Alistipes spp.

Alistipes is a genus of gram-negative, anaerobic bacteria from the gut microbiome, notable for its roles in health and disease. 

Producing butyrate, acetate, and propionate, Alistipes exhibits both pro- and anti-inflammatory effects. Alistipes can also produce sulfonolipids, which have anti-inflammatory properties. 

These bacteria are bile-resistant, allowing them to thrive in the distal ileum, and are involved in the metabolism of plant polysaccharides. 

Despite its normal presence in the microbiome, Alistipes is linked to conditions like colorectal cancer, liver diseases, cardiovascular issues, and mental health disorders.

What is Alistipes spp.?

Alistipes is a gram negative, anaerobic genus of bacteria isolated from clinical samples, primarily from the gut microbiome. This genus, belonging to the Bacteroidetes phylum, includes 13 known species.  [8.] 

It is a butyrate-producing species with both pro- and anti-inflammatory effects.  [6.]   It also produces acetate and propionate.  [8.]

Most members of the Alistipes spp. are bile-resistant, making them tolerant to colonizing areas of the distal ileum where most bile reabsorption happens.  [2., 8.] This may have clinical relevance regarding relative abundance or absence of Alistipes spp. in certain conditions involving bile resorption.  [8.] 

Alistipes is associated with the metabolism of plant cell wall polysaccharides and resistant starch, compounds found in fruits and vegetables.  [15.]   

Alistipes species, excluding A. inops, produce sulfonolipids—a unique class of sphingolipids that are associated with anti-inflammatory benefits.  [14.] 

‍Alistipes spp. was discovered in 2003 after being isolated from samples from children with appendicitis.  [10.] It’s recognized as a normal part of the human microbiome, although it can also be associated with various health conditions, showing both protective and pathogenic roles.  [12.]

Clinical Isolation and Identification

Alistipes species, such as A. finegoldii, A. putredinis, and A. onderdonkii, have been isolated from patients with appendicitis, abscesses, and other conditions.  [8.] 

However, their clinical identification is often underrepresented due to limitations in current mass spectrometry (MS-TOF) methods.  [P8.] 

Alistipes spp. Pathogenic and Protective Roles in Human Health  [8.] 

Alistipes shows contrasting roles in health:

Protective Effects 

Alistipes spp. demonstrates protective roles against liver fibrosis, colitis, cancer immunotherapy, and cardiovascular disease.

Pathogenic Effects

Alistipes spp. has been linked to colorectal cancer and mental health issues like depression.

Alistipes spp. Association with Health and Diseases

Liver Health and Diseases 

Reduced Alistipes abundance is associated with liver cirrhosis, non-alcoholic steatohepatitis (NASH), and non-alcoholic fatty liver disease (NAFLD).  [8.] 

As liver cirrhosis progresses from compensated to decompensated stages, a notable decrease in Alistipes indistinctus is observed.  [8.] 

Similarly, NASH patients exhibit a substantial reduction in Alistipes finegoldii compared to healthy controls, with a fold-change of -1.829. [8.] 

In NAFLD patients with significant fibrosis, Alistipes onderdonkii is markedly reduced, showing a fold change of -2.566.  [8.]  Other studies have demonstrated decreases in Alistipes with increasing liver damage from NAFLD.  [15.] 

This trend extends to pediatric cases, where obese children with NAFLD display significantly diminished abundance of Bacteroidetes, particularly Alistipes. [15.] 

Alistipes is associated with the metabolism of plant cell wall polysaccharides and resistant starch, two compounds found in fruits and vegetables, and lower levels are seen in obesity.  [15.] This may provide a correlation between Alistipes and obesity.

Cardiovascular Health and Diseases  [8.] 

The relationship between Alistipes and cardiovascular health and disease is complex and multifaceted, as evidenced by recent scientific studies. 

While some research suggests a protective role for Alistipes in cardiovascular diseases (CVDs), other findings indicate potential pathogenic associations. 

