Mycobiota and C-Type Lectin Receptors in Cancers: Know thy Neighbors

The gastrointestinal mycobiome in inflammation and cancer: unraveling fungal dysbiosis, pathogenesis, and therapeutic potential

The gastrointestinal mycobiome, comprising diverse fungal species, plays a significant role in gastrointestinal carcinogenesis and inflammatory bowel disease (IBD) pathogenesis. Recent studies have demonstrated that dysbiosis of the gut mycobiome, characterized by an overrepresentation of pathogenic fungi such as Candida albicans and Aspergillus, correlates with increased inflammation and cancer risk. For instance, C. albicans has been shown to induce colonic inflammation through the activation of pattern recognition receptors and the release of pro-inflammatory cytokines, exacerbating IBD symptoms and potentially facilitating tumorigenesis. Additionally, metagenomic analyses have revealed distinct fungal signatures in colorectal cancer tissues compared to adjacent healthy tissues, highlighting the potential of fungi as biomarkers for disease progression. Mechanistically, gut fungi contribute to disease through biofilm formation, mycotoxin secretion (e.g., aflatoxins, candidalysin), pro-inflammatory cytokine induction (e.g., IL-1β, IL-17), and disruption of epithelial barriers-creating a tumor-promoting and inflammation-prone environment. Furthermore, the interplay between fungi and the bacterial microbiome can amplify inflammatory responses, contributing to chronic inflammation and cancer development. Fungal interactions with bacterial communities also play a synergistic role in shaping mucosal immune responses and enhancing disease severity in both cancer and IBD contexts. As research continues to elucidate these complex fungal-host and fungal-bacterial interactions, targeting the gut mycobiome may offer novel therapeutic avenues for managing IBD and gastrointestinal cancers, emphasizing the need for integrated, mechanistically informed approaches to microbiome research.

Lung Microbiota: From Healthy Lungs to Development of Chronic Obstructive Pulmonary Disease

Lung health is dependent on a complex picture of the lung microbiota composed of bacteriobiota, mycobiota, and virome. The studies have demonstrated that the lung microbiota has a crucial role in host protection by regulating innate and adaptive lung immunity. Chronic obstructive pulmonary disease (COPD) is an inflammatory lung disease featuring changed microbiota composition and diversity, known as a dysbiosis. The lung dysbiosis increases with the progress of COPD and during exacerbation. Two models of dysbiosis have been proposed: dysbiosis and inflammation cycles and the disturbance of bacterial interactome. Still, it is unknown if the driving factor of the pathogenesis of COPD belongs to the host or microbiota. Recently, host-microbiota and microbe-microbe interactions have been highlighted in COPD, but the mechanisms behind these interactions need further exploration. The function of the gut-lung axis is crucial for the maintenance of lung health and is affected in COPD. The application of probiotics has resulted in host-beneficial effects, and it is likely that future progress in this field will aid in the therapy of COPD. In this review, the composition of the lung microbiota, molecular mechanisms, and clinical aspects relating to host and microbiota in health and COPD are comprehensively provided.

The implication of microbiome in lungs cancer: mechanisms and strategies of cancer growth, diagnosis and therapy

Available evidence illustrates that microbiome is a promising target for the study of growth, diagnosis and therapy of various types of cancer. Lung cancer is a leading cause of cancer death worldwide. The relationship of microbiota and their products with diverse pathologic conditions has been getting large attention. The novel research suggests that the microbiome plays an important role in the growth and progression of lung cancer. The lung microbiome plays a crucial role in maintaining mucosal immunity and synchronizing the stability between tolerance and inflammation. Alteration in microbiome is identified as a critical player in the progression of lung cancer and negatively impacts the patient. Studies suggest that healthy microbiome is essential for effective therapy. Various clinical trials and research are focusing on enhancing the treatment efficacy by altering the microbiome. The regulation of microbiota will provide innovative and promising treatment strategies for the maintenance of host homeostasis and the prevention of lung cancer in lung cancer patients. In the current review article, we presented the latest progress about the involvement of microbiome in the growth and diagnosis of lung cancer. Furthermore, we also assessed the therapeutic status of the microbiome for the management and treatment of lung cancer.

