A tetrazolium-based colorimetric assay for quantification of HIV-1-induced cytopathogenicity in monocyte-macrophages exposed to macrophage-colony-stimulating factor

Platelet-rich plasma, especially when combined with a TGF-β inhibitor promotes proliferation, viability and myogenic differentiation of myoblasts in vitro

Regeneration of skeletal muscle after injury is limited by scar formation, slow healing time and a high recurrence rate. A therapy based on platelet-rich plasma (PRP) has become a promising lead for tendon and ligament injuries in recent years, however concerns have been raised that PRP-derived TGF-β could contribute to fibrotic remodelling in skeletal muscle after injury. Due to the lack of scientific grounds for a PRP -based muscle regeneration therapy, we have designed a study using human myogenic progenitors and evaluated the potential of PRP alone and in combination with decorin (a TGF-β inhibitor), to alter myoblast proliferation, metabolic activity, cytokine profile and expression of myogenic regulatory factors (MRFs). Advanced imaging multicolor single-cell analysis enabled us to create a valuable picture on the ratio of quiescent, activated and terminally committed myoblasts in treated versus control cell populations. Finally high-resolution confocal microscopy validated the potential of PRP and decorin to stimulate the formation of polynucleated myotubules. PRP was shown to down-regulate fibrotic cytokines, increase cell viability and proliferation, enhance the expression of MRFs, and contribute to a significant myogenic shift during differentiation. When combined with decorin further synergistc effects were identified. These results suggest that PRP could not only prevent fibrosis but could also stimulate muscle commitment, especially when combined with a TGF-β inhibitor.

In vitro selection and characterization of new probiotic candidates from table olive microbiota

To date, only a few studies have investigated the complex microbiota of table olives in order to identify new probiotic microorganisms, even though this food matrix has been shown to be a suitable source of beneficial lactic acid bacteria (LAB). Two hundred and thirty eight LAB, belonging to Lactobacillus plantarum, Lactobacillus pentosus and Leuconostoc mesenteroides species, and isolated from Nocellara Etnea table olives, have been screened in this survey through an in vitro approach. A simulation of transit tolerance in the upper human gastrointestinal tract, together with autoaggregation and hydrophobicity, have been decisive in reducing the number of LAB to 17 promising probiotics. None of the selected strains showed intrinsic resistances towards a broad spectrum of antibiotics and were therefore accurately characterized on an undifferentiated and 3D functional model of the human intestinal tract made up of H4-1 epithelial cells. As far as the potential colonization of the intestinal tract is concerned, a high adhesion ratio was observed for Lb. plantarum O2T60C (over 9%) when tested in the 3D functional model, which closely mimics real intestinal conditions. The stimulation properties towards the epithelial barrier integrity and the in vitro inhibition of L. monocytogenes adhesion and invasion have also been assessed. Lb. plantarum S1T10A and S11T3E enhanced trans-epithelial electrical resistance (TEER) and therefore the integrity of the polarized epithelium in the 3D model. Moreover, S11T3E showed the ability to inhibit L. monocytogenes invasion in the undifferentiated epithelial model. The reduction in L. monocytogenes infection, together with the potential enhancement of barrier integrity and an adhesion ratio that was above the average in the 3D functional model (6.9%) would seem to suggest the Lb. plantarum S11T3E strain as the most interesting candidate for possible in vivo animal and human trials.

In vitro study of the effect of a probiotic bacterium Lactobacillus rhamnosus against herpes simplex virus type 1

Background

Due to the emergence of drug resistance in herpes simplex virus type 1 (HSV-1), researchers are trying to find other methods for treating herpes simplex virus type 1 infections. Probiotic bacteria are effective in macrophage activation and may have antiviral activities.

Objective

This study aimed at verifying the direct effect of Lactobacillus rhamnosus, a probiotic bacterium, in comparison with Escherichia coli, a non-probiotic one, on HSV-1 infection, and determining its effect on macrophage activation for in vitro elimination of HSV-1 infection.

