Repositioning of pentoxifylline as an immunomodulator and regulator of the renin-angiotensin system in the treatment of COVID-19

Small molecule mediators of host-T. cruzi-environment interactions in Chagas disease

Small molecules (less than 1,500 Da) include major biological signals that mediate host-pathogen-microbiome communication. They also include key intermediates of metabolism and critical cellular building blocks. Pathogens present with unique nutritional needs that restrict pathogen colonization or promote tissue damage. In parallel, parts of host metabolism are responsive to immune signaling and regulated by immune cascades. These interactions can trigger both adaptive and maladaptive metabolic changes in the host, with microbiome-derived signals also contributing to disease progression. In turn, targeting pathogen metabolic needs or maladaptive host metabolic changes is an important strategy to develop new treatments for infectious diseases. Trypanosoma cruzi is a single-celled eukaryotic pathogen and the causative agent of Chagas disease, a neglected tropical disease associated with cardiac and intestinal dysfunction. Here, we discuss the role of small molecules during T. cruzi infection in its vector and in the mammalian host. We integrate these findings to build a theoretical interpretation of how maladaptive metabolic changes drive Chagas disease and extrapolate on how these findings can guide drug development.

Pentoxifylline inhibits phosgene-induced lung injury via improving hypoxia

Inhalation of high concentrations of phosgene often causes pulmonary edema, which obstructs the airway and causes tissue hypoxia. There is currently no specific antidote. This study was performed to investigate the effect behind pentoxifylline (PTX) treatment for phosgene-induced lung injury in rat models. Rats were exposed to phosgene. The protein levels of hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), and occludin proteins in lung tissue were determined. The effect of both prophylactic and therapeutic administration of PTX (50 mg/kg and 100 mg/kg) was evaluated. The lung permeability index and HIF-1α protein level increased, the arterial blood oxygenation index (PaO2/FIO2 ratio) and occludin protein level decreased significantly 6 h after phosgene exposure (P < 0.05). PTX exerted protective effects by HIF-1α-VEGF-occludin signaling pathway to some extent. Moreover, prophylactic, but not therapeutic administration of PTX (100 mg/kg), exhibited a significant protective effect. Pretreatment with PTX protected against phosgene-induced lung injury, possibly by inhibiting differential expression of HIF-1α, VEGF, and occludin.

Pentoxifylline Effects on Hospitalized COVID-19 Patients with Cytokine Storm Syndrome: A Randomized Clinical Trial

COVID-19 is a fatal, fast-spreading pandemic, and numerous attempts are being made around the world to understand and manage the disease. COVID-19 patients may develop a cytokine-release syndrome, which causes serious respiratory diseases and, in many cases, death. The study examined the feasibility of employing legally available anti-inflammatory pentoxifylline (PTX), a low toxicity and cost medication, to mitigate the hyper-inflammation caused by COVID-19. Thirty adult patients who tested positive for SARS-CoV2 were hospitalized owing to the cytokine storm syndrome. They were given 400 mg of pentoxifylline orally TID according to the standard COVID-19 protocol of the Egyptian Ministry of Health. Besides this, a group of thirty-eight hospitalized COVID-19 patients who received the standard COVID-19 protocol was included in the study as a control group. The outcomes included laboratory test parameters, clinical improvements, and number of deaths in both groups. After receiving PTX, all patients showed a significant improvement in C reactive protein (CRP), and interleukin-6 (IL-6) levels at p < 0.01 and p = 0.004, respectively, while there was an increase in total leukocyte count (TLC) and neutrophil-to-leucocyte ratio (NLR) at p < 0.01 compared to their baseline levels. The D-dimer level showed a significant increase in the treatment group at p < 0.01, while showing no statistically significant difference in the control group. The median initial ALT (42 U/L) in the treatment group showed a decrease compared to the control group (51 U/L). No statistical significance was reported regarding clinical improvement, length of stay, and death percentages between the two groups. Our results showed no significant improvement of PTX over controls in clinical outcomes of hospitalized COVID-19 patients. Nevertheless, PTX displayed a positive effect on certain inflammatory biomarkers.

High intensity interval training is superior to moderate intensity continuous training in enhancing the anti-inflammatory and apoptotic effect of pentoxifylline in the rat model of endometriosis

