Category Archives: Infections

How to Recognize and Fix a Brain Infection

I thought I’d pull up an interesting tale from the comments. It is a great illustration of what we’re trying to accomplish on this blog.

Thomas first commented here on December 31:

I just got your book from a relative for Christmas (I told them to buy me it!) and am reading through it now. Very interesting, although some of it is beyond a simple layman like me.

The part of this blog post that starts “Thus common symptoms of a bacterial infection of the brain are those of cognitive hypoglycemia and serotonin deficiency” and continues for several paragraphs describes precisely the mysterious changes I have experience over the last decade of life (I am now 33), with the one variation being that I suffer extreme fatigue rather than insomnia or restlessness. Every other sympton, including the odd mental state you mention, is a perfect match, and I experience them all to a marked degree….

I have been diagnosed with general anxiety but never depression. I do not feel sad ever, just irritable and anhedonia-ac, if I may coin a word. Anti-depressants, and I’ve tried a bunch, do absolutely nothing for me.

Brain infections are widespread – I wouldn’t be surprised if 20% of the adult population has a brain infection of mild severity – but they are hardly ever diagnosed or treated.

Fortunately, there are some symptoms that are almost universally generated by brain infections, so it’s not necessarily that difficult to diagnose them. But I think no one knows the symptoms. Infections are generally allowed to progress for decades.

One of my crucial steps forward was when I recognized that I had the cognitive symptoms of hypoglycemia when my blood sugar was normal. I could relieve the symptoms if my blood sugar became highly elevated. Thinking about why that might be led me toward the idea of bacterial infections.

Thomas went on to describe the origin of his symptoms:

I began to decline after suffering the second subdural hematoma of my life at age 20 when I was in Italy, followed by a 5 year binge on alcohol.

This was another clue. Traumatic brain injuries, such as hematomas, often initiate brain infections, because they breach the blood-brain barrier. Alcohol is also a risk factor, as I pointed out in my reply to Thomas:

Alcohol abuse depresses bacterial immunity and would be a risk factor for a brain infection: http://www.ncbi.nlm.nih.gov/pubmed/16413723, http://www.ncbi.nlm.nih.gov/pubmed/20161709. Subdural hematomas frequently show infections, e.g. http://www.ncbi.nlm.nih.gov/pubmed/20430901.

We next heard from Thomas on February 22, when he had been on our diet for 7 weeks and had just tried his first ketogenic fast:

I’ve been doing PHD for about 7 weeks now, and tried a ketogenic fast this past weekend. I ended up going 33 hours with some coconut oil and cream. It was a bit tough having to eat a bunch of oil on an empty stomach, but nothing too bad.

I can’t say there was any improvement cognitively or with anhedonia, but there seemed to me to be a pronounced calming effect after about 24 hours of fasting. I often stutter or stumble over words (again, for about 10 years now), which usually goes away only with two or three alcoholic drinks. But the speech problems stopped almost completely during the fast, which makes me thing that there is some link to anxiety and stuttering.

Positive changes in brain function during ketosis suggest that the brain isn’t functioning normally when it relies on glucose as a fuel. There are several possible causes of this, but one is a bacterial infection. Another clue.

I generally recommend getting on our diet and supplement regimen, and reaching a stable health condition, before starting antibiotics. There are several reasons for this, which I’ll elaborate on later, but briefly:

  • Antibiotics work well on a good diet but may fail on a bad diet.
  • Pathogen die-off toxins can cause significant neurological damage and this toxicity may be substantially increased on a bad diet.
  • There is considerable diagnostic value in being able to clearly discern the reaction to antibiotics. Rarely is it certain that a brain infection is bacterial, or that the antibiotic in question is the correct one. To judge whether the antibiotic is working, it’s important that health be stable and as good as possible.

I therefore recommend being on our diet and supplement regimen for 3-4 months before starting antibiotics.

