Therapeutic Cloning

In April of 2014, a major breakthrough was established in human stem cell research.  In that month two laboratories independently reported the successful production of human embryonic stem (ES) cells derived from skin cells cultured in the laboratory ( in-vitro).  This a significant achievement in that an application of this technique could be exceedingly useful in the production of replacement tissues in-vitro for the treatment of such diseases as  juvenile (type 1)diabetes and Parkinson’s disease – both of which arise from the precipitous loss of the cells required to manufacture insulin and dopamine, respectively.  The added benefit of such an approach is that since the cells can be derived from the patient being treated, graft rejection is no longer an issue.

The cloning technique that was employed is referred to as somatic cell nuclear transfer (SCNT); an analogous method was used to clone the now famous sheep, Dolly.  It was subsequently applied to cloning cattle, mice dogs and other animals.  There is no desire among members of the scientific community to apply this approach to cloning humans but rather to produce early-stage human embryos from which ES cells could be derived.   Heretofore, human cells have been problematic in regards to cloning.

Dr. Dong Ryul Lee and his colleagues at CHA University in Seoul, Korea successfully created human ES cells from the skin cells of two individuals – men ranging in ages from 35 to 75 years old.  Later in April of the same year, Dr. Dieter Egli and his collaborators from the New York Stem Cell Foundation (NYSCF) Research Institute used the skin cells of a young woman patient suffering from type 1 diabetes to also produce ES cells and then induced these cells to become insulin-producing cells.  Following this momentous result, the investigative team then introduced these insulin-producing  cells into experimental mice where it was shown that the hormone insulin was made in-vivo.  This latter finding has yet to be published.

The overall technique that was employed in Egli’s laboratory is briefly described below –

·         DNA is removed from an unfertilized human egg cell (oocyte)

·         The DNA from skin cells grown in-vitro from a patient with type 1 diabetes is transferred to the oocyte that had its own DNA removed

·         If the transfer is successful, the oocyte begins to divide

·         At a very early point in cell division – the Blastocyst stage – ES cells are harvested

·         Finally, these cells are coaxed into differentiating into insulin-producing pancreatic cells.

These results are very exciting; however, the possible application to human disease faces considerable obstacles that need to be addressed.  Nonetheless, it is a significant step in the goal to successfully treat implacable diseases such as type 1 diabetes and Parkinson’s through tissue –replacement therapies. 

Antibiotic Treatment for Yaws – A Plan to Eradicate the Disease

Yaws is an infectious disease that is prevalent among human populations in the tropical regions.  It is a disfiguring ailment that impacts hundreds of thousands of individuals.   There are not many fatalities associated with yaws; however, it produces considerable suffering among those afflicted, especially children.  The primary symptoms include serious skin ulcers especially on the face, back, buttocks and legs.  It has been reported that approximately 100,000 new cases show up every year, of which 75% are children.  Although most suffers heal over time with no chronic side effects, about 10% suffer from erosion of connective tissues including cartilage and bone.

The pathogen responsible for yaws is Treponema pallidum - an organism closely related to the infectious agent that causes syphilis.  However, unlike syphilis, yaws is not sexually transmitted.  Yaws is readily treated by the use of antibiotics.  An attempt was made in 1952 to completely eradicate this disease using benzathine penicillin in over 46 countries.  As a result of this intensive effort, disease incidence had dropped by 95 percent, but by the 1970s, the disease began to return and ultimately reached current levels.

In 2012, a new plan has emerged, sponsored by the World Health Organization (WHO), to eradicate the disease – referred to as the Morges Plan.  The ambitious strategy involved is to use the relatively inexpensive antibiotic azithromycin requiring only one oral dose.  In addition to administering this drug to those individuals infected, the plan is to include at least 90% of the population in the infected areas.  This strategy is designed to treat not only those individuals who are clearly ill but also those with latent infection and who are asymptomatic.

Epidemiologists are hopeful that this scheme might prove successful, but are also aware of the many obstacles that have to be overcome including the magnitude of the administrative task involved, the scope of the project and its cost. 