Integration of Gut Mycobiota and Oxidative Stress to Decipher the Roles of C-Type Lectin Receptors in Inflammatory Bowel Diseases

BACKGROUND

Ulcerative colitis (UC) and Crohn's disease (CD) are two subtypes of inflammatory bowel disease (IBD) with rapidly increased incidence worldwide. Although multiple factors contribute to the occurrence and progression of IBD, the role of intestinal fungal species (gut mycobiota) in regulating the severity of these conditions has been increasingly recognized. C-type lectin receptors (CLRs) on hematopoietic cells, including Dectin-1, Dectin-2, Dectin-3, Mincle and DC-SIGN, are a group of pattern recognition receptors (PRRs) that primarily recognize fungi and mediate defense responses, such as oxidative stress. Recent studies have demonstrated the indispensable role of CLRs in protecting the colon from intestinal inflammation and mucosal damage.

METHODS AND RESULTS

This review provides a comprehensive overview of the role of CLRs in the pathogenesis of IBD. Given the significant impact of mycobiota and oxidative stress in IBD, this review also discusses recent advancements in understanding how these factors exacerbate or ameliorate IBD. Furthermore, the latest developments in CLR-guided IBD therapy are examined to highlight the modulation of CLRs in fungal recognition and oxidative burst during the IBD process.

CONCLUSION

This review emphasizes the importance of CLRs in IBD, offering new perspectives on the etiology and therapeutic approaches for this disease.

Causal relationship between gut microbiota and risk of esophageal cancer: evidence from Mendelian randomization study

BACKGROUND

The causative implications remain ambiguous. Consequently, this study aims to evaluate the putative causal relationship between gut microbiota and Esophageal cancer (EC).

METHODS

The genome-wide association study (GWAS) pertaining to the microbiome, derived from the MiBioGen consortium-which consolidates 18,340 samples across 24 population-based cohorts-was utilized as the exposure dataset. Employing the GWAS summary statistics specific to EC patients sourced from the GWAS Catalog and leveraging the two-sample Mendelian randomization (MR) methodology, the principal analytical method applied was the inverse variance weighted (IVW) technique. Cochran's Q statistic was utilized to discern heterogeneity inherent in the data set. Subsequently, a reverse MR analysis was executed.

RESULTS

Findings derived from the IVW technique elucidated that the Family Porphyromonadaceae (P = 0.048) and Genus Candidatus Soleaferrea (P = 0.048) function as deterrents against EC development. In contrast, the Genus Catenibacterium (P = 0.044), Genus Eubacterium coprostanoligenes group (P = 0.038), Genus Marvinbryantia (P = 0.049), Genus Ruminococcaceae UCG010 (P = 0.034), Genus Ruminococcus1 (P = 0.047), and Genus Sutterella (P = 0.012) emerged as prospective risk contributors for EC. To assess reverse causal effect, we used EC as the exposure and the gut microbiota as the outcome, and this analysis revealed associations between EC and seven different types of gut microbiota. The robustness of the MR findings was substantiated through comprehensive heterogeneity and pleiotropy evaluations.

CONCLUSIONS

This research identified certain microbial taxa as either protective or detrimental elements for EC, potentially offering valuable biomarkers for asymptomatic diagnosis and prospective therapeutic interventions for EC.

Implications of oral dysbiosis and HPV infection in head and neck cancer: from molecular and cellular mechanisms to early diagnosis and therapy

