Colonization with ubiquitous protist Blastocystis ST1 ameliorates DSS-induced colitis and promotes beneficial microbiota and immune outcomes

Decoding Blastocystis-Driven Mechanisms in Gut Microbiota and Host Metabolism

Blastocystis, a prevalent eukaryotic microorganism in the gut microbiota, has emerged as a potential link between healthy diets and improved cardiometabolic health. Despite its genetic diversity and varied host interactions, Blastocystis is consistently associated with healthier dietary patterns and reduced risk of cardiometabolic diseases. Current evidence suggests that Blastocystis may influence host metabolism by modulating gut microbial composition, short-chain fatty acids (SCFAs) production, and immune cell differentiation. Moreover, its role in tryptophan metabolism provides intriguing insights into its potential impact on host signaling pathways. However, mechanistic evidence connecting Blastocystis to improved metabolic health remains limited. This perspective explores plausible pathways, including SCFAs-mediated signaling, tryptophan metabolism, and immune modulation, through which Blastocystis may exert its effects. A systematic research framework integrating axenic cultivation, in vitro co-culture systems, animal models, and multi-omics approaches is proposed to further elucidate these mechanisms and expand the understanding of Blastocystis in gut health and disease.

Edible plants as significant sources of Blastocystis spp. infections: A systematic review and meta-analysis

This systematic review and meta-analysis were conducted to comprehensively overview the global epidemiology and subtypes (STs) distribution of Blastocystis spp. in edible plants. A comprehensive search of various electronic databases (PubMed, Scopus, Google Scholar, and Web of Science) until May 19, 2024, found 27 studies/41 datasets meeting inclusion criteria, covering 8794 edible plants from 15 countries globally. Examined edible plants were composed of fruits (six datasets, 1198 samples), non-leafy green vegetables (10 datasets, 1158 samples), leafy green vegetables (18 datasets, 4245 samples), and uncategorized plants (seven datasets, 2193). This study revealed that 9.4 % (95 % CI: 6.6-13.4 %) of global edible plants harbored Blastocystis spp. Fruits had the highest Blastocystis spp. contamination rate among edible plants at 12.5 % (95 % CI: 5.4-26.6 %), followed by uncategorized plants at 10.2 % (95 % CI: 4.5-21.5 %), leafy green vegetables at 9.3 % (95 % CI: 6.1-13.9 %), and non-leafy green vegetables at 5.6 % (95 % CI: 2.5-12.1 %). Sensitivity analysis evaluated weighted prevalence changes after excluding specific studies. Subgroup analysis was conducted considering publication years, countries, continents, WHO regions, sample sizes, and diagnostic methods. Interestingly, zoonotic STs (ST1 and ST3) of Blastocystis spp. have been found in edible plants. These results highlight the potential risk of Blastocystis spp. transmission through consuming contaminated edible plants, emphasizing the importance of implementing adequate food safety measures to decrease the prevalence of this parasite in the food chain.

Detection and molecular characterization of Blastocystis sp., Enterocytozoon bieneusi and Giardia duodenalis in asymptomatic animals in southeastern Iran

Domestic animals can harbor a variety of enteric unicellular eukaryotic parasites (EUEP) with zoonotic potential that pose risks to human health. The aim of this study was to evaluate the occurrence and genetic diversity of EUEP of zoonotic relevance in domestic animals in Iran. Faecal samples were collected from cattle, sheep, camels, goats, donkeys, horse, and dogs. A real-time PCR was performed to detect the parasites, followed by sequence-based genotyping analyses on isolates that tested positive for Enterocytozoon bieneusi, Giardia duodenalis, and Blastocystis sp.. Overall, 53 out of 200 faecal samples (26.5%, 95% CI 20.5-33.2) were positive for one or more EUEP. Enterocytozoon bieneusi was found in 23.8%, 12.0%, 26.1%, and 13.3% of cattle, sheep, goats, and camels, respectively. Giardia duodenalis was identified in 19.3% of cattle and 6.7% of camels. Blastocystis sp. was detected in 5.7% of cattle and 16.7% of camels. Enterocytozoon bieneusi genotypes macaque1, J, BEB6, and CHG3 were identified in 3.7% (1/27), 3.7% (1/27), 44.4% (12/27), and 48.2% (13/27) of the isolates, respectively. Giardia duodenalis assemblage B and Blastocystis subtype 10 were identified in one cattle and one camel isolate, respectively. These findings suggest that domestic animals could serve as potential reservoirs for EUEP of zoonotic relevance and might play a significant role in transmitting these parasites to humans and other animals.

