Archive for décembre 2015

More on diabetes and malaria from Palestine

décembre 18, 2015

n diabetes and malaria from PalestineAs stated in previous blogs diabetes is on the rise everywhere. It is a debilitating and often fatal disease per se but it also increases the incidence of malaria because higher glucose contents in the blood are a fertile terrain for Plasmodium falciparum.
It is the general belief that malaria patients are poor in antioxidant defenses and that supplementation with antioxidants (vitamins, polyphenols) will alleviate the severity of malaria infections. It is thus surprising that the University of Al Quds finds that the total antioxidant status in type 2 diabetic patients in Palestine in significantly higher compared to control subjects. The study involved 212 diabetic subjects and 208 normal subjects (AT Kharroubi et al., J Diabetes Research, 2015 ID461271).
A similar finding had already been made in Romania on a reduced number of 15 patients: the total antioxidant capacity of plasma increased in type 2 diabetes (O Saviu et al, J Internat Med Res. 2012, 40, 709-716).
Already in 1999 it had been found that in diabetic condition antioxidant enzyme levels are elevated (M Ramanathan et al., Indian J Exp Biol 1999, 37, 182-3). It is generally accepted that reactive oxygen species and oxidative stress impair beta-cell function in the pancreas and reduce insulin secretion. Pancreatic islets are known for their extremely low antioxidative defense status and their unusual susceptibility to ROS (E Gurgul et al., Diabetes 2004, 53, 2271-78). And any increase in ROS can markedly impair insulin secretion.
Confronted with low levels of insulin, which has anti-inflammatory properties (Aljada et al., Metab Clin Exp 55, 2006, 1177-85), diabetic beta-cells try self-protection against oxidative stress through an adaptive up-regulation of their antioxidant defenses (Gregory Lacraz et al, PLoS ONE 2009, 4-8, e6500). But often this protection is not sufficient and it is often proposed to supplement antioxidants in the treatment of diabetes. A review published in 2011 reviews all human clinical trials where antioxidants were studied as an adjuvant to standard diabetes treatment. The authors came to the surprising conclusion that there is not any established benefit for antioxidants use in the management of diabetic complications. They interfer with the physiologic redox balance. Therefore, routine vitamin of mineral supplementation should not be generally recommended (S Golbidi et al, Curr Diabetes Rev 20117, 106-25).

One of the neglected side effects of diabetes is the generation of large quantities of hydrogen peroxide.
Healthy pancreatic beta-cells exhibit a dramatic response to nutrients and glucose through hypersecretion of insulin in order to maintain energy homeostasis. Many studies have suggested that chronic exposure of pancreatic beta-cells to high levels of glucose may contribute to impaired beta-cell function, leading to the production of ROS. Intriguingly, compared to other tissues, beta-cells have a lower abundance of antioxidant defense such as superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPx). The ROS produced include superoxide and hydroxyl radicals. These may subsequently be converted to hydrogen peroxide (Y Ihara et al., Diabetes. 1999 , 48 927-32). A study from Tunesia shows that the hydrogen peroxide concentration in plasma is increased fourfold in type 2 diabetes compared to controls (A Msolly et al., J Cardiovascul Disease, 2013, 1, 48-51). It was based on 200 confirmed type 2 diabetes patients and 200 controls recruited in the regional blood transfusion center of Sousse. There was a strong positive linear correlation between glycated hemoglobin and hydrogen peroxide, between free fatty acids and hydrogen peroxide concentration and a negative correlation between quantitative insulin index and hydrogen peroxide. Another paper documents that insulin treatment reduces the hydrogen peroxide concentration in blood (A Bravard et al., Am J Physiol Endocrinol Metab, 2011, 300, E581-E591).
At sites of inflammation hydrogen peroxide appears to modulate the inflammatory process and inactivates NFκB. Due to its permeability in many tissues, it operates as an intracellular and intercellular messenger, but at high concentrations it becomes toxic, especially in insulin producing cells known for their extremely low antioxidant equipment against hydrogen peroxide (B Halliwell et al., FEBS Letters 2000, 486, 10-13). Hydrogen peroxide could also plays a role in the regulation of renal function. Renal medullary hydrogen peroxide production is increased in diabetics (D Patinha et al., Life Sci, 2014, 108, 71-9).
Hydrogen peroxide has another side effect. It decreases endothelial nitric oxide synthase NOS promoter activity (Kumar S et al., DNA Cell Biol. 2009, 2:119-29). It is well documented that NOS and NO generated by this enzyme have important endothelial functions and its inhibition may explain most of the cardiovascular problems generated by diabetes.

