A Dual Pharmacological Strategy against COVID-19: The Therapeutic Potential of Metformin and Atorvastatin

Metformin (MET) and atorvastatin (ATO) are promising treatments for COVID-19. This review explores the potential of MET and ATO, commonly prescribed for diabetes and dyslipidemia, respectively, as versatile medicines against SARS-CoV-2. Due to their immunomodulatory and antiviral capabilities, as well as their cost-effectiveness and ubiquitous availability, they are highly suitable options for treating the virus. MET's effect extends beyond managing blood sugar, impacting pathways that can potentially decrease the severity and fatality rates linked with COVID-19. It can partially block mitochondrial complex I and stimulate AMPK, which indicates that it can be used more widely in managing viral infections. ATO, however, impacts cholesterol metabolism, a crucial element of the viral replicative cycle, and demonstrates anti-inflammatory characteristics that could modulate intense immune reactions in individuals with COVID-19. Retrospective investigations and clinical trials show decreased hospitalizations, severity, and mortality rates in patients receiving these medications. Nevertheless, the journey from observing something to applying it in a therapeutic setting is intricate, and the inherent diversity of the data necessitates carefully executed, forward-looking clinical trials. This review highlights the requirement for efficacious, easily obtainable, and secure COVID-19 therapeutics and identifies MET and ATO as promising treatments in this worldwide health emergency.

Histone deacetylase (HDAC) inhibitors- based drugs are effective to control Mycobacterium tuberculosis infection and promote the sensibility for rifampicin in MDR strain

BACKGROUND

Tuberculosis (TB) is a major public health problem, which has been aggravated by the alarming growth of drug-resistant tuberculosis. Therefore, the development of a safer and more effective treatment is needed.

OBJECTIVES

The aim of this work was repositioning and evaluate histone deacetylases (HDAC) inhibitors- based drugs with potential antimycobacterial activity.

METHODS

Using an in silico pharmacological repositioning strategy, three molecules that bind to the catalytic site of histone deacetylase were selected. Pneumocytes type II and macrophages were infected with Mycobacterium tuberculosis and treated with pre-selected HDAC inhibitors (HDACi). Subsequently, the ability of each of these molecules to directly promote the elimination of M. tuberculosis was evaluated by colony-forming unit (CFU)/mL. We assessed the expression of antimicrobial peptides and respiratory burst using reverse transcription-quantitative polymerase chain reaction (RT-qPCR).

FINDINGS

Aminoacetanilide (ACE), N-Boc-1,2-phenylenediamine (N-BOC), 1,3-Diphenylurea (DFU), reduce bacillary loads in macrophages and increase the production of β-defensin-2, LL-37, superoxide dismutase (SOD) 3 and inducible nitric oxide synthase (iNOS). While only the use of ACE in type II pneumocytes decreases the bacterial load through increasing LL-37 expression. Furthermore, the use of ACE and rifampicin inhibited the survival of intracellular multi-drug resistance M. tuberculosis.

MAIN CONCLUSIONS

Our data support the usefulness of in silico approaches for drug repositioning to provide a potential adjunctive therapy for TB.

Novel antimicrobial cecropins derived from O. curvicornis and D. satanas dung beetles

Antibiotic resistance is an increasing global problem and therapeutic alternatives to traditional antibiotics are needed. Antimicrobial and host defense peptides represent an attractive source for new therapeutic strategies, given their wide range of activities including antimicrobial, antitumoral and immunomodulatory. Insects produce several families of these peptides, including cecropins. Herein, we characterized the sequence, structure, and biological activity of three cecropins called satanin 1, 2, and curvicin, found in the transcriptome of two dung beetle species Dichotomius satanas and Onthophagus curvicornis. Sequence and circular dichroism analyses show that they have typical features of the cecropin family: short length (38-39 amino acids), positive charge, and amphipathic α-helical structure. They are active mainly against Gram-negative bacteria (3.12-12.5 μg/mL), with low toxicity on eukaryotic cells resulting in high therapeutic indexes (TI > 30). Peptides also showed effects on TNFα production in LPS-stimulated PBMCs. The biological activity of Satanin 1, 2 and Curvicin makes them interesting leads for antimicrobial strategies.

Long-term exposure to particulate matter from air pollution alters airway β-defensin-3 and -4 and cathelicidin host defense peptides production in a murine model

Epidemiological studies have associated long-term exposure to environmental air pollution particulate matter (PM) with the development of diverse health problems. They include infectious respiratory diseases related to the deregulation of some innate immune response mechanisms, such as the host defense peptides' expression. Herein, we evaluated in BALB/c mice the effect of long-standing exposure (60 days) to urban-PM from the south of Mexico City, with aerodynamic diameters below 2.5 μm (PM_2.5) and 10 μm (PM₁₀) on the lung's gene expression and production of three host defense peptides (HDPs); murine beta-defensin-3, -4 (mBD-3, mBD-4) and cathelin-related antimicrobial peptide (CRAMP). We also evaluated mRNA levels of Il1b and Il10, two cytokines related to the expression of host defense peptides. Exposure to PM_2.5 and PM₁₀ differentially induced lung inflammation, being PM_2.5, which caused higher inflammation levels, probably associated with a differential deposition on the airways, that facilitate the interaction with alveolar macrophages. Inflammation levels were associated with an early upregulation of the three HDPs assessed and an increment in Il1b mRNA levels. Interestingly, after 28 days of exposure, Il10 mRNA upregulation was observed and was associated with the downregulation of HDPs and Il1b mRNA levels. The upregulation of Il10 mRNA and suppression of HDPs might facilitate microbial colonization and the development of diseases associated with long-term exposure to PM.