A pilot study of intestinal protist detection in humans, animals, and the environment in a slum area in Mymensingh, Bangladesh

The purpose of this study was to investigate the presence and transmission of Cryptosporidium spp., Blastocystis sp., Giardia intestinalis and Entamoeba histolytica between different hosts and their shared environment in a slum area of Bangladesh. A total of 102 samples were collected from Mymensingh, Bangladesh. This collection encompassed 16 human samples, 35 soil samples and 51 animal samples from various households within the region. The detection of Cryptosporidium spp., Blastocystis sp., G. intestinalis, and E. histolytica was carried out using nested PCR and/or quantitative PCR methodologies. Among the samples, 24 human, animal, and soil out of 102 were found positive for Blastocystis sp., spanning seven subtypes: ST2, ST3, ST7, ST10, ST23, ST24 and ST25. Additionally, eight samples (8/102) including human, animal and soil tested positive for Cryptosporidium spp., including C. parvum, C. baileyi, C. bovis, and C. meleagridis. Furthermore, one soil sample tested positive for G. intestinalis assemblage B, while no samples tested positive for E. histolytica. The detection of Cryptosporidium spp., Blastocystis sp., and G. intestinalis in this study has provided insights into their presence, extending beyond humans. Moreover, these findings highlight the importance of embracing a One Health perspective with an emphasis on specific parasitic microorganisms.

Blastocystis and Giardia duodenalis infection in a male prison in Spain

Background

General conditions in a prison may facilitate water- or food-borne infections.

Methods

Detection of intestinal parasites was achieved in 471 male prison inmates by standard microscopic procedures on their stool samples. Positive samples were processed by PCR amplification of a 600-bp fragment of the Blastocystis SSU rRNA gene and partial sequences of the Giardia duodenalis bg genes. Identification of subtypes/genotypes was based on Sanger sequencing methods.

Results

Blastocystis was found in 7.9 % (37/471) and G. duodenalis was found in 2.1 % (10/471). Out of the 37 Blastocystis positive samples, 54 % (20/37) were successfully subtyped, allowing the identification of the subtypes ST3 (50 %), ST1 (25 %), ST2 (15 %), ST4 (5 %) and ST6 (5 %). Out of 10 G. duodenalis positive samples, 50 % (5/10) were successfully genotyped, allowing the identification of genotypes A (80 %) and B (20 %).

Conclusions

The predominance of ST3 within the prison inmates, together with its low intra-ST genetic variability, reflected inter-human transmission with spatial stability. The G. duodenalis distribution is not wide enough to consider the possibility of a generalized transmission via contaminated water or food. Personal hygiene practices among male prison inmates may be an important measure to prevent the transmission.

Genetic diversity of single-celled microorganism Blastocystis sp. and its associated gut microbiome in free-ranging marine mammals from North-Western Mediterranean Sea

Blastocystis sp. is frequently identified in humans and several animal hosts exhibiting a wide genetic diversity. Within One Health perspective, data on Blastocystis sp. distribution and its circulating subtypes (STs) from the terrestrial environment are available, while those from the marine environment remain still scare. A genetic and 16S rRNA gene sequencing analysis were conducted over the period 2022-2024 by screening fecal samples from four different species of free-ranging marine mammals (sperm, fin, long-finned pilot and Cuvier's beaked whales) circulating within North-Western Mediterranean Sea. 10 out of 43 fecal samples (23.2 %) were found positive to Blastocystis sp. using molecular tools. A predominance of zoonotic subtype ST3 among different species of marine mammals as well as the presence of ST1 allele 4 subtype and even untypable subtype within the fin whale specimen was reported. Moreover, Firmicutes, Bacteroidetes and Proteobacteria within the different Blastocystis-carrier marine mammal species as well the identification of Archaebacteria from Methanomethylophilaceae family within the fin whale isolate were detected by Illumina V3-V4 generated data. The present survey presents new insights regarding Blastocystis sp. prevalence and its circulating zoonotic ST1-ST3 subtypes from the marine environment, as well as its associated gut microbiome, providing hence baseline data for a better understanding of the associated risk and to prevent human and marine ecosystem exposure to these anthropogenic microorganisms.

