THE HUMAN MICROBIOME AND PROBIOTICS

THE HUMAN MICROBIOME

• The ecological community of commensal, symbiotic, and pathogenic microorganisms that share our body

• Remember… You are made of 10x more microbial cells than human cells

• Typical adult microbiome weighs between 200 and 1,400 grams, with 400-500 species of intestinal microflora

• Modern genetic analysis in the 1990’s led to the discovery of microbiome; its impact on human health is only beginning to be understood

POSSIBLE EFFECTS OF THE MICROBIOME

• Roles in auto-immune diseases like diabetes, rheumatoid arthritis, muscular dystrophy, multiple sclerosis, fibromyalgia, some cancers and obesity

• Regulation of mood through the production of neurotransmitters involved in schizophrenia, depression, bipolar disorder and other neuro-chemical imbalances

• The microbes being discussed are generally non-pathogenic (do not cause disease unless they grow abnormally); they exist in harmony and symbiotically with their hosts

• Much of the human microbiome is composed of archaea

MICROBIOME EXPERIMENTAL EVIDENCE

• Germ free mice have an exaggerated stress response and reduced expression of brain-derived neurotrophic factor in the cortex and hippocampus

• Treating maternally separated mice with a probiotic culture of Bifodobacterium infantis minimizes weight loss, causes mice to swim longer and increases the serotonin precursor tryptophan

• Human patients with depression are less able to properly digest fructose, which is also associated with a reduction in tryptophan production

• Eliminating fructose from their diet improved depression in human test subjects

HOLOGENOME THEORY OF EVOLUTION

• All animals and plants establish symbiotic relationships with microorganisms

• Different host species contain different symbiont populations; individuals of the same species may contain different symbiont populations

• Host organism + microbial community relationships affect both the host and its microbiota

• Genetic info encoded by microorganisms can change under environmental demands more rapidly and diversely than the genes encoded by the host organism

• The host genome can act in harmony with the genomes of the associated symbiotic microorganisms to create a hologenome

• The holobiont with its hologenome should be considered as the unit of natural selection in evolution

• If a given holobiont is to be considered a unit of natural selection the hologenome must be heritable from generation to generation

COEVOLUTION OF THE HOLOBIONT

• Holobiont = host + symbiotic microbiota

• Coral reefs are examples of holobionts – Oculina patagonia – Mediterranean coral infected by Vibrio bacteria – coral developed resistance by adaptive changes in microbiota, not immune response by O. patagonia

• The microbiome coevolves with the immune system and controls it – “germ free animals” possess severely underdeveloped immune systems

WHAT ARE PROBIOTICS?

• Dietary supplements or food products with viable microbe populations to alter the microflora of the host with potential beneficial health effects

• 1877 – Pasteur – antagonistic relationships between bacteria suggested non-pathogenic microbes could be used to control pathogens

• 1907 - Elie Metchnikoff noticed lactic acid fermentation of milk stopped spoilage; introduced the idea of eating lactic acid bacteria (LAB) to promote health; attributed the longevity/health of populations in the Balkans to bacteria in their traditional yogurt

• 1950’s researchers confirm the effects of antibiotics on beneficial intestinal microbes

• Fermentation effects are known to: improve digestion, produce amino acids and vitamins, but the actual health benefits of probiotics are somewhat uncertain

THE MICROBIAL ECOSYSTEM OF THE HUMAN GI TRACT

• Complexity and access of GI tract makes research on probiotics difficult

• Human GI tract – 400 + species of bacteria

• Acidity of stomach destroys many potential probiotics; acid/bile resistant strains of Lactobacillus acidophilus and Bifidobacterium have been isolated from humans and used in yogurt cultures

COMMON PROBIOTIC GENERA

• Bifidobacterium – genus of non-motile, gram-positive anaerobes found in human mouth, colon, and GI tract; common and ubiquitous human endosymbiotic bacteria

• Some introduced through breastfeeding; babies with Bifidobacterium as intestinal microflora were observed to suffer less from GI disorders

• Lactobacillus – Gram-positive facultative anaerobic or microaerophilic rod-shaped bacteria