Thomas seems to have followed this advice, since he has just reported starting antibiotics:

I’ve been on PHD for a few months, and about a month ago went to the low-carb therapeutic ketogenic version of the PHD. After reading some of Paul’s posts, I believe that I might have a brain infection as a result of a head injury from more than a decade ago (Paul, if you recall, my condition has a lot of similarities to the one you once had). I started taking doxycycline a few days ago, and I have already noticed pronounced improvement (whether due to the diet or the antibiotic or both) in controlling the irritability and anxiety that have plagued me for years….

I definitely feel great since making the diet changes. My blood pressure, which has been creeping upwards over the last few years to 135/80 or so, is back down to 110/70. My testosterone is 824, and I am pleased to see that I maintaining my strength in the gym despite being on a ketogenic diet.

Pronounced improvement in the first days of doxycycline is quite possible, because doxy acts as a protein synthesis inhibitor. It essentially blocks bacterial functions and switches them into a state of hibernation. The bacteria are still there, but they are not interfering with brain function as much as before.

This improvement is confirmation that Thomas has a bacterial infection of the brain. If there were no infection, he wouldn’t notice an effect from the antibiotics.

Over a period of months, the doxycycline plus ketogenic dieting should help his innate immune defenses clear the brain of most bacteria. Combination antibiotic protocols may be even more effective.

In a follow-up comment, Thomas mentioned Ben Franklin and the blessing of good health:

Thanks for the response Paul, as well as all your help. If this works, I owe you my first-born child and then some! Ben Franklin (I think it was him) might have been right about health being the greatest blessing. The improvements I’ve seen recently have done more for my well-being than anything in the last decade, and I am profoundly grateful to you for all your excellent advice.

It’s comments like this that make blogging and book writing worthwhile.

It’s probably hard for those who have never had ill health to appreciate how enjoyable it can be for those with chronic diseases to recover good health. I’ve blogged on this before (Of Recovery, Hope, and Happiness, July 13, 2010 – don’t miss Ladybug’s painting).

Thomas, antibiotics and ketogenic dieting will work, I’m pretty sure. May you come to perfect health, and always remain grateful for the many blessings that are yours.

Blood Lipids and Infectious Disease, Part II

OK, after a diversion into hunter-gatherer lipid profiles I’m back on the original goal of this series: trying to understand why serum cholesterol is protective against infections — and considering whether or under what circumstances that knowledge should affect how we eat.

In part I (Blood Lipids and Infectious Disease, Part I, Jun 21, 2011), we learned that mortality from infectious disease is essentially zero as long as serum cholesterol remains in the physiologically normal range of 200 to 240 mg/dl, and rises precipitously as serum cholesterol falls below 180 mg/dl.

Why is that? In a previous post we found that HDL has important immune functions (HDL and Immunity, April 12, 2011). Today, we’ll look at the immune functions of lipoproteins more generally.

The Logic of Evolution and the Multiple Functions of Lipoproteins

In understanding why these particles have immune functions, it may be helpful to understand the thrust of evolution.

By the time of the Cambrian explosion 530 million years ago, organisms had similar numbers of genes to organisms today, and most of these genes must have been similar in sequence to their modern descendants. We know this because their descendant genes in nearly all modern species are “homologous” and share nucleotide sequences.

So for the last 500 million years, evolution has not been adding genes or even changing genes dramatically. It’s been tweaking a fairly stable genome. And the direction of the tweaking has been toward making the genes interact in a wider and more complex number of ways with the other genes.

The effect is to give every molecule in the body a diversity of functions. Possibly serum lipoprotein particles started out merely as transporters. But they developed new functions. The most important additional functions were roles in immunity.

Because these particles circulate in the blood, and pathogens have to transit the blood in order to cause tissue infections, blood is the natural location for the strongest defenses against pathogens. For hundreds of millions of years, every blood component will have been under selective pressure to develop immune functions.

It’s commonly said that the primary function of LDL and HDL is lipid transport. But this is too narrow a view. Since pathogens are the primary cause of disease, it may be the immune functions of LDL and HDL which account for their significance as biomarkers of health and disease.

The Immune Functions of Lipoproteins

Most of the following discussion will draw from a recent review, “Plasma lipoproteins are important components of the immune system” [1]. References from this paper will be listed in parentheses, eg (1).