The Role of Dopamine Deficiency in Obesity

Dopamine, a potent neural transmitter found in the human brain, has been implicated in a variety of reward circuits including eating.  It has been well established that the production of dopamine in the dorsal striatum of the brain markedly increases during feeding in both rodents and humans.  Controlled levels of dopamine production are also required for normal eating behavior.  These finding are consistent with the known role that dopamine plays in the reward circuitry of the brain. 

Given this critical role played by dopamine in relation to eating behavior, it has been suggested that overeating may be a compensation for a diminished function in regard to the reward circuitry dependent upon dopamine levels.  In fact, dopamine receptor deficiency has been reported in studies involving obese patients.  This is certainly consistent with significantly reduced response to food stimuli in individuals suffering from obesity.  Additionally, rats that were purposefully depleted of dopamine receptors demonstrated obsessive feeding behavior.

The physiological mechanism linking incessant high-fat intake to dopamine deficiency has been unclear.   Dr. Luis A. Tellez and his colleagues at the John B Pierce Laboratory in New Haven, CT focused their research in an attempt to elucidate the physiological mechanism linking obesity and dopamine levels in the brain.  In their experimental approach, they administered oleoylethanolamine to mice fed a diet rich in fat.  Oleoylethanolamine is, in fact, a lipid messenger whose production is suppressed in individuals subjected to high-fat dietary intake.  Upon administration of this lipid messenger, the experimental mice demonstrated increased levels of dopamine release.   Exposure of these mice to oleoylethanolamine also reinstated normal eating habits.

From these data, the authors of this report concluded that high-fat dietary intake as evidence of gastrointestinal malfunction seems to play a pivotal role in dopamine deficiency and, most importantly, restoring gut-related lipid messenger may  increase the reward feedback mechanism in regard to the intake of healthier lower-fat food.    

Mechanism of Immune Reponses Related to Allergic Airway Diseases such as Asthma

Asthma is a chronic condition that adversely impacts the airway passages. This disease presents as episodic events typified by difficulty in breathing as a result of obstruction of the airways as well as inflammatory responses. This condition is provoked by response of the immune system to allergens. The inflammatory response manifests itself by the enhanced production of interleukin-4 (IL-4), increased activity of a particular subset of T helper lymphocytes (TH2) and serum immunoglobulins. A link has also been established between proteinases – enzymes that cleave proteins, the immune Toll-like receptor 4 (TLR4) and asthma. These proteinases that have been shown to initiate TH2-mediated allergic reactions are secreted by fungi, pollen and dust mite antigens.

 A full understanding of the underlying factors that trigger asthmatic episodes would, of course, be invaluable in developing therapeutic strategies to treat this illness. Dr. Valentine Ongeri Millien and colleagues from the Translational and Molecular Medicine Program at Baylor College of Medicine at Houston Texas have made some important discoveries in this light. The research efforts of this investigative team have established that airway- derived proteinases trigger allergic disease and innate immunity against fungal infection. Furthermore, they have shown that these particular outcomes were a direct result of the breakdown of fibrinogen, an essential clotting factor, by these proteinases. It is the products of this breakdown that bind to TLR4 on both epithelial cells that line the airways and to macrophages – a type of circulating cell of the immune system that has the role of ingesting invading infectious agents. From these results, it seems apparent that inflammation of the airways that is characteristic of asthma is a direct result of the immune antifungal defense strategy.

The Elucidation of this mechanism may prove to be invaluable in terms of developing therapeutic strategies for the treatment of allergen-induced pulmonary diseases such as asthma. In fact, this group when on to show that the use of hirudin, a drug that functions as a potent protease inhibitor, can lessen the severity of allergic lung disease. This may prove to be a very important finding.