Methods

The above bacteria were introduced into HSV-1 infected Vero cells, and their effects were examined using both MTT and plaque assay. To determine macrophage activation against in vitro HSV-1 infection, J774 cells were exposed to these bacteria; then, macrophage viability was examined with the MTT method, and tumor necrosis factor alpha (TNF-α), Interferon-gamma (IFN-γ), and nitric oxide (NO) assessments were performed using the ELISA method.

Results

A significant increased viability of macrophages was observed (p < 0.05) in the presence of Lactobacillus rhamnosus before and after HSV-1 infection when compared with Escherichia coli as a non-probiotic bacterium. However, tumor necrosis factor α concentration produced by Escherichia coli-treated J774 cells was significantly higher than Lactobacillus rhamnosus-treated J774 cells (p < 0.05). Interferon-gamma and NO production were not different in the groups treated with Escherichia coli or with Lactobacillus rhamnosus.

Conclusion

The results of this study indicate that Lactobacillus rhamnosus enhances macrophage viability for HSV-1 elimination and activation against HSV-1 more effectively, when compared with non-probiotic Escherichia coli. It also seems that receptor occupation of macrophage sites decreases HSV-1 infectivity by both of the studied bacteria.

Interactions of macrophages with probiotic bacteria lead to increased antiviral response against vesicular stomatitis virus

Macrophages are an important cellular component of the innate immune system and are normally rapidly recruited and/or activated at the site of virus infection. They can participate in the antiviral response by killing infected cells, by producing antiviral cytokines such as nitric oxide and by producing chemokines and immunoregulatory cytokines that enable the adaptive immune response to recognize infected cells and perform antiviral effector functions. Probiotics, as a part of the normal gut intestinal flora, are important in supporting a functional yet balanced immune system. Improving our understanding of their role in the activation of macrophages and their stimulation of proinflammatory cytokine production in early viral infection was the main goal of this study. Our in vitro model study showed that probiotic bacteria, either from the species Lactobacillus or Bifidobacteria have the ability to decrease viral infection by establishing the antiviral state in macrophages, by production of NO and inflammatory cytokines such as interleukin 6 and interferon-gamma. These effects correlated with the mitochondrial activity of infected macrophages, therefore, the measurements of mitochondrial dehydrogenases activity could be implied as the first indicator of potential inhibitory effects of the probiotics on virus replication. The interactions between probiotic bacteria, macrophages and vesicular stomatitis virus (VSV), markedly depended on the bacterial strain studied.

Specific targeting highly conserved residues in the HIV-1 reverse transcriptase primer grip region. Design, synthesis, and biological evaluation of novel, potent, and broad spectrum NNRTIs with antiviral activity

Pyrrolobenzoxazepinones (PBOs) represent a new class of human immunodeficiency virus type 1 (HIV-1) nonnucleoside reverse transcriptase (RT) inhibitors (NNRTIs) whose prototype is 5. Molecular modeling studies based on the X-ray structures of HIV-1 RT prompted the synthesis of novel analogues which were tested as anti-HIV agents. The PBO derivatives specifically designed to target the highly conserved amino acid residues within the beta12-beta13 hairpin, namely primer grip, proved to be very potent against the most common mutant enzymes, including the highly resistant K103N mutant strain. Structure-activity relationships (SARs) are discussed in terms of a possible interaction with the RT binding site, depending on the nature of the substituents at C-6. Among the pyrrolobenzoxazepines investigated, 15c appeared to be the most promising NNRTI of the series characterized by potent antiviral activity, broad spectrum, and low cytotoxicity. 15c showed synergistic antiviral activity with AZT.