This study investigated the effects of pentoxifylline (PTX), high intensity interval training (HIIT) and moderate intensity continuous training (MICT) separately and in combination, on inflammatory and apoptotic pathways in the rat model of induced endometriosis. Endometriosis was induced through surgery on female Sprague-Dawley rats. Six weeks after the first surgery, the second look laparotomy was performed. After induction of endometriosis in rats, they were divided into control, MICT, PTX, MICT+ PTX, HIIT, HIIT+PTX groups. Two weeks after the second look laparotomy, PTX and exercise training interventions were performed for eight weeks. Endometriosis lesions were assessed histologically. Proteins content of the NF-κB, PCNA and Bcl-2 were measured by immunoblotting and genes expression of the TNF-α and VEGF were measured by Real-time PCR methods. Findings of the study indicated that, PTX significantly decreased volume and histological grading of lesions, proteins of NF-κB and Bcl-2; and genes expression of the TNF-α, and VEGF in lesions. HIIT significantly decreased volume and histological grading of lesions, NF-κB, TNF-α and VEGF in lesions. MICT did not induce any significant effect on the study variables. Although, MICT+PTX decreased significantly volume and histological grading of lesions, as well as NF-κB, and Bcl-2 in lesions, however, these factors were not significantly different with the PTX group. HIIT+PTX decreased significantly all of the study variables compared to other interventions, except for VEGF when compared to PTX. In summary, combination of PTX and HIIT can induce enhancing effect on suppression of endometriosis through suppressing inflammation, angiogenesis, and proliferation and enhancing apoptosis.

Therapeutic considerations for prevention and treatment of thrombotic events in COVID-19

Thrombosis is a known complication of SARS-CoV-2 infection, particularly within a severely symptomatic subset of patients with COVID-19 disease, in whom an aggressive host immune response leads to cytokine storm syndrome (CSS). The incidence of thrombotic events coinciding with CSS may contribute to the severe morbidity and mortality observed in association with COVID-19. This review provides an overview of pharmacologic approaches based upon an emerging understanding of the mechanisms responsible for thrombosis across a spectrum of COVID-19 disease involving an interplay between immunologic and pro-thrombotic events, including endothelial injury, platelet activation, altered coagulation pathways, and impaired fibrinolysis.

Comparative effectiveness of pharmacological interventions on mortality and the average length of hospital stay of patients with COVID-19: a systematic review and meta-analysis of randomized controlled trials

INTRODUCTION

Up to now, numerous randomized controlled trials (RCTs) have examined various drugs as possible treatments for Coronavirus Disease 2019 (COVID-19), but the results were diverse and occasionally even inconsistent with each other. To this point,we performed a systematic review and meta-analysis to assess the comparative effectiveness of pharmacological agents in published RCTs.

AREAS COVERED

A literature search was performed using PubMed, SCOPUS, EMBASE, and Web of Science databases. RCTs evaluating mortality and the average length of hospital stay to standard of care (SOC)/placebo/control were included. RCTs mainly were classified into five categories of drugs, including anti-inflammatory, antiviral, antiparasitic, antibody and antibiotics. Meta-analysis was done on 5 drugs classes and sub-group meta-analysis was done on single drugs and moderate or severe stage of disease.

EXPERT OPINION

Mortality and the average length of hospital stay of COVID-19 patients were significantly reduced with anti-inflammatory drugs (odds ratio [OR]: 0.77, 95% confidence interval [CI]: 0.69 to 0.85, P<0.00001, and mean difference [MD]: -1.41, CI:-1.75 to -1.07, P<0.00001, respectively) compared to SOC/control/placebo. Furthermore, antiparasitic was associated with reduced length of hospital stay (MD: -0.65, CI: -1.26 to -0.03, P<0.05) in comparison to SOC/placebo/control. However, no effectiveness was found in other pharmacological interventions.

Pentoxifylline effects on hospitalized patients with COVID19: A randomized, double-blind clinical trial

Pentoxifylline (PTX) has broad-spectrum properties such as anti-inflammatory, anticoagulant, and antiviral effects. The aim of this study was to evaluate the efficacy and safety of PTX in hospitalized patients with COVID-19.

This double-blind, placebo-controlled randomized clinical trial was conducted on hospitalized patients with COVID-19. The recruited patients were randomly (1:1) assigned to the PTX group and the placebo group. The intervention group received PTX capsules at a dose of 400 mg three times a day for 10 days along with the national regimen, including interferon plus lopinavir/ritonavir and hydroxychloroquine. The primary outcome was the improvement of clinical scores. The secondary outcomes, on the other hand, were improvement in inflammatory and oxidative stress factors and hospital complications.

From a total of 102 patients who met the inclusion criteria, 72 individuals completed the study and were analyzed. No significant differences were shown in demographics and baseline clinical characteristics. Clinical scores was not significant between the two groups (P = 0.31 and 0.07 for day 5 and 11, respectively). Although the mean serum levels of interleukin-6 (IL-6) and glutathione changed significantly after 5 days in the PTX group (P = 0.03 and p = 0.04), ICU admission, intubation, and hospital stay did not differ between the two groups.

The results of our study did not show any superiority of PTX over placebo in improving the clinical outcomes of patients with COVID-19. Although PTX had a beneficial effect on IL-6 and showed an acceptable safety profile, it did not offer any clinical benefit for COVID-19 complications.

