Melatonin may decrease risk for and aid treatment of COVID-19 and other RNA viral infections.

A recent retrospective study has provided evidence that COVID-19 infection may be notably less common in those using supplemental melatonin. It is suggested that this phenomenon may reflect the fact that, via induction of silent information regulator 1 (Sirt1), melatonin can upregulate K63 polyubiquitination of the mitochondrial antiviral-signalling protein, thereby boosting virally mediated induction of type 1 interferons. Moreover, Sirt1 may enhance the antiviral efficacy of type 1 interferons by preventing hyperacetylation of high mobility group box 1 (HMGB1), enabling its retention in the nucleus, where it promotes transcription of interferon-inducible genes. This nuclear retention of HMGB1 may also be a mediator of the anti-inflammatory effect of melatonin therapy in COVID-19-complementing melatonin's suppression of nuclear factor kappa B activity and upregulation of nuclear factor erythroid 2-related factor 2. If these speculations are correct, a nutraceutical regimen including vitamin D, zinc and melatonin supplementation may have general utility for the prevention and treatment of RNA virus infections, such as COVID-19 and influenza.

Azithromycin and glucosamine may amplify the type 1 interferon response to RNA viruses in a complementary fashion.

Previous research demonstrates that, in clinically relevant concentrations, azithromycin can boost the ability of RNA viruses to induce type 1 interferon by amplifying the expression and virally-mediated activation of MDA5. O-GlcNAcylation of MAVS, a down-stream target of MDA5, renders it more effective for type 1 interferon induction. High-dose glucosamine administration up-regulates O-GlcNAcylation by increasing the cellular pool of UDP-N-acetylglucosamine. Hence, it is proposed that joint administration of azithromycin and high-dose glucosamine, early in the course of RNA virus infections, may interact in a complementary fashion to aid their control by enhancing type 1 interferon induction.

Harnessing adenosine A2A receptors as a strategy for suppressing the lung inflammation and thrombotic complications of COVID-19: Potential of pentoxifylline and dipyridamole.

Counterproductive lung inflammation and dysregulated thrombosis contribute importantly to the lethality of advanced COVID-19. Adenosine A2A receptors (A2AR), expressed by a wide range of immune cells, as well as endothelial cells and platelets, exert cAMP-mediated anti-inflammatory and anti-thrombotic effects that potentially could be highly protective in this regard. The venerable drug pentoxifylline (PTX) exerts both anti-inflammatory and antithrombotic effects that reflect its ability to boost the responsiveness of A2AR to extracellular adenosine. The platelet-stabilizing drug dipyridamole (DIP) blocks intracellular uptake of extracellularly-generated adenosine, thereby up-regulating A2AR signaling in a way that should be functionally complementary to the impact of PTX in that regard. Moreover, DIP has recently been reported to slow the cellular replication of SARS-CoV-2 in clinically feasible concentrations. Both PTX and DIP are reasonably safe, well-tolerated, widely available, and inexpensive drugs. When COVID-19 patients can be treated within several days of symptom onset, using PTX + DIP in conjunction with hydroxychloroquine (HCQ) and an antibiotic - azithromycin (AZM) or doxycycline - might be warranted. HCQ and AZM can suppress SARS-CoV-2 proliferation in vitro and may slow the cell-to-cell spread of the virus; a large case series evaluating this combination in early-stage patients reported an impressively low mortality rate. However, whereas HCQ and AZM can promote QT interval lengthening and may be contraindicated in more advanced COVID-19 entailing cardiac damage, doxycycline has no such effect and exerts a potentially beneficial anti-inflammatory action. In contrast to HCQ, we propose that the combination of PTX + DIP can be used in both early and advanced stages of COVID-19. Concurrent use of certain nutraceuticals - yeast beta-glucan, zinc, vitamin D, spirulina, phase 2 inducers, N-acetylcysteine, glucosamine, quercetin, and magnesium - might also improve therapeutic outcomes in COVID-19.

