background TB is often made too late to guarantee timely and effective antifungal treatment with negative consequences on patients’ outcomes. Improving clinical and laboratory capacities is essential to reducing mortality from PA in healthcare facilities.

Modeling a human STAT4 mutation that predisposes to disseminated Coccidioidomycosis in mice

Abstract Coccidioidomycosis is a common fungal respiratory disease caused by the fungus Coccidioides spp. fungi in Arizona and the central valley of California. Disseminated Coccidioidomycosis (DCM) occurs in 8% of identified cases, causing significant morbidity and mortality. DCM occurred in 3 generations of a family in Tucson, Arizona who all shared a heterozygous missense mutation (p.E626G) in STAT4. Transfection of STAT4 E626G in WT human cells showed dampened responses to STAT4-dependent cytokine gene induction, suggesting the mutation is a dominant negative. To understand the function of E626G mutation, we generated the homologous mutation in Stat4 in B6 mice. Mice carrying E626G were grossly normal with normal numbers of innate and adaptive immune cells in primary and secondary lymphoid organs. To examine the effect of E626G on susceptibility to Coccidioides infection, we infected mice with C. posadasii strain 1038 intranasally. After infection E626G heterozygous mice all died by 50 days post infection (dpi), median time to death 45.5 days; range 30–50 dpi. 87% of WT B6 controls were alive when the experiment ended at a predetermined 70 dpi, resulting in a median time to death of >70 days. Mediastinal lymph nodes in E626G heterozygous mice had reduced numbers of B cells and activated (CD62Llow) T cells compared to B6 controls on 14 dpi. Cells from infected lungs from E626G heterozygotes produced less IFN-gamma after infection on 28, 35 and 42 dpi. Interferon stimulated cytokines (IP-10, MIG, MIP-2) were also significantly reduced compared to WT controls. Ongoing work includes examining the cells requiring STAT4 signaling and IFN-gamma production as well as the mechanism of reduced accumulation of immune cells in the draining lymph nodes.

Communicating Risk for a Climate-Sensitive Disease: A Case Study of Valley Fever in Central California.

Valley Fever, or Coccidioidomycosis, a fungal respiratory disease, is prevalent with increasing incidence in the Southwestern United States, especially in the central region of California. Public health agencies in the region do not have a consistent strategy for communication and health promotion targeting vulnerable communities about this climate-sensitive disease. We used the behavior adaptation communication model to design and conduct semi-structured interviews with representatives of public health agencies in five California counties: Fresno, Kern, Kings, San Luis Obispo, and Tulare County. While none of the agencies currently include climate change information into their Valley Fever risk messaging, the agencies discuss future communication methods similar to other health risk factors such as poor air quality days and influenza virus season. For political reasons, some public health agencies deliberately avoided the use of climate change language in communicating health risk factors to farmers who are particularly vulnerable to soil and dust-borne fungal spores. The effectiveness of health communication activities of the public health agencies has not been measured in reducing the prevalence of Valley Fever in impacted communities. Given the transboundary nature of climate influence on Valley Fever risk, a concerted and consistent health communication strategy is expected to be more effective than current practices.

Construction and Evaluation of a Novel Recombinant T Cell Epitope-Based Vaccine against Coccidioidomycosis

Clinical and animal studies of coccidioidomycosis have demonstrated that activated CD4(+) T lymphocytes are essential for protection against this fungal respiratory disease. We previously reported a vaccine against Coccidioides infection which contained three recombinant CD4(+) T cell-reactive proteins and induced a robust, protective immune response in mice. Due to the anticipated high cost of production and clinical assessment of this multivalent vaccine, we generated a single protein which contained immunodominant T cell epitopes of the three polypeptides. Epitopes were initially identified by computational prediction of their ability to bind promiscuously to human major histocompatibility complex class II (MHC II) molecules. Cellular immunoassays confirmed the immunogenicity of the synthesized epitope peptides, while in vitro binding assays revealed a range of peptide affinity for MHC II. A DNA construct was synthesized for bacterial expression of a recombinant protein vaccine which contained five epitopes with the highest affinity for human MHC II, each fused with leader and spacer peptides proposed to optimize epitope processing and presentation to T cell receptors. Recall assays of immune T lymphocytes obtained from human MHC II-expressing HLA-DR4 transgenic mice confirmed that 4 of the 5 epitope peptides were processed. Mice immunized with the epitope-based vaccine admixed with a synthetic oligodeoxynucleotide adjuvant or loaded into yeast glucan particles and then challenged intranasally with Coccidioides showed early lung infiltration of activated T helper-1 (Th1), Th2, and Th17 cells, elevated gamma interferon (IFN-γ) and interleukin (IL)-17 production, significant reduction of fungal burden, and prolongation of survival compared to nonvaccinated mice. This is the first report of an epitope-based vaccine against coccidioidomycosis.

