Gut bacteria could help patients recover from spinal cord injury

 Researchers at The Ohio State University have found that disruptions to microbial communities in the gut – a common occurrence after spinal cord injury – hinder recovery. They’ve also found a way to minimize these detrimental effects: In a study with mice, administering probiotics boosted inflammation-suppressing immune cells and improved neurological recovery. Authors Phillip Popovich and Kristina Kigerl tell us more.

ResearchGate: How do spinal cord injuries alter the makeup of gut bacteria? 

Phillip Popovich and Kristina Kigerl: Spinal cord injury causes severe neurological and psychological complications that can predispose individuals to gut dysbiosis, a disruption of the microbial community. For example, acute and often chronic stress are expected due to the sudden and dramatic life changes experienced by someone with a spinal cord injury. Bladder and bowel function are impaired after a spinal cord injury because of damage to the autonomic nervous system. A spinal cord injury also impairs immune function, increasing the need for repeat antibiotic dosing to fight infections. All of these factors can contribute to gut dysbiosis.

We found changes in the abundance of the two major bacterial communities that make up the gut microbiome: Bacteria from Bacteroidales decreased while those of Clostridiales increased after a spinal cord injury. These changes became more pronounced several weeks after the injury.    

 ^{Disrupting the gut microbiome with antibiotics before spinal cord injury (bottom) increases the number of inflammatory cells (brown) in the damaged region of the spine. Credit: Kigerl et al., 2016}

RG: How does dysbiosis in turn impact recovery from spinal cord injuries?

Popovich and Kigerl: We found that if normal (uninjured) mice were given a cocktail of broad-spectrum antibiotics before they receive a spinal cord injury, the cocktail caused gut dysbiosis. When these mice then received a spinal cord injury, they were unable to recover locomotor function as efficiently as mice with injured spinal cords that had a normal gut microbiota before the injury. This dysbiosis also increased spinal inflammation and activated immune cells found with the gut.

RG: Could you describe your study on probiotics in mice?

Popovich and Kigerl: In an effort to restore a healthy gut microbiota and block the detrimental effects of dysbiosis after a spinal cord injury, we treated mice with VSL#3, a medical-grade probiotic, starting immediately after the injury and continuing daily for the duration of the study.

RG: What did you find?

Popovich and Kigerl: We found that VSL#3 treatment improved neurological recovery and reduced spinal cord pathology, while simultaneously increasing gut-associated regulatory T cells, a type of immune cell that can suppress inflammation. Furthermore, we were able to boost the levels of probiotic bacteria – Lactobacilllales and Bifidobacteriales – in the gut microbiome after injury.

RG: What kind of probiotic is VSL#3?

Popovich and Kigerl: We used VSL#3 from Sigma Tau Pharmaceuticals. It’s a commercially available probiotic formulation that has been tested in models of irritable bowel syndrome and ulcerative colitis. VSL#3 consists of eight strains of live bacteria: Streptococcus thermophiles, Bifidobacterium breve, Bifidobacterium longum, Bifidobacterium infantis, Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus paracasei, and Lactobacillus delbrueckii subsp. Bulgaricus.

RG: Why do those particular bacteria help?

Popovich and Kigerl: One of the challenging aspects of choosing a probiotic is that many effects are strain specific. VSL#3 appealed to us because it contains eight different species of live bacteria, which broadens the potential mechanisms of action.

The probiotics, containing large numbers of lactic acid-producing bacteria, activated a regulatory T cells, a type of immune cell that can suppress inflammation. These cells may prevent damage to the spinal cord after injury. Additionally, the probiotic bacteria may boost spinal cord recovery by secreting factors that enhance neuronal growth and function. Both of these mechanisms could explain how post-injury disruption of the gut microbiome contributes to the pathology of spinal cord injuries, and how probiotics block or reverse these effects.

RG: What are the next steps in this research?