Lipoproteins have been shown to:

  1. Prevent bacterial, viral, and parasitic infections.
  2. Detoxify pathogen “die-off” toxins and protect against pathogen toxin-induced tissue damage.
  3. Present pathogen “die-off” toxins to the immune system to trigger antibody formation.

Detoxification and Toxin Defense

When a pathogen dies, it typically fragments and releases compounds which are toxic to humans. Such “die-off” toxins include lipopolysaccharides (LPS) and lipooligosaccharides (LOS) from Gram-negative bacteria, lipoteichoic acid (LTA) from Gram-positive bacteria, fungal cell wall components, and so on.

During infection, the number of such circulating toxins can be vastly larger than the number of pathogens. Such toxins can do a great deal of harm, and often account for most of the ill effects of disease. Medical researchers studying the often-fatal condition of sepsis commonly induce nearly all the characteristics of sepsis in animals merely by injecting LPS.

VLDL, LDL, lipoprotein(a) and HDL can all detoxify LPS and LTA; HDL is the most potent (2, 4, 5). Injecting reconstituted HDL (rHDL) into humans relieves endotoxemia (6) and LPS-induced inflammation in cirrhosis patients (7). Both LDL and HDL detoxify E. coli LPS (35).

LDL binds and inactivates some toxins, including Staphylococcus aureus ?-toxin (8), Yersinia pestis topH6-Ag (30). (Methicillin-resistant S. aureus, or MRSA, is an increasing cause of death in hospitals, and last year claimed my next-door neighbor. See The FDA Is On The Side of the Microbes, Aug 11, 2010).

LDL probably works against many other toxins too, since rats with low LDL have higher mortality when infected, but the mortality can be lessened with injections of human LDL (9). Injections of LDL prevent lethality in Vibrio vulnificus infections of mice (34).

In mice with the LDL receptor knocked out, LDL concentrations in blood are higher and there is enhanced immunity to Klebsiella pneumoniae (27) and Salmonella typhimurium (29). If the gene for apoE, a protein found in IDL which upregulates VLDL levels, is knocked out, mice become more susceptible to infection, so it appears that apoE also has immune functions (28). Mice lacking apoE are susceptible to Listeria monocytogenes (32) and Mycobacterium tuberculosis (33).

Lipoproteins may be even more important against viruses. HDL has a broad antiviral activity (18-20), and can prevent many virus species including influenza and hepatitis C from entering cells. VLDL and LDL have specific activity against certain types of virus including togaviruses and rhabdoviruses (3). Trypanosoma brucei, the parasite that causes sleeping sickness, does not always cause disease in humans because a subspecies can be destroyed by a subfraction of HDL particles which include haptoglobin-related protein and apolipoprotein L-I (10).

The role of oxLDL

Evolution has a way of turning lemons into lemonade, and fragile molecules into sensors. In the book we discuss how the body uses fragile polyunsaturated fats as signaling molecules, exploiting their proclivity to oxidize. Something similar happens with LDL.

LDL particles are fragile and easily oxidized. The body uses them as a sensor of infections, and as signaling molecules that control the response to infections.

For instance, LPS (an endotoxin) induces neutrophils to adhere to endothelial cells, promoting vascular inflammation. LPS also oxidizes LDL, creating a compound called oxPAPC which inhibits neutrophil adhesion to endothelial cells, thereby limiting the inflammatory response (12). Minimally oxidized LDL detoxifies LPS (13).

OxLDL is taken in not by the LDL receptor, but by receptors on immune cells called macrophages. When macrophages take up oxLDL they upregulate their scavenger receptors (classes A and E) by which they phagocytose (eat) bacteria and clear endotoxins (39). It has been shown that infection causes an increase in oxidation of LDL and that the resulting oxLDL promotes phagocytosis by macrophages of the specific pathogens which oxidized the LDL (42).

This may explain why atherosclerotic lesions contain large amounts of bacterial and viral DNA. Macrophages in these lesions have been stimulated by oxLDL to scavenge bacteria and viruses from the blood.