Oxidative stress therapy for solid tumors - a proposal.

Many cancers are deficient in catalase activity, and maintain a moderate level of oxidative stress to aid their proliferation and survival. It may prove feasible to achieve substantial selective tumor kill with a three-pronged strategy for acutely exacerbating oxidative stress in cancer cells: inducing increased production of oxidants in tumors with sustained high-dose infusions of sodium ascorbate and menadione, while concurrently undercutting the antioxidant defenses of cancer cells by imposing glucose deprivation - as with 2-deoxyglucose administration or a hypoglycemic insulin clamp - and by suppressing hypoxia-inducible factor-1 activity with available agents such as salicylate, rapamycin, and irinotecan. Inhibition of pyruvate dehydrogenase-1 with dichloroacetate may also promote oxidative stress in hypoxic cancer cells. Cell culture studies could be employed to devise effective protocols that could be tested in xenografted rodents and, ultimately, in exploratory clinical trials.

Practical strategies for suppressing hypoxia-inducible factor activity in cancer therapy.

The utility of anti-angiogenic strategies for cancer control is strongly compromised by hypoxia-driven phenotypic changes in cancer cells, which make cancer cells more invasive and more prone to give rise to metastases. A key mediator of this phenotypic shift is the transcription factor hypoxia-inducible factor-1 (HIF-1), which acts directly and indirectly to promote the epidermal-mesenchymal transition, boost cancer invasiveness, increase production of angiogenic factors, and induce chemoresistance. In some cancers, HIF-1 activity is constitutively elevated even in aerobic environments, making the cancer harder to treat and control. Practical strategies for suppressing HIF-1 activation may include the following: inhibiting NF-kappaB activation with salicylic acid and/or silibinin, which should decrease transcription of the HIF-1alpha gene; suppressing translation of HIF-1alpha mRNA with drugs that inhibit mTOR or topoisomerase I; supporting the effective activity of prolyl hydroxylases - which promote proteasomal degradation of HIF-1alpha under aerobic conditions - with antioxidant measures, alpha-ketoglutarate, and possibly dichloroacetate; promoting the O(2)-independent proteasomal degradation of HIF-1alpha with agents that inhibit the chaperone protein Hsp90; and blocking HIF-1 binding to its DNA response elements with anthracyclines. The utility of various combinations of these strategies should be tested in cancer cell cultures and rodent xenograft models; initial efforts in this regard have yielded encouraging results. Comprehensive strategies for suppressing HIF-1 activity can be expected to complement the efficacy of cancer chemotherapy and of effective anti-angiogenic regimens.

Practical strategies for targeting NF-kappaB and NADPH oxidase may improve survival during lethal influenza epidemics.

The most foolproof way to promote survival in epidemics of potentially lethal influenza is to target, not highly mutable viral proteins, but rather intracellular signaling pathways which promote viral propagation or lung inflammation. NF-kappaB, activated in influenza-infected lung epithelial cells and macrophages, is one likely target in this regard, as it plays a role both in viral replication and in the excessive lung inflammation often evoked by influenza infection. Indeed, salicylates, which suppress NF-kappaB activation, have been shown to reduce the lethality of H5N1 avian-type influenza in mice. Another potential target is NADPH oxidase, as this may be a major source of influenza-evoked oxidant stress in lung epithelial cells as well as in phagocytes attracted to lung parenchyma. A number of studies demonstrate that oxidant stress contributes to overexuberant lung inflammation and lethality in influenza-infected mice. The documented utility of N-acetylcysteine, a glutathione precursor, for promoting survival in influenza-infected mice, and diminishing the severity of influenza-like infections in elderly humans, presumably reflects a key role for oxidative stress in influenza. The lethality of influenza is also reduced in mice pretreated with adenovirus carrying the gene for heme oxygenase-1; this benefit may be mediated, at least in part, by the ability of bilirubin to inhibit NADPH oxidase. It may be feasible to replicate this benefit clinically by administering biliverdin or its homolog phycocyanobilin, richly supplied by spirulina. If this latter speculation can be confirmed in rodent studies, a practical and inexpensive regimen consisting of high-dose salicylates, spirulina, and N-acetylcysteine, initiated at the earliest feasible time, may prove to have life-saving efficacy when the next killer influenza pandemic strikes.