The Role of Pathogens in Tumorigenesis

The Role of Pathogens in Tumorigenesis

A Long Noncoding RNA Involved in Activation and Repression of Immune Genes

The human body’s immune-based response to the presence of deleterious microbes engages a very intricate and complex system that has evolved over many millions of years.  In this regard, we share many aspects in common with the entire vertebrate world.   Immunity can be regarded as consisting of two categories of responses – innate and adaptive.  In the present discussion, we will focus our attention on the innate immune system.

   

The innate immune system has the extraordinary capability of recognizing a wide range of microbes and inducing the production of many proteins that become engaged in an elaborate defense against the invading organism and ultimately involve the adaptive response.  Over many years of concerted research efforts, it has been shown that the molecular basis of this recognition system involves a host of genetically determined pattern recognition receptors – an example being the so-called “Toll-like receptors” (TLRs).  It is the binding to these receptors that triggers a cascade of immune responses.

It has recently been discovered that long non-coding RNAs (lncRNAs) play a significant role in this process.  As a class of biologically active compounds, literally thousands of these lncRNAs have been discovered in mammalian genomes and they have been shown to regulate gene expression in a number of biological processes.   It is, therefore, of some interest to determine whether lncRNAs play a role in the innate immune system as well.

The work of Dr. Susan Carpenter and her colleagues at the Division of Infectious Diseases and Immunology in the Department of Medicine at the University of Massachusetts Medical School has helped answer this question.  The efficacy of the antimicrobial innate defense is wholly dependent upon the induction of inflammatory gene expression.   Implicated in this complex response is the activation of transcription factors, transcription co-regulators and other factors.

Carpenter and her associates have found that the activation of TLRs – as described previously – induce the expression of many lncRNAs and one of these – lincRNA-Cox2 – has been shown to be involved in the activation and repression of distinct groups of immune-related genes.  This finding is significant in that it helps to further elucidate the mechanism that underlies the innate immune response.

Hypercholesterolemia and Breast Cancer

It has been clearly established that obesity and the metabolic syndrome are risk factors for estrogen receptor (ER) positive breast cancer – a type of breast cancer in which the tumor cells bind the female hormone estrogen – in postmenopausal women.

This increased risk has been attributed to a number of factors including:

• Increased levels of insulin and insulin-like substances in the circulation
• Localized production of estrogen in adipose (fat) tissues
• The role of inflammatory substances like cytokines in enhancing tumor cell growth.

Recent studies have implicated hypercholesterolemia – high levels of cholesterol in the bloodstream – as a definitive risk factor in for estrogen receptor (ER) positive breast cancer in postmenopausal women.  Hypercholesterolemia correlates with obesity and together these conditions have been shown to increase morbidity.  In addition, it has been shown that disease-free survival is improved in those patients who were taking statins prior to diagnosis.  Statins are members of  a class of compounds designed to inhibit cholesterol production in the liver

Although it has been proposed that statins exert their effect by directly inhibiting tumor cell growth, the amount of circulating statins in individuals who use the drug at the typical dose level is far below the amount required to inhibit cancer cell growth as has been reported in–vitro  (in the laboratory).  Therefore, there must be some other explanation.  An understanding of the role of cholesterol in breast cancer pathology would be invaluable in regards to possible therapeutic approaches.  Dr. Eric R. Nelson and his colleagues from the Department of Pharmacology and Cancer Biology at the Duke Institute for Genome Sciences and Policy at Duke University in Durham, NC, have made a significant contribution in this regard.

Nelson and his group have shown that the actual substance that seems to be responsible for accelerating the growth of breast cancer tumors is a metabolite of cholesterol – 27-Hydoxycholesterol (27HC).  Furthermore, 27HC is a product of the action of the enzyme cytochrome P450 oxidase (CYP27A1).   The expressed level of CYP27A1 correlates well with tumor grade in breast cancer patients and inhibition of this enzyme had a positive impact on the suppression of tumor growth.

 

From this data, the authors conclude that lowering the level of circulating cholesterol or inhibiting its conversion to 27HC represent effective strategies in the treatment of estrogen receptor (ER) positive breast cancer in postmenopausal women.  This is, indeed, an important finding.