First Report on the Frequency and Subtype Distribution of Blastocystis sp. in Extensively Reared Holstein-Friesian Cattle from Terceira Island, Azores Archipelago, Portugal

This study is the first to report Blastocystis sp. in dairy cattle from Terceira Island, part of the Azores Archipelago. Blastocystis sp. is an enteric protozoan with high genetic diversity and is associated with both zoonotic and non-zoonotic subtypes (STs). The present survey aimed to fill the gap in knowledge regarding the occurrence and genetic characterization of Blastocystis sp. isolates in Holstein-Friesian cattle in this geographical area. A total of 116 stool samples were thus collected from dairy cows, and Blastocystis sp. DNA was detected using qPCR. The results revealed a 14.7% occurrence rate (17/116), with seven STs identified including ST3, ST5, ST7, ST10, ST14, ST25, and ST42, with variable frequency. Some of these STs (ST5, ST7, ST10, and ST14) are potentially zoonotic, underscoring their potential public health significance. However, the low frequency of Blastocystis sp. in this animal cohort possibly attributed to the extensive grazing system practiced on Terceira Island and the limited presence of zoonotic isolates, suggests a minimal risk of transmission from cattle to humans. This study highlights the importance of further research on the transmission dynamics of Blastocystis sp., particularly in regions with varying farming practices, to better understand its epidemiology and zoonotic potential.

Global Prevalence and Subtype Distribution of Blastocystis sp. in Rodent Populations: A Systematic Review and Meta-Analysis

BACKGROUND

The present systematic review and meta-analysis aimed to gather and analyse global data on the prevalence, subtypes (STs) distribution and zoonotic potential of Blastocystis sp. in rodents.

METHODS

A systematic literature search was performed across multiple databases (PubMed, Scopus, Web of Science and ProQuest) for studies published by 23 July 2024. The analysis included 34 studies/78 datasets, comprising 5661 samples from various rodent species across 15 countries. Statistical analyses were performed using comprehensive meta-analysis (CMA) software, employing a random-effects model to estimate pooled prevalence and 95% confidence intervals (CIs) and the I2 index for assessing heterogeneity.

RESULTS

This review found that 16% (95% CI: 12.6%-20.2%) of rodents worldwide were infected with Blastocystis sp. Voles and squirrels exhibited the highest infection rates at 29.8% (95% CI: 14.7%-51%) and 28.8% (95% CI: 14.4%-49.2%), whereas civets and porcupines had the lowest rates at 9.5% (95% CI: 6.6%-13.6%) and 7.1% (95% CI: 3.3%-14.7%), respectively. The findings indicated that rodents can host various Blastocystis sp. STs (ST1-ST8, ST10, ST13, ST15, ST17), with several (ST1-ST8 and ST10) having zoonotic potential. Globally, ST4, ST5, ST1 and ST3 were the most commonly reported STs in rodents. China and the UK showed the highest ST diversity in rodents, with 10 (ST1-ST7, ST10, ST13, ST17) and 7 (ST1-ST5, ST10, ST15) distinct STs, respectively. ST6, ST7 and ST13 were unique to China, whereas ST15 was found only in the United Kingdom. Squirrels, rats, mice and voles had the highest ST diversity of Blastocystis sp., with 8, 7, 5 and 5 distinct STs, respectively. Notably, ST6 and ST13 were unique to squirrels, ST7 only appeared in rats, and ST15 was found only in voles. Most ST1, ST3-ST5 and ST17 came from Asia. ST6, ST7 and ST13 were also isolated there, whereas ST15 was only found in Europe. ST17 was reported in Africa, ST4 and ST17 in North America, and ST1-ST3 and ST8 in South America.

CONCLUSIONS

This review emphasizes the widespread presence of Blastocystis sp. in rodent populations globally, underscoring the need for continued surveillance and research into its zoonotic potential.

