Transient Mitochondria Dysfunction Confers Fungal Cross-Resistance against Phagocytic Killing and Fluconazole

Candida glabrata is an opportunistic pathogen whose incidence has been increasing in the last 40 years. It has risen to become the most prominent non- Candida albicans Candida (NCAC) species to cause candidemia, constituting about one-third of isolates in the United States, and steadily increasing in European countries and in Australia.

Nonimmune antibody interactions of Group A Streptococcus M and M-like proteins

M and M-like proteins are major virulence factors of the widespread and potentially deadly bacterial pathogen Streptococcus pyogenes. These proteins confer resistance against innate and adaptive immune responses by recruiting specific human proteins to the streptococcal surface. Nonimmune recruitment of immunoglobulins G (IgG) and A (IgA) through their fragment crystallizable (Fc) domains by M and M-like proteins was described almost 40 years ago, but its impact on virulence remains unresolved. These interactions have been suggested to be consequential under immune conditions at mucosal surfaces and in secretions but not in plasma, while other evidence suggests importance in evading phagocytic killing in nonimmune blood. Recently, an indirect effect of Fc-binding through ligand-induced stabilization of an M-like protein was shown to increase virulence. Nonimmune recruitment has also been seen to contribute to tissue damage in animal models of autoimmune diseases triggered by S. pyogenes infection. The damage was treatable by targeting Fc-binding. This and other potential therapeutic applications warrant renewed attention to Fc-binding by M and M-like proteins.

Sulforaphane Pre-treatment Protects From Alcohol-induced Phagocytic Dysfunction During Burkholderia thailandensis E264 Infection

Binge drinking is associated with increased mortality and morbidity. Burkholderia pseudomallei, the causative agent of pneumonic melioidosis can occur in healthy humans; however, binge alcohol intoxication is a major risk factor. Previous findings indicate that a single binge alcohol episode increases Burkholderia spp. infection by reducing alveolar macrophage function. The aim of this study was to test the ability of the phytonutrient sulforaphane (SFN) to rescue the phagocytic function of alveolar macrophages when infected with Burkholderia spp. in vitro. B. thailandensis E264 was used as a useful BSL-1 model to determine the effects of SFN pre-treatment. The primary outcome was macrophage phagocytic killing, while the secondary outcome was the nuclear factor (erythroid-derived 2)-like (Nrf2) signaling response measured by western blot analysis. Results indicate that alveolar macrophages pre-treated with SFN (5 M) and challenged with 0.2% (v/v) alcohol for 3 or 8 h prior to live B. thailandensis infection improved intracellular killing of B. thailandensis ~2-fold compared to MH-S cells treated with alcohol alone. These data demonstrate that SFN may be an effective pre-treatment option to prevent alcohol mediated immune dysfunction and restore macrophage phagocytic killing of Burkholderia spp. and other similar opportunistic pathogens.

Bacteria Modify Candida albicans Hypha Formation, Microcolony Properties, and Survival within Macrophages

ABSTRACT Phagocytic cells are crucial components of the innate immune system preventing Candida albicans mucosal infections. Streptococcus gordonii and Pseudomonas aeruginosa often colonize mucosal sites, along with C. albicans, and yet interkingdom interactions that might alter the survival and escape of fungi from macrophages are not understood. Murine macrophages were coinfected with S. gordonii or P. aeruginosa, along with C. albicans to evaluate changes in fungal survival. S. gordonii increased C. albicans survival and filamentation within macrophage phagosomes, while P. aeruginosa reduced fungal survival and filamentation. Coinfection with S. gordonii resulted in greater escape of C. albicans from macrophages and increased size of fungal microcolonies formed on macrophage monolayers, while coinfection with P. aeruginosa reduced macrophage escape and produced smaller microcolonies. Microcolonies formed in the presence of P. aeruginosa cells outside macrophages also had significantly reduced size that was not found with P. aeruginosa phenazine deletion mutants. S. gordonii cells, as well as S. gordonii heat-fixed culture supernatants, increased C. albicans microcolony biomass but also resulted in microcolony detachment. A heat-resistant, trypsin-sensitive pheromone processed by S. gordonii Eep was needed for these effects. The majority of fungal microcolonies formed on human epithelial monolayers with S. gordonii supernatants developed as large floating structures with no detectable invasion of epithelium, along with reduced gene expression of C. albicans HYR1, EAP1, and HWP2 adhesins. However, a subset of C. albicans microcolonies was smaller and had greater epithelial invasiveness compared to microcolonies grown without S. gordonii. Thus, bacteria can alter the killing and escape of C. albicans from macrophages and contribute to changes in C. albicans pathogenicity. IMPORTANCE Candida albicans is the predominant fungus colonizing the oral cavity that can have both synergistic and antagonistic interactions with other bacteria. Interkingdom polymicrobial associations modify fungal pathogenicity and are believed to increase microbial resistance to innate immunity. However, it is not known how these interactions alter fungal survival during phagocytic killing. We demonstrated that secreted molecules of S. gordonii and P. aeruginosa alter C. albicans survival within the phagosome of macrophages and alter fungal pathogenic phenotypes, including filamentation and microcolony formation. Moreover, we provide evidence for a dual interaction between S. gordonii and C. albicans such that S. gordonii signaling peptides can promote C. albicans commensalism by decreasing microcolony attachment while increasing invasion in epithelial cells. Our results identify bacterial diffusible factors as an attractive target to modify virulence of C. albicans in polymicrobial infections.

Appraisal of Immunological Impacts of Melaleuca leucadendra Extract over Macrophage Performance in Vitro

This trial research was performed to discuss the immune-influence of Melaleuca leucadendra ‘paper-bark tree’ dried leaves which is an important medical plant known in many regions in the world. The leaves were dissolved in a mixture of (ethanol + water) (3:1) mixture, then filtered, evaporated and dried under reduced pressure to obtain leaves extract. The macrophages of blood derived origin were provided from rats and mixed with three different leaves extracts doses in tissue culture plates and incubated then stained with fluorescent acridine orange and examined under fluorescent microscope to assess the phagocytic and killing potency. The wells contents were aspirated and assayed for nitric oxide and interleukin-2 levels. The results displayed an obvious increase in phagocytic, killing performance as well as nitric oxide and IL-2 level production than control in a dose dependent manner. The obtained results suggested the immune-stimulant impact of the paper-bark tree leaves.

Phagocytic predation by the fungivorous amoeba Protostelium aurantium targets metal ion and redox homeostasis

SummaryPredatory interactions among microbes are considered to be a major evolutionary driving force for biodiversity and the defense against phagocytic killing. The fungivorous amoeba Protostelium aurantium has a wide fungal food spectrum but strongly discriminates among major pathogenic members of the Saccharomycotina. While C. albicans is not recognized, C. glabrata is rapidly internalized, but remains undigested. Phagocytic killing and feeding by P. aurantium is highly effective for the third major fungal pathogen, C. parapsilosis. Here we show that the different prey patterns of the three yeasts were reflected by distinct transcriptional responses, indicating fungal copper and redox homeostasis as primary targets during intracellular killing of C. parapsilosis. Gene deletions in this fungus for the highly expressed copper exporter Crp1 and the peroxiredoxin Prx1 confirmed their role in copper and redox homeostasis, respectively and identified methionine biosynthesis as a ROS sensitive metabolic target during predation. Both, intact Cu export and redox homeostasis contributed to the survival of C. parapsilosis not only when encountering P. aurantium, but also in the presence of human macrophages. As both genes were found to be widely conserved within the entire Candida clade, our results suggest that they could be part of a basic tool-kit to survive phagocytic attacks by environmental predators.