Retinoic acid induces antimicrobial peptides and cytokines leading to Mycobacterium tuberculosis elimination in airway epithelial cells

Tuberculosis (TB) is the leading cause of death by a single infectious agent, Mycobacterium tuberculosis (Mtb). Alveolar macrophages and respiratory epithelial cells are the first cells exposed to Mtb during the primary infection, once these cells are activated, secrete cytokines and antimicrobial peptides that are associated with the Mtb contention and elimination. Vitamins are micronutrients that function as boosters on the innate immune system, however, is unclear whether they have any protective activity during Mtb infection. Thus, we investigated the role of vitamin A (retinoic acid), vitamin C (ascorbic acid), vitamin D (calcitriol), and vitamin E (alfa-tocopherol) as inductors of molecules related to mycobacterial infection in macrophages and epithelial cells. Our results showed that retinoic acid promotes the expression of pro- and anti-inflammatory molecules such as Thymic stromal lymphopoietin (TSLP), β-defensin-2, IL-1β, CCL20, β-defensin-3, Cathelicidin LL-37, TGF-β, and RNase 7, whereas calcitriol, ascorbic acid, and α-tocopherol lead to an anti-inflammatory response. Treatment of Mtb-infected epithelial cells and macrophage-like cells with the vitamins showed a differential response, where calcitriol reduced Mtb in macrophages, while retinoic acid reduced infection in epithelial cells. Thereby, we propose that a combination of calcitriol and retinoic acid supplementation can drive the immune response, and promotes the Mtb elimination by increasing the expression of antimicrobial peptides and cytokines, while simultaneously modulating inflammation.

Modulation of cathelicidin and defensins by histone deacetylase inhibitors: A potential treatment for multi-drug resistant infectious diseases

Infectious diseases are an important growing public health problem, which perspective has worsened due to the increasing number of drug-resistant strains in the last few years. Although diverse solutions have been proposed, one viable solution could be the use of immune system modulators. The induction of the immune response can be increased by histone deacetylase inhibitors (iHDAC), which in turn modulate the chromatin and increase the activation of different cellular pathways and nuclear factors such as STAT3, HIF-1α NF-kB, C/EBPα and, AP-1. These pathways are capable to promote several immune response-related molecules including those with antimicrobial properties such as antimicrobial peptides (AMPs) that lead to the elimination of pathogens including multi drug-resistant strains.

Nicotine promotes the intracellular growth of Mycobacterium tuberculosis in epithelial cells

Several epidemiological studies have identified the cigarette smoke as a risk factor for the infection and development of tuberculosis. Nicotine is considered the main immunomodulatory molecule of the cigarette. In the present study, we evaluated the effect of nicotine in the growth of M. tuberculosis. Lung epithelial cells and macrophages were infected with M. tuberculosis and/or treated with nicotine. The results show that nicotine increased the growth of M. tuberculosis mainly in type II pneumocytes (T2P) but not in airway basal epithelial cells nor macrophages. Further, it was observed that nicotine decreased the production of β-defensin-2, β-defensin-3, and the cathelicidin LL-37 in all the evaluated cells at 24 and 72 h post-infection. The modulation of the expression of antimicrobial peptides appears to be partially mediated by the nicotinic acetylcholine receptor α7 since the blockade of this receptor partially reverted the production of antimicrobial peptides. In summary, it was found that nicotine decreases the production of HBD-2, HBD-3, and LL-37 in T2P during the infection with M. tuberculosis promoting its intracellular growth.

Calcitriol promotes proangiogenic molecules in keratinocytes in a diabetic foot ulcer model

Foot ulceration is one of the most common and complex sequelae of diabetes mellitus, generally posing a therapeutic challenge due to poor healing responses and high rates of complications, including peripheral vascular disease, ischemia and infections. Calcitriol, the most active vitamin D metabolite, induces antimicrobial peptides production in keratinocytes from diabetic foot ulcers (DFU); however, little is known about its effects on angiogenic factors in this pathology. Herein we aimed at studying whether calcitriol induces angiogenic molecules in keratinocytes under normoxic and hypoxic conditions, and if these molecules are able to improve cell migration in vitro. Evaluation of DFU samples by immunohistochemistry showed increased VEGF and decreased angiogenin and HIF-1α expression compared to controls, suggesting an altered pattern of angiogenic factors in DFU. Interestingly, incubation of keratinocytes with calcitriol significantly upregulated VEGFA, HIF-1α and angiogenin gene expression, while the resulting cell culture media stimulated both endothelial cells and keratinocytes migration in an in vitro wound closure assay under a normoxic environment (p<0.05). Moreover, the culture media of calcitriol-treated keratinocytes stimulated cell migration in a similar extent as exogenous VEGF or EGF in endothelial and keratinocytes cells. These results suggest that the altered profile of angiogenic molecules in DFU might be improved by local or systemic treatment with calcitriol under normoxic conditions, which could probably be achieved with hyperbaric oxygen therapy. Given that calcitriol not only augments proangiogenic factors but also induces antimicrobial peptides expression, this hormone should be further investigated in clinical trials of DFU.