Saccharomyces cerevisiae and Candida albicans stimulate cytokine secretion from human neutrophil-like HL-60 cells differentiated with retinoic acid or dimethylsulfoxide

Probiotic Yeasts Inhibit Virulence of Non-albicans Candida Species

Systemic infections of Candida species pose a significant threat to public health. Toxicity associated with current therapies and emergence of resistant strains present major therapeutic challenges. Here, we report exploitation of the probiotic properties of two novel, food-derived yeasts, Saccharomyces cerevisiae (strain KTP) and Issatchenkia occidentalis (strain ApC), as an alternative approach to combat widespread opportunistic fungal infections. Both yeasts inhibit virulence traits such as adhesion, filamentation, and biofilm formation of several non-albicans Candida species, including Candida tropicalis, Candida krusei, Candida glabrata, and Candida parapsilosis as well as the recently identified multidrug-resistant species Candida auris They inhibit adhesion to abiotic surfaces as well as cultured colon epithelial cells. Furthermore, probiotic treatment blocks the formation of biofilms of individual non-albicans Candida strains as well as mixed-culture biofilms of each non-albicans Candida strain in combination with Candida albicans The probiotic yeasts attenuated non-albicans Candida infections in a live animal. In vivo studies using Caenorhabditis elegans suggest that exposure to probiotic yeasts protects nematodes from infection with non-albicans Candida strains compared to worms that were not exposed to the probiotic yeasts. Furthermore, application of probiotic yeasts postinfection with non-albicans Candida alleviated pathogenic colonization of the nematode gut. The probiotic properties of these novel yeasts are better than or comparable to those of the commercially available probiotic yeast Saccharomyces boulardii, which was used as a reference strain throughout this study. These results indicate that yeasts derived from food sources could serve as an effective alternative to antifungal therapy against emerging pathogenic Candida species.IMPORTANCE Non-albicans Candida-associated infections have emerged as a major risk factor in the hospitalized and immunecompromised patients. Besides, antifungal-associated complications occur more frequently with these non-albicans Candida species than with C. albicans Therefore, as an alternative approach to combat these widespread non-albicans Candida-associated infections, here we showed the probiotic effect of two yeasts, Saccharomyces cerevisiae (strain KTP) and Issatchenkia occidentalis (ApC), in preventing adhesion and biofilm formation of five non-albicans Candida strains, Candida tropicalis, Candida krusei, Candida glabrata, Candida parapsilosis, and Candida auris The result would influence the current trend of the conversion of conventional antimicrobial therapy into beneficial probiotic microbe-associated antimicrobial treatment.

Yeast-based vaccines: New perspective in vaccine development and application

In presently licensed vaccines, killed or attenuated organisms act as a source of immunogens except for peptide-based vaccines. These conventional vaccines required a mass culture of associated or related organisms and long incubation periods. Special requirements during storage and transportation further adds to the cost of vaccine preparations. Availability of complete genome sequence, well-established genetic, inherent natural adjuvant and non-pathogenic nature of yeast species viz. Saccharomyces cerevisiae, Pichia pastoris makes them an ideal model system for the development of vaccines both for public health and for on-farm consumption. In this review, we compile the work in this emerging field during last two decades with major emphases on S. cerevisiae and P. pastoris which are routinely used worldwide for expression of heterologous proteins with therapeutic value against infectious diseases along with possible use in cancer therapy. We also pointed towards the developments in use of whole recombinant yeast, yeast surface display and virus-like particles as a novel strategy in the fight against infectious diseases and cancer along with other aspects including suitability of yeast in vaccines preparations, yeast cell wall component as an immune stimulator or modulator and present status of yeast-based vaccines in clinical trials.