For instance, a significant decrease in Alistipes species has been observed in the intestinal tracts of patients with atrial fibrillation, the most common form of arrhythmia.  This reduction may be linked to an increase in other bacteria like Streptococcus, suggesting a possible antagonistic effect. 

Conversely, studies have shown an increase in certain Alistipes species, particularly A. finegoldii and A. indistinctus, positively correlating with systolic blood pressure in hypertensive patients, which may also indicate gut inflammation and dysbiosis in this pathogenesis.  [4.] 

These species are known to trigger intestinal inflammation and may contribute to gut barrier dysfunction, potentially driving inflammation associated with hypertension. 

The pro-inflammatory nature of Alistipes is attributed to its lipopolysaccharide (LPS) content, which could lead to a hypotensive phenotype of inflammation.  

Additionally, Alistipes shahii has been mentioned in the context of atherosclerotic cardiovascular disease, though its specific role requires further investigation.  

One article highlights that an animal-based diet increases the abundance of bile-tolerant microorganisms, including Alistipes, and links that to cardiovascular disease and atherosclerosis. [13.] 

This shift in microbiota composition with a high-fat, animal-based diet is associated with decreased levels of beneficial bacteria that metabolize dietary plant polysaccharides, such as Roseburia and Eubacterium rectale, resulting in reduced fecal acetate and butyrate concentrations. 

These changes in gut microbiota composition can influence cardiovascular health by affecting metabolic processes and inflammation, thus contributing to the development of atherosclerosis.

Obesity

Alistipes obesi, a species closely related to Alistipes onderdonkii, was specifically isolated from the fecal microbiota of a French patient suffering from obesity, indicating a potential link between this bacterium and obesity.  [8.] 

However, higher levels of Alistipes have also been correlated with long-term weight loss, which indicates that Alistipes may play a beneficial role in long-term metabolism and would exert positive effects on overall cardiometabolic health.  [5.] 

Gut Health and Inflammation 

As with cardiovascular disease, Alistipes and gut inflammation also demonstrate a complex and somewhat contradictory relationship.  

While Alistipes species, particularly A. finegoldii, are known to trigger intestinal inflammation, contrasting results about their contribution to disease have also been reported.  [8.] 

As Gram-negative bacteria, Alistipes contain lipopolysaccharide (LPS) in their cell membranes, which can stimulate the innate immune system via TLR-4 activation, potentially leading to inflammation. [1.] 

However, some studies suggest Alistipes may have protective effects against certain inflammatory conditions, including liver fibrosis and colitis.  [8.] 

In conditions like non-alcoholic steatohepatitis and hepatic encephalopathy, gut dysbiosis seems to influence the compositional abundance of Alistipes in the feces. [8.] 

Potential mechanisms of Alistipes' influence on inflammation include its indole-positive nature, which may affect tryptophan availability and potentially disrupt the serotonergic system balance.  [3., 7.] 

Additionally, the LPS from Alistipes is believed to be pro-inflammatory, potentially leading to an increase in Th17 cells and a decrease in anti-inflammatory butyrate-producing bacteria. [1.] 

Alistipes produce sulfonolipids, which show potential anti-inflammatory effects and might influence immune responses and gut health. [14.] 

Cancer  [8.] 

Several human metagenomic studies have revealed an association between Alistipes and colorectal cancer.

Some studies indicate that Alistipes may play a pathogenic role in colorectal cancer through inflammatory pathways.  Conversely, they may aid cancer immunotherapy by modulating tumor environments.

Mental Health

Increased Alistipes levels are linked to stress, chronic fatigue syndrome, and depression [7.]  

Studies have shown increases in Alistipes spp. in stressed mice, as well as in humans with chronic fatigue syndrome.  [8.] 

Elevated levels of Alistipes spp. have also been correlated with depression. [3., 7.]  This may be due to the fact that they use tryptophan to produce indole, decreasing the supply of tryptophan available for serotonin production.  By decreasing the level of serotonin available, Alistipes spp. may participate in the pathogenesis of depression.  [3.] 