Pyroptosis: A New Regulating Mechanism in Cardiovascular Disease

Pyroptosis is a kind of pro-inflammatory cell death. Compared with autophagy and apoptosis, pyroptosis has unique characteristics in morphology and mechanism. Specifically, pyroptosis is a kind of cell lysis mediated by the Gasdermin family, releases inflammatory cytokines IL-1β and IL-18. There are three different forms of mechanism, which are caspase-1-mediated, caspase-4/5/11-mediated and caspase-3-mediated. A large number of studies have proved that pyroptosis is closely related to cardiovascular disease. This paper reviewed the recent progress in the related research on pyroptosis and myocardial infarction, ischemia-reperfusion, atherosclerosis, diabetic cardiomyopathy, arrhythmia, heart failure hypertension and Kawasaki disease. Therefore, we believe that pyroptosis may be a new therapeutic target in the cardiovascular field.

Drug Repurposing in the COVID-19 Era: Insights from Case Studies Showing Pharmaceutical Peculiarities

COVID-19 may lead to severe respiratory distress syndrome and high risk of death in some patients. So far (January 2021), only the antiviral remdesivir has been approved, although no significant benefits in terms of mortality and clinical improvement were recently reported. In a setting where effective and safe treatments for COVID-19 are urgently needed, drug repurposing may take advantage of the fact that the safety profile of an agent is already well known and allows rapid investigation of the efficacy of potential treatments, at lower costs and with reduced risk of failure. Furthermore, novel pharmaceutical formulations of older agents (e.g., aerosolized administration of chloroquine/hydroxychloroquine, remdesivir, heparin, pirfenidone) have been tested in order to increase pulmonary delivery and/or antiviral effects of potentially active drugs, thus overcoming pharmacokinetic issues. In our review, we will highlight the importance of the drug repurposing strategy in the context of COVID-19, including regulatory and ethical aspects, with a specific focus on novel pharmaceutical formulations and routes of administration.

Phosphodiesterase Inhibitors in Acute Lung Injury: What Are the Perspectives?

Despite progress in understanding the pathophysiology of acute lung damage, currently approved treatment possibilities are limited to lung-protective ventilation, prone positioning, and supportive interventions. Various pharmacological approaches have also been tested, with neuromuscular blockers and corticosteroids considered as the most promising. However, inhibitors of phosphodiesterases (PDEs) also exert a broad spectrum of favorable effects potentially beneficial in acute lung damage. This article reviews pharmacological action and therapeutical potential of nonselective and selective PDE inhibitors and summarizes the results from available studies focused on the use of PDE inhibitors in animal models and clinical studies, including their adverse effects. The data suggest that xanthines as representatives of nonselective PDE inhibitors may reduce acute lung damage, and decrease mortality and length of hospital stay. Various (selective) PDE3, PDE4, and PDE5 inhibitors have also demonstrated stabilization of the pulmonary epithelial-endothelial barrier and reduction the sepsis- and inflammation-increased microvascular permeability, and suppression of the production of inflammatory mediators, which finally resulted in improved oxygenation and ventilatory parameters. However, the current lack of sufficient clinical evidence limits their recommendation for a broader use. A separate chapter focuses on involvement of cyclic adenosine monophosphate (cAMP) and PDE-related changes in its metabolism in association with coronavirus disease 2019 (COVID-19). The chapter illuminates perspectives of the use of PDE inhibitors as an add-on treatment based on actual experimental and clinical trials with preliminary data suggesting their potential benefit.

Pentoxifylline: A Drug with Antiviral and Anti-Inflammatory Effects to Be Considered in the Treatment of Coronavirus Disease 2019

In December 2019, a new coronavirus, named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged from China, causing pneumonia outbreaks first in the Wuhan region and has now spread worldwide. There are no specific drugs for the disease caused by this virus, coronavirus disease 2019 (COVID-19). Considering that new synthesized drugs cannot be applied immediately to patients, conventional drug in new use is a feasible solution. Chloroquine, remdesivir, favipiravir, lopinavir, ribavirin, and ritonavir have shown efficacy to inhibit coronavirus in vitro. Pentoxifylline, a drug with anti-inflammatory, immunomodulatory, and bronchodilatory effects, has previously been shown to inhibit several viral infections. Immunological studies have shown that most patients with severe COVID-19 exhibit substantially elevated serum levels of pro-inflammatory cytokines. Pentoxifylline is a phosphodiesterase inhibitor that increases the levels of cyclic adenosine monophosphate, which in turn activates protein kinase, leading to a reduction in the synthesis of pro-inflammatory cytokines and immune cell migration. Here, we propose pentoxifylline, a drug with low cost and toxicity, as a possible treatment for COVID-19 based on its interesting properties.