Popovich and Kigerl: We hope that these data will help increase awareness in pre-clinical and clinical research programs about the important role of biochemical signaling among the gut, immune system, and central nervous system in recovery from spinal cord injury. Future studies should consider the role of gut dysbiosis in other organ systems and functions affected by spinal cord injury. For example, in addition to affecting motor function, sensory and autonomic dysfunction occur after a spinal cord injury. Also, there is profound immune suppression, metabolic and cardiovascular disease and various nutritional deficiencies that could be traced back to changes in the gut microbiota. Probiotics are one of many possible approaches for treating or at least reducing the detrimental effects of dysbiosis after a spinal cord injury.

The health implications of our gut microbiome - the trillions of bacteria that live in our gastrointestinal tract - have been uncovered in recent years. But a new study finds a surprising benefit of maintaining a healthy gut: better recovery from spinal cord injury.

So-called good bacteria, found in probiotics, could help aid recovery from spinal cord injury. So conclude researchers after conducting a study in mice.

The researchers, led by Phillip G. Popovich of Ohio State University, publish their findings in The Journal of Experimental Medicine.
They note that our gut microbiota communicates with the central nervous system (CNS) by interacting with immune cells and secreting metabolites that pass through the blood-brain barrier.
"Most (~70-80 percent) immune cells in the body are located within gut-associated lymphoid tissues," the researchers write. "There, an ongoing dialogue between immune cells and gut bacteria produces cytokines that affect CNS function."
The influence of our gut bacteria is far-reaching. From boosting the effectiveness of chemotherapy to affecting obesity risk in youth, the gut microbiome is incredibly important for our body's overall health.
In addition to the more overt effects of traumatic spinal cord injuries, the researchers say they have secondary effects, including loss of bowel control, which can cause disruption to the gut microbiome.
Termed "dysbiosis," this disruption happens when "good" bacteria are depleted or overrun by "bad" bacteria in the gut. Previously, autoimmune diseases - such as multiple sclerosis and type 1 diabetes - have been linked to dysbiosis, and the researchers say it has been found to play a role in the progression of neurological disorders.

Probiotics: 'A previously unappreciated role in spinal cord injury'

With all of their background knowledge on the effects of the gut microbiome, the researchers hypothesized that changes in the gut microbiome could affect spinal cord injury recovery.
To test their theory, the researchers performed an experiment in mice. They found that mice that were pretreated with antibiotics to alter their gut microbiomes before spinal cord injury showed higher levels of spinal inflammation. These mice also recovered poorly from their injuries.
On the flip side, injured mice that were given daily probiotic doses showed less spinal damage and were able to regain more hindlimb movement. The researchers indicate that the probiotics contained large numbers of lactic acid-producing bacteria, which activated a gut-associated immune cell that can inhibit inflammation.
The researchers say these immune cells - called regulatory T cells - could prevent extra damage to the spinal cord after injury. Additionally, by releasing molecules that promote neuronal growth, the probiotic bacteria may actually boost spinal cord recovery.
Popovich explains that one or both of these functions "could explain how post-injury disruption of the gut microbiome contributes to the pathology of spinal cord injuries and how probiotics block or reverse these effects."

"Our data highlight a previously unappreciated role for the gut-central nervous system-immune axis in regulating recovery after spinal cord injury. No longer should 'spinal-centric' repair approaches dominate research or standards of clinical care for affected individuals."

Phillip G. Popovich

Although the researchers' findings from their mouse study suggest that counteracting gut changes with probiotics could help patients who are recovering from spinal cord injuries, the results have not yet been confirmed in humans.
Read more about gut bacteria and the brain.

Written by Marie Ellis

 

The diet was originally developed for childhood epilepsy a century ago and is now studied to treat migraines.

Before the ketogenic diet became the latest low-carb diet trend, it was used to treat childhood epilepsy. Doctors had observed that fasting reduced the amount of seizures, and eating mainly fat and little else mimicked the effect of starvation in the brain. In recent years, researchers have made similar positive observations with migraines. Cherubino Di Lorenzo studies the effect of a ketogenic diet on migraine patients and, in his latest paper, their brains at the Sapienza University of Rome.

ResearchGate: What is a ketogenic diet?