Quinoxalinylethylpyridylthioureas (QXPTs) as potent non-nucleoside HIV-1 reverse transcriptase (RT) inhibitors. Further SAR studies and identification of a novel orally bioavailable hydrazine-based antiviral agent

Quinoxalinylethylpyridylthioureas (QXPTs) represent a new class of human immunodeficiency virus type 1 (HIV-1) non-nucleoside reverse transcriptase (RT) inhibitors (NNRTIs) whose prototype is 6-FQXPT (6). Docking studies based on the three-dimensional structure of RT prompted the synthesis of novel heteroarylethylpyridylthioureas which were tested as anti-HIV agents. Several compounds proved to be potent broad-spectrum enzyme inhibitors and significantly inhibited HIV-1 replication in vitro. Their potency depends on the substituents and the nature of the heterocyclic skeleton linked to the ethyl spacer, and structure-activity relationships are discussed in terms of the possible interaction with the RT binding site. Although the new QXPTs analogues show potent antiviral activity, none of the compounds tested overcome the pharmacokinetic disadvantages inherent to ethylpyridylthioureidic antiviral agents, which in general have very low oral bioavailability. Through an integrated effort involving synthesis, docking studies, and biological and pharmacokinetic evaluation, we investigated the structural dependence of the poor bioavailability and rapid clearance within the thioureidic series of antivirals. Replacing the ethylthioureidic moiety with a hydrazine linker led to a new antiviral lead, offering promising pharmacological and pharmacokinetic properties in terms of antiviral activity and oral bioavailability.

Non-nucleoside HIV-1 reverse transcriptase inhibitors: synthesis and biological evaluation of novel quinoxalinylethylpyridylthioureas as potent antiviral agents

New heterocyclic derivatives of ethylpyridylthiourea, quinoxalinylethylpyridylthiourea (QXPT) and analogues, inhibited human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) activity and prevented HIV-1 cytopathogenicity in T4 lymphocytes. Several of these novel non-nucleoside RT inhibitors, with a substituted pyrroloquinoxalinone heteroaromatic skeleton, showed inhibitory activity against wild-type RT as well as against mutant RTs containing the single amino acid substitutions L1001, K103N, V106A, Y1811 and Y188L that was much greater than other non-nucleoside inhibitors such as nevirapine. Maximum potency in enzymatic assays was achieved with a fluoropyrroloquinoxaline skeleton linked to the ethylpyridylthiourea moiety (FQXPT). In cell-based assays on different cell lines and on human monocyte-macrophages, 6-FQXPT exhibited EC50 values in the nanomolar range, with a promising selectivity index. Moreover, 6-FQXPT showed synergistic antiviral activity with zidovudine.

Antifungal properties of substituted 1-phenyl-5-mercaptotetrazoles and their oxidation product, 5-bis-(1-phenyltetrazolyl)disulfide

The antifungal effect of substituted 1-phenyl-5-mercaptotetrazoles was tested with Candida tropicalis, C. pseudotropicalis, C. mogii, Trichosporon cutaneum, Cryptococcus albidus and S. cerevisiae. Candida strains exhibited the lowest sensitivity to the compounds; the most sensitive was S. cerevisiae. The MIC values ranged from 40 to > 1000 mg/mL. The antifungal effect of halogenated compounds decreased in the series of bromo > chloro > fluoro derivatives. The electrochemical oxidation of substituted 1-phenyl-5-mercaptotetrazole derivatives in an acetonitrile medium was studied as a model for the enzymic oxidation of the substance, including study of the effect of water, perchloric and trifluoromethanesulfuric acids on E1/2 and I1. 5-Bis-(1-phenyltetrazolyl)disulfide, the compound with no antifungal effect, has been identified as the main oxidation product of 1-phenyl-5-mercaptotetrazole.

