Human laminin-332 degradation by Candida proteinases

Role of the microbiome in oral cancer occurrence, progression and therapy

The oral cavity, like other digestive or mucosal sites, contains a site-specific microbiome that plays a significant role in maintaining health and homeostasis. Strictly speaking, the gastrointestinal tract starts from the oral cavity, with special attention paid to the specific flora of the oral cavity. In healthy people, the microbiome of the oral microenvironment is governed by beneficial bacteria, that benefit the host by symbiosis. When a microecological imbalance occurs, changes in immune and metabolic signals affect the characteristics of cancer, as well as chronic inflammation, disruption of the epithelial barrier, changes in cell proliferation and cell apoptosis, genomic instability, angiogenesis, and epithelial barrier destruction and metabolic regulation. These pathophysiological changes could result in oral cancer. Rising evidence suggests that oral dysbacteriosis and particular microbes may play a positive role in the evolution, development, progression, and metastasis of oral cancer, for instance, oral squamous cell carcinoma (OSCC) through direct or indirect action.

Lingonberries-General and Oral Effects on the Microbiome and Inflammation

Lingonberry (Vaccinium vitis ideae L.) is a low-bush wild plant found in the northern hemisphere. The berries are used in traditional medicine in Finland to treat oral yeast infections. General and oral effects of lingonberries on the microbiome and inflammation are reviewed. A brief introduction to oral microbiome symbiosis and dysbiosis, innate and adaptive immunity and inflammation are included, and special features in microbe/host interactions in the oral environment are considered. In vitro anticancer, antimicrobial, antioxidant, anti-inflammatory, and in vivo mouse and human studies are included, focusing on the symbiotic effect of lingonberries on oral and general health.

The Role of the Microbiome in Oral Squamous Cell Carcinoma with Insight into the Microbiome-Treatment Axis

Oral squamous cell carcinoma (OSCC) is one of the leading presentations of head and neck cancer (HNC). The first part of this review will describe the highlights of the oral microbiome in health and normal development while demonstrating how both the oral and gut microbiome can map OSCC development, progression, treatment and the potential side effects associated with its management. We then scope the dynamics of the various microorganisms of the oral cavity, including bacteria, mycoplasma, fungi, archaea and viruses, and describe the characteristic roles they may play in OSCC development. We also highlight how the human immunodeficiency viruses (HIV) may impinge on the host microbiome and increase the burden of oral premalignant lesions and OSCC in patients with HIV. Finally, we summarise current insights into the microbiome–treatment axis pertaining to OSCC, and show how the microbiome is affected by radiotherapy, chemotherapy, immunotherapy and also how these therapies are affected by the state of the microbiome, potentially determining the success or failure of some of these treatments.

[Research progress of Candida albicans on malignant transformation of oral mucosal diseases]

Oral cancer is the most common malignant tumor in the head and neck, and is one of the world's top ten malignancies. Microbial infection is an important risk factor of oral cancer. Candida albicans is the most popular opportunistic fungal pathogen. Epidemiological studies have shown that Candida albicans is closely tied to oral malignancy. Animal experimentation have also proven that infection of Candida albicans can promote the development of oral epithelial carcinogenesis. The current studies have revealed several mechanisms involved in this process, including destroying the epithelial barrier, producing carcinogenic substances (nitrosamines, acetaldehyde), inducing chronic inflammation, activating immune response, etc. However, current researches on mechanisms are still inadequate, and some hypotheses remain controversial. Here, we review the findings related to Candida albicans' effect on the malignant transformation of oral mucosa, hoping to provide reference for deep research and controlling oral cancer clinically.