Cherubino di Lorenzo: The ketogenic diet is a particular nutritional regimen that mimics starvation by restricting carbohydrate intake. It was developed 95 years ago in order to treat drug-resistant epilepsy in children. Traditionally, the ketogenic diet is rich in fat and low in carbohydrates, but in the past decades another type of ketogenic diet was developed to treat obesity and metabolic syndrome: the low fat (10-15 grams/day) low carb (20-50 grams/day) diet, also known as the very low calorie ketogenic diet (VLCKD).

RG: What does this diet do to the body and the brain in particular?  

Di Lorenzo: During a ketogenic diet, carbohydrate restriction induces the fat metabolism to produce so-called ketone bodies. These ketone bodies act as a replacement for carbohydrates and fuel several types of cells, including neurons. In the classic ketogenic diet, the fat that’s taken in with the food is the source for the production of ketone bodies . In the very low calorie ketogenic diet, however, the ketone bodies are produced from fats in adipose tissue. You could think of this process as the body’s own biochemical liposuction. Each molecule of ketone bodies produces more energy than glucose, but less oxidative stress, so the brain and the muscles work more efficiently. This effect of ketone bodies as energetic boosters is very important in migraine patients, or migraineurs, because they have an energetic deficit in the brain. Ketone bodies also have an anti-inflammatory effect. This is also important because ‘sterile inflammation’ – inflammation caused by damage rather than by microbes – is at the heart of migraines. The ketone bodies dampen the neural inflammation that’s both common in epilepsy and migraines and modulate the cortical excitability, the firing rate of neurons.

 ^{Source: Cortical functional correlates of responsiveness to short-lasting preventive intervention with ketogenic diet in migraine: A multimodal evoked potentials study}

RG: How did you get the idea to study the effects of a ketogenic diet on migraineurs?

Di Lorenzo: Our interest in ketogenic diets was born in 2009. A common side effect of most drugs for migraine prophylaxis, including antidepressants, anti-epileptics, calcium antagonists, and beta-blockers, is weight gain. The problem: increased weight can also worsen headaches in these patients. For this reason, we recommended that overweight patients see a dietician prior to or during preventive treatment. One of these dieticians, Giulio Sirianni, observed that patients who underwent very low calorie ketogenic diets had fewer headaches. In most cases, the headaches even disappeared during the ketogenic phase of the diet.

RG: How did you study the diet on your patients?

Di Lorenzo: After we saw these effects, we decided to confirm our findings in a large population of patients. We studied two groups of migraineurs who visited the dietician for the weight-loss and evaluated the effect of a ketogenic and a non-ketogenic diet on their migraines. Our dietician strictly followed the protocol of an Italian Society of Medical Dieting (SDM) that says to restrict the ketogenic diet to one month, followed by a five month long non-ketogenic phase of dieting. We observed that the headaches dramatically improved only during the ketogenic phase of the diet, and worsened again at the end of that month. We concluded that the ketogenic diet was the reason for that improvement.

However, we are not sure that the reason why the ketogenic diet works so well in our patients is only due to the ketone body production. In fact, we have observed that in a majority of cases, our patients also show abnormal results in oral glucose tolerance tests both in the way their blood sugar and their insulin levels responds to sugar intake. Since carbs are a form of sugar, a low-carb diet could mitigate these responses. Our hypothesis is that the combination of ketone bodies and changed glucose response could lead to the outstanding therapeutic effect we have observed in our patients.

More recently, we found similar results for non-overweight migraineurs and patients with the most severe form of headache, cluster headache, who consumed a high-fat ketogenic diet with normal calorie intake. However, we found that the diet is not effective in tension-type headaches and cervicogenic headaches, a form of headache that originates in the bone or soft tissue of the neck.

RG: What’s the next step in your research?

Di Lorenzo: Next, we’d like to study the positive effect of ketogenesis on chronic migraine patients (more than 15 days of migraine per month) for prolonged periods and on drug-resistant episodic migraineurs, and patients who do not respond to common prophylactic treatments, in a more comprehensive way. We’d also like to explore the influence of ketogenic diet on the cortical excitability of migraineurs. Currently, we’re conducting an ongoing a double-blind study on obese episodic migraineurs.