Head and neck cancer (HNC) is the sixth most common type of cancer, with more than half a million new cases annually. This review focuses on the role of oral dysbiosis and HPV infection in HNCs, presenting the involved taxons, molecular effectors and pathways, as well as the HPV-associated particularities of genetic and epigenetic changes and of the tumor microenvironment occurred in different stages of tumor development. Oral dysbiosis is associated with the evolution of HNCs, through multiple mechanisms such as inflammation, genotoxins release, modulation of the innate and acquired immune response, carcinogens and anticarcinogens production, generation of oxidative stress, induction of mutations. Thus, novel microbiome-derived biomarkers and interventions could significantly contribute to achieving the desideratum of personalized management of oncologic patients, regarding both early diagnosis and treatment. The results reported by different studies are not always congruent regarding the variations in the abundance of different taxons in HNCs. However, there is a consistent reporting of a higher abundance of Gram-negative species such as Fusobacterium, Leptotrichia, Treponema, Porphyromonas gingivalis, Prevotella, Bacteroidetes, Haemophilus, Veillonella, Pseudomonas, Enterobacterales, which are probably responsible of chronic inflammation and modulation of tumor microenvironment. Candida albicans is the dominant fungi found in oral carcinoma being also associated with shorter survival rate. Specific microbial signatures (e.g., F. nucleatum, Bacteroidetes and Peptostreptococcus) have been associated with later stages and larger tumor, suggesting their potential to be used as biomarkers for tumor stratification and prognosis. On the other hand, increased abundance of Corynebacterium, Kingella, Abiotrophia is associated with a reduced risk of HNC. Microbiome could also provide biomarkers for differentiating between oropharyngeal and hypopharyngeal cancers as well as between HPV-positive and HPV-negative tumors. Ongoing clinical trials aim to validate non-invasive tests for microbiome-derived biomarkers detection in oral and throat cancers, especially within high-risk populations. Oro-pharyngeal dysbiosis could also impact the HNCs therapy and associated side-effects of radiotherapy, chemotherapy, and immunotherapy. HPV-positive tumors harbor fewer mutations, as well as different DNA methylation pattern and tumor microenvironment. Therefore, elucidation of the molecular mechanisms by which oral microbiota and HPV infection influence the HNC initiation and progression, screening for HPV infection and vaccination against HPV, adopting a good oral hygiene, and preventing oral dysbiosis are important tools for advancing in the battle with this public health global challenge.

Prognostic value of lactate dehydrogenase in patients with uveal melanoma treated with immune checkpoint inhibition

OBJECTIVE

We performed the meta-analysis to explore the predictive value of lactate dehydrogenase (LDH) levels in uveal melanoma (UM) patients receiving immune checkpoint inhibitors (ICIs).

METHODS

Eligible articles were obtained through EMBASE, PubMed, Google Scholar, and the Cochrane Library, until March 23, 2023. The clinical outcomes evaluated in this study encompassed overall survival (OS) and progression-free survival (PFS).

RESULTS

This meta-analysis comprised eight studies with a combined total of 383 patients. The results showed that patients with high LDH levels had noticeably worse OS (HR: 3.445, 95% CI: 2.504-4.740, p < 0.001) and PFS (HR: 1.720, 95% CI: 1.429-2.070, p < 0.001). Subgroup analysis confirmed that the upper limit of normal was the ideal cut-off value for LDH. In multivariate analysis, we also found that high LDH levels significantly predicted shorter OS (HR: 3.405, 95% CI: 1.827-6.348, p < 0.001) and PFS (HR: 2.519, 95% CI: 1.557-4.076, p < 0.001) in UM patients. The sensitivity analysis and publication bias test supported the reliability of our results.

CONCLUSIONS

In UM patients treated with ICIs, the LDH levels were reliable indicators of prognosis.

Characterization of the intestinal fungal microbiome in patients with hepatocellular carcinoma

OBJECTIVE

Gut mycobiota plays a crucial role in benign liver diseases; however, its correlation with hepatocellular carcinoma (HCC) remains elusive. This study aimed to elucidate fungal differences in patients with HCC-associated cirrhosis compared to cirrhotic patients without HCC and healthy controls.

METHODS

The 72 fecal samples from 34 HCC patients, 20 cirrhotic patients, and 18 healthy controls were collected and analyzed using ITS2 rDNA sequencing.