Several biomarkers of metabolic acidosis, including lower plasma bicarbonate have been associated with insulin in cross-sectional studies. A team from Canada conducted a study called the “Nurses Health Study”. Plasma bicarbonate was measured in 630 women who did not have type 2 diabetes mellitus at the time of the blood draw in 1989 but developed the disease during 10 years of follow-up. The outcome was that higher plasma bicarbonate levels were associated with lower odds of incident type 2 diabetes mellitus (EI Mandel et al., CMAJ, 2012, 184, E179)
The pancreas generates a lot of sodium bicarbonate. The rate of decomposition of hydrogen peroxide has been measured in aqueous sodium carbonate solutions (0.1-1.0 M). It is decomposed in a few minutes and 10 times faster than in a sodium hydroxide solution (HH Lee et al., 2000, Tappi Journal)(U von Gunten et al, Ozone Science and Engineering Journal, 2000, 22, 305-328).
The role of bicarbonate and hydrogen peroxide in diabetes deserve much more research. Because it has an impact on malaria too. As the University of Quds has shown bicarbonate strongly contributes to the inhibition of beta-hematin crystallization (Suhair Jaber et al., J Pharmacy Pharmacol 2015, 3, 63-72).

It is astonishing and frustrating that the impact of diabetes on Plasmodium proliferation is known since more than 100 years. In 1912 Bass and Johnson reported that the addition of glucose was necessary for successful in vitro cultivation of the human malaria parasites Plasmodium falciparum and vivax. However, blood from a diabetic person was successfully used in the culture medium without addition of glucose. They also reported that the amount of quinine sufficient to control malaria infections was ineffective in this case. As a result of these observations they came to the conclusion that the elevated blood sugar from a diabetic patient provided a medium which could better support the growth and reproduction of parasites than could the blood of a non-diabetic person.

Pierre Lutgen
Mutaz Akkawi
17 december 2015.


Does artesunate promote malaria transmission?

décembre 12, 2015

The amino acid arginine is the only molecule in our food known to generate nitric oxide NO via NOS enzymes. It plays a key role in malaria therapy and cerebral malaria as described in previous blogs on NO derived from arginine is not only lethal for merozoites but also for gametocytes. NO is efficient against other diseases like leishmaniasis or filariasis (R O’Connor et al., Infection and Immunity, 2000, 68, 6101-6107).

The inducible nitric oxide synthase (iNOS) is NF-kB-regulated. Many botanical medicinal herbs and drugs derived from these herbs have been shown to have effects on the NO signaling pathway.

Polysaccharides may enhance this production, through a potent macrophage/monocyte activation. This has been demonstrated for acidic polysaccharides from Artemisia tripartita (Gang Xie et al., Photochemistry, 2008, 69, 1359-71), from Tanacetum vulgare (Gang Xie et al., Int Immunopharmacol 2007, 7, 1639-50), from mushrooms (JJ Volman et al., Mol Nutr Food Res, 2010, 54, 268-76). Also for Ginseng saponins and polysaccharides through the activation of NF-kB in macrophages (JY Kim et al., Biosc Biotechnol Biochem. 2005, 69, 891-895). But the polysaccharide with the strongest stimulation of NO synthesis is inulin (HN Koo et al, J Nutr Biochem, 2003, 14, 598-605).) The activation of NF-kB by inulin plays a key role (F Bahmani et al., J Am Coll Nutr, 2015 2, 1-8) and may explain the antimicrobial and tumoricidal activity. This explains why current research is directed to develop inulin as an adjuvant for influenza vaccines, hepatitis B vaccines, malaria vaccines and anti-tumour drugs (D Silva et al., Immunol Cell Biology 2004, 82, 611-16).

On the opposite, vitamins, particularly vitamin E and C inhibit iNOS and are detrimental for this reason during a malaria infection (see « Vitamin C and Malaria : beware ! » on Mar 15 2015).

