Development of a tetrahydroindazolone-based HDAC6 inhibitor with in-vivo anti-arthritic activity.

Histone deacetylase 6 (HDAC6) induces the expression of pro-inflammatory cytokines in macrophages; therefore, HDAC inhibitors may be beneficial for the treatment of macrophage-associated immune disorders and chronic inflammatory diseases, including atherosclerosis and rheumatoid arthritis. Structure-activity relationship studies were conducted on various phenyl hydroxamate HDAC6 inhibitors with indolone/indazolone-based bi- or tricyclic ring moieties as the cap group aiming to develop novel anti-arthritic drug candidates. Several compounds exhibited nanomolar activity and HDAC6 selectivity greater than 500-fold over HDAC1. Compound 21, a derivative with the tetrahydroindazolone cap group, is a potent HDAC6 inhibitor with an IC50 of 18 nM and 217-fold selectivity over HDAC1 and showed favorable oral bioavailability in animals. Compound 21 increases the acetylation level of tubulin without affecting histone acetylation in cutaneous T-cell lymphoma cells and inhibits TNF-α secretion in LPS-stimulated macrophage cells. The anti-arthritic effects of compound 21 were evaluated using a rat adjuvant-induced arthritis (AIA) model. Treatment with compound 21 significantly reduced the arthritis score, and combination treatment with methotrexate showed a synergistic effect in AIA models. We identified a novel HDAC6 inhibitor, compound 21, with excellent in vivo anti-arthritic efficacy, which can lead to the development of oral anti-arthritic drugs.

A mathematical model to evaluate the role of memory B and T cells in heterologous secondary dengue infection.

We propose a mathematical model to investigate the antibody-dependent enhancement (ADE) phenomenon during secondary dengue infection. The model consists of an ODE system that describes the interaction of the dengue virus with macrophages and memory B and T cell role during the infection. The qualitative model analysis is done in terms of memory B and T cell cloning parameters and the basic reproduction number R0. In the absence of memory B and T cell cloning, if R0<1 the dengue virus population extinguishes, while for R0>1, it tends asymptotically to a positive equilibrium. However, when we consider the memory B cell cloning, it is possible to occur dengue infection even when R0<1. Memory T cells have an essential role in eliminating the possibility of ADE occurrence when R0<1.

Mathematical modeling of the transmission of SARS-CoV-2-Evaluating the impact of isolation in São Paulo State (Brazil) and lockdown in Spain associated with protective measures on the epidemic of CoViD-19.

Coronavirus disease 2019 (CoViD-19), with the fatality rate in elder (60 years old or more) being much higher than young (60 years old or less) patients, was declared a pandemic by the World Health Organization on March 11, 2020. A mathematical model considering young and elder subpopulations under different fatality rates was formulated based on the natural history of CoViD-19 to study the transmission of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The model considered susceptible, exposed, asymptomatic, pre-symptomatic, mild CoViD-19, severe CoViD-19, and recovered compartments, besides compartments of isolated individuals and those who were caught by test. This model was applied to study the epidemiological scenario resulting from the adoption of quarantine (isolation or lockdown) in many countries to control the rapid propagation of CoViD-19. We chose as examples the isolation adopted in São Paulo State (Brazil) in the early phase but not at the beginning of the epidemic, and the lockdown implemented in Spain when the number of severe CoViD-19 cases was increasing rapidly. Based on the data collected from São Paulo State and Spain, the model parameters were evaluated, and we obtained a higher estimation for the basic reproduction number R0 (9.24 for São Paulo State, and 8 for Spain) compared to the currently accepted estimation of R0 around 2 using the SEIR (susceptible, exposed, infectious, and recovered compartments) model. In comparison with the lockdown in Spain, the relatively early adoption of the isolation in São Paulo State resulted in enlarging the period of the first wave of the epidemic and delaying its peak. The model allowed to explain the flattening of the epidemic curves by quarantine when associated with the protective measures (face mask, washing hands with alcohol and gel, and social distancing) adopted by the population. The description of the epidemic under quarantine and protections can be a background to foreseen the epidemiological scenarios from the release strategies, which can help guide public health policies by decision-makers.