Fungal Diagnostics in Pneumonia

Fungal pneumonia is increasingly common, particularly in highly immunosuppressed patients, such as solid organ or hematopoietic stem cell transplant recipients, and the diagnosis is evolving. Although standard techniques such as microscopy and culture remain the mainstays of diagnosis, relatively recent advances in serological and molecular testing are important additions to the field. This article reviews the laboratory tools used to diagnose fungal respiratory disease.

HistoplasmaVirulence and Host Responses

Histoplasma capsulatum is the most prevalent cause of fungal respiratory disease. The disease extent and outcomes are the result of the complex interaction between the pathogen and a host's immune system. The focus of our paper consists in presenting the current knowledge regarding the multiple facets of the dynamic host-pathogen relationship in the context of the virulence arsenal displayed by the fungus and the innate and adaptive immune responses of the host.

Fungal respiratory disease

Fungal respiratory disease is associated with a high mortality in immunocompromised patients. This review aims to describe the recent advances in the aetiology, clinical presentation, diagnosis and management of fungal respiratory disease. Invasive aspergillosis is an uncommon complication of hematopoietic stem cell transplants and solid-organ transplants but continues to be associated with poor outcome. Isolation of Aspergillus spp. from respiratory samples preceded acute rejection in lung-transplantation recipients. Molecular typing suggested that there was a very weak correlation between the environmental and patient isolates of Aspergillus fumigatus in invasive pulmonary aspergillosis. Serological and molecular detection of Aspergillus antigens or fungal DNA may improve the diagnosis of pulmonary aspergillosis, but the sensitivity is variable and more studies are needed. Voriconazole and caspofungin are choice to Aspergillus and Candida infection, especially to azole-resistant Candida spp. Treatment combining amphotericin B preparations, early surgical resection of infected tissue and discontinuation of immunosuppressive treatment may improve prognosis of mucormycosis. Invasive filamentaous fungal infections of lung remain important causes of death in immunocompromised patients. Development of new early diagnostic tools and well-designed multicenter evaluations of diagnostic methods and therapeutic regimens available at present are the important work in the next 2-3 years.

Mortality of common loons in New England, 1987 to 2000.

Diagnostic findings are presented on 522 common loons (Gavia immer) found dead or moribund in New England (Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont, USA) between 1987 and 2000. Common loon numbers and range in New England have decreased from historic levels over the last century due to a number of proposed factors. Goals of this study were to identify and categorize causes of mortality and quantify natural versus anthropogenic causes. The majority of identifiable mortality in chicks was from intraspecific aggression (25%) and other causes of trauma (32%). Death in immature loons was primarily from fungal respiratory disease (20%) and trauma (18%). Causes of adult loon mortality differed significantly in breeding and wintering habitats. Wintering adults primarily died of trauma (17%) and infection (11%) and had significantly poorer body condition than breeding loons. In breeding adults, confirmed and suspected lead toxicosis from ingested fishing weights accounted for almost half of all mortality. Direct anthropogenic factors accounted for 52% of loon mortality in this study. Because of high carcass recovery rates, we believe these data are a good representation of loon mortality in New England. Results highlight the importance of human influences on conservation and management of the common loon in New England.

Intracellular parasitism by Histoplasma capsulatum: fungal virulence and calcium dependence.

Histoplasma capsulatum is an effective intracellular parasite of macrophages and causes the most prevalent fungal respiratory disease in the United States. A "dimorphic" fungus, H. capsulatum exists as a saprophytic mold in soil and converts to the parasitic yeast form after inhalation. Only the yeasts secrete a calcium-binding protein (CBP) and can grow in calcium-limiting conditions. To probe the relation between calcium limitation and intracellular parasitism, we designed a strategy to disrupt CBP1 in H. capsulatum using a telomeric linear plasmid and a two-step genetic selection. The resultingcbp1 yeasts no longer grew when deprived of calcium, and they were also unable to destroy macrophages in vitro or proliferate in a mouse model of pulmonary infection.

Aspergillus and other human respiratory disease agents in turkey confinement houses.

The atmosphere of a turkey confinement house on a large Minnesota farm was examined over the course of a year in order to determine levels of airborne contaminants and to evaluate the hazard potential posed by the contaminants to farm workers. Air concentrations of total and respirable dust, ammonia, carbon monoxide, hydrogen sulfide, nitrogen dioxide, methane, and Aspergillus (a fungal respiratory disease agent) were evaluated. Inter- and intra-seasonal variations in confinement house contaminant concentrations were observed. The highest concentrations of dust, ammonia and Aspergillus occurred during the winter months when dust levels averaged 9.3 mg/m3 and ammonia levels averaged 35 parts per million (ppm). Aspergillus levels were lower than expected, never exceeding 73 colony forming units per cubic meter (cfu/m3). Ammonia levels were found to be particularly high during tilling of the confinement house when concentrations greater than 100 ppm were reached. Concentrations of carbon monoxide, hydrogen sulfide, nitrogen dioxide and methane were below detectable levels.