Inhibition of nuclear factor-kappab activation in mouse macrophages and the RAW 264.7 cell line by a synthetic adenyl carbocyclic nucleoside

Dual active pyrimidine-based carbocyclic nucleoside derivatives: synthesis, and in silico and in vitro anti-diabetic and anti-microbial studies

Diabetes mellitus (DM) is a chronic metabolic disorder marked by high blood glucose levels, impairing glucose production in the body. Its prevalence has steadily risen over the past decades, leading to compromised immunity and heightened susceptibility to microbial infections. Immune dysfunction associated with diabetes raises vulnerability, while neuropathy dulls sensation in the extremities, reducing injury awareness. Hence, the development of novel chemical compounds for anti-diabetic and anti-infective treatments is imperative to mitigate adverse effects. In this study, we designed and synthesized pyrimidine-based carbocyclic nucleoside derivatives with C-4 substitution to assess their potential in inhibiting α-glucosidase for managing diabetes mellitus (DM) and microbial infections. Compounds 8b and 10a displayed promising IC50 values against α-glucosidase (43.292 nmol and 48.638 nmol, respectively) and noteworthy docking energies (-9.4 kcal mol-1 and -10.3 kcal mol-1, respectively). Additionally, compounds 10a and 10b exhibited better antimicrobial activity against Bacillus cereus, with the zone of inhibition values of 2.2 ± 0.25 mm and 1.4 ± 0.1 mm at a 100 μl concentration, respectively. Compound 10a also exhibited a modest zone of inhibition of 1.2 ± 0.15 mm against Escherichia coli at 100 μl.

Adenosine in the Thymus

Adenosine is an ancient extracellular signaling molecule that regulates various biological functions via activating four G-protein-coupled receptors, A₁, A_2A, A_2B, and A₃ adenosine receptors. As such, several studies have highlighted a role for adenosine signaling in affecting the T cell development in the thymus. Recent studies indicate that adenosine is produced in the context of apoptotic thymocyte clearance. This review critically discusses the involvement of adenosine and its receptors in the complex interplay that exists between the developing thymocytes and the thymic macrophages which engulf the apoptotic cells. This crosstalk contributes to the effective and immunologically silent removal of apoptotic thymocytes, as well as affects the TCR-driven T-cell selection processes.

Orchestration of angiogenesis by immune cells

It is widely accepted that the tumor microenvironment (TUMIC) plays a major role in cancer and is indispensable for tumor progression. The TUMIC involves many "players" going well beyond the malignant-transformed cells, including stromal, immune, and endothelial cells (ECs). The non-malignant cells can acquire tumor-promoting functions during carcinogenesis. In particular, these cells can "orchestrate" the "symphony" of the angiogenic switch, permitting the creation of new blood vessels that allows rapid expansion and progression toward malignancy. Considerable attention within the context of tumor angiogenesis should focus not only on the ECs, representing a fundamental unit, but also on immune cells and on the inflammatory tumor infiltrate. Immune cells infiltrating tumors typically show a tumor-induced polarization associated with attenuation of anti-tumor functions and generation of pro-tumor activities, among these angiogenesis. Here, we propose a scenario suggesting that the angiogenic switch is an immune switch arising from the pro-angiogenic polarization of immune cells. This view links immunity, inflammation, and angiogenesis to tumor progression. Here, we review the data in the literature and seek to identify the "conductors" of this "orchestra." We also suggest that interrupting the immune → inflammation → angiogenesis → tumor progression process can delay or prevent tumor insurgence and malignant disease.

Direct Rel/NF-κB inhibitors: structural basis for mechanism of action

The Rel/NF-κB transcription factors have emerged as novel therapeutic targets for a variety of human diseases and pathological conditions, including inflammation, autoimmune diseases, cancer, ischemic injury, osteoporosis, transplant rejection and neurodegeneration. Several US FDA-approved drugs may, in part, attribute their therapeutic effects to the inhibition of the Rel/NF-κB pathway. Strategies for blocking the Rel/NF-κB signaling pathway have inspired the pharmaceutical industry to develop inhibitors for I-κB kinase, however, this article focuses instead on identifying natural compounds that directly target and inhibit DNA binding and transcription activity of Rel/NF-κB. These include compounds containing a quinone core, an α,β unsaturated carbonyl and a benzene diamine. By investigating the mechanisms of action of existing natural inhibitors, novel strategies and synthetic approaches can be devised that will facilitate the development of novel and selective Rel/NF-κB inhibitors with better safety profiles.

Target specificity and off-target effects as determinants of cancer drug efficacy

Targeted therapeutics are aimed to hit one or a few key cellular targets. Agents that target single signaling molecules (such as EGFR and IGF-R1) often show limited clinical activities, at least in the major groups of solid tumors. Nevertheless, some signaling inhibitors are effective in the treatment of previously difficult-to-treat diseases such as renal carcinoma. Similarly, these drugs inhibit multiple kinases and/or may display off-target activities. Inhibition of cellular targets such as the proteasome, heat-shock protein 90, and histone deacetylase induces complex cellular effects, and agents that inhibit these targets show promising clinical activities. Clinically effective targeted agents are therefore reminiscent of conventional agents such as cisplatin and doxorubicin, which are known to have several cellular targets. It is becoming increasingly clear that a comprehensive understanding of the spectrum of effects exerted by an anticancer agent is fundamental for understanding its efficacy and toxicity profile.