The Interaction of Human Pathogenic Fungi With C-Type Lectin Receptors

Fungi, usually present as commensals, are a major cause of opportunistic infections in immunocompromised patients. Such infections, if not diagnosed or treated properly, can prove fatal. However, in most cases healthy individuals are able to avert the fungal attacks by mounting proper antifungal immune responses. Among the pattern recognition receptors (PRRs), C-type lectin receptors (CLRs) are the major players in antifungal immunity. CLRs can recognize carbohydrate ligands, such as β-glucans and mannans, which are mainly found on fungal cell surfaces. They induce proinflammatory immune reactions, including phagocytosis, oxidative burst, cytokine, and chemokine production from innate effector cells, as well as activation of adaptive immunity via Th17 responses. CLRs such as Dectin-1, Dectin-2, Mincle, mannose receptor (MR), and DC-SIGN can recognize many disease-causing fungi and also collaborate with each other as well as other PRRs in mounting a fungi-specific immune response. Mutations in these receptors affect the host response and have been linked to a higher risk in contracting fungal infections. This review focuses on how CLRs on various immune cells orchestrate the antifungal response and on the contribution of single nucleotide polymorphisms in these receptors toward the risk of developing such infections.

Upgrading well plates using open microfluidic patterning

Cellular communication between multiple cell types is a ubiquitous process that is responsible for vital physiological responses observed in vivo (e.g., immune response, organ function). Many in vitro coculture strategies have been developed, both in traditional culture and microscale systems, and have shown the potential to recreate some of the physiological behaviors of organs or groups of cells. A fundamental limitation of current systems is the difficulty of reconciling the additional engineering requirements for creating soluble factor signaling systems (e.g., segregated cell culture) with the use of well-characterized materials and platforms that have demonstrated successful results and biocompatibility in assays. We present a new open-microfluidic platform, the Monorail Device, that is placed in any existing well plate or Petri dish and enables patterning of segregated coculture regions, thereby allowing the direct upgrade of monoculture experiments into multiculture assays. Our platform patterns biocompatible hydrogel walls via microfluidic spontaneous capillary flow (SCF) along a rail insert set inside commercially available cultureware, creating customized pipette-accessible cell culture chambers that require fewer cells than standard macroscale culture. Importantly, the device allows the use of native surfaces without additional modification or treatments, while creating permeable dividers for the diffusion of soluble factors. Additionally, the ease of patterning afforded by our platform makes reconfiguration of the culture region as simple as changing the rail insert. We demonstrate the ability of the device to pattern flows on a variety of cell culture surfaces and create hydrogel walls in complex and precise shapes. We characterize the physical parameters that enable a reproducible SCF-driven flow and highlight specialized design features that increase the ease of use of the device and control of the open microfluidic flow. Further, we present the performance of our platform according to useful coculture criteria, including permeability and integrity of our hydrogel walls and surface-sensitive cell culture. Lastly, we show the potential of this type of platform to create modular multikingdom culture systems that can be used to study soluble factor signaling between mammalian cells, bacteria, and fungi, as well as the potential for adaptation of this technology by researchers across multiple fields.

Role of monocyte chemoattractant protein-1, stromal derived factor-1 and retinoic acid in pathophysiology of neuropathic pain in rats

BACKGROUND

Chemokines have been recently recognized to play a role in chronic pain syndromes' pathophysiology. This study investigated the role of monocyte chemoattractant protein-1 (MCP-1), stromal cell derived factor-1 (SDF-1), and retinoic acid (RA) as targets for the therapeutic approach of neuropathic pain.

METHODS

A chronic constriction injury (CCI) model of neuropathic pain by unilateral ligation of left sciatic nerve was performed in adult female Wistar rats. The effects of doxycycline (Dox, 50 mg/kg/day i.p. for 7 days), single dose of bicyclam (5 mg/kg i.p.), RA (15 mg/kg/day i.p. for 7 days), and their combination(s) on behavioral tests of nociception (Von Frey filaments; paw pressure test) on days 0, 1, 3, 5, and 7 of operation were studied. Serum concentrations of MCP-1 and SDF-1 were measured by ELISA. Histological examination of the sciatic nerve was investigated.

RESULTS

CCI of sciatic nerve significantly induced mechanical allodynia and hyperalgesia and an increase of MCP-1 and SDF-1 serum levels. Dox-treated groups (Dox, Dox+bicyclam, Dox+RA, Dox+bicyclam+RA) and bicyclam-treated groups (bicyclam, Dox+bicyclam, bicyclam+RA, Dox+bicyclam+RA) attenuated CCI-induced behavioral and biochemical changes. RA inhibited CCI-induced mechanical hyperalgesia but produced a time-dependent reversal of allodynia. Histological findings showed degenerative changes of sciatic nerve after CCI that were partially recovered in Dox-treated groups.

