Antifungal immunity and adjuvant cytokine immune enhancement in cancer patients with invasive fungal infections

Transcriptomic Crosstalk between Fungal Invasive Pathogens and Their Host Cells: Opportunities and Challenges for Next-Generation Sequencing Methods

Fungal invasive infections are an increasing health problem. The intrinsic complexity of pathogenic fungi and the unmet clinical need for new and more effective treatments requires a detailed knowledge of the infection process. During infection, fungal pathogens are able to trigger a specific transcriptional program in their host cells. The detailed knowledge of this transcriptional program will allow for a better understanding of the infection process and consequently will help in the future design of more efficient therapeutic strategies. Simultaneous transcriptomic studies of pathogen and host by high-throughput sequencing (dual RNA-seq) is an unbiased protocol to understand the intricate regulatory networks underlying the infectious process. This protocol is starting to be applied to the study of the interactions between fungal pathogens and their hosts. To date, our knowledge of the molecular basis of infection for fungal pathogens is still very limited, and the putative role of regulatory players such as non-coding RNAs or epigenetic factors remains elusive. The wider application of high-throughput transcriptomics in the near future will help to understand the fungal mechanisms for colonization and survival, as well as to characterize the molecular responses of the host cell against a fungal infection.

Black yeasts and their filamentous relatives: principles of pathogenesis and host defense

Among the melanized fungi, the so-called "black yeasts" and their filamentous relatives are particularly significant as agents of severe phaeohyphomycosis, chromoblastomycosis, and mycetoma in humans and animals. The pathogenicity and virulence of these fungi may differ significantly between closely related species. The factors which probably are of significance for pathogenicity include the presence of melanin and carotene, formation of thick cell walls and meristematic growth, presence of yeast-like phases, thermo- and perhaps also osmotolerance, adhesion, hydrophobicity, assimilation of aromatic hydrocarbons, and production of siderophores. Host defense has been shown to rely mainly on the ingestion and elimination of fungal cells by cells of the innate immune system, especially neutrophils and macrophages. However, there is increasing evidence supporting a role of T-cell-mediated immune responses, with increased interleukin-10 (IL-10) and low levels of gamma interferon (IFN-γ) being deleterious during the infection. There are no standardized therapies for treatment. It is therefore important to obtain in vitro susceptibilities of individual patients' fungal isolates in order to provide useful information for selection of appropriate treatment protocols. This article discusses the pathogenesis and host defense factors for these fungi and their severity, chronicity, and subsequent impact on treatment and prevention of diseases in human or animal hosts.

Recruitment of circulating breast cancer cells is stimulated by radiotherapy

Radiotherapy (RT) is a localized therapy that is highly effective in killing primary tumor cells located within the field of the radiation beam. We present evidence that irradiation of breast tumors can attract migrating breast cancer cells. Granulocyte-macrophage colony stimulating factor (GM-CSF) produced by tumor cells in response to radiation stimulates the recruitment of migrating tumor cells to irradiated tumors, suggesting a mechanism of tumor recurrence after radiation facilitated by transit of unirradiated, viable circulating tumor cells to irradiated tumors. Data supporting this hypothesis are presented through in vitro invasion assays and in vivo orthotopic models of breast cancer. Our work provides a mechanism for tumor recurrence in which RT attracts cells outside the radiation field to migrate to the site of treatment.

Overview of invasive fungal infections

The incidence of invasive fungal infections (IFIs) has seen a marked increase in the last two decades. This is especially evident among transplant recipients, patients suffering from AIDS, in addition to those in receipt of immunosuppressive therapy. Worryingly, this increased incidence includes infections caused by opportunistic fungi and emerging fungal infections which are resistant to or certainly less susceptible than others to standard antifungal agents. As a direct response to this phenomenon, there has been a resolute effort over the past several decades to improve early and accurate diagnosis and provide reliable screening protocols thereby promoting the administration of appropriate antifungal therapy for fungal infections. Early diagnosis and treatment with antifungal therapy are vital if a patient is to survive an IFI. Substantial advancements have been made with regard to both the diagnosis and subsequent treatment of an IFI. In parallel, stark changes in the epidemiological profile of these IFIs have similarly occurred, often in direct response the type of antifungal agent being administered. The effects of an IFI can be far reaching, ranging from increased morbidity and mortality to increased length hospital stays and economic burden.

Immunotherapy against invasive mold infections

Invasive infections due to filamentous fungi, such as Aspergillus spp., Zygomycetes, Scedosporium and Fusarium spp., cause significant morbidity and mortality in immunocompromised patients with hematological malignancies, recipients of hematopoietic stem cell transplants and those with chronic granulomatous disease. Despite antifungal therapy, the outcome is often unfavorable in these patients; immune restoration is considered as the cornerstone of successful treatment. Important aspects of human immune response against fungi include effective innate immune response expressed as effective phagocytic functions and a balance between proinflammatory and regulatory adaptive immune responses. A number of immunomodulatory approaches, including the administration of enhancing cytokines, adoptive transfer of pathogen-specific T lymphocytes and granulocyte transfusions have been investigated as adjunctive treatments against serious mold infections. Despite encouraging in vitro and in vivo data, current clinical evidence is not sufficient to allow firm recommendations on the use of these immunomodulatory modalities in serious mold infections.