Inhibition of tumor growth by NF-kappaB inhibitors

NF-kappaB is a transcription factor that induces inflammatory cytokines and anti-apoptotic proteins. NF-kappaB is often constitutively activated in human cancers and leukemias, which might increase the malignant character of neoplastic diseases. Therefore, NF-kappaB inhibitors might be useful as anticancer agents. Our research team designed a new NF-kappaB inhibitor that is based on the structure of the antibiotic epoxyquomicin C isolated from a microorganism. The designed compound, DHMEQ, inhibited the ligand-induced activation of NF-kappaB, and it also inhibited the constitutively activated NF-kappaB in cancer cells. DHMEQ is a unique inhibitor of NF-kappaB that acts at the level of the nuclear translocation. It inhibited both canonical and non-canonical NF-kappaB activating pathways. It inhibited various carcinomas and leukemias in animal models without any toxicity, and might be useful as an anticancer agent.

Adenosine 5'-triphosphate and adenosine as endogenous signaling molecules in immunity and inflammation

Human health is under constant threat of a wide variety of dangers, both self and nonself. The immune system is occupied with protecting the host against such dangers in order to preserve human health. For that purpose, the immune system is equipped with a diverse array of both cellular and non-cellular effectors that are in continuous communication with each other. The naturally occurring nucleotide adenosine 5'-triphosphate (ATP) and its metabolite adenosine (Ado) probably constitute an intrinsic part of this extensive immunological network through purinergic signaling by their cognate receptors, which are widely expressed throughout the body. This review provides a thorough overview of the effects of ATP and Ado on major immune cell types. The overwhelming evidence indicates that ATP and Ado are important endogenous signaling molecules in immunity and inflammation. Although the role of ATP and Ado during the course of inflammatory and immune responses in vivo appears to be extremely complex, we propose that their immunological role is both interdependent and multifaceted, meaning that the nature of their effects may shift from immunostimulatory to immunoregulatory or vice versa depending on extracellular concentrations as well as on expression patterns of purinergic receptors and ecto-enzymes. Purinergic signaling thus contributes to the fine-tuning of inflammatory and immune responses in such a way that the danger to the host is eliminated efficiently with minimal damage to healthy tissues.

Adenosine suppresses activation of nuclear factor-kappaB selectively induced by tumor necrosis factor in different cell types

Adenosine is an endogenous immunomodulator that has been shown to exhibit anti-inflammatory and immunosuppressive properties through a mechanism that is not fully established. Owing to the pivotal role of nuclear factor (NF)-kappaB in these responses, we tested the hypothesis that adenosine mediates its effects through suppression of NF-kappaB activation. We investigated the effects of adenosine on NF-kappaB activation induced by various inflammatory agents in human myeloid KBM-5 cells. The treatment of these cells with adenosine suppressed TNF-induced NF-kappaB activation, but had no effect on activation of another redox-sensitive transcription factor, AP-1. These effects were not restricted to myeloid cells, as NF-kappaB activation in other lymphocytic and epithelial cell types was also inhibited. The effect on TNF-induced NF-kappaB activation was selective as adenosine had minimal effect on NF-kappaB activation induced by H(2)O(2), PMA, LPS, okadaic acid, or ceramide, suggesting differences in the pathway leading to NF-kappaB activation by different agents. Adenosine also suppressed NF-kappaB-dependent reporter gene expression activated by TNF or by overexpression of TNFR1, TRAF 2, NIK, and p65 subunit of NF-kappaB. The suppression of TNF-induced NF-kappaB activation by adenosine was found not to be because of inhibition of TNF-induced IkappaBalpha phosphorylation and degradation or IkappaBalpha kinase activation. The suppression of TNF-induced NF-kappaB activation was unique to adenosine, as neither its metabolites (inosine, AMP, and ATP) nor pyrimidines (thymidine and uridine) had any effect. Overall, our results clearly demonstrate that adenosine selectively suppresses TNF-induced NF-kappaB activation, which may contribute to its role in suppression of inflammation and of the immune system.

