The neuropathic pain: An overview of the current treatment and future therapeutic approaches

Neuropathic pain is characterized by abnormal hypersensitivity to stimuli (hyperalgesia) and nociceptive responses to non-noxious stimuli (allodynia). The conditions and the pathophysiological states that determine the onset of neuropathic pain are heterogeneous, such as metabolic disorders, neuropathy caused by viral infections, and autoimmune diseases affecting the central nervous system (CNS). Neuropathic pain in the general population is estimated to have a prevalence ranging between 3% and 17%. Most of the available treatments for neuropathic pain have moderate efficacy and present side effects that limit their use; therefore, other therapeutic approaches are needed for patients. In this article, the current standard of care treatment, the emerging pharmacological approaches from the completed phase III clinical trials, and the preclinical studies on novel promising therapeutic options will be reviewed.

Use of Cannabidiol in the Treatment of Epilepsy: Efficacy and Security in Clinical Trials

Cannabidiol (CBD) is one of the cannabinoids with non-psychotropic action, extracted from Cannabis sativa. CBD is a terpenophenol and it has received a great scientific interest thanks to its medical applications. This compound showed efficacy as anti-seizure, antipsychotic, neuroprotective, antidepressant and anxiolytic. The neuroprotective activity appears linked to its excellent anti-inflammatory and antioxidant properties. The purpose of this paper is to evaluate the use of CBD, in addition to common anti-epileptic drugs, in the severe treatment-resistant epilepsy through an overview of recent literature and clinical trials aimed to study the effects of the CBD treatment in different forms of epilepsy. The results of scientific studies obtained so far the use of CBD in clinical applications could represent hope for patients who are resistant to all conventional anti-epileptic drugs.

Pathogenic role for macrophage migration inhibitory factor in glioblastoma and its targeting with specific inhibitors as novel tailored therapeutic approach

Macrophage Migration Inhibitory Factor (MIF) is a pro-inflammatory cytokine expressed by a variety of cell types. Although MIF has been primarily studied for its role in the pathogenesis of autoimmune diseases, it has also been shown to promote tumorigenesis and it is over expressed in various malignant tumors. MIF is able to induce angiogenesis, cell cycle progression, and to block apoptosis. As tailored therapeutic approaches for the inhibition of endogenous MIF are being developed, it is important to evaluate the role of MIF in individual neoplastic conditions that may benefit from specific MIF inhibitors. Along with this line, in this paper, we have reviewed the evidence of the involvement of MIF in the etiopathogenesis and progression of glioblastoma and the preclinical data suggesting the possible use of specific MIF inhibition as a potential novel therapeutic strategy for brain tumors.

Human gingival mesenchymal stem cells pretreated with vesicular moringin nanostructures as a new therapeutic approach in a mouse model of spinal cord injury

Spinal cord injury (SCI) is a neurological disorder that arises from a primary acute mechanical lesion, followed by a pathophysiological cascade of events that leads to further spinal cord tissue damage. Several preclinical and clinical studies have highlighted the ability of stem cell therapy to improve long-term functional recovery in SCI. Previously, we demonstrated that moringin (MOR) treatment accelerates the differentiation process in mesenchymal stem cells inducing an early up-regulation of neural development associated genes. In the present study, we investigated the anti-inflammatory, anti-apoptotic, and regenerative effects of gingival mesenchymal stem cells (GMSCs) pretreated with nanostructured liposomes enriched with MOR in an animal model of SCI. SCI was produced by extradural compression of the spinal cord at levels T6-T7 in ICR (CD-1) mice. Animals were randomly assigned to the following groups: Sham, SCI, SCI + GMSCs (1 × 106  cell/i.v.), SCI + MOR-GMSCs (1 × 106  cell/i.v.). Our data show that MOR-treated GMSCs exert anti-inflammatory and anti-apoptotic activities. In particular, MOR-treated GMSCs are able to reduce the spinal cord levels of COX-2, GFAP, and inflammatory cytokines IL-1β and IL-6 and to restore spinal cord normal morphology. Also, MOR-treated GMSCs influenced the apoptotic pathway, by reducing Bax, caspase 3, and caspase 9 expressions.

Involvement of the Nrf2/HO-1/CO axis and therapeutic intervention with the CO-releasing molecule CORM-A1, in a murine model of autoimmune hepatitis

Concanavalin A (ConA)-induced hepatitis is an experimental model of human autoimmune hepatitis induced in rodents by i.v. injection of Con A. The disease is characterized by increase in serum levels of transaminases and massive immune infiltration of the livers. Type 1, type 2, and type 17 cytokines play a pathogenic role in the development of ConA-induced hepatitis. To understand further the immunoregulatory mechanisms operating in the development and regulation of ConA-induced hepatitis, we have evaluated the role of the anti-inflammatory pathway Nrf2/HO-1/CO (Nuclear Factor E2-related Factor 2/Heme Oxygenase-1/Carbon Monoxide) in this condition and determined whether the in vivo administration of CO via the CO-releasing molecule (CORM) CORM-A1, influences serological and histological development of Con-A-induced hepatitis. We have firstly evaluated in silico the genes belonging to the Nrf2/HO-1/CO pathway that are involved in the pathogenesis of autoimmune hepatitis (AIH). The data obtained from the in silico study demonstrate that a significant number of genes modulated in the liver of ConA-challenged mice belong to the Nrf2 pathway; on the other hand, the administration of CORM-A1 determines an improvement in several sero-immunological and histological parameters, and it is able to modulate genes identified by the in silico analysis. Collectively, our data indicate that the Nrf2/HO-1/CO pathway is fundamental for the regulation of the immune responses, and that therapeutic intervention aimed at its modulation by CORM-A