Oral phycocyanobilin may diminish the pathogenicity of activated brain microglia in neurodegenerative disorders.

There is considerable evidence that activated microglia play a central role in the pathogenesis of many prominent neurodegenerative disorders, including Parkinson's and Alzheimer's diseases. The elevated NADPH oxidase activity of these microglia contributes importantly to their pathogenic impact, collaborating with increased iNOS activity to generate the cytotoxic oxidant peroxynitrite. Phycocyanobilin (PCB), a chromophore derived from biliverdin that constitutes up to 1% of the dry weight of spirulina, has recently been shown to be a potent inhibitor of NADPH oxidase. The possibility that orally administered PCB could reach the brain parenchyma in sufficient concentrations to influence microglial function is consistent with the findings of two rodent studies: orally administered C-phycocyanin (the spirulina holoprotein that includes PCB) suppresses the neurotoxic impact of the excitotoxin kainite in rats, and a diet high in spirulina ameliorates the loss of dopaminergic neurons in the MPTP-induced Parkinsonian syndrome in mice. Hence, supplemental PCB may have considerable potential for preventing or slowing the progression of a range of neurodegenerative disorders. Some of the central physiological effects of PCB may also reflect inhibition of neuronal NADPH oxidase, which is now known to have a modulatory impact on neuron function, and can mediate neurotoxicity in certain circumstances. Neuronal NADPH oxidase activation is an obligate mediator of the central pressor effect of angiotensin II, and there is suggestive evidence that it may also play a role in inflammatory hyperalgesia; these findings point to possible antihypertensive and analgesic applications for PCB. The likely favorable effects of PCB on vascular health may also protect the brain by decreasing stroke risk, and inhibition of NADPH oxidase in rodents has been shown to lessen the neurotoxic impact of temporary cerebral ischemia. PCB may thus have versatile potential for preserving the healthful function of the central nervous system into advanced old age--albeit optimal neuroprotection may require more complex regimens that incorporate PCB along with other well tolerated nutraceuticals and drugs, in conjunction with prudent lifestyle modifications.

NADPH oxidase mediates glucolipotoxicity-induced beta cell dysfunction--clinical implications.

An impairment of glucose-stimulated insulin secretion--reflecting decreased glucokinase expression--and a moderate decrease in beta cell mass attributable to increased apoptosis, constitute the key features of beta cell failure in type 2 diabetes. Oxidative stress, provoked by prolonged exposure to excessive levels of glucose and/or fatty acids (glucolipotoxicity), appears to be a key mediator of these defects. Oxidant-provoked JNK activation induces nuclear export of the PDX-1 transcription factor, required for expression of glucokinase and other beta cell proteins. Conversely, increases in cAMP induced by incretin hormones promote the nuclear importation of PDX-1, counteracting the diabetogenic impact of oxidant stress; this may explain the utility of measures that slow dietary carbohydrate absorption for diabetes prevention. The ability of oxidative stress to boost apoptosis in beta cells is poorly understood, but may also entail JNK activation. Recent work establishes a phagocyte-type NADPH oxidase as the chief source of glucotoxicity-mediated oxidative stress in beta cells. Since bilirubin is now known to function physiologically as an inhibitor of NADPH oxidase, and phycocyanobilin (PCB) derived from spirulina likewise can inhibit this enzyme complex, supplemental PCB may have utility in the prevention and control of diabetes, and Gilbert syndrome, associated with chronically elevated free bilirubin, may be associated with decreased diabetes risk.

Potential complementarity of high-flavanol cocoa powder and spirulina for health protection.

