The important role of fungi in inflammatory bowel diseases

A comprehensive guide to assess gut mycobiome and its role in pathogenesis and treatment of inflammatory bowel disease

Inflammatory bowel disease (IBD) is an immune mediated chronic inflammatory disorder of gastrointestinal tract, which has underlying multifactorial pathogenic determinants such as environmental factors, susceptibility genes, gut microbial dysbiosis and a dysregulated immune response. Human gut is a frequent inhabitant of complex microbial ecosystem encompassing bacteria, viruses, parasites, fungi and other microorganisms that have an undisputable role in maintaining balanced homeostasis. All of these microbes interact with immune system and affect human gut physiology either directly or indirectly with interaction of each other. Intestinal fungi represent a smaller but crucial component of the human gut microbiome. Besides interaction with bacteriome and virome, it helps in balancing homoeostasis between pathophysiological and physiological processes, which is often dysregulated in patients with IBD. Understanding of gut mycobiome and its clinical implications are still in in its infancy as opposed to bacterial component of gut microbiome, which is more often focused. Modulation of gut mycobiome represents a novel and promising strategy in the management of patients with IBD. Emerging mycobiome-based therapies such as diet interventions, fecal microbiota transplantation (FMT), probiotics (both fungal and bacterial strains) and antifungals exhibit substantial effects in calibrating the gut mycobiome and restoring dysbalanced immune homeostasis by restoring the core gut mycobiome. In this review, we summarized compositional and functional diversity of the gut mycobiome in healthy individuals and patients with IBD, gut mycobiome dysbiosis in patients with IBD, host immune-fungal interactions and therapeutic role of modulation of intestinal fungi in patients with IBD.

The role of fungi in the diagnosis of colorectal cancer

Colorectal cancer (CRC) is a prevalent tumour with high morbidity rates worldwide, and its incidence among younger populations is rising. Early diagnosis of CRC can help control the associated mortality. Fungi are common microorganisms in nature. Recent studies have shown that fungi may have a similar association with tumours as bacteria do. As an increasing number of tumour-associated fungi are discovered, this provides new ideas for the diagnosis and prognosis of tumours. The relationship between fungi and colorectal tumours has also been recently identified by scientists. Therefore, this paper describes the limitations and prospects of the application of fungi in diagnosing CRC and predicting CRC prognosis.

Malassezia in Inflammatory Bowel Disease: Accomplice of Evoking Tumorigenesis

Accumulating evidence indicates that patients with inflammatory bowel disease (IBD) have a significantly higher risk of developing different cancers, while the exact mechanism involved is not yet fully understood. Malassezia is a lipid-dependent opportunistic yeast, which colonizes on mammalian skin and internal organs. Also, dysbiosis in fungal communities accompanied by high level of Malassezia are fairly common in inflammatory diseases such as IBD and various cancers. In cancer patients, higher levels of Malassezia are associated with worse prognosis. Once it is ablated in tumor-bearing mice, their prognostic conditions will be improved. Moreover, Malassezia manifests multiple proinflammatory biological properties, such as destruction of epithelial barrier, enrichment of inflammatory factors, and degradation of extracellular matrix (ECM), all of which have been reported to contribute to tumor initiation and malignant progression. Based on these facts, we hypothesize that high levels of Malassezia together with mycobiome dysbiosis in patients with IBD, would aggravate the microecological imbalance, worsen the inflammatory response, and further promote tumorigenesis and deterioration. Herein, we will discuss the detrimental properties of Malassezia and explore the key role of this fungus in the correlation between IBD and cancer, in order to take early surveillance and intervention to minimize the cancer risk in individuals with IBD.