Assessing the effects of diagnostic sensitivity on schistosomiasis dynamics.

Schistosomiasis is a parasite infection that affects millions of people around the world. It is endemic in 13 different states in Brazil and responsible for increasing morbidity in the population. One of its main characteristics is a heterogeneous distribution of worm burden in the human population, which makes the diagnosis difficult. We aimed to investigate how the sensitivity of the diagnostic method may contribute to successful control interventions against infections in a population. In order to do that, we present an ordinary differential equations model that considers three levels of worm burden in the human population, a snail population, and a miracidium reservoir. Through a steady-state analysis and its local stability, we show how this worm-burden heterogeneity can be responsible for the persistence of infection, especially due to reinfection in the highest level of worm burden. The analysis highlights sensitive diagnosis, besides treatment and sanitary improvements, as a key factor for schistosomiasis transmission control.

Polyphyllin D Shows Anticancer Effect through a Selective Inhibition of Src Homology Region 2-Containing Protein Tyrosine Phosphatase-2 (SHP2).

Natural products have continued to offer tremendous opportunities for drug development, as they have long been used in traditional medicinal systems. SHP2 has served as an anticancer target. To identify novel SHP2 inhibitors with potential anticancer activity, we screened a library containing 658 natural products. Polyphyllin D was found to selectively inhibit SHP2 over SHP1, whereas two other identified compounds (echinocystic acid and oleanolic acid) demonstrated dual SHP1 and SHP2 inhibition. In a cell-based assay, polyphyllin D exhibited cytotoxicity in Jurkat cells, an acute lymphoma leukemia cell line, whereas the other two compounds were ineffective. Polyphyllin D also decreased the level of phosphorylated extracellular signal-regulated kinase (p-ERK), a proliferation marker in Jurkat cells. Furthermore, knockdown of protein tyrosine phosphatase (PTP)N6 (SHP1) or PTPN11 (SHP2) decreased p-ERK levels. However, concurrent knockdown of PTPN6 and PTPN11 in Jurkat cells recovered p-ERK levels. These results demonstrated that polyphyllin D has potential anticancer activity, which can be attributed to its selective inhibition of SHP2 over SHP1.

Competition for nutritional resources masks the true frequency of bacterial mutants.

BACKGROUND: It is widely assumed that all mutant microorganisms present in a culture are able to grow and form colonies, provided that they express the features required for selection. Unlike wild-type Escherichia coli, PHO-constitutive mutants overexpress alkaline phosphatase and hence can hydrolyze glycerol-2-phosphate (G2P) to glycerol and form colonies on plates having G2P as the sole carbon source. These mutations mostly occur in the pst operon. However, the frequency of PHO-constitutive colonies on the G2P selective plate is exceptionally low. RESULTS: We show that the rate in which spontaneous PHO-constitutive mutations emerge is about 8.0 × 10-6/generation, a relatively high rate, but the growth of most existing mutants is inhibited by their neighboring wild-type cells. This inhibition is elicited only by non-mutant viable bacteria that can take up and metabolize glycerol formed by the mutants. Evidence indicates that the few mutants that do form colonies derive from microclusters of mutants on the selective plate. A mathematical model that describes the fate of the wild-type and mutant populations under these circumstances supports these results. CONCLUSION: This scenario in which neither the wild-type nor the majority of the mutants are able to grow resembles an unavoidable "tragedy of the commons" case which results in the collapse of the majority of the population. Cooperation between rare adjacent mutants enables them to overcome the competition and eventually form mutant colonies. The inhibition of PHO-constitutive mutants provides an example of mutant frequency masked by orders of magnitude due to a competition between mutants and their ancestral wild-type cells. Similar "tragedy of the commons-like" cases may occur in other settings and should be taken into consideration while estimating true mutant frequencies and mutation rates.

A simple mathematical model to describe antibody-dependent enhancement in heterologous secondary infection in dengue.