OxLDL stimulates antibody formation, including antibodies against phosphorylcholine (PC), a compound found on a wide range of pathogens including bacteria, parasites, and fungi (45-49). Anti-PC antibodies help to prevent upper airway infections (50-53).

It is thought that oxidation of LDL is an important part of the host defense to infections. OxLDL inhibits cell entry of hepatitis C (59) and Plasmodium sporozite (60).

The role of Lp(a)

Lp(a) is essentially an LDL particle with an extra apo(a) molecule bound to the apoB100 molecule by a disulfide bridge.

Some insight into the immune functions of Lp(a) developed after considering the role of plasminogen. Many pathogens recruit human plasminogen and use it to penetrate tissue barriers, enabling them to invade tissue (70, 71, 72). For instance, group A streptococcus releases an enzyme called streptokinase that activates human plasminogen and promotes invasion (73). Lp(a) has anti-fibrinolytic activity and recruits plasminogen itself, reducing availability for pathogens. For instance, Lp(a) blocks streptokinase activity (75), inhibits Staphylococcus aureus activation of plasminogen.

Moreover, Lp(a) inhibits the inflammatory response to LPS. As there is great variation in Lp(a) levels among individuals (76), this may account for variability in inflammatory response to infections.

The Exception: Candida

HDL may promote fungal infections. A recent study found that infusion of reconstituted HDL enhances the growth of Candida (25).

LDL also seems to promote fungal infections. In LDL receptor knockout mice, which have high levels of LDL, there is decreased resistance to Candida (37, 38).

OxLDL also loses its normal anti-infective role against Candida. Worse, it inhibits production of antibodies against Candida albicans (63), thus actually hurting anti-fungal immunity.

Candida is an unusual pathogen that is unusually well-adapted to living in the human body. It has learned to turn an important part of human immune defense to its own advantage.

Conclusion

High serum cholesterol protects against a host of bacterial and viral infections and some parasites, but increases risk for Candida fungal infections.

Related Posts

Other posts in this series include:

References

[1] Han R. Plasma lipoproteins are important components of the immune system. Microbiol Immunol. 2010 Apr;54(4):246-53. http://pmid.us/20377753.

HDL and Immunity

HDL – high-density lipoprotein – particles are good for you: High HDL levels are associated with lower mortality overall and lower mortality from many diseases – not only cardiovascular disease but also cancer and infection.

People with high HDL are only one-sixth as likely to develop pneumonia [1], and in the Leiden 85-Plus study, those with high HDL experienced 35% lower mortality from infection [2].

Each rise of 16.6 mg/dl in HDL reduced the risk of bowel cancer by 22% in the EPIC study. [3]

In terms of overall mortality, in the VA Normative Aging Study, “Each 10-mg/dl increment in HDL cholesterol was associated with a 14% [decrease] in risk of mortality before 85 years of age.” [4]

This must be surprising to those who think HDL is only a carrier of cholesterol. The lipid hypothesis presumed that the function of HDL is to clear toxic cholesterol from arteries, cholesterol having evolved for the purpose of giving us heart attacks. HDL then brings cholesterol to the liver which disposes of it returns it to the blood via LDL (which evolved for the purpose of poisoning arteries with cholesterol, and giving HDL something to do). (Hat tip to Peter for this formulation of the lipid hypothesis.)

But there is an alternative hypothesis: that infections cause disease, and that HDL has an immune function. This hypothesis would explain why HDL protects against infections and against all diseases of aging.

Immune Functions of HDL

I got interested in immune functions of HDL upon reading an article in ScienceDaily last year (“How Disease-Causing Parasite Gets Around Human Innate Immunity,” Sept 13, 2010). The article states:

Several species of African trypanosomes infect non-primate mammals and cause important veterinary disease yet are unable to infect humans. The trypanosomes that cause human disease, Trypanosoma brucei gambiense and T. b. rhodensiense, have evolved mechanisms to avoid the native human defense molecules in the circulatory system that kill the parasites that cause animal disease….

Human innate immunity against most African trypanosomes is mediated by a subclass of HDL (high density lipoprotein, which people know from blood tests as “good cholesterol”) called trypanosome lytic factor-1, or TLF-1….