Coumarins, particularly scopoletin, strongly inhibit iNOS (Tien-Ning Chang et al., Evidence Based Complement Alternat Med, 2012, 595603). Its action to this effect is as strong as that of vitamin C (Xiujuan Yao et al., Int Immunopharmac. 2012, 14, 434-462). Quercetin is a NO inhibitor too, but scopoletin is ten times stronger (Aneta Janecki, Thesis, 2012, Universität Berlin). It needs to be mentionned at this stage that all genotypes of Artemisia annua are poor in quercetin (Laboratory Celabor, personal communication). Scopoletin is well present in most species of the Artemisia family. The NO inhibitory effect by scopoletin was demonstrated in Artemisia feddei (TH Kang et al., Planta Med 1999, 65, 400-3). It was even patented for Artemisia annua (US 6337095, 2002). The authors find higher concentrations of scopoletin in the stems than in the leaves (0.3 vs 0.2%). Very important in this context appears the fact that Artemisia annua from Luxembourg genotype only contains 0.02 % of scopoletin versus 0.2 % for Artemisia annua of the high artemisinin hybrid (Rosine Chougouo, Thesis, Université des Montagnes, Cameroon, 2011) and (Laboratory Celabor, personal communication). This to some extent may explain its excellent performance in clinical trials.

But sesquiterpene lactones even appear to be stronger NO inhibitors. This was first evidenced in 1997 for Artemisia ludoviciana in Mexico (P Bork et al., FEBS letters, 1997, 402, 85-90). The sesquiterpene lactones parthenolide and isohelenin prevented NF-kB activation completely as low as 5 microM. A similar effect was confirmed for the sesquiterpene lactone helenalin (G Lyss et al., J Biol Chem. 1998, 273, 33508-16). Ergolide, a sesquiterpene lactone from Inula britannica inhibits iNOS in macrophages (Jeung Whan Han et al., Brit J Pharmacol 2001. 133, 503-12). A similar effect for artemisinin was found in Italy (E Aldieri et al., FEBS letters, 2003, 552, 141-144). A more extensive study on 5 artemisin derivatives at the University of Heidelberg showed that among the five in a mouse macrophage model artesunate revealed the highest ability to inhibit generation of NO (J.Badireenath et al., Nitric Oxide, 2008, 19, 184-191).

In our own research we had found that in vitro pure artemisinin pretreatment strongly inhibited NF-kB activation (Dr Mario Dicato, personal communication 2008). We have performed extensive chemical analysis of the Artemisia annua produced at Luxembourg in comparison with the Mediplant hybrid variety. In all laboratories (Laboratoire National de la Santé in Luxembourg, Celabor in Belgium) we confirmed that Artemisia annua from Luxembourg is poor in artemisinin (0.1%) and scopoletin (0,02%) compared with 1.2% artemisinin and 0.2 % scopoletin in the hybrid. In the froth test the Artemisia from Luxembourg is also much richer in saponin than the Artemisia hybrid from Cameroon. We have confirmed that the Luxembourg genotype has better anti-inflammatory properties i.e.lower IL-6 and IL-8 activation PM de Magalhaes et al., Food Chemistry, 2012, 134, 864-71). In all clinical trials we have run in several African countries with infusion or capsules with Artemisia annua from Luxembourg the cure rate was >95%. In the literature we find two clinical trials with the Anamed high artemisin herb. In both cases the cure rate is much lower, around 75% and the recrudescence is high (CH Blanke, G Naisabhaet al., Tropical Doctor, 208, 38 . 113.6)(MS Müller et al., Trans R Soc Trop Med Hyg 2004, 98, 318-21)

We are currently running clinical trials to study the effect of different Artemisia species on gametocytogenesis.
Besides the inhibition of NO which leeds to the proliferation of gametocytes, artemisinin derivatives are strong immunosuppressors (AF Tawfik et al., Int J Immunopharmacol. 1990, 12 385-389) opening a wide angle door for recrudescence and reinfection.

The result of greed and stubborness : a Pyrrhic victory for Bigpharma and WHO, but a genocide looming for Africa.
Pierre Lutgen
3 december 2015