CONCLUSIONS

These findings demonstrate an association between serum MCP-1 and SDF-1 concentrations and behavioral manifestations of neuropathic pain. RA administration decreased neuropathic pain (antihyperalgesic effect) but did not cause any improvement in sciatic nerve tissues, either alone or in combination with chemokine antagonists. Thus, chemokines may serve as potential targets for drug development in neuropathic pain treatment.

Candida glabrata induced infection of rat tracheal epithelial cells is mediated by TLR-2 induced activation of NF-κB

An increasing number of reports identified Candida glabrata (C. glabrata) as the important causative agent of invasive pulmonary fungal infection. However, little is known about immune responses to C. glabrata in rat tracheal epithelial cell (RTEC). Here, the effect of C. glabrata on RTEC and the role of TLR-2 and NF-κB in the immune response were investigated by treatment with TLR-2 siRNA and NF-κB inhibitor pyrrolidine dithiocarbamate (PDTC), respectively. Our results showed that the knockdown of TLR-2 and pretreatment of PDTC led to inhibition of cell proliferation by C. glabrata, further enhanced cells in G0/G1 phases, and promoted C. glabrata -induced apoptosis. C. glabrata infection induced the expression or secretion of TLR-2, NF-κB, TNF-α, and IL-6, and its effect was inhibited by knockdown of TLR-2. Pretreatment with PDTC inhibited the C. glabrata -induced expression of TLR2, and also inhibited the expression of p65 subunit of NF-κB in the first 4 h. Although the expression of p65 subunit at 6 h was elevated compared to baseline, the C. glabrata -induced expression of TNF-α and IL-6 remained attenuated by PDTC pretreatment. Therefore, C. glabrata recognized the TLR-2 in rat tracheal epithelial cell (RTEC), and then activated the transcription factor NF-κB and further promoted the secretion of TNF-α and IL-6 to contribute to the immune response and inflammation.

Review of current methods for characterizing virulence and pathogenicity potential of industrial Saccharomyces cerevisiae strains towards humans

Most industrial Saccharomyces cerevisiae strains used in food or biotechnology processes are benign. However, reports of S. cerevisiae infections have emerged and novel strains continue to be developed. In order to develop recommendations for the human health risk assessment of S. cerevisiae strains, we conducted a literature review of current methods used to characterize their pathogenic potential and evaluated their relevance towards risk assessment. These studies revealed that expression of virulence traits in S. cerevisiae is complex and depends on many factors. Given the opportunistic nature of this organism, an approach using multiple lines of evidence is likely necessary for the reasonable prediction of the pathogenic potential of a particular strain. Risk assessment of S. cerevisiae strains would benefit from more research towards the comparison of virulent and non-virulent strains in order to better understand those genotypic and phenotypic traits most likely to be associated with pathogenicity.

Immunomodulatory effects of testosterone evaluated in all-trans retinoic acid differentiated HL-60 cells, granulocytes, and monocytes

The sex hormones are known to affect innate immunity in humans. In this study we evaluated the immunomodulatory effects of testosterone in a model system comprising of all-trans retinoic acid differentiated HL-60 cells, and confirmed the results in human granulocytes and monocytes. Results showed that testosterone at pharmacological doses reduced the production of interleukin-8 and reactive oxygen species from differentiated HL-60 cells in a concentration dependent manner without affecting phagocytosis. The cells were stimulated with zymosan, lipopolysaccharide, or Bacillus subtilis. At the highest concentration of testosterone (120 μM), interleukin-8 secretion was reduced 42-80%, and production of reactive oxygen species was reduced 32-46%. Flutamide, an antagonist of the classical intracellular androgen receptor, was unable to antagonize the immunosuppressive effect of testosterone. We further demonstrated that the suppressive effect of testosterone has a short onset time. Our results suggest that testosterone affects the fast operating membrane bound androgen receptor or a rapid acting enzyme system. Testosterone, at pharmacological doses, was also shown to suppress generation of reactive oxygen species and interleukin-8 in human granulocytes and monocytes, respectively, to a similar extent as observed in differentiated HL-60 cells.