The parasite that causes fast-onset, acute sleeping sickness in humans, T. b. rhodensiense, is able to cause disease because it has evolved an inhibitor of TLF-1 called Serum Resistance Associated (SRA) protein…. T. b. gambiense resistance to TLF-1 is caused by a marked reduction of TLF-1 uptake by the parasite….

To survive in the bloodstream of humans, these parasites have apparently evolved mutations in the gene encoding a surface protein receptor. These mutations result in a receptor with decreased TLF-1 binding, leading to reduced uptake and thus allow the parasites to avoid the toxicity of TLF-1.

“Humans have evolved TLF-1 as a highly specific toxin against African trypanosomes by tricking the parasite into taking up this HDL because it resembles a nutrient the parasite needs for survival,” said Hajduk, “but T. b. gambiense has evolved a counter measure to these human ‘Trojan horses’ simply by barring the door and not allowing TLF-1 to enter the cell, effectively blocking human innate immunity and leading to infection and ultimately disease.”

So HDL is actually an immune particle carrying proteins that poison pathogens. The TLF-1 HDL subclass consists of those HDL particles carrying two anti-trypanosome proteins, apolipoprotein L-1 and haptoglobin-related protein. [5]

Any HDL particle can become an anti-trypanosome defender simply by acquiring and carrying these proteins.

It turns out that HDL can carry a great assortment of immune proteins. The orchestrator of HDL’s immune functions seems to be a circulating plasma protein called phospholipid transfer protein (PLTP), which forms complexes with immune molecules and then associates with apolipoprotein A-I (the primary HDL protein). PLTP brings 24 different immune molecules into HDL particles, including apolipoproteins such as clusterin (apoJ), coagulation factors, and complement factors. [6] These immune protein complexes add protein but not fat to HDL particles:

Unexpectedly, lipids accounted for only 3% of the mass of the PLTP complexes. Collectively, our observations indicate that PLTP in human plasma resides on lipid-poor complexes dominated by clusterin and proteins implicated in host defense and inflammation. [6]

It looks like HDL may not be primarily a carrier of cholesterol, but rather a carrier of antimicrobial proteins. Its cholesterol and lipids may serve, as the ScienceDaily article suggests, to make the HDL particle attractive to pathogens so that it may enter as a “Trojan Horse.”

HDL-associated immune proteins under strong selection

As pathogens evolve, immune proteins have to evolve. It turns out that apolipoprotein L-1, the immune protein that protects against trypanosomes, is under strong selection in both Africa and Europe.

The version selected in Europe does not protect against Trypanosoma brucei rhodesiense, cause of one of the African sleeping sickness diseases, but the version selected in Africa does. Unfortunately, the African version also increases risk of kidney disease – which may explain why African-Americans have higher rates of kidney disease than white Americans. [7]

So Africans have sacrificed kidney health for greater immunity against sleeping sickness. This suggests that African sleeping sickness may be a relatively recently evolved human disease.

HDL neutralizes toxins

HDL binds bacterial endotoxins, especially lipopolysaccharide (LPS), and neutralizes their toxicity. As a result, people with high HDL have substantially less release of tumor necrosis factor-alpha (TNF-α) during infection. [8]

TNF-α is an inflammatory molecule that stimulates the acute phase response to infections. Levels of C-reactive protein are a good index of TNF-α levels, so generally speaking high HDL will lead to low TNF-α and low CRP.

What’s the best HDL profile?

It should be desirable to have more HDL particles. Since each HDL particle is capable of poisoning a pathogen, the more you have, the stronger your immune defenses.

However, the weight of each HDL particle is likely to be an indicator of infection severity. An infection-free person will have few immune proteins to pick up; the HDL particles will be fat-rich and buoyant. But a person with extensive infections will have heavier HDL particles freighted with immune proteins.

Conventional tests in the doctor’s office measure the weight of HDL in mg per deciliter of blood. Since having more HDL particles (which raises the weight) is good, but having heavy HDL particles indicates infection which is bad, mass is not the best measure of HDL status. We would expect the number or concentration of HDL particles to provide a better indicator of health.