Recent studies show that ingestion of flavanol-rich cocoa powder provokes increased endothelial production of nitric oxide - an effect likely mediated by epicatchin - and thus may have considerable potential for promoting vascular health. The Kuna Indians of Panama, who regularly consume large amounts of flavanol-rich cocoa, are virtually free of hypertension and stroke, even though they salt their food. Of potentially complementary merit is the cyanobacterium spirulina, which has been used as a food in certain cultures. Spirulina is exceptionally rich in phycocyanobilin (PCB), which recently has been shown to act as a potent inhibitor of NADPH oxidase; this effect likely rationalizes the broad range of anti-inflammatory, cytoprotective, and anti-atherosclerotic effects which orally administered spirulina has achieved in rodent studies. In light of the central pathogenic role which NADPH oxidase-derived oxidant stress plays in a vast range of disorders, spirulina or PCB-enriched spirulina extracts may have remarkable potential for preserving and restoring health. Joint administration of flavanol-rich cocoa powder and spirulina may have particular merit, inasmuch as cocoa can mask the somewhat disagreeable flavor and odor of spirulina, whereas the antioxidant impact of spirulina could be expected to amplify the bioactivity of the nitric oxide evoked by cocoa flavanols in inflamed endothelium. Moreover, there is reason to suspect that, by optimizing cerebrovascular perfusion while quelling cerebral oxidant stress, cocoa powder and spirulina could collaborate in prevention of senile dementia. Thus, food products featuring ample amounts of both high-flavanol cocoa powder and spirulina may have considerable potential for health promotion, and merit evaluation in rodent studies and clinical trials.

Activation of AMP-activated kinase as a strategy for managing autosomal dominant polycystic kidney disease.

There is evidence that overactivity of both mammalian target of rapamycin (mTOR) and cystic fibrosis transmembrane conductance regulator (CFTR) contributes importantly to the progressive expansion of renal cysts in autosomal dominant polycystic kidney disease (ADPKD). Recent research has established that AMP-activated kinase (AMPK) can suppress the activity of each of these proteins. Clinical AMPK activators such as metformin and berberine may thus have potential in the clinical management of ADPKD. The traditional use of berberine in diarrhea associated with bacterial infections may reflect, in part, the inhibitory impact of AMPK on chloride extrusion by small intestinal enterocytes.

A "mini-fast with exercise" protocol for fat loss.

From the standpoint of promoting leanness, exercise is of most value if oxidation of stored fat is maximized during and following the exercise sessions. Bahadori has proposed that this can best be achieved if prolonged exercise of moderate intensity is performed during a 12-14 h "mini-fast" that entails skipping a meal; if subsequent food consumption features low-fat foods, the fat stores expended during and after the exercise will not be fully repleted by dietary fat. Thus, prolonged compliance with such a regimen should lead to steady loss of body fat until a much leaner equilibrium body composition is attained. The feasibility and efficacy of this strategy has been examined in an open pilot study. Participants were asked to perform prolonged, moderate-intensity aerobic exercise at least 3-5 times weekly, nesting each exercise session within a 12-14 h mini-fast. No restrictions were placed on daily calorie consumption, but low-fat, low-glycemic-index food choices were recommended. Of the 34 subjects originally enrolled, 27 returned for follow-up evaluations at 6 and 12 weeks. During the 12 week study, the average fat loss in these 27 subjects - 7.4 kg - corresponded to one-quarter of their baseline fat mass. Fasting insulin levels likewise fell by 25%. The rate of fat loss was at least as great in the second 6 weeks as in the first, suggesting that fat loss might have persisted for some time if the study had been prolonged. This protocol, combining elements of exercise training, fasting, and low-fat eating, is both sustainable and healthful, and in reasonably compliant subjects may have considerable potential for promoting and maintaining leanness and insulin sensitivity.

High-dose folate and dietary purines promote scavenging of peroxynitrite-derived radicals--clinical potential in inflammatory disorders.