Suppression of monocyte chemoattractant protein 1, but not IL-8, by alprazolam: effect of alprazolam on c-Rel/p65 and c-Rel/p50 binding to the monocyte chemoattractant protein 1 promoter region

Alprazolam is a hypnotic/tranquilizer that has been shown to specifically inhibit the platelet-activating factor (PAF)-induced aggregation of human platelets. The goal of this study was to elucidate whether alprazolam modulates IL-1alpha-initiated responses. For this purpose we investigated the effects of alprazolam on the IL-1alpha-induced production of inflammatory cytokines (IL-8 and monocyte chemoattractant protein 1 (MCP-1)) in a human glioblastoma cell line, T98G, and explored the signaling pathways involved. We found that alprazolam inhibited IL-1alpha-elicited MCP-1 production within a range of 0.1-3 micro M. In contrast, it did not inhibit IL-1alpha-induced IL-8 production. Although NF-kappaB is involved in regulating the IL-1alpha-induced expression of MCP-1 and IL-8, the degradation of IkappaB-alpha stimulated by IL-1alpha was not inhibited by alprazolam. Alprazolam prevented NF-kappaB from binding to the MCP-1 promoter region (the A2 and A1 oligonucleotide probes), but binding of NF-kappaB to IL-8/NF-kappaB was not inhibited. Moreover, alprazolam inhibited c-Rel/p50 binding to the A2 oligonucleotide probe, but not p50/p65 from binding to the IL-8/NF-kappaB site. While AP-1 is involved in regulating the IL-1alpha-induced expression of IL-8, but not MCP-1, alprazolam potentiated the binding of c-Jun/c-Fos to the AP-1 oligonucleotide probe. These results show that the inhibition of IL-1alpha-mediated MCP-1 production by alprazolam is mainly due to inhibition of c-Rel/p65 and c-Rel/p50 binding to the MCP-1 promoter region, since alprazolam did not affect the IL-1alpha-mediated activation of NF-kappaB (p50/p65) or AP-1 (c-Jun/c-Fos) binding to the IL-8 promoter region. In conclusion, a new action of alprazolam was elucidated, as shown in the inhibition of c-Rel/p65- and c-Rel/p50-regulated transcription.

Inhibition of tumor necrosis factor-alpha -induced nuclear translocation and activation of NF-kappa B by dehydroxymethylepoxyquinomicin

We previously designed and synthesized an NF-kappaB inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ), that showed anti-inflammatory activity in vivo. In the present study we looked into its mechanism of inhibition. DHMEQ inhibited tumor necrosis factor-alpha (TNF-alpha)- and 12-O-tetradecanoylphorbol-13-acetate-induced transcriptional activity of NF-kappaB in human T cell leukemia Jurkat cells. It also inhibited the TNF-alpha-induced DNA binding of nuclear NF-kappaB but not the phosphorylation and degradation of IkappaB. Moreover, DHMEQ inhibited the TNF-alpha-induced nuclear accumulation of p65, a component of NF-kappaB. It also inhibited TNF-alpha-induced nuclear transport of green fluorescent protein-tagged p65. On the other hand, DHMEQ did not inhibit the nuclear transport of Smad2 and large T antigen. Also, it did not inhibit TNF-alpha-induced activation of JNK but synergistically induced apoptosis with TNF-alpha in Jurkat cells. Taken together, these data indicate that DHMEQ is a unique inhibitor of NF-kappaB acting at the level of nuclear translocation.

Potent inhibition of lipopolysaccharide-inducible nitric oxide synthase expression by dibenzylbutyrolactone lignans through inhibition of I-kappaBalpha phosphorylation and of p65 nuclear translocation in macrophages

AIMS

Arctigenin and demethyltraxillagenin, dibenzylbutyrolactone lignans, are phenylpropanoid metabolites with antioxidant and anti-inflammatory activities. The effects of arctigenin and demethyltraxillagenin on the nuclear factor-kappaB (NF-kappaB)-mediated inducible nitric oxide synthase (iNOS, EC1.14.13.39) gene expression were studied in Raw264.7 cells.

METHODS

Activation of NF-kappaB was determined by gel mobility shift assay, immunocytochemistry and immunoblot analysis of I-kappaBalpha. Expression of the iNOS gene was assessed by Northern and Western blot analyses. NO production was monitored by chemiluminescent detection using a nitric oxide analyzer.

RESULTS

Arctigenin (1 microM) inhibited lipopolysaccharide (LPS)-inducible nuclear NF-kappaB activation and nuclear translocation of p65, which was accompanied by inhibition of I-kappaBalpha phosphorylation, whereas demethyltraxillagenin was less active. LPS-inducible increase in the iNOS mRNA was 80-90% inhibited by 0.01-1 microM arctigenin, whereas similar extents of inhibition were noted by 50-100 microM demethyltraxillagenin. Immunoblot analysis revealed that arctigenin potently inhibited the induction of iNOS by LPS (IC50 < 0.01 microM). The IC50 value of demethyltraxillagenin was approximately 50 microM. Production of nitrite and nitrate by LPS in culture medium was also comparably suppressed by the lignans.

CONCLUSION

These results demonstrated that arctigenin potently inhibited LPS-inducible iNOS expression in murine macrophages through suppression of I-kappaBalpha phosphorylation and nuclear translocation of p65. Potent inhibition of LPS-inducible NO production in macrophages may constitute anti-inflammatory effects of the dibenzylbutyrolactone lignans.