Immunotherapy of infections caused by rare filamentous fungi

Invasive fungal infections caused by rare filamentous fungi constitute a significant cause of morbidity and mortality in patients with defective immune responses. Despite the advent of new antifungal agents, the problem is escalating as the number of susceptible hosts increases and virulent, more resistant fungal strains emerge. There is evidence that reconstitution of the host immune function is a major contributor to the resolution of these infections. Therapeutic modalities aimed at increasing phagocyte numbers, such as granulocyte transfusions, stimulating the immune response, such as administration of haematopoietic growth factors and other proinflammatory cytokines, or indirectly augmenting immune function have shown promising results in the preclinical setting. Because of the rarity of the infections, multicentre clinical trials are needed to demonstrate the efficacy and safety of the new immunomodulating approaches.

Mucormycosis: its contemporary face and management strategies

Several countries have seen rising frequencies of mucormycosis among patients with haematological disorders, malignancies, or diabetes mellitus, and among transplant recipients. Growing numbers of immunocompromised hosts, widespread use of antifungal agents inactive against mucormycosis, or other unidentified factors, could be contributing to this situation. The predominant clinical manifestations of mucormycosis vary from host to host. Additionally, risk factors specific to different subgroups have been identified, such as leukaemia, allogeneic haemopoietic stem-cell transplant, voriconazole prophylaxis, diabetes, and malnutrition. We summarise the current state of knowledge of characteristics and risk factors and discuss topical developments in therapeutic methods and strategies in the management of mucormycosis.

Validation of double digest selective label database for sequenced prokaryotic genomes

SUMMARY

A database for simulation of double digest selective label (DDSL) typing technique has been created and validated against a sequenced strain (Salmonella enterica serovar Typhimurium strain LT2). In silico bands were in agreement with experimental, and the technique was able to discriminate among strains belonging to the same species. When compared with other strain discrimination techniques, DDSL showed a higher discriminatory power. The database contains precomputed data which may be searched to retrieve experimental conditions for typing all up-to-dated sequenced prokaryotic microorganisms.

AVAILABILITY

This is a new resource for molecular biology freely available on the Internet at http://insilico.ehu.es/DDSL.

Epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) among residents of nursing homes in Belgium

OBJECTIVES

A national survey was conducted to determine the prevalence, risk factors and molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) carriage among nursing home (NH) residents in Belgium.

METHODS

A random stratified, cross-sectional prevalence survey was conducted in NH residents who were screened for MRSA carriage by multisite enriched culture. Characteristics of NHs and residents were collected by a questionnaire survey and analysed by two-stage logistic regression modelling. MRSA isolates were genotyped by PFGE, staphylococcal cassette chromosome mec (SCCmec) typing, multilocus sequence typing (MLST) and resistance genes.

RESULTS

Of 2953 residents screened in 60 NHs, 587 (19.9%) were MRSA carriers. Risk factors included hospital contact, antibiotic exposure, impaired mobility and skin lesions at the resident level, and lack of MRSA surveillance, lack of antibiotic therapeutic formulary and the combination of less-developed infection control activities and a high ratio of physicians to residents at the institution level. MRSA isolates showed eight major types, three of which were predominant: B2-ST45-SCCmec IV (49%; where ST stands for sequence type); A21-ST8-SCCmec IV (13%); and A20-ST8-SCCmec IV (10%). Each was recovered in 55, 21 and 25 NHs, respectively. The geographical distribution of NH genotypes paralleled that of acute-care hospitals.

CONCLUSIONS

A high prevalence of MRSA carriage in NH residents was associated with hospital care, co-morbidities and less-developed coordination of institutional care. The predominant MRSA strains from NH residents and hospitalized patients of the same area were identical. Strengthening and coordination of MRSA surveillance and control activities are warranted within and between NHs and hospitals.

Recommendations for the treatment of established fungal infections

Evidence-based guidelines for the treatment of established fungal infections in the adult haematology/oncology setting were developed by a national consensus working group representing clinicians, pharmacists and microbiologists. These updated guidelines replace the previous guidelines published in the Internal Medicine Journal by Slavin et al. in 2004. The guidelines are pathogen-specific and cover the treatment of the most common fungal infections including candidiasis, aspergillosis, cryptococcosis, zygomycosis, fusariosis, scedosporiosis, and dermatophytosis. Recommendations are provided for management of refractory disease or salvage therapies, and special sites of infections such as the cerebral nervous system and the eye. Because of the widespread use newer broad-spectrum triazoles in prophylaxis and empiric therapy, these guidelines should be implemented in concert with the updated prophylaxis and empiric therapy guidelines published by this group.