Gut microbiome and NAFLD: impact and therapeutic potential

Non-Alcoholic Fatty Liver Disease (NAFLD) affects approximately 32.4% of the global population and poses a significant health concern. Emerging evidence underscores the pivotal role of the gut microbiota-including bacteria, viruses, fungi, and parasites-in the development and progression of NAFLD. Dysbiosis among gut bacteria alters key biological pathways that contribute to liver fat accumulation and inflammation. The gut virome, comprising bacteriophages and eukaryotic viruses, significantly shapes microbial community dynamics and impacts host metabolism through complex interactions. Similarly, gut fungi maintain a symbiotic relationship with bacteria; the relationship between gut fungi and bacteria is crucial for overall host health, with certain fungal species such as Candida in NAFLD patients showing detrimental associations with metabolic markers and liver function. Additionally, the "hygiene hypothesis" suggests that reduced exposure to gut parasites may affect immune regulation and metabolic processes, potentially influencing conditions like obesity and insulin resistance. This review synthesizes current knowledge on the intricate interactions within the gut microbiota and their associations with NAFLD. We highlight the therapeutic potential of targeting these microbial communities through interventions such as probiotics, prebiotics, and fecal microbiota transplantation. Addressing the complexities of NAFLD requires comprehensive strategies that consider the multifaceted roles of gut microorganisms in disease pathology.

Gut microbiome profile to the level species in diarrheic protozoan-carrier patients in Italy

The human gastrointestinal microbiota contains a diverse consortium of microbes, including bacteria, protozoa, viruses, and fungi that are involved in many physiological and metabolic as well pathogenetic processes. However, microbiological research is dominated by studies describing the impact of prokaryotic bacteria on gut microbiome with a limited understanding of their relationship with other integral microbiota constituents as protozoa. Here, we investigated the gut microbiome composition using Oxford Nanopore Technology approach in relation to protozoan colonization of Giardia duodenalis, Cryptosporidium parvum, Blastocystis sp. and Dientamoeba fragilis in patients with diarrheal diseases in Italy, taking into consideration different risk factors as protozoan coinfection, Blastocystis-subtypes, gender, age classes, origin, eosinophilia level and positivity to SARS-CoV-2 infection. Overall, out of 1413 investigated patients, 123 (8.7 %) have found positive to one or more protozoan microorganisms with a prevalence statistically significant in individuals from Northern Africa (p < 0.0001) and in the age classes 40-59 years-old (p < 0.0022). Within the 57 individuals eligible for gut microbiome analysis, diverse profiles are observed but interestingly, a predominance of the emergent Escherichia fergusonii ATCC 35469, was found across the different risk factors. Our results emphasize the importance of studies to investigate these aspects of protozoa colonization that will undoubtedly increase our understanding of complex interactions between intestinal protozoa, other microbiota organisms, and the human host.

An Update on Blastocystis: Possible Mechanisms of Blastocystis-Mediated Colorectal Cancer

Blastocystis is an anaerobic parasite that colonizes the intestinal tract of humans and animals. When it was first discovered, Blastocystis was considered to be a normal flora with beneficial effects on human health, such as maintaining gut hemostasis and improving intestinal barrier integrity. Later, with increasing research on Blastocystis, reports showed that Blastocystis sp. is associated with gastrointestinal disorders, colorectal cancer (CRC), and neurological disorders. The association between Blastocystis sp. and CRC has been confirmed in several countries. Blastocystis sp. can mediate CRC via similar mechanisms to CRC-associated bacteria, including infection-mediated inflammation, increased oxidative stress, induced gut dysbiosis, and damage to intestinal integrity, leading to a leaky gut. IL-8 is the main inflammatory cytokine released from epithelial cells and can promote CRC development. The causal association of Blastocystis sp. with other diseases needs further investigation. In this review, we have provided an update on Blastocystis sp. and summarized the debate about the beneficial and harmful effects of this parasite. We have also highlighted the possible mechanisms of Blastocystis-mediated CRC.

Intestinal microbiota analysis of different Blastocystis subtypes and Blastocystis-negative individuals in Taiwan

BACKGROUND

Intestinal parasitic infections are the most common infectious diseases among Southeast Asian migrant workers in Taiwan, especially for infections with Blastocystis hominis. However, little is known about the impact of Blastocystis subtypes (STs) on the gut microbiota.