Additionally, Alistipes expresses glutamate decarboxylase, which converts glutamate into gamma-aminobutyric acid (GABA), a neurotransmitter.  [9.]  The production of GABA by Alistipes could influence host behavior and mood, possibly contributing to conditions such as depression.  [9.] 

Laboratory Testing for Alistipes spp. Levels

Test Type, Sample Collection and Preparation

Alistipes spp. levels are assessed in stool samples.  Stool samples may be collected from the comfort of home.  

Testing may require avoidance of certain medications and/or supplements including probiotics prior to sample collection.  It is important to consult with the ordering provider for full test preparation instructions. 

Interpretation of Test Results

Optimal Levels of Alistipes spp.

Optimal levels are generally determined by assessing the balance of healthy vs. unhealthy microbiota.  It is important to consult with the laboratory company used for test interpretation. 

One company reports Alistipes levels on a reference range from -3 to +3.  -3 may mean decreased levels of Alistipes spp., while +3 may mean that the individual is tending towards an overgrowth of Alistipes spp.  [11.] 

Overall, a moderate amount of Alistipes spp. as part of a healthy microbiome is likely ideal for health.  

Clinical Implications of High Alistipes Levels

The significance of high Alistipes levels is complex.

Some studies suggest that Alistipes may have protective effects against certain conditions, including colitis, liver fibrosis, and cardiovascular disease.  [8.] 

Additionally, Alistipes produces short-chain fatty acids (SCFAs) like butyrate, acetate and propionate, which have healthy anti-inflammatory properties.  [6., 8., 14.] 

However, possible detrimental effects have also been associated with elevated Alistipes levels:

Elevated levels of Alistipes have been linked to colorectal cancer (CRC).  [8.] 

Increased abundance of Alistipes finegoldii and A. indistinctus has been positively correlated with systolic blood pressure in patients with hypertension, suggesting a potential role in gut barrier dysfunction and inflammation.  [4.] 

Alistipes has also been implicated in various conditions including depression, stress, and chronic fatigue.  [3., 7., 8.] 

Additionally, while some research suggests a protective role in cardiovascular diseases, other studies have found a decrease in Alistipes species in patients with atrial fibrillation.  [8.] 

Ultimately, it's important to note that the evidence for Alistipes' role in various conditions is often contradictory, with some associations being protective and others potentially pathogenic.  Therefore, a moderate amount of Alistipes in the setting of appropriate microbiological diversity is likely optimal.  

Clinical Significance of Low Alistipes Levels

Low levels of Alistipes spp. have positive and negative connotations for health; results should be correlated with an individual’s health history and current symptoms.  

Low levels of Alistipes have been correlated with: 

Liver Health and Diseases [8., 15.]

Reduced levels of Alistipes spp. are associated with liver cirrhosis, non-alcoholic steatohepatitis (NASH), and non-alcoholic fatty liver disease (NAFLD). As liver cirrhosis progresses, there is a notable decrease in A. indistinctus. 

In NASH patients, a significant reduction in A. finegoldii is observed, while in NAFLD patients with significant fibrosis, A. onderdonkii levels markedly decrease.

Cardiovascular Health and Diseases [8., 13.] 

Patients with atrial fibrillation show a significant decrease in Alistipes species, which might be linked to an increase in other bacteria like Streptococcus.

Increased levels of A. finegoldii and A. indistinctus correlate with higher systolic blood pressure, suggesting that lower levels may be protective against hypertension.

Gut Health and Inflammation [8.] 

Lower levels of Alistipes, particularly A. finegoldii, may contribute to the severity of conditions like colitis. Alistipes spp. are known to produce sulfonolipids with anti-inflammatory properties, potentially beneficial for gut health.

Cancer (CRC) [8.] 

Reduced levels of Alistipes are linked to a decreased risk of colorectal cancer. Alistipes spp. can play a role in modulating the tumor microenvironment, aiding in cancer immunotherapy.