Pyrrolobenzoxazepinone derivatives as non-nucleoside HIV-1 RT inhibitors: further structure-activity relationship studies and identification of more potent broad-spectrum HIV-1 RT inhibitors with antiviral activity

Pyrrolobenzoxazepinone (PBO) derivatives represent a new class of human immunodeficiency virus type 1 (HIV-1) non-nucleoside reverse transcriptase (RT) inhibitors (NNRTs) whose prototype is (+/-)-6-ethyl-6-phenylpyrrolo[2,1-d][1,5]benzoxazepin-7(6H)- one (6). Docking studies based on the three-dimensional structure of RT prompted the synthesis and biological evaluation of novel derivatives and analogues of 6 featuring a meta-substituted phenyl or a 2-thienyl ring at C-6 and a pyridine system in place of the fused-benzene ring to yield pyrrolopyridooxazepinones (PPOs). Compared with the lead 6 and nevirapine, several of the synthesized compounds (PBOs 13a-d and PPOs 13i-k) displayed higher inhibitory activity against wild-type RT and clinically relevant mutant RTs containing the single amino acid substitutions L100I, K103N, V106A, Y181I, and Y188L. The most potent inhibitors were further evaluated for in vitro antiviral activity on lymphocytes and monocyte-macrophages, for cytotoxicity on a panel of cell lines, and for potential synergistic antiviral activity with AZT. Pharmacokinetic studies performed on 13b, 13c, and 13i showed that these compounds achieve high concentrations in the brain. The results of the biological and pharmacokinetic experiments suggest a potential clinical utility of analogues such as 13b-d, 13i, and 13j, in combination with nucleoside RT inhibitors, against strains of HIV-1 bearing those mutations that confer resistance to known NNRTI.

A cytopathic infectivity assay of human immunodeficiency virus type 1 in human primary macrophages

In addition to CD4+ T lymphocytes, cells of monocyte/macrophage lineage are a major target for human immunodeficiency virus type 1 (HIV-1) infection. In vitro studies of HIV-1 infection in human monocyte-derived macrophages can be undertaken by a reproducible cell-based assay. A macrophage-based infectivity assay was developed based on the semi-quantitative scoring of HIV-1 induced cytopathology in monolayer macrophage cultures. The assay exhibited dilution-dependent linearity with all three primary macrophage-tropic isolates tested. The end-point infectivity titers determined by this assay correlated with the results obtained by detecting viral p24 antigen in the culture supernatant. The applications of the assay in both neutralization and anti-viral protocols yielded identical results with the more time-consuming and costly p24 formats. Since the assay offers a simple and low-cost method of measuring HIV-1 infectivity in human primary macrophages, it can be used quite easily for large-scale screening or evaluation of candidate vaccines and anti-viral agents.

A sensitive assay system screening antiviral compounds against herpes simplex virus type 1 and type 2

A highly sensitive and accurate assay system was developed for in vitro evaluation of anti-herpes simplex virus (anti-HSV) agents using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and human embryonic lung fibroblast (MRC-5) cells. This assay system was found to be highly sensitive for both HSV-1 and -2. Confluent MRC-5 cells were infected with either HSV-1 KOS strain or HSV-2 G strain of 25 TCID50 in the presence of various concentrations of test compounds. The optical density of formazan was used to determine cell viability. The EC50 values of acyclovir and several other anti-HSV agents were found to be similar to those obtained by the plaque reduction method. These results indicate that this MTT assay is useful for screening anti-HSV-1 and -2 agents.

Macrophage-colony stimulating factor (M-CSF) stimulation induces cell death in HIV-infected human monocytes

We show here that HIV-infected monocyte-macrophages stimulated by macrophage-colony stimulating factor (M-CSF) undergo massive syncytia formation and die. The M-CSF-stimulated HIV-infected monocyte-macrophages (M/M) destroy themselves by blebbing out particles (resembling apoptotic bodies) which may contain condensed and marginated chromatin. The death of monocyte-macrophages is also characterized by the expression of "Tissue" Transglutaminase (tTG) which is one of the genes specifically expressed and activated in apoptising cells. Noteworthy, when the syncytia formation and consequently death is prevented, infected monocyte-macrophages remain viable and produce large amounts of virus for an extended period. The concentrations of M-CSF (1000 U/ml) used in this work are similar to those that stimulate macrophages in vivo. This suggests that HIV killing of M/M in the presence of M-CSF could lead, in vivo, to a greater than expected loss of immune cells and may contribute to explain the complex derangement of the immune function observed in HIV-infected patients.