Indeed, this appears to be what is observed. The most important determinant of HDL status is the number of HDL particles:

The association between HDL size and CAD risk was abolished on adjustment for apolipoprotein B and triglyceride levels (adjusted odds ratio, 1.00 [95% CI, 0.71 to 1.39] for top vs. bottom quartile), whereas HDL particle concentration remained independently associated with CAD risk (adjusted odds ratio, 0.50 [CI, 0.37 to 0.66]). [9]

Conclusion

HDL particles are “Trojan Horses” that attack pathogens and neutralize their toxins.

If you want to remain free from infectious diseases – which is to say, all diseases – to a ripe old age, it’s important to make your HDL particles numerous.

On Thursday, I’ll discuss ways to do that.

References

[1] Gruber M et al. Prognostic impact of plasma lipids in patients with lower respiratory tract infections – an observational study. Swiss Med Wkly. 2009 Mar 21;139(11-12):166-72. http://pmid.us/19330560.

[2] Berbée JF et al. Plasma apolipoprotein CI protects against mortality from infection in old age. J Gerontol A Biol Sci Med Sci. 2008 Feb;63(2):122-6. http://pmid.us/18314445

[3] van Duijnhoven FJ et al. Blood lipid and lipoprotein concentrations and colorectal cancer risk in the European Prospective Investigation into Cancer and Nutrition. Gut. 2011 Mar 7. [Epub ahead of print] http://pmid.us/21383385.

[4] Rahilly-Tierney CR et al. Relation Between High-Density Lipoprotein Cholesterol and Survival to Age 85 Years in Men (from the VA Normative Aging Study). Am J Cardiol. 2011 Apr 15;107(8):1173-7. http://pmid.us/21296318.

[5] Kieft R et al. Mechanism of Trypanosoma brucei gambiense (group 1) resistance to human trypanosome lytic factor. Proc Natl Acad Sci U S A. 2010 Sep 14;107(37):16137-16141. http://pmid.us/20805508.

[6] Cheung MC et al. Phospholipid transfer protein in human plasma associates with proteins linked to immunity and inflammation. Biochemistry. 2010 Aug 31;49(34):7314-22. http://pmid.us/20666409.

[7] Genovese G et al. Association of trypanolytic ApoL1 variants with kidney disease in African Americans. Science. 2010 Aug 13;329(5993):841-5. http://pmid.us/20647424.

[8] Henning MF et al. Contribution of the C-terminal end of apolipoprotein AI to neutralization of lipopolysaccharide endotoxic effect. Innate Immun. 2010 May 25. [Epub ahead of print] http://pmid.us/20501516.

[9] El Harchaoui K et al. High-density lipoprotein particle size and concentration and coronary risk. Ann Intern Med. 2009 Jan 20;150(2):84-93. http://pmid.us/19153411.

What Telomeres Tell Us About Human Disease

We believe that almost all diseases are caused by food toxins, malnutrition, and infections. Toxic and malnourishing diets depress immunity and make infections worse.

Once you have this point of view in mind, supporting evidence is everywhere.

Take, for example, a story today in ScienceDaily about depression. Depression is not just a mental illness, but a whole body illness:

Previously considered a mental illness affecting only the brain, major depressive disorder, or MDD, now is believed to be tied to significant physical damage outside the brain, explained Wolkowitz. For example, depressed individuals are more likely to develop the diseases of advanced age, including diabetes, heart disease, osteoporosis, stroke and dementia. [1]

The ScienceDaily article summarizes new research showing a link between depression and telomere length in white blood cells. Telomeres are the end-caps on chromosomes. If telomeres become too short, DNA becomes unstable, genetic integrity is lost during cell division, and cells become senescent (crippled beyond hope of recovery) or commit apoptosis (suicide).

An enzyme called telomerase lengthen telomeres. Normally, most cell types maintain a balance between telomerase levels and replication so that telomeres are maintained at healthy lengths throughout normal cell life.