RG: Would you advise migraine patients to try a ketogenic diet?

Di Lorenzo: Currently, we advise the ketogenic diet in its hypocaloric form for overweight and obese migraine patients, and for all drug-resistant migraine and cluster headache patients. I don’t know why, but it is very rare to find an obese person among cluster headache patients.

In our experience, motivated patients don’t find it difficult to follow a ketogenic diet, especially since there are fewer side-effects and adverse events compared to common preventive pharmacologic treatments.

RG: Ketogenic diets are also popular for weight-loss and endurance. Would you recommend the diet to people without medical indication?

Di Lorenzo: There are not particular risks for patients who follow the diet. Apart from type I diabetes patients, there are not contraindications for it. As I mentioned, the ketogenic diet is better tolerated than common pharmacological prophylactic treatments. The most common side effects are mild to moderate gastro-intestinal symptoms, easily managed with over-the-counter products. Some migraineurs reported hair loss as a side effect. This is strange because this symptom was never reported by any other populations of patients.

I know hundreds of patients who have followed a ketogenic diet for weight loss and endurance performances under medical supervision without a problem. I do, however, recommend professional medical supervision. If the diet is done incorrectly, it might be unhealthy. That’s why some counties regard ketogenic diets as unsafe, but this is not my experience. Personally, for patients with metabolic syndrome and risk factors for cerebrovascular accidents, I recommend the very low ketogenic diet as first-choice treatment, perhaps in association with Aspirin, before any other pharmacological treatment.

 

In seven out of ten cases, genetic tests on the dead could unveil the likely cause of death.

Each year, 11,000 people under the age of 45 die suddenly and unexpectedly of natural causes in the United States. If the cause of death isn’t determined, it leaves living relatives with an incomplete family health history, and at risk. Using genetic testing in autopsies may be one way to resolve the uncertainty. Ali Torkamani, Director of Genome Informatics and Drug Discovery at The Scripps Translational Science Institute explored the potential of “molecular autopsies” in his latest study. 

ResearchGate: Why is it important to know the cause of death?

Ali Torkamani: Knowing the cause of death can inform whether living relatives are at risk. Many of the causes of sudden death can either be monitored or, in some cases, a direct intervention is possible. Knowing whether a living relative is at risk can reduce their risk of succumbing to the same fate.

RG: Have genetic tests played a role in autopsies in the past?

Torkamani: Yes, but not in a systematic manner. There is certainly a subset of medical examiners that utilize genetic testing in their practice, but it tends to be of limited scope - generally just testing for suspected arrhythmias. Recent surveys have shown that the majority of medical examiners have never ordered a genetic test. The primary reason for this appears to be the cost.

RG: The rate of autopsies has declined from 50 percent to 10 percent in 2008. Why do you think that is?

Torkamani: The reasons most commonly cited for a decline in the rate of clinical autopsies are: firstly, lack of reimbursement or financial support for clinical autopsies, and secondly, reluctance for living relatives to consent to an invasive procedure.

RG: Is postmortem genetic testing different to genetic testing in the living?

Torkamani: Fundamentally, no. The technical procedures involved are largely the same. In postmortem genetic testing you can do certain things that are not possible in genetic testing of the living, for example testing for somatic mosaicism in the heart tissue of the deceased.

RG: How did you study postmortem genetic testing?

Torkamani: We worked with the San Diego medical examiner to recruit cases of sudden death in individuals under 45 years of age. For cases that qualified, we performed exome sequencing on the deceased and their family where possible.

RG: What were your results?

Torkamani: 25 cases were sequenced, with nine including both parents of the deceased. Clinical autopsies discovered the likely cause of death in five cases. A likely cause of death was identified by molecular autopsy in four cases (16 percent), a plausible cause in six (24 percent), and a speculative cause in seven (28 percent); no mutations were identified in eight (32 percent). The likely genetic cause of death was corroborated with clinical autopsy findings in two of five cases. All other clinical autopsy findings (three cases) could be linked to a plausible or speculative genetic cause. Seventy percent (7/10 cases) of likely and plausible pathogenic mutations were inherited from relatives who did not die suddenly.