• Streptococcus

• Saccharomyces

PROBIOTICSMANY POTENTIAL USES

• Infectious diarrhea and day care related illness• Antibiotic Associated Diarrhea

• Clostridium difficile

• Inflammatory bowel disease• Traveler’s diarrhea• Prevention of NEC (necrotizing enterocolitus)• Allergy• Irritable Bowel Syndrome

Yogurt (364)

Yogurt+L. casei

(360)

P-value

Children with diarrhea

87 (22%)

61 (16%) 0.029

Duration of diarrhea (days) 3.95 3.53 0.24Rotavirus positive stool 2.2% 0.3%

Prevention of Diarrheal Illness

18 Week Therapy in French Children (6-24 months) in Day Care

CA Pedone, et al. Int J Clin Pract 54(9):568-71, 2000

Controls (60)

B. lactis (73)

L. reuteri (68)

P-value

Days with diarrhea 0.59 0.37 0.15 <0.00

1Episodes of diarrhea

0.31 0.13 0.02 <0.001

Clinic visits 0.55 0.51 0.23 0.002Absences

0.43 0.41 0.14 0.015

Prevention of Diarrheal Illness

12 Week Therapy in Israeli Infants (4-10 months) in Day Care

Z Weizman, et al. Pediatrics 115:5-9, 2005

Control (19)

L. reuteri/L.

rhamnosus (24)

P-value

Duration of diarrhea (hours) 115.7 75.9 0.05Duration of watery diarrhea 37 38.1 0.94Duration of fever (days) 1.1 1.4 0.59Diarrhea after 120 hours 7 2 0.03

Treatment of Acute Diarrhea5 Day Therapy in Danish Children (9 to 44 months) in Day Care with

Acute Diarrhea

V Rosenfeldt, et al. Pediatr Infect Dis J 21:417-9, 2002

Whole Study Group

PROBIOTIC TREATMENT IN CASES OFINFECTIOUS DIARRHEA

• Experiment conducted with children up to 2 years of age in chronic care facility

• Subjects were randomized to receive B. bifidum and S. thermophilus or placebo

• Probiotic supplement resulted in statistically less diarrhea (7% vs 31%)

• Statistically less rotavirus shedding (10% vs 39%) with probiotics

Saavedra et al, Lancet 1994

PROBIOTICS IN ANTIBIOTIC ASSOCIATED DIARRHEA

• Diarrhea is a common side effect of antibiotic therapy

• Up to 40% of children receiving broad spectrum antibiotic therapy

• Likely due to altered microbial flora• Leads to altered metabolism of osmotically active

substances

PREBIOTICS AND SYNBIOTICS

• Prebiotics: Non-digestable food ingredients with positive effects on endogenous microbiota

• Stimulate the growth and activity of one or more species of beneficial microbiota; usually confer benefits to a range of beneficial microblora, especially Bifidobacterium and LAB

• Prebiotic examples: Inulin (a dietary fiber found in some plants/roots), oligosaccharides (polymers of simple sugars found in cell membranes)

• Synbiotics – a probiotic combined with its own, specific prebiotic food – improves survival rate of probiotics through the GI tract

TOP 10 FOODS CONTAINING PREBIOTICS

Food Prebiotic Fiber Content by Weight

Raw Chicory Root 64.6%

Raw Jerusalem Artichoke 31.5%

Raw Dandelion Greens 24.3%

Raw Garlic 17.5%

Raw Leek 11.7%

Raw Onion 8.6%

Cooked Onion 5%

Raw Asparagus 5%

Raw Wheat bran 5%

Whole Wheat flour, Cooked 4.8%

Raw Banana 1%

PROBIOTICSPRACTICAL ISSUES

• Correctly purified strains of bacteria?