Reduced folates have been shown to reconstitute the proper activity of "uncoupled" endothelial nitric oxide synthase in inflamed endothlelium. There is recent evidence that this phenomenon may reflect an ability of reduced folates to scavenge peroxynitrite - or, more likely, nitrogen dioxide and carbonate radicals derived from carbonate-induced decomposition of peroxynitrite. This suggests that, at least in those tissues capable of achieving high intracellular levels of reduced folates following high-dose folate administration, high-dose folate may have important anti-inflammatory potential. It would be of interest to examine the impact of high-dose folate in rodent models of disorders in which peroxynitrite plays a key pathogenic role - including diabetes, septic or hemorrhagic shock, ischemia-reperfusion, congestive heart failure, and inflammatory mutagenesis. In particular, this strategy may be useful in many pathologies in which oxidant-mediated PARP activation leads to cell death or dysfunction. Recent evidence that high-dose folate administration preserves myocyte viability following cardiac ischemia-reperfusion likely reflects folate's impact on the cytotoxicity of peroxynitrite. For use in medical emergencies, parenteral leucovorin (racemic 5-formyltetrahydrofolate) is already clinically available. Since uric acid can also function physiologically as a scavenger of peroxynitrite-derived radicals, supplemental inosine or dietary nucleic acids - which raise tissue levels of urate more effectively than does oral uric acid - may usefully complement the protective impact of high-dose folate on nitroxidative stress. Epidemiological associations of high urate levels with low risk for Parkinson's disease may reflect urate's radical scavenging activity, and suggest the possible utility of dietary purines in prevention or treatment of CNS inflammatory disorders.

AMP-activated kinase may suppress NADPH oxidase activation in vascular tissues.

Activation of AMP-activated kinase (AMPK) suppresses NF-kappaB-mediated transcription in endothelial cells exposed to palmitate or TNF-alpha; it also impedes angiotensin II-driven proliferation in vascular smooth muscle cells. These phenomena become predictable if we postulate that AMPK can inhibit activation of NADPH oxidase. Such an effect would make sense from a homeostatic perspective, and moreover there is direct evidence that AMPK suppresses NADPH oxidase activation in neutrophils. New evidence that sub-pathological levels of peroxynitrite can activate AMPK suggest that this enzyme may act as an "early warning signal" for oxidant stress; inhibiting NADPH oxidase would constitute a rational feedback response to such a signal.

Regular thermal therapy may promote insulin sensitivity while boosting expression of endothelial nitric oxide synthase--effects comparable to those of exercise training.

Regular thermal therapy, using saunas or hot baths, has the potential to improve impaired insulin sensitivity and boost endothelial expression of the "constitutive" isoform of nitric oxide synthase--effects, analogous to those of aerobic training that should promote vascular health. Previous clinical reports suggest that hot tubs may be beneficial for diabetic control, and that sauna therapy can decrease blood pressure in essential hypertension and provide symptomatic benefit in congestive heart failure. For those who lack ready access to a sauna or communal hot tub, regular hot baths at home may suffice as practical thermal therapy. Thermal therapy might be viewed as an alternative to exercise training in patients too physically impaired for significant aerobic activity.

The hyperpolarizing impact of glycine on endothelial cells may be anti-atherogenic.

Studies to date indicate that endothelial cells express glycine-activated chloride channels, which promote hyperpolarization of the endothelial plasma membrane. If such channels are expressed by endothelial cells lining conduit arteries, glycine is likely to have anti-atherogenic activity. This reflects the fact that endothelial hyperpolarization promotes calcium influx, activating the endothelial isoform of nitric oxide synthase, while also down-regulating the activity of the membrane-bound NADPH oxidase, chief endothelial source of superoxide. Since macrophages express glycine-activated chloride channels that suppress production of oxidants and cytokines, glycine may also oppose atherogenesis by influencing intimal macrophage function. In rats, supplemental glycine exerts anti-inflammatory and anti-angiogenic effects attributed to chloride channel activation. Administration of large daily doses of glycine would appear to be practical and safe, and has already been shown to inhibit protein glycation in human diabetics.