It turns out that in depressed people, white blood cell telomeres are shorter than in normal people, even though telomerase is more active. [2] Moreover, for a given telomere length, the more telomerase activity, the more depressed the patient. [3] Finally, telomerase activity predicts which patients will recover: patients who recovered from depression had the highest telomerase activity along with their short telomeres. [3]

This suggests that some exogenous factor, not part of normal human biology, is shortening telomeres in the depressed; and that the body’s capacity to resist this factor determines its ability to recover from depression. If the body can overcome the exogenous factor, eliminating its ability to shorten telomeres, then the depression goes away.

What could this exogenous factor be?

Telomeres and Viral Infections

Well, it happens that a number of viruses shorten telomeres in white blood cells.

Cytomegalovirus reduces telomere length in T cells:

After primary CMV infection, we observed … a steep drop in telomere length. Moreover, we found in a cohort of 159 healthy individuals that telomere shortening was more rapid in CMV-seropositive individuals and correlated with the amount of differentiated T cells in both CD4(+) T cells and CD8(+) T cells. [4]

The Epstein-Barr virus (EBV) is carried by more than 90% of the adult world population and has been implicated in several human cancers. [5]  EBV disrupts the caps of telomeres, creating dysfunctional telomeres: “The telomere capping protein TRF2 was partially displaced from telomeres in EBV-infected cells, suggesting an EBV-mediated uncapping problem.” [5]

HIV also shortens telomeres: “Analysis of telomere length in HIV-1 exposed U373 showed a statistically significant telomere shortening” [6]. Interestingly, telomere shortening by HIV was reversed by providing N-acetylcysteine, suggesting that NAC should be beneficial for AIDS and possibly other chronic viral infections.

Connections between viruses and telomere loss run deep. In fact, it has been proposed that cellular senescence, the usual outcome of telomere loss, evolved as an anti-viral defense mechanism. [7]

If viruses cause major depression, then they probably also cause the diseases associated with depression. After all, they have to infect the rest of the body before they can infiltrate the brain. So we should look at viruses and other systemic diseases, and see if the connection with telomere shortening holds in those diseases.

Cancer and Blood Cell Telomeres

There is steadily increasing evidence implicating viruses as causes of cancers. Wikipedia (“Infectious causes of cancer”) has a summary:

Worldwide approximately 18% of cancers are related to infectious diseases…. Viruses are usual infectious agents that cause cancer but bacteria and parasites may also have an effect.

A virus that can cause cancer is called an oncovirus. These include human papillomavirus (cervical carcinoma), Epstein-Barr virus (B-cell lymphoproliferative disease and nasopharyngeal carcinoma), Kaposi’s sarcoma herpesvirus (Kaposi’s Sarcoma and primary effusion lymphomas), hepatitis B and hepatitis C viruses (hepatocellular carcinoma), and Human T-cell leukemia virus-1 (T-cell leukemias). Bacterial infection may also increase the risk of cancer, as seen in Helicobacter pylori-induced gastric carcinoma.[2] Parasitic infections strongly associated with cancer include Schistosoma haematobium (squamous cell carcinoma of the bladder) and the liver flukes, Opisthorchis viverrini and Clonorchis sinensis (cholangiocarcinoma).[3]

According to some authors, viruses are one of the most important risks factor for cancer development in humans, second only to tobacco use.[4]

This summary overlooks some known associations (such as that between XMRV and prostate cancer, see our post Retroviruses and Chronic Fatigue Syndrome, Aug 24, 2010) and evidence that tobacco use raises cancer risk primarily in people with a high viral infectious burden (see ref. [10] below). Although only 18% of cancers may yet have been confidently linked to infectious pathogens, it is not impossible that 100% of cancers are caused by as-yet-mostly-unidentified infectious pathogens, probably mainly viruses.

If viruses cause cancers, and if viruses shorten white blood cell telomeres, then we would expect cancer patients to have shortened telomeres.