• Must be selected for ability to:• Survive acid/bile in upper GI tract• Colonize• Adhere

• Must have shelf viability

• Should have quality control

• Not FDA regulated

PROBIOTICSPRACTICAL ISSUES

• Typically $1 to $3 per day• VSL3: $56 for 20 day supply• Culturelle (LGG): $55 for 30 day supply• Custom Probiotics CP-1: $40 for 30 day supply

• May need several months of therapy to see an effect • Likely stop working after discontinued• Concentration (dose) highly variable

MICROBIOME AND PROBIOTICS TAKE HOME MESSAGE

• All organisms form symbiotic relationships with microbial communities

• These “microbiomes” are more important to health/survival/behavior of organisms than previously understood

• The adaptive traits conferred by the microbiome are coded as part of the hologenome – the sum of organismal and microbial genes that are transferred down through generations

EMERGING MICROBIAL DISEASES

• Hanta Virus - single-stranded, enveloped, RNA viruses. Passed to humans through contact with rodent urine, saliva, or feces. Some strains may be fatal, others are benign in humans.

• Discovered in the 1950’s; symptoms include renal failure, generalized hemorrhage, fever, and shock.

• More than eight states had reported 30 + cases of Hantavirus since 1993[ – New Mexico (84), Colorado (70), Arizona (62), California (42), Washington (41), Texas (37), Utah (31) and Montana (30). Other states reporting a significant number of cases include Idaho (16), Kansas (15), South Dakota (15), North Dakota (12) and Oregon (11).

• In late August and early September of 2012, eight new cases of Hantavirus were confirmed, including three deaths, in Yosemite National Park.[19]

HANTA VIRUS CONTINUED

• No known antiviral treatment; natural recovery is possible with supportive treatment.

• The virus can be transmitted by rodent saliva, excretia, and bites, control of rats and mice in areas frequented by humans is key for disease prevention.

• Cases reported worldwide – Africa, Europe, Asia, South America

• Hanta virus likely originated in South Korea

WEST NILE VIRUS

• Likely from African tropics, found in warm climates, transferred by mosquito vector

• Only 80% of infections in humans manifest clinical symptoms; symptoms include fever, headaches, fatigue, muscle pain or aches, malaise, nausea, anorexia, vomiting, myalgias and rash.

• There are no medications to treat or vaccines to prevent WNV infection. About 1 in 5 people who are infected will develop a fever with other symptoms. Less than 1% of infected people develop a serious, sometimes fatal, neurologic illness.

FUKUSHIMA

• On 11 March 2011 the Fukushimi Daiici nuclear reactor suffered a catastrophic failure

• The failure occurred when the plant was hit by the tsunami. The plant began releasing substantial amounts of radioactive materials beginning on 12 March, becoming the largest nuclear incident since the 1986 Chernobyl disaster and the second (with Chernobyl) to measure Level 7 on the International Nuclear Event Scale.

• At least 300,000 people evacuated the area and as of August 2013 there have been approximately 1,600 deaths were related to the evacuation conditions, such as living in temporary housing and hospital closures

FUKUSHIMA HAPPENS…

• A 2013 WHO report predicts that for populations living in nearby areas there is a 70% higher risk of developing thyroid cancer for girls exposed as infants, a 7% higher risk of leukemia in males exposed as infants, a 6% higher risk of breast cancer in females exposed as infants and a 4% higher risk, overall, of developing solid cancers for females

• On 22 July 2013 it was revealed that the plant is leaking radioactive water into the Pacific Ocean. This had been denied by TEPCO.

• Fukushima Daiichi was central to a falsified-records scandal that led to the departure of senior TEPCO executives. Dale Bridenbaugh, a lead GE designer, claimed that GE was warned of major design flaws in 1976, resulting in the resignations of several GE designers who protested GE's negligence

FUKED-UPDATE• Unexplained plumes of radioactive steam have been rising from

Fukushima's Reactor Building 3. TEPCO has confirmed the reports, adding that they were not clear on the details of the sudden change at the reactor because of "lethal radiation levels in that building."

• Fukushima's Reactor Building 3 exploded on 13th March 2011 as a result of a hydrogen buildup, breaching the building's containment and emitting a huge plume of radiation. The reactor itself is in meltdown.

• And now fresh plumes of steam have been seen coming out the structure. These have now been confirmed by TEPCO, the owner of the nuclear plant, from 19th December 2013 onwards.

• High levels of radiation are being recorded on the West Coast and throughout the US