METHODS

We retrospectively evaluated the prevalence of intestinal parasites in a teaching hospital in Northern Taiwan in the period of 2015-2019. Blastocystis-positive stool specimens were collected for ST analysis by polymerase chain reaction in 2020. Intestinal microbiota analyses of different Blastocystis STs and Blastocystis-free individuals were conducted by 16S rRNA sequencing.

RESULTS

A total of 13,859 subjects were analyzed, of which 1802 cases (13%) were diagnosed with intestinal parasitic infections. B. hominis infections were the most prevalent (n = 1546, 85.7%). ST analysis of Blastocystis-positive samples (n = 150) indicated that ST1 was the most common type, followed by ST3, ST4, ST2, ST7, and ST5. Different Blastocystis STs (ST1, ST3, and ST4) were associated with distinct richness and diversity of the microbiota. Taxonomic profiles revealed that Akkermansia muciniphila was significantly enriched for all analyzed Blastocystis STs, whereas Holdemanella biformis was more abundant in the Blastocystis-free group. Additionally, Succinivibrio dextrinosolvens and Coprococcus eutactus were specifically more abundant in ST3 carriers than in non-infected individuals.

CONCLUSION

This study demonstrates that A. muciniphila is positively associated with all Blastocystis STs, while H. biformis was negatively associated with them. Several bacteria were enriched in specific STs, highlighting the need for further microbiota analysis at the ST level to elucidate the pathogenicity of Blastocystis.

Unveiling Blastocystis epidemiology in Morocco: subtype diversity among clinical patients with and without gastrointestinal manifestations in the Meknes region

Blastocystis is an intestinal protist frequently identified in humans and other animals, though its clinical significance remains controversial. This study aimed to determine the prevalence and genetic diversity of Blastocystis in faecal samples from symptomatic (n = 55) and asymptomatic (n = 50) individuals seeking medical care in Meknes, Morocco. Detection of the protist was accomplished through coproparasitological examination and culture in Jones medium. Culture-positive samples were subjected to molecular analyses (PCR and Sanger sequencing) based on sequences of the small subunit ribosomal RNA gene. Epidemiological questionnaires on demographics and potential risk factors were collected from participating patients. The overall Blastocystis infection rate was 51.4% (54/105), with no differences between symptomatic (52.7%, 29/55) and asymptomatic (50.0%, 25/50) individuals. Sequence analyses identified three Blastocystis subtypes, with ST3 being the most prevalent (42.0%), followed by ST1 (34.0%), and ST2 (12.0%). Regarding intra-subtype diversity, allele 4 was found within ST1; alleles 11/12 and alleles 34/36 (alone or in combination) were identified within ST2 and ST3 respectively. Allele 34 in ST3 (40.8%) and allele 4 in ST1 (34.7%) were the most common genetic variants circulating in the surveyed clinical population. A statistically significant association between ST2 and the presence of flatulence was observed. This is the first study assessing the epidemiology and genetic diversity of Blastocystis sp. in the Meknes region, Morocco.

Large-Scale Molecular Epidemiological Survey of Blastocystis sp. among Herbivores in Egypt and Assessment of Potential Zoonotic Risk

Given the proven zoonotic potential of the intestinal protozoan Blastocystis sp., a fast-growing number of surveys are being conducted to identify potential animal reservoirs for transmission of the parasite. Nevertheless, few epidemiological studies have been conducted on farmed animals in Egypt. Therefore, a total of 1089 fecal samples were collected from herbivores (sheep, goats, camels, horses, and rabbits) in six Egyptian governorates (Dakahlia, Gharbia, Kafr El Sheikh, Giza, Aswan, and Sharqia). Samples were screened for the presence of Blastocystis sp. by real-time PCR followed by sequencing of positive PCR products and phylogenetic analysis for subtyping of the isolates. Overall, Blastocystis sp. was identified in 37.6% of the samples, with significant differences in frequency between animal groups (sheep, 65.5%; camels, 62.2%; goats, 36.0%; rabbits, 10.1%; horses, 3.3%). Mixed infections were reported in 35.7% of the Blastocystis sp.-positive samples. A wide range of subtypes (STs) with varying frequency were identified from single infections in ruminants including sheep (ST1-ST3, ST5, ST10, ST14, ST21, ST24, ST26, and ST40), goats (ST1, ST3, ST5, ST10, ST26, ST40, ST43, and ST44), and camels (ST3, ST10, ST21, ST24-ST26, ST30, and ST44). Most of them overlapped across these animal groups, highlighting their adaptation to ruminant hosts. In other herbivores, only three and two STs were evidenced in rabbits (ST1-ST3) and horses (ST3 and ST44), respectively. The greater occurrence and wider genetic diversity of parasite isolates among ruminants, in contrast to other herbivores, strongly suggested that dietary habits likely played a significant role in influencing both the colonization rates of Blastocystis sp. and ST preference. Of all the isolates subtyped herein, 66.3% were reported as potentially zoonotic, emphasizing the significant role these animal groups may play in transmitting the parasite to humans. These findings also expand our knowledge on the prevalence, genetic diversity, host specificity, and zoonotic potential of Blastocystis sp. in herbivores.