Saccharomyces cerevisiae modulates immune gene expressions and inhibits ETEC-mediated ERK1/2 and p38 signaling pathways in intestinal epithelial cells

BACKGROUND

Enterotoxigenic Escherichia coli (ETEC) infections result in large economic losses in the swine industry worldwide. ETEC infections cause pro-inflammatory responses in intestinal epithelial cells and subsequent diarrhea in pigs, leading to reduced growth rate and mortality. Administration of probiotics as feed additives displayed health benefits against intestinal infections. Saccharomyces cerevisiae (Sc) is non-commensal and non-pathogenic yeast used as probiotic in gastrointestinal diseases. However, the immuno-modulatory effects of Sc in differentiated porcine intestinal epithelial cells exposed to ETEC were not investigated.

METHODOLOGY/PRINCIPAL FINDINGS

We reported that the yeast Sc (strain CNCM I-3856) modulates transcript and protein expressions involved in inflammation, recruitment and activation of immune cells in differentiated porcine intestinal epithelial IPEC-1 cells. We demonstrated that viable Sc inhibits the ETEC-induced expression of pro-inflammatory transcripts (IL-6, IL-8, CCL20, CXCL2, CXCL10) and proteins (IL-6, IL-8). This inhibition was associated to a decrease of ERK1/2 and p38 MAPK phosphorylation, an agglutination of ETEC by Sc and an increase of the anti-inflammatory PPAR-γ nuclear receptor mRNA level. In addition, Sc up-regulates the mRNA levels of both IL-12p35 and CCL25. However, measurement of transepithelial electrical resistance displayed that Sc failed to maintain the barrier integrity in monolayer exposed to ETEC suggesting that Sc does not inhibit ETEC enterotoxin activity.

CONCLUSIONS

Sc (strain CNCM I-3856) displays multiple immuno-modulatory effects at the molecular level in IPEC-1 cells suggesting that Sc may influence intestinal inflammatory reaction.

Immune responses induced by heat killed Saccharomyces cerevisiae: a vaccine against fungal infection

Heat-killed Saccharomyces cerevisiae (HKY) used as a vaccine protects mice against systemic aspergillosis and coccidioidomycosis. Little is known about the immune response induced by HKY vaccination, consequently our goal was to do an analysis of HKY-induced immune responses involved in protection. BALB/c mice were vaccinated subcutaneously 3 times with HKY, a protective reagent, and bronchoalveolar lavage fluid, spleen, lymph nodes, and serum collected 2-5 weeks later. Cultured spleen or lymph node cells were stimulated with HKY. Proliferation of HKY-stimulated spleen or lymph node cells was tested by Alamar Blue reduction and flow cytometry. Cytokines from lymphocyte supernatants and antibody to glycans in serum collected from HKY-vaccinated mice were measured by ELISA. The results show that HKY promoted spleen cell and lymph node cell proliferation from HKY-vaccinated mice but not from PBS-vaccinated control mice (all P<0.05). Cytokine measurement showed HKY significantly promoted IFNγ, IL-6 and IL-17A production by spleen cells and lymph node cells (all P<0.05 and P<0.01, respectively). Cytokine production by HKY-stimulated cells from PBS-vaccinated mice was lower than those from HKY-vaccinated (P<0.05). Cytokines in BAL from HKY-vaccinated were higher, 1.7-fold for IFNγ and 2.1-fold for TNFα, than in BAL from PBS-vaccinated. Flow cytometry of lymphocytes from HKY-vaccinated showed 52% of CD3(+) or 56% of CD8(+) cells exhibited cell division after stimulation with HKY, compared to non-stimulated controls (26 or 23%, respectively) or HKY-stimulated cells from PBS-vaccinated (31 or 34%). HKY also induced antibody against Saccharomyces glucan and mannan with titers 4- or 2-fold, respectively, above that in unvaccinated. Taken together, the results suggested that HKY vaccination induces significant and specific Th1 type cellular immune responses and antibodies to glucan and mannan.