Candida glabrata's Genome Plasticity Confers a Unique Pattern of Expressed Cell Wall Proteins

Candida glabrata is the second most common cause of candidemia, and its ability to adhere to different host cell types, to microorganisms, and to medical devices are important virulence factors. Here, we consider three characteristics that confer extraordinary advantages to C. glabrata within the host. (1) C. glabrata has a large number of genes encoding for adhesins most of which are localized at subtelomeric regions. The number and sequence of these genes varies substantially depending on the strain, indicating that C. glabrata can tolerate high genomic plasticity; (2) The largest family of CWPs (cell wall proteins) is the EPA (epithelial adhesin) family of adhesins. Epa1 is the major adhesin and mediates adherence to epithelial, endothelial and immune cells. Several layers of regulation like subtelomeric silencing, cis-acting regulatory regions, activators, nutritional signaling, and stress conditions tightly regulate the expression of many adhesin-encoding genes in C. glabrata, while many others are not expressed. Importantly, there is a connection between acquired resistance to xenobiotics and increased adherence; (3) Other subfamilies of adhesins mediate adherence to Candida albicans, allowing C. glabrata to efficiently invade the oral epithelium and form robust biofilms. It is noteworthy that every C. glabrata strain analyzed presents a unique pattern of CWPs at the cell surface.

A novel Candida glabrata cell wall associated serine protease

We set out to identify the Candida glabrata cell wall attached proteases which may play a role as virulence factors in candidosis, particularly in the immunocompromized host. We studied a clinical C. glabrata strain T-1639, which was isolated from a patient from the Helsinki University Central Hospital. With non-reducing 2-D electrophoresis using parallel fluorogenic gels and mass spectrometry we identified a novel appr. 25 kDa (192 aa in length) cell wall located protease with an estimated pI of 7.6. The LC-MS/MS peptides matched with the ORF of predicted C. glabrata CBS138 cell wall protein Cwp1.2p/pI 7.7/212 aa (http://cbi.labri.fr/Génolevures/[NCBI access 49525604, UniProt access Q6FTZ7]), which is an ortholog to Saccharomyces cerevisiae cell wall protein Cwp1p (UniProt access P28319). The novel serine protease was released by β-1,3-glucanase treatment from the cell wall. In contrast to previous predictions this protease has an enzymatic function instead of being merely a structural cell wall protein. The protease showed gelatinolytic activity and was inhibited by PMSF, a known serine protease inhibitor. Further characterization of the protease may give insight to its role in infections caused by C. glabrata and possibly aid in the development of new kinds of antifungal drugs.

Relevant and selective activity of Pancratium illyricum L. against Candida albicans clinical isolates: a combined effect on yeast growth and virulence

Background

Alkaloids present in plants of the Amaryllidaceae family are secondary metabolites of high biological interest, possessing a wide range of pharmacological activities. In the search for new plant-derived compounds with antimicrobial activities, two alkaloid extracts obtained from bulbs and leaves of Pancratium illyricum L., a plant of the Amarillydaceae family, were tested for their effect on bacterial and yeast growth.

Methods

The broth microdilution susceptibility test was applied to study the effect of plant extracts on the growth of reference bacterial strains and Candida albicans reference and clinical isolates strains. Extracts obtained from the different parts of the plant were tested and compared with the pure components identified in the extracts. Since matrix metalloproteinase enzymes play a role in the dissemination process of Candida albicans, the effect of the bulb extract and pure alkaloids on in vitro collagenase activity was tested. Cell viability test was carried out on human embryo lung fibroblasts (HEL 299).

Results

Whilst both extracts did not show any inhibitory activity against neither Gram positive nor Gram negative bacteria, a strong antifungal activity was detected, in particular for the bulb extract. All clinical isolates were susceptible to the growth inhibitory activity of the bulb extract, with endpoint IC₅₀ values ranging from 1.22 to 78 μg/mL. The pure alkaloids lycorine and vittatine, identified as components of the extract, were also assayed for their capacity of inhibiting the yeast growth, and lycorine turned very active, with endpoint IC₅₀ values ranging from 0.89 to 28.5 μg/mL. A potent inhibition of the in vitro collagenase activity was found in the presence of the bulb extract, and this effect was much higher than that exerted by the pure alkaloids. Viability of cell lines tested was not affected by the extract.

Conclusions

Taken together, results suggest that the extract of Pancratium illyricum may act as antifungal agent both directly on the yeast growth and by altering the tissue invasion process.

Electronic supplementary material

The online version of this article (doi:10.1186/1472-6882-14-409) contains supplementary material, which is available to authorized users.