Molecular Identification and Subtype Analysis of Blastocystis sp. Isolates from Wild Mussels (Mytilus edulis) in Northern France

Blastocystis sp. is the most common single-celled eukaryote colonizing the human gastrointestinal tract worldwide. Because of the proven zoonotic potential of this protozoan, sustained research is therefore focused on identifying various reservoirs of transmission to humans, and in particular animal sources. Numerous groups of animals are considered to be such reservoirs due to their handling or consumption. However, some of them, including mollusks, remain underexplored. Therefore, a molecular epidemiological survey conducted in wild mussels was carried out in Northern France (Hauts-de-France region) to evaluate the frequency and subtypes (STs) distribution of Blastocystis sp. in these bivalve mollusks. For this purpose, 100 mussels (Mytilus edulis) were randomly collected in two sampling sites (Wimereux and Dannes) located in the vicinity of Boulogne-sur-Mer. The gills and gastrointestinal tract of each mussel were screened for the presence of Blastocystis sp. by real-time polymerase chain reaction (qPCR) assay followed by direct sequencing of positive PCR products and subtyping through phylogenetic analysis. In parallel, sequences of potential representative Blastocystis sp. isolates that were previously obtained from temporal surveys of seawater samples at marine stations offshore of Wimereux were integrated in the present analysis. By taking into account the qPCR results from all mussels, the overall prevalence of the parasite was shown to reach 62.0%. In total, more than 55% of the positive samples presented mixed infections. In the remaining mussel samples with a single sequence, various STs including ST3, ST7, ST14, ST23, ST26 and ST44 were reported with varying frequencies. Such distribution of STs coupled with the absence of a predominant ST specific to these bivalves strongly suggested that mussels might not be natural hosts of Blastocystis sp. and might rather be carriers of parasite isolates from both human and animal (bovid and birds) waste. These data from mussels together with the molecular identification of isolates from marine stations were subsequently discussed along with the local geographical context in order to clarify the circulation of this protozoan in this area. The identification of human and animal STs of Blastocystis sp. in mussels emphasized the active circulation of this protozoan in mollusks and suggested a significant environmental contamination of fecal origin. This study has provided new insights into the host/carrier range and transmission of Blastocystis sp. and emphasized its potential as an effective sentinel species for water quality and environmental contamination.

Oat-based postbiotics ameliorate high-sucrose induced liver injury and colitis susceptibility by modulating fatty acids metabolism and gut microbiota

High-sucrose (HS) consumption leads to metabolic disorders and increases susceptibility to colitis. Postbiotics hold great potentials in combating metabolic diseases and offer advantages in safety and processability, compared with living probiotics. We developed innovative oat-based postbiotics and extensively explored how they could benefit in rats with long-term high-sucrose consumption. The postbiotics fermented with Lactiplantibacillus plantarum (OF-1) and OF-5, the one fermented with the optimal selection of five probiotics (i.e., L. plantarum, Limosilactobacillus reuteri, Lacticaseibacillus rhamnosus, Lactobacillus acidophilus, and Bifidobacterium lactis) alleviated HS induced liver injury, impaired fatty acid metabolism and inflammation through activating AMPK/SREBP-1c pathways. Moreover, oat-based postbiotics restored detrimental effects of HS on fatty acid profiles in liver, as evidenced by the increases in polyunsaturated fatty acids and decreases in saturated fatty acids, with OF-5 showing most pronounced effects. Furthermore, oat-based postbiotics prevented HS exacerbated susceptibility to dextran sodium sulfate caused colitis and reconstructed epithelial tight junction proteins in colons. Oat-based postbiotics, in particular OF-5 notably remodeled gut microbiota composition, e.g., enriching the relative abundances of Akkermansia, Bifidobacterium, Alloprevotella and Prevotella, which may play an important role in the liver-colon axis responsible for improvements of liver functions and reduction of colitis susceptibility. The heat-inactivated probiotics protected against HS-induced liver and colon damage, but such effects were less pronounced compared with oat-based postbiotics. Our findings emphasize the great value of oat-based postbiotics as nutritional therapeutics to combat unhealthy diet induced metabolic dysfunctions.