Can moderate elevations of parathyroid hormone acutely increase risk for ischemic cardiac arrhythmias?

There is suggestive evidence that chronic elevations of parathyroid hormone (PTH), associated with poor vitamin D status or low calcium intake, can increase risk for insulin resistance, weight gain, hypertension, and left ventricular hypertrophy, while stimulating production of acute phase reactants. New evidence that elevated PTH is prognostic for increased vascular mortality in very elderly subjects, prompts an examination of the possible impact of PTH on risk for arrhythmias. The cardiac effects of PTH are mediated by G protein-coupled receptors that activate phospholipase C (PLC). Catecholamines, angiotensin II, and endothelin have been shown to be arrhythmogenic for ischemic myocardium in animal studies; the receptors mediating this effect are all likewise linked to activation of PLC. Thus, it is reasonable to presume that a sufficient concentration of PTH can be arrhythmogenic in the ischemic heart. The extent to which this effect can be evoked by the high-normal PTH levels prevalent in many elderly subjects, can be assessed in epidemiological studies.

Genistein and phycocyanobilin may prevent hepatic fibrosis by suppressing proliferation and activation of hepatic stellate cells.

Hepatic fibrosis reflects hepatotoxin-mediated activation of hepatic stellate cells, resulting in their proliferation and transformation to myofibroblasts that secrete collagen. This activation is suppressed by estrogen, an effect which explains the decreased risk for hepatic fibrosis enjoyed by premenopausal women and by postmenopausal women receiving hormone replacement therapy. Since stellate cells have been found to express the beta but not the alpha isoform of the estrogen receptor, it can be predicted that nutritional intakes of the soy isoflavone genistein - a selective agonist for ERbeta in the low nanomolar plasma concentrations achievable with these intakes - have potential for suppressing hepatic fibrosis, in both men and women. The antiproliferative impact of estrogen on stellate cells is mediated at least in part by suppression of NADPH oxidase activity; oxidant production by this enzyme complex plays a crucial role in stellate cell activation. Alternatively, it may be feasible to inhibit NADPH oxidase with phycocyanobilin (PCB), a biliverdin homolog found in spirulina that has recently been shown to inhibit the NADPH oxidase activity of human cell cultures in low micromolar concentrations. Joint administration of soy isoflavones and PCB in appropriate doses might have considerable potential for prevention of hepatic fibrosis in at-risk subjects.

The "rejuvenatory" impact of lipoic acid on mitochondrial function in aging rats may reflect induction and activation of PPAR-gamma coactivator-1alpha.

In aging rats, lipoic acid exerts a "rejuvenative" impact on mitochondria in various tissues, boosting mitochondrial membrane potential and oxygen consumption, while decreasing mitochondrial production of oxidants. A likely explanation for this phenomenon is that the mitochondria in aging rodents are structurally and functionally impaired by excessive oxidant stress - and that lipoic acid reverses this damage by amplifying key antioxidant mechanisms that protect mitochondria. A likely mediator of this effect is PPARgamma coactivator-1alpha (PGC-1alpha), which recently has been shown to promote transcription of the manganese-dependent superoxide dismutase, uncoupling protein-2, and an array of other proteins which provide antioxidant protection to mitochondria. Lipoic acid has been reported to activate both p38 MAP kinase and AMP-activated kinase (AMPK); p38 MAP kinase can boost the transcription, half-life, and coactivational activity of PGC-1alpha, and AMPK is known to promote its transcription in skeletal muscle and endothelial cells. Thus, it is intriguing to speculate that the remarkable antioxidant effects of lipoic acid therapy reflect not only induction of phase 2 antioxidants (e.g. glutathione and heme oxygenase-1), but also induction of various proteins that function expressly to protect mitochondria from self-generated oxidant stress. Further research is required to evaluate this model.