Well, gastric cancer patients have shorter white blood cell telomeres, and being in the bottom half of telomere length doubles gastric cancer risk:

GC patients had significantly shorter average telomere length than matched controls (mean +/- SD 0.89 +/- 0.19 vs 1.06 +/- 0.25, P < 0.001)…. We found that short telomere length was associated with a significantly increased GC risk (adjusted odds ratio = 2.14, 95% confidence interval = 1.52-2.93)…. Collectively, our findings provide the first evidence linking the short telomere length in peripheral blood lymphocytes to elevated GC risk. [8]

Lung cancer patients have shorter white blood cell telomeres, and being in the bottom half of telomere length triples lung cancer risk:

Telomere length was significantly shorter in lung cancer patients than in controls (mean +/- standard deviation: 1.59 +/- 0.75 versus 2.16 +/- 1.10, P < 0.0001). When the subjects were categorized into quartiles based on telomere length, the risk of lung cancer was found to increase as telomere length shortened (P(trend) < 0.0001)…. [I]ndividuals with short telomeres were at a significantly higher risk of lung cancer than those with long telomeres (adjusted odds ratio = 3.15, 95% confidence interval = 2.12-4.67, P < 0.0001). [9]

Bladder cancer patients also had short white blood cell telomeres. Being in the bottom quarter of telomere length increases risk 4.5-fold, 6.3-fold for smokers:

Patients with bladder cancer displayed significantly shorter telomeres than control subjects (P = 0.001). Median telomere length ratio was 0.95 (range 0.53-3.2) for cases and 1.1 (0.51-2.4) for controls. Moreover, the adjusted odds ratio (OR) for bladder cancer was significantly increased in the quartile with the shortest telomere length OR = 4.5 [95% confidence interval (CI) 1.7-12]. [10]

Same story with head and neck cancer [11], renal cancer [12], breast cancer [13], and probably also thyroid cancer [14].

Cardiovascular Disease

A weakness of those cancer studies is that they only looked at blood cell telomeres and the presence of cancer; they didn’t also measure viral burden, for instance by looking for antibody seropositivity.

So I was pleased to find a study that did that in coronary heart disease. Again, white blood cell telomeres were shorter in heart disease patients:

Telomere length (TL) was approximately 0.5 kilobases (kb) shorter in leukocytes from patients with CHD than in their age-matched control subjects….

TL shortening was particularly pronounced in CD8+CD28(-) T cells obtained from cytomegalovirus-seropositive CHD patients. [15]

So cytomegalovirus may be involved in coronary heart disease.

The reason all these studies have looked at white blood cells is because it is easy to get blood samples. But sometimes it is possible to get samples from diseased and normal tissues and do a direct comparison.

That was done in this study of atherosclerotic plaques:

Arterial segments which did not develop atherosclerosis such as the saphenous vein and internal mammary artery, had longer telomere length than aortic segments. On the other hand, telomere length was shorter in aortic tissues which presented atherosclerotic lesions compared to corresponding tissues without atherosclerotic lesions. These results also suggest tissue regulation of telomere size by local factors likely related to oxidative stress responses.

So the normal vessels have long telomeres, indicating an absence of viral infections, but the atherosclerotic plaques have short telomeres, suggesting of high infectious burden.

Conclusion

Telomere shortening is probably a marker of infectious burden, especially of viral infections. Telomere shortening in blood cells is associated with major depression, cancer, heart disease, and probably nearly every other disease.

Diseases probably result from a combination of factors, but a heavy burden of chronic infectious pathogens is probably almost always one of them. These pathogens are usually little more than parasites, sapping nutrients from human cells and disabling their immune defenses. But combined with toxic and malnourishing diets, they cripple the body and shorten lifespan.

The association of shortened telomeres with shortened lifespan may be due to the life-shortening effects of infections.

This is why the immunity-enhancing dietary steps discussed in Step Four of our book are so central to a long and healthy life. We cannot avoid exposure to these pathogens. But we can keep their numbers down, so that they do minimal harm to us throughout life.

References

[1] University of California – San Francisco (2011, April 6). Link between chronic depression and accelerated immune cell aging. ScienceDaily. Retrieved April 7, 2011, from http://www.sciencedaily.com/releases/2011/04/110405151223.htm.

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