Blastocystis: A Mysterious Member of the Gut Microbiome

Blastocystis is the most common gastrointestinal protist found in humans and animals. Although the clinical significance of Blastocystis remains unclear, the organism is increasingly being viewed as a commensal member of the gut microbiome. However, its impact on the microbiome is still being debated. It is unclear whether Blastocystis promotes a healthy gut and microbiome directly or whether it is more likely to colonize and persist in a healthy gut environment. In healthy people, Blastocystis is frequently associated with increased bacterial diversity and significant differences in the gut microbiome. Based on current knowledge, it is not possible to determine whether differences in the gut microbiome are the cause or result of Blastocystis colonization. Although it is possible that some aspects of this eukaryote's role in the intestinal microbiome remain unknown and that its effects vary, possibly due to subtype and intra-subtype variations and immune modulation, more research is needed to characterize these mechanisms in greater detail. This review covers recent findings on the effects of Blastocystis in the gut microbiome and immune modulation, its impact on the microbiome in autoimmune diseases, whether Blastocystis has a role like bacteria in the gut-brain axis, and its relationship with probiotics.

Molecular Prevalence and Subtypes Distribution of Blastocystis spp. in Humans of Latin America: A Systematic Review

Blastocystis spp. are among the few enteric parasites with a prevalence that can reach up to approximately 80% in communities of developing countries. This systematic review updates and summarizes available literature on the molecular prevalence and subtype distribution of Blastocystis spp. in Latin American people. This work follows the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The literature revised covers from 1 January 2015 to 6 October 2023 in seven different scientific databases, and the material was selected through inclusion and exclusion criteria. According to data found in the 36 selected articles, the prevalence of Blastocystis spp. in Latin America ranged between 5.8% (Bolivian rural communities) and 94.0% (Colombian general public). Generally, genomic DNA was extracted from approximately 200 mg fecal sediments using commercial kits, such as the QIAamp Stool Mini Kit (QIAGEN, Hilden, Germany) or the Norgen Stool DNA Isolation Kit (Norgen Biotek Corporation, Thorold, ON, Canada). Subtype-specific primers (such as the couple of primers BhRDr-RD5) developed from unique sequences of the SSU rRNA gene were applied to Blastocystis subtyping. Ten specific subtypes (STs) were found as well as various mixed infections, and the most circulating Blastocystis STs were in the order ST3, ST1, ST2, and ST4. The most recent data about Blastocystis spp. molecular epidemiology and the STs in communities of Latin America are limited to studies from specific countries. Novel scientific data from the other countries are required to obtain a complete picture and truly understand the distribution and prevalence of Blastocystis spp. and the STs.

Prevalence of Blastocystis and Dientamoeba fragilis in diarrheal patients in Corum, Türkiye

To investigate the prevalence of Blastocystis and Dientamoeba fragilis in diarrhea patients and healthy individuals in Corum, Türkiye, fecal samples from 92 diarrhea patients and 50 healthy individuals were collected and evaluated using direct microscopy and molecular methods to screen for bacteria, protozoa, and viruses. The prevalence of Blastocystis was 24.6% in total and more frequent in the healthy group (30.0%). The commonly detected STs (subtypes) were ST3 (40.0%) and ST2 (34.2%). The distribution of Blastocystis STs in the healthy and diarrheal groups did not show any difference in sex and age, but ST3 was detected more frequently in patients aged from 40 to 59 years (p < 0.05). Alleles 4 (8/12) and 2 (4/12) were present in ST1; 9 (3/5) and 12 (2/5) in ST2; 34 (9/14), 36 (3/14), and 38 (2/14) in ST3; and only allele 42 (2/2) in ST4. D. fragilis was present in 8.4% of the population. However, there was no statistically significant difference between the healthy and diarrheic groups (12.0% and 6.5%, respectively), neither with respect to age nor sex. Co-infection was 58.3% and was more frequent in healthy individuals (33.3%) than in diarrhea patients (25.0%). Blastocystis ST3 was the most common subtype detected, with D. fragilis at 33.3%. Salmonella, Shigella, or helminth eggs were not observed in all groups, but Entamoeba histolytica, Giardia intestinalis, Cryptosporidium, Rotavirus, Adenovirus, and Clostridium difficile toxin were found only in diarrhea patients. These findings support the hypothesis that Blastocystis and D. fragilis may be part of the healthy human gut microbiome.