RESULTS

Our results revealed the presence of intestinal fungal dysbiosis with significant enrichment of opportunistic pathogenic fungi such as Malassezia, Malassezia sp., Candida, and C. albicans in HCC patients compared with healthy controls and cirrhosis patients. Alpha-diversity analysis demonstrated that patients with HCC and cirrhosis showed decreased fungal diversity compared to healthy controls. Beta diversity analysis indicated that the three groups exhibited significant segregated clustering. Besides, C. albicans was found to be significantly more abundant in the HCC patients with TNM stage III-IV than those with stage I-II, in contrast to the commensal organism S. cerevisiae. We also confirmed that the HCC patients were successfully classified with an area under the curve value of 0.906 based on the fecal fungal signature. Finally, our animal experiments confirm that aberrant colonization of the intestine by C. albicans and M. furfur can promote the development of HCC.

CONCLUSIONS

This study indicates that dysbiosis of the gut mycobiome might be involved in HCC development.

TRIAL REGISTRATION

ChiCTR, ChiCTR2100054537. Registered 19 December 2021, http://www.chictr.org.cn/edit.aspx?pid=144550&htm=4.

Alterations of gut mycobiota profiles in intrahepatic cholangiocarcinoma

Objective

Intrahepatic cholangiocarcinoma (ICC) is a silent liver malignancy with an increasing incidence. Gut mycobiota plays a crucial role in benign liver diseases; however, its correlation with ICC remains elusive. This study aimed to elucidate fungal differences in patients with ICC compared to healthy controls.

Methods

The 40 fecal samples from 23 ICC patients and 17 healthy controls were collected and analyzed using ITS2 rDNA sequencing. Obtaining the OTUs and combining effective grouping, we carried out the biodiversity and composition of the fungi, as well as FUNGuild functional annotation.

Results

Our results revealed the presence of intestinal fungal dysbiosis with significant enrichment of opportunistic pathogenic fungi such as Candida and C. albicans, and significant depletion of the beneficial fungus Saccharomyces cerevisiae in ICC patients compared with healthy controls. Alpha-diversity analysis demonstrated that patients with ICC showed decreased fungal diversity compared to healthy controls. Beta diversity analysis indicated that the two groups exhibited significant segregated clustering. Besides, C. albicans was found to be significantly more abundant in the ICC patients with TNM stage III-IV than those with stage I-II. The FUNGuild functional classification predicted that pathotrophs were the most abundant taxon in the ICC group, well above their abundance in healthy controls.

Conclusion

This study indicates that dysbiosis of the fecal mycobiome might be involved in ICC development. Further research into gut fungi may contribute to new therapeutic options for ICC patients.

The associated risk of Blastocystis infection in cancer: A case control study

Background

Blastocystis is an anaerobic intestinal protozoan. Nine Blastocystis subtypes (STs) were detected in humans. A subtype-dependent association between Blastocystis and different cancer types has been debated in many studies. Thus, this study aims to assess the possible association between Blastocystis infection and cancer, especially colorectal cancer (CRC). We also screened the presence of gut fungi and their association with Blastocystis.

Methods

We used a case-control design; cancer patients and cancer-free (CF) participants. The cancer group was further sub-group into CRC group and cancers outside the gastrointestinal tract (COGT) group. Macroscopic and microscopic examinations were performed to identify intestinal parasites in participants' stool samples. Molecular and phylogenetic analyses were conducted to identify and subtype Blastocystis. Furthermore, gut fungi were investigated molecularly.

Results

104 stool samples were collected and matched between CF (n=52) and cancer patients (n=52); CRC (n=15) and COGT (n=37). As anticipated, Blastocystis prevalence was significantly higher among CRC patients (60%, P=0.002) and insignificant in COGT patients (32.4%, P=0.161) compared to CF group (17.3%). The most common subtypes were ST2 among cancer group and ST3 in the CF group.

Conclusion

Cancer patients have a higher risk of Blastocystis infection compared to CF individuals (OR=2.98, P=0.022). Increased risk of Blastocystis infection was associated with CRC patients (OR=5.66, P=0.009). Nevertheless, further studies are required to understand the underlying mechanisms of Blastocystis and cancer association.