Depression and Chronic Fatigue [8.]

Low levels of Alistipes spp. are associated with better mental health outcomes. Higher levels are linked to stress, chronic fatigue syndrome, and depression due to their potential to decrease serotonin availability by utilizing tryptophan for indole production.

Alistipes spp. Related Biomarkers

In addition to Alistipes spp., other members of the gut microbiome and associated metabolites have been studied as potential biomarkers for various health conditions.

Other Gut Bacteria as Biomarkers

Several other bacterial genera within the gut microbiome have been investigated as potential biomarkers including Bacteroides, Prevotella, Faecalibacterium, and Akkermansia. 

Changes in the abundance and composition of these bacteria have been linked to conditions such as inflammatory bowel diseases, obesity, and metabolic disorders.  [1.] 

Metabolites and Compounds Associated with Alistipes spp.

Alistipes spp. and other gut bacteria are involved in the production and metabolism of various compounds, some of which may serve as biomarkers. 

For example, short-chain fatty acids (SCFAs), such as acetate, butyrate and propionate, are produced by gut bacteria and have been associated with gut health and inflammation.  [6., 8.] 

FAQ: Alistipes spp.

What are Alistipes spp.?

Alistipes spp. refers to a genus of bacteria within the Bacteroidetes phylum. These bacteria are commonly found in the human gut microbiota and are also present in the gastrointestinal tracts of various animals.

What Role Do Alistipes spp. Play in the Gut Microbiota?

Alistipes spp. are involved in maintaining the balance of the gut microbiota. They contribute to the breakdown of dietary fibers, production of short-chain fatty acids, and modulation of the host's immune response. These activities help maintain a healthy gut environment.

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How Are Alistipes spp. Detected?  [8.] 

Alistipes spp. can be detected through several methods, including:

• 16S rRNA gene sequencing/PCR: This technique identifies bacterial species based on their genetic material.

• Metagenomic sequencing: A comprehensive approach that sequences all the genetic material in a sample to identify and quantify different microbial species.

• Culture-based methods: Growing the bacteria under specific conditions to identify them, although this is less common for Alistipes species.

What Are the Potential Health Implications of Alistipes spp.?

Research on Alistipes spp. suggests they may have both beneficial and detrimental health effects:

• Positive effects: They may contribute to the production of beneficial metabolites and support a healthy gut environment.

• Negative effects: Some studies suggest a potential association with certain diseases, such as colorectal cancer, inflammatory bowel disease (IBD), and depression, though more research is needed to confirm these links.

Can Alistipes spp. Be Used as Probiotics?

Currently, Alistipes spp. are not used as probiotics. Probiotics are typically selected for their well-established benefits and safety profiles, and more research is needed to determine whether Alistipes spp. could be beneficial and safe for such use.

How Can I Support a Healthy Gut Microbiota?

To support a healthy gut microbiota, consider the following:

• Diet: Eat a balanced diet rich in fiber, fruits, vegetables, and fermented foods.

• Probiotics and prebiotics: Consume foods and supplements that promote beneficial bacteria.

• Avoid unnecessary antibiotics: Use antibiotics only when necessary, as they can disrupt the gut microbiota.

• Regular exercise: Physical activity can positively influence gut health.

• Stress management: Reducing stress can help maintain a healthy gut microbiota.

Are There Any Known Interactions Between Alistipes spp. and Other Gut Bacteria?

Alistipes spp. interact with other gut bacteria to maintain a balanced microbiota. These interactions can influence the overall composition and function of the gut microbiome, impacting the host's health. However, specific interactions and their implications are still being studied.

Where Can I Find More Information About Alistipes spp. and Gut Health?

For more information about Alistipes spp. and gut health, consider consulting:

• Healthcare providers: Medical professionals can provide personalized advice and information.

• Scientific literature: Research articles and reviews on gut microbiota and specific bacterial species.

• Reputable health organizations: Websites of organizations such as the National Institutes of Health (NIH) and the American Gastroenterological Association (AGA).

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