Effect of minocycline, methyl prednisolone, or combination treatment on the colonic bacterial population in a state of colonic inflammation using the murine dextran sulfate sodium model

BACKGROUND

Several reports demonstrated anti-inflammatory properties of minocycline in various inflammatory disorders including colitis. We have experimental evidence suggesting synergistic anti-inflammatory effect of minocycline with methyl prednisolone in reducing colitis severity in mice, but if this effect is in part related to modulating the composition of colonic microbiota is still unknown.

METHODS

the effect of vehicle (V), minocycline (M), methyl prednisolone (MP), or combination (C) regimen on the composition of the microbiota of mice in a state of colon inflammation compared to untreated (UT) healthy mice was determined using 16s metagenomic sequencing, and the taxonomic and functional profiles were summarized.

RESULTS

Overall, the bacterial flora from the phylum Firmicutes followed by Bacteroidota were found to be predominant in all the samples. However, the composition of Firmicutes was decreased relatively in all the treatment groups compared to UT group. A relatively higher percentage of Actinobacteriota was observed in the samples from the C group. At the genus level, Muribaculaceae, Bacteroides, Bifidobacterium, and Lactobacillus were found to be predominant in the samples treated with both drugs (C). Whereas "Lachnospiraceae NK4A136 group" and Helicobacter in the M group, and Helicobacter in the MP group were found to be predominant. But, in the UT group, Weissella and Staphylococcus were found to be predominant. Eubacterium siraeum group, Clostridia vadinBB60 group, Erysipelatoclostridium and Anaeroplasma genera were identified to have a significant (FDR p < 0.05) differential abundance in V compared to C and UT groups. While at the species level, the abundance of Helicobacter mastomyrinus, Massiliomicrobiota timonensis and uncultured Anaeroplasma were identified as significantly low in UT, C, and M compared to V group. Functional categories related to amino acid, carbohydrate, and energy metabolism, cell motility and cell cycle control were dominated overall across all the samples. Methane metabolism was identified as an enriched pathway. For the C group, "Colitis (decrease)" was among the significant (p = 1.81E-6) associations based on the host-intrinsic taxon set.

CONCLUSION

Combination regimen of minocycline plus methyl prednisolone produces a synergistic anti-inflammatory effect which is part related to alternation in the colonic microbiota composition.

A tryptophan metabolite made by a gut microbiome eukaryote induces pro-inflammatory T cells

The large intestine harbors microorganisms playing unique roles in host physiology. The beneficial or detrimental outcome of host-microbiome coexistence depends largely on the balance between regulators and responder intestinal CD4+ T cells. We found that ulcerative colitis-like changes in the large intestine after infection with the protist Blastocystis ST7 in a mouse model are associated with reduction of anti-inflammatory Treg cells and simultaneous expansion of pro-inflammatory Th17 responders. These alterations in CD4+ T cells depended on the tryptophan metabolite indole-3-acetaldehyde (I3AA) produced by this single-cell eukaryote. I3AA reduced the Treg subset in vivo and iTreg development in vitro by modifying their sensing of TGFβ, concomitantly affecting recognition of self-flora antigens by conventional CD4+ T cells. Parasite-derived I3AA also induces over-exuberant TCR signaling, manifested by increased CD69 expression and downregulation of co-inhibitor PD-1. We have thus identified a new mechanism dictating CD4+ fate decisions. The findings thus shine a new light on the ability of the protist microbiome and tryptophan metabolites, derived from them or other sources, to modulate the adaptive immune compartment, particularly in the context of gut inflammatory disorders.