Pentoxifylline decreases serum LDH levels and increases lymphocyte count in COVID-19 patients: Results from an external pilot study

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Pentoxifylline could be beneficial for the treatment of COVID-19.

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Serum lactate dehydrogenase and lymphocyte count are accessible biomarkers that correlate with the severity of COVID-19.

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Pentoxifylline treatment was associated with an increase in the lymphocyte count and decreased LDH levels.

We have previously hypothesized that pentoxifylline could be beneficial for the treatment of COVID-19 given its potential to restore the immune response equilibrium, reduce the impact of the disease on the endothelium and alveolar epithelial cells, and improve the circulatory function. Serum lactate dehydrogenase (LDH) and lymphocyte count are accessible biomarkers that correlate with the severity of COVID-19, the need for hospitalization, and mortality, reflecting the host immune response’s contribution to the seriousness of SARS-CoV-2 infection.

We carried out this external pilot study on 38 patients with moderate and severe COVID-19 to test the effect pentoxifylline on parameters such as LDH, lymphocyte count, days of hospitalization, mortality, and proportion of patients requiring intubation. Twenty-six patients were randomized to receive 400 mg of pentoxifylline t.i.d. plus standard therapy (pentoxifylline group), while the rest received the standard treatment (control group). Linear regression models were built for statistically significant parameters.

Pentoxifylline treatment was associated with a 64.25% increase (CI95% 11.83, 116.68) in lymphocyte count and a 29.61% decrease (CI95% 15.11, 44.10) in serum LDH. Although a trend towards reduced days of hospitalization, mortality, and proportion of patients requiring intubation was observed, no statistically significant difference was found for these parameters.

Our findings open the possibility of pentoxifylline being repositioned as a drug for COVID-19 treatment with the advantages of a proven safety profile, availability, and no risk of immunosuppression; however, this evidence needs to be confirmed in a pragmatic randomized controlled trial.

Pentoxifylline and Oxypurinol: Potential Drugs to Prevent the "Cytokine Release (Storm) Syndrome" Caused by SARS-CoV-2?

BACKGROUND

COVID-19, caused by SARS-CoV-2, is a potentially lethal, rapidly-expanding pandemic and many efforts are being carried out worldwide to understand and control the disease. COVID-19 patients may display a cytokine release syndrome, which causes severe lung inflammation, leading, in many instances, to death.

OBJECTIVE

This paper is intended to explore the possibilities of controlling the COVID-19-associated hyperinflammation by using licensed drugs with anti-inflammatory effects.

HYPOTHESIS

We have previously described that pentoxifylline alone, or in combination with oxypurinol, reduces the systemic inflammation caused by experimentally-induced pancreatitis in rats. Pentoxifylline is an inhibitor of TNF-α production and oxypurinol inhibits xanthine oxidase. TNF-α, in turn, activates other inflammatory genes such as Nos2, Icam or IL-6, which regulate migration and infiltration of neutrophils into the pulmonary interstitial tissue, causing injury to the lung parenchyma. In acute pancreatitis, the anti-inflammatory action of pentoxifylline seems to be mediated by the prevention of the rapid and presumably transient loss of PP2A activity. This may also occur in the hyperinflammatory -cytokine releasing phase- of SARS-CoV-2 infection. Therefore, it may be hypothesized that early treatment of COVID-19 patients with pentoxifylline, alone or in combination with oxypurinol, would prevent the potentially lethal acute respiratory distress syndrome.

CONCLUSION

Pentoxifylline and oxypurinol are licensed drugs used for diseases other than COVID-19 and, therefore, phase I clinical trials would not be necessary for the administration to SARS-CoV-2- infected people. It would be worth investigating their potential effects against the hyperinflammatory response to SARS-CoV-2 infection.

Hypothesis: Pentoxifylline is a potential cytokine modulator therapeutic in COVID-19 patients

We propose a new hypothesis that the established drug pentoxifylline deserves attention as a potential repurposed therapeutic for COVID-19. Pentoxifylline is an immunomodulator with anti-inflammatory properties. It is a nonselective phosphodiesterase inhibitor and through Adenosine A2A Receptor-mediated pathways reduces tumor necrosis factor alpha, interleukin 1, interleukin 6, and interferon gamma and may act to reduce tissue damage during the cytokine storm host response to SARS-CoV-2 infection. This agent has been used clinically for many years and has a favorable profile of safety and tolerability. Pre-clinical data support pentoxifylline as effective in cytokine-driven lung damage. Clinical studies of pentoxifylline in radiation and cytokine-induced lung damage in humans are positive and consistent with anti-inflammatory efficacy. Pentoxifylline is a readily available, off-patent and inexpensive drug, suitable for large-scale use including in resource-limited countries. Current trials of therapeutics are largely focused on the inhibition of viral processes. We advocate urgent randomized trials of pentoxifylline for COVID-19 as a complementary approach to target the host responses.