We develop a mathematical model to describe the role of antibody-dependent enhancement (ADE) in heterologous secondary infections, assuming that antibodies specific to primary dengue virus (DENV) infection are being produced by immunological memory. The model has a virus-free equilibrium (VFE) and a unique virus-presence equilibrium (VPE). VFE is asymptotically stable when VPE is unstable; and unstable, otherwise. Additionally, there is an asymptotic attractor (not a fixed point) due to the fact that the model assumes unbounded increase in memory cells. In the analysis of the model, ADE must be accounted in the initial stage of infection (a window of time of few days), period of time elapsed from the heterologous infection until the immune system mounting an effective response against the secondary infection. We apply the results yielded by model to evaluate ADE phenomonon in heterologous DENV infection. We also associate the possible occurrence of severe dengue with huge viremia mediated by ADE phenomenon.

Mathematical Model of Interaction Between Bacteriocin-Producing Lactic Acid Bacteria and Listeria. Part 2: Bifurcations and Applications.

The big challenge for the food industry is the attending to demands for minimally processed foods, avoiding intense heat treatments and reducing the addition of chemical preservatives, but at the same time ensuring microbiological safety of these products. Lactic acid bacteria are traditionally used in the production of fermented foods. They are responsible for the production of antimicrobial compounds, such as organic acids and bacteriocins, which are protein compounds with bactericidal effect against related species and bacteria such as Listeria monocytogenes and Staphylococcus aureus. Aiming to study quantitatively the biological control as a technique of conservation, we developed a mathematical model to describe the interaction between lactic acid bacteria and Listeria in the food. The steady state and dynamical trajectories analyses of the model permit us to study the suitability of including lactic acid bacteria in order to reduce the growth of Listeria in food.

Mathematical Model of Interaction Between Bacteriocin-Producing Lactic Acid Bacteria and Listeria. Part 1: Steady States and Thresholds.

Mathematical modeling is an important tool to assessing quantitative conjectures and to answer specific questions. In the modeling, we assume that a competitor represented by a lactic acid bacterium produces antimicrobial compounds (substances that kill microorganisms or inhibit their growth), such as lactic acid and bacteriocins, with some cost to its own growth. Bacteriocins are protein compounds with antimicrobial effect against related species and bacteria such as Listeria monocytogenes, which is foodborne pathogen that cause listeriosis. From the analysis of the model, we found the thresholds which determine the existence of multiple equilibria and we studied their stability, in order to evaluate the interaction between lactic acid bacteria and L. monocytogenes.

The transovarial transmission in the dynamics of dengue infection: Epidemiological implications and thresholds.

The anthropophilic and peridomestic female mosquito Aedes aegypti bites humans to suck blood to maturate fertilized eggs, during which dengue virus can be spread between mosquito and human populations. Besides this route of transmission, there is a possibility of dengue virus being passed directly to offspring through transovarial (or vertical) transmission. The effects of both horizontal and transovarial transmission routes on the dengue virus transmission are assessed by mathematical modeling. From the model, the reproduction number is obtained and the contribution of transovarial transmission is evaluated for different levels of horizontal transmission. Notably, the transovarial transmission plays an important role in dengue spread when the reproduction number is near one. Another threshold parameter arises, which is the product of the fractions of the susceptible populations of humans and mosquitoes. Interestingly, these two threshold parameters can be obtained from three different approaches: the spectral radius of the next generation matrix, the Routh-Hurwitz criteria and M-matrix theory.

Fitting the Incidence Data from the City of Campinas, Brazil, Based on Dengue Transmission Modellings Considering Time-Dependent Entomological Parameters.

Four time-dependent dengue transmission models are considered in order to fit the incidence data from the City of Campinas, Brazil, recorded from October 1st 1995 to September 30th 2012. The entomological parameters are allowed to depend on temperature and precipitation, while the carrying capacity and the hatching of eggs depend only on precipitation. The whole period of incidence of dengue is split into four periods, due to the fact that the model is formulated considering the circulation of only one serotype. Dengue transmission parameters from human to mosquito and mosquito to human are fitted for each one of the periods. The time varying partial and overall effective reproduction numbers are obtained to explain the incidence of dengue provided by the models.