Comparative adherence of Candida albicans and Candida dubliniensis to human buccal epithelial cells and extracellular matrix proteins

Candida albicans and Candida dubliniensis are very closely related pathogenic yeast species. Despite their close relationship, C. albicans is a far more successful colonizer and pathogen of humans. The purpose of this study was to determine if the disparity in the virulence of the two species is attributed to differences in their ability to adhere to human buccal epithelial cells (BECs) and/or extracellular matrix proteins. When grown overnight at 30°C in yeast extract peptone dextrose, genotype 1 C. dubliniensis isolates were found to be significantly more adherent to human BECs than C. albicans or C. dubliniensis genotypes 2-4 (P < 0.001). However, when the yeast cells were grown at 37°C, no significant difference between the adhesion of C. dubliniensis genotype 1 and C. albicans to human BECs was observed, and C. dubliniensis genotype 1 and C. albicans adhered to BECs in significantly greater numbers than the other C. dubliniensis genotypes (P < 0.001). Using surface plasmon resonance analysis, C. dubliniensis isolates were found to adhere in significantly greater numbers than C. albicans to type I and IV collagen, fibronectin, laminin, vitronectin, and proline-rich peptides. These data suggest that C. albicans is not more adherent to epithelial cells or matrix proteins than C. dubliniensis and therefore other factors must contribute to the greater levels of virulence exhibited by C. albicans.

Human pathogens utilize host extracellular matrix proteins laminin and collagen for adhesion and invasion of the host

Laminin (Ln) and collagen are multifunctional glycoproteins that play an important role in cellular morphogenesis, cell signalling, tissue repair and cell migration. These proteins are ubiquitously present in tissues as a part of the basement membrane (BM), constitute a protective layer around blood capillaries and are included in the extracellular matrix (ECM). As a component of BMs, both Lns and collagen(s), thus function as major mechanical containment molecules that protect tissues from pathogens. Invasive pathogens breach the basal lamina and degrade ECM proteins of interstitial spaces and connective tissues using various ECM-degrading proteases or surface-bound plasminogen and matrix metalloproteinases recruited from the host. Most pathogens associated with the respiratory, gastrointestinal, or urogenital tracts, as well as with the central nervous system or the skin, have the capacity to bind and degrade Lns and collagen(s) in order to adhere to and invade host tissues. In this review, we focus on the adaptability of various pathogens to utilize these ECM proteins as enhancers for adhesion to host tissues or as a targets for degradation in order to breach the cellular barriers. The major pathogens discussed are Streptococcus, Staphylococcus, Pseudomonas, Salmonella, Yersinia, Treponema, Mycobacterium, Clostridium, Listeria, Porphyromonas and Haemophilus; Candida, Aspergillus, Pneumocystis, Cryptococcus and Coccidioides; Acanthamoeba, Trypanosoma and Trichomonas; retrovirus and papilloma virus.

Diverse microbial interactions with the basement membrane barrier

During primary contact with susceptible hosts, microorganisms face an array of barriers that thwart their invasion process. Passage through the basement membrane (BM), a 50-100-nm-thick crucial barrier underlying epithelia and endothelia, is a prerequisite for successful host invasion. Such passage allows pathogens to reach nerve endings or blood vessels in the stroma and to facilitate spread to internal organs. During evolution, several pathogens have developed different mechanisms to cross this dense matrix of sheet-like proteins. To breach the BM, some microorganisms have developed independent mechanisms, others hijack host cells that are able to transverse the BM (e.g. leukocytes and dendritic cells) and oncogenic microorganisms might even trigger metastatic processes in epithelial cells to penetrate the underlying BM.

Are oral and dental diseases linked to cancer?

OBJECTIVE

Infection and inflammation play a role in carcinogenesis, and highly prevalent oral and dental diseases have been significantly linked to some types of cancer. This article reviews current literature in this area.

MATERIALS AND METHODS

Open literature review using the PubMed database and focused on publications from 2000 to 2010.