RG: Which role do you see postmortem genetic tests play in the future?

Torkamani: As the cost of sequencing continues to decline, I suspect postmortem genetic testing will become more and more prevalent. It will likely start with suspected cases of arrhythmia and other cardiovascular conditions. I believe the benefits to living relatives would support the case.

 

Donor’s cells integrated with no sign of rejection to regenerate recipient’s heart.

Today’s Nature study reveals that cardiac muscle cells grown from the stem cells of one macaque monkey can be used to regenerate the hearts of other macaques. The transplanted cells improved the heart’s ability to contract after an induced heart attack and integrated with no sign of rejection by the recipient’s immune system. However, the recipient’s heart did suffer from an irregular heart beat in the first four weeks after the transplant, but this passed and was non-lethal.

Yuji Shiba, Shinshu University, Matsumoto, Japan and colleagues used cardiac muscle cells derived from induced pluripotent stem cells (iPSC-CMs) from a donor instead of the patient’s own cells. Donor cells are considerably easier to manufacture but increase the risk of being rejected by the recipient’s immune systems. Shiba overcame this by matching a surface protein on the donor and recipient’s cells that is used by the immune system to recognize foreign cells.
We spoke to Yuji Shiba.

ResearchGate: What motivated this study?

Yuji Shiba: We previously reported that human embryonic stem cells regenerated injured guinea pig hearts when I worked at the University of Washington as a post-doctoral fellow. I came back to Japan in 2011 and wanted to start something a bit different.

RG: What were the results?

Shiba: We found that monkey iPSC-CMs or cardiac muscle cells derived from induced pluripotent stem cells survived in the damaged monkey heart and electrically coupled with the host heart. In addition, the heart’s ability to contract was partially recovered by the transplantation.

RG: What heart conditions could this treat?

Shiba: We blocked oxygen from the heart for three hours which caused myocardial infarction (MI). The heart also suffered from reperfusion, which is tissue damage caused by the blood and oxygen returning to the heart. The induced pluripotent stem cells (iPSC-CMs) were transplanted two weeks after the induction of MI.

So far, we only have evidence that an acutely or sub-acutely infarcted heart was rescued by this treatment, but in a clinical setting, patients with chronic infarction would be more likely to receive this treatment.

 iPS cells were generated from MHC homozygous monkey and differentiated into cardiomyocytes. The cardiomyocytes were transplanted into another monkey in which either of the MHC haplotypes was identical to the donor. Credit: Yuji Shiba

RG: Were you confident that this would work when you started? What were the biggest challenges in the study?

Shiba: To some extent, yes. We had a hard time handling monkey iPS cells. Unlike human iPS cells, they are somewhat tricky. The condition of iPS cells are critical for generating high purity cardiac muscle cells. Also, it took a long time to get grafted cardiac muscle cells to survive in the recipients.

RG: How did you avoid an immune response from the recipient when using a donor’s cells?

Shiba: In addition to daily treatments of the immunosuppressant drugs methylprednisolone and tacrolimus, we made sure the surface protein MHC, which is used by the immune system to recognize foreign cells, was carefully matched on the donor and recipient’s cells.

RG: What negative side effects did you encounter? Can these be overcome?

Shiba: Ventricular arrhythmia was induced by the transplantation, typically within the first four weeks. However, this post-transplant arrhythmia seems to be transient and non-lethal. All five recipients of iPSC-CMs survived without any abnormal behavior for 12 weeks, even during the arrhythmia. So I think we can manage this side effect in clinic.

RG: How long before we could see this in human clinical trials?

Shiba: Human embryonic stem cell-derived cardiac muscle cells have already been used in clinic as a new therapy for post myocardial infarction (MI) heart failure. But I think it will take at least a couple of years for this treatment to become more widely-used.

RG: What excites you most about the future of stem cell therapy?

Shiba: Our ultimate goal is to provide autologous, meaning the cells are the patient’s own, patient specific cardiac muscle cells to cure not only myocardial infarction (MI) but any kind of heart disease.