The basic reproduction number obtained from Jacobian and next generation matrices - A case study of dengue transmission modelling.

The basic reproduction number is a key parameter in mathematical modelling of transmissible diseases. From the stability analysis of the disease free equilibrium, by applying Routh-Hurwitz criteria, a threshold is obtained, which is called the basic reproduction number. However, the application of spectral radius theory on the next generation matrix provides a different expression for the basic reproduction number, that is, the square root of the previously found formula. If the spectral radius of the next generation matrix is defined as the geometric mean of partial reproduction numbers, however the product of these partial numbers is the basic reproduction number, then both methods provide the same expression. In order to show this statement, dengue transmission modelling incorporating or not the transovarian transmission is considered as a case study. Also tuberculosis transmission and sexually transmitted infection modellings are taken as further examples.

Variability modeling of rainfall, deforestation, and incidence of american tegumentary leishmaniasis in orán, Argentina, 1985-2007.

American tegumentary leishmaniasis (ATL) is a disease transmitted to humans by the female sandflies of the genus Lutzomyia. Several factors are involved in the disease transmission cycle. In this work only rainfall and deforestation were considered to assess the variability in the incidence of ATL. In order to reach this goal, monthly recorded data of the incidence of ATL in Orán, Salta, Argentina, were used, in the period 1985-2007. The square root of the relative incidence of ATL and the corresponding variance were formulated as time series, and these data were smoothed by moving averages of 12 and 24 months, respectively. The same procedure was applied to the rainfall data. Typical months, which are April, August, and December, were found and allowed us to describe the dynamical behavior of ATL outbreaks. These results were tested at 95% confidence level. We concluded that the variability of rainfall would not be enough to justify the epidemic outbreaks of ATL in the period 1997-2000, but it consistently explains the situation observed in the years 2002 and 2004. Deforestation activities occurred in this region could explain epidemic peaks observed in both years and also during the entire time of observation except in 2005-2007.

Modeling the emergence of HIV-1 drug resistance resulting from antiretroviral therapy: insights from theoretical and numerical studies.

The use of antiretroviral therapy has proven to be remarkably effective in controlling the progression of human immunodeficiency virus (HIV) infection and prolonging patient's survival. Therapy however may fail and therefore these benefits can be compromised by the emergence of HIV strains that are resistant to the therapy. In view of these facts, the question of finding the reason for which drug-resistant strains emerge during therapy has become a worldwide problem of great interest. This paper presents a deterministic HIV-1 model to examine the mechanisms underlying the emergence of drug-resistance during therapy. The aim of this study is to determine whether, and how fast, antiretroviral therapy may determine the emergence of drug resistance by calculating the basic reproductive numbers. The existence, feasibility and local stability of the equilibriums are also analyzed. By performing numerical simulations we show that Hopf bifurcation may occur. The model suggests that the individuals with drug-resistant infection may play an important role in the epidemic of HIV.

Anti-inflammatory activity of ethanol extract derived from Phaseolus angularis beans.

ETHNOPHARMACOLOGICAL SIGNIFICANCE: Phaseolus angularis Wight (adzuki bean) is an ethnopharmacologically well-known folk medicine that is prescribed for infection, edema, and inflammation of the joints, appendix, kidney and bladder in Korea, China and Japan. AIM OF STUDY: The anti-inflammatory effect of this plant and its associated molecular mechanisms will be investigated. MATERIALS AND METHODS: The immunomodulatory activity of Phaseolus angularis ethanol extract (Pa-EE) in toll like receptor (TLR)-activated macrophages induced by ligands such as lipopolysaccharide (LPS), Poly (I:C), and pam3CSK was investigated by assessing nitric oxide (NO) and prostaglandin (PG)E(2) levels. To identify which transcription factors such as nuclear factor (NF)-κB and their signaling enzymes can be targeted to Pa-EE, biochemical approaches including reporter gene assays, immunoprecipitation, kinase assays, and immunoblot analyses were also employed. Finally, whether Pa-EE was orally available, ethanol (EtOH)/hydrochloric acid (HCl)-induced gastritis model in mice was used. RESULTS: Pa-EE dose-dependently suppressed the release of PGE(2) and NO in LPS-, Poly(I:C)-, and pam3CSK-activated macrophages. Pa-EE strongly down-regulated LPS-induced mRNA expression of inducible NO synthase (iNOS) and cyclooxygenase (COX)-2. Interestingly, Pa-EE markedly inhibited NF-κB, activator protein (AP)-1, and cAMP response element binding protein (CREB) activation; further, according to direct kinase assays and immunoblot analyses, Pa-EE blocked the activation of the upstream signaling molecules spleen tyrosine kinase (Syk), p38, and transforming growth factor ß-activated kinase 1 (TAK1). Finally, orally administered Pa-EE clearly ameliorated EtOH/HCl-induced gastritis in mice. CONCLUSION: Our results suggest that Pa-EE can be further developed as a promising anti-inflammatory remedy because it targets multiple inflammatory signaling enzymes and transcription factors.

Inhibitory effect of Sanguisorba officinalis ethanol extract on NO and PGE2 production is mediated by suppression of NF-κB and AP-1 activation signaling cascade.

AIM OF THE STUDY: Sanguisorba officinalis, a well known valuable medicinal plant in Korea, China and Japan used traditionally for the treatment of inflammatory and metabolic diseases such as diarrhea, chronic intestinal infections, duodenal ulcers, and bleeding. Recent studies have revealed that its aqueous or ethanolic extracts exhibit a variety of pharmacological activities such as anti-oxidative, anti-cancer, anti-lipid peroxidation, anti-atherogenic, and vasorelaxant effects. Systematic studies on the anti-inflammatory effect of this plant and its molecular mechanisms have not yet been fully investigated. Ethanol extract of Sanguisorba officinalis (So-EE) the lipopolysaccharide (LPS)-stimulated macrophages and production of inflammatory mediators were employed to assess these properties. RESULTS: So-EE significantly suppressed the production of nitric oxide (NO) and prostaglandin (PG) E(2) from LPS-activated RAW264.7 cells and peritoneal macrophages in a dose-dependent manner. This extract effectively diminished the mRNA levels of inducible NO synthase (iNOS) and cyclooxygenase (COX)-2, implying that the blockade is generated at the transcriptional level. So-EE strongly blocked the activation and translocation of NF-κB and AP-1 by suppressing the upstream kinases including inhibitor of κBα (IκBα), IκBα kinase (IKK), Akt (protein kinase B), phosphoinositide-dependent kinase 1 (PDK1), p85/phosphoinositide-3-kinase (PI3K), and mitogen activated protein kinase (MAPK) such as extracellular signal-regulated kinase (ERK), p38, and c-Jun N-terminal kinase (JNK). Moreover, So-EE suppressed the phosphorylation of Src, its kinase activity, and complex formation between Src and p85. CONCLUSION: This study suggests that So-EE has a potent anti-inflammatory activity mediated by NF-κB, and AP-1 inhibitory properties linked to the suppression of Src and MAPK activation.

Follow up estimation of Aedes aegypti entomological parameters and mathematical modellings.

The dengue virus is a vector-borne disease transmitted by mosquito Aedes aegypti and the incidence is strongly influenced by temperature and humidity which vary seasonally. To assess the effects of temperature on dengue transmission, mathematical models are developed based on the population dynamics theory. However, depending on the hypotheses of the modelling, different outcomes regarding to the risk of epidemics are obtained. We address this question comparing two simple models supplied with model's parameters estimated from temperature-controlled experiments, especially the entomological parameters regarded to the mosquito's life cycle in different temperatures. Once obtained the mortality and transition rates of different stages comprising the life cycle of mosquito and the oviposition rate, we compare the capacity of vector reproduction (the basic offspring number) and the risk of infection (basic reproduction number) provided by two models. The extended model, which is more realistic, showed that both mosquito population and dengue risk are situated at higher values than the simplified model, even that the basic offspring number is lower.