RESULTS

Numerous potential mechanisms are implicated in the oral disease/carcinogenesis paradigm, including infection- and inflammation-associated cell pathology and microbial carcinogen metabolism. Poor oral hygiene is associated with oral cancer, but there is also evidence of a possible link between oral or dental infections and malignancies in general.

CONCLUSION

Oral infections may trigger malignant transformation in tissues of the mouth and other organs. However, scientific evidence to date remains weak and further well-conducted studies are warranted before cancer can be properly added to the list of oral infection-related systemic diseases.

Revisiting the association between candidal infection and carcinoma, particularly oral squamous cell carcinoma

Background

Tobacco and alcohol are risk factors associated with cancer of the upper aerodigestive tract, but increasingly the role of infection and chronic inflammation is recognized as being significant in cancer development. Bacteria, particularly Helicobacter pylori, and viruses such as members of the human papilloma virus family and hepatitis B and C are strongly implicated as etiological factors in certain cancers. There is less evidence for an association between fungi and cancer, although it has been recognized for many years that white patches on the oral mucosa, which are infected with Candida, have a greater likelihood of undergoing malignant transformation than those that are not infected.

Objective

This article reviews the association between the development of oral squamous cell carcinoma in potentially malignant oral lesions with chronic candidal infection and describes mechanisms that may be involved in Candida-associated malignant transformation.

Prevalence and antifungal drug sensitivity of non-albicans Candida in oral rinse samples of self-caring elderly

AIM

To assess the prevalence and antifungal drug sensitivity of non-albicans Candida (NAC) species in elderly outpatients.

MATERIALS AND METHODS

We investigated oral rinse samples of 194 self-caring elderly population (mean age 83 years) with emphasis on background factors for harbouring NAC. Susceptibility of Candida species to antifungal drugs was determined using standard methodology. Multiple logistic regression analysis was performed taking positive NAC count as the dependent variable and a number of known Candida risk factors as independent variables.

RESULTS

Prevalence of candidal carriage of the population was 78.4%, of which 0.5% of the subjects were NAC positive. Candida dubliniensis was the most prevalent NAC species, followed by Candida glabrata and Candida parapsilosis. The NAC positive elderly were more often edentulous with dental prostheses or had fewer teeth than Candida albicans-positive or yeast-negative subjects. Dental caries slightly increased the risk for having NAC strains (odds ratio 1.08), whilst greater age appeared to lower the risk (odds ratio 0.77). Candida species were susceptible to the commonly used antifungal agents in general, but with considerable variation among species. Occasionally, some NAC exhibited lower antifungal susceptibility.

CONCLUSION

The possibility of oral reservoirs of NAC strains which are resistant to common antifungals should be noted in elderly outpatients.

Enhanced enzymatic activity of Candida species responsible for oral candidiasis in renal transplant recipients

Renal transplant recipients (RTRs) are regarded to be predisposed to oral candidiasis. This study was undertaken to evaluate the activity of hydrolytic enzymes in strains causing oral candidiasis in RTR. A total of 123 Candida albicans and 10 Candida krusei strains were isolated from 200 RTRs (39 RTRs suffered from symptomatic candidiasis, the remaining patients had no clinical symptoms of infection). All fungi were identified based on routine mycological procedures. Because of a small number of non-albicans strains, only C. albicans isolates were compared for enzymatic activity. The activity of 19 hydrolytic enzymes was assessed by API ZYM(®) test. The usage of mycophenolate mofetil was connected with higher ratio of clinically apparent oral candidiasis compared to immunosuppressive regimens without this drug (74.4% vs. 46.8%, respectively, P < 0.01). Candida albicans from RTRs showed higher enzymatic activity compared with strains from immunocompetent patients. Only two enzymes were found to be more active in C. albicans causing symptomatic candidiasis in RTRs (cystine arylamidase: P = 0.001, and α-fucosidase: P = 0.01) compared with saprophytic strains. Atrophic candidiasis showed higher activity of esterase lipase (C8) and α-mannosidase compared with the pseudomembraneous type. We suggest that the enhanced enzymatic activity is responsible for higher invasiveness of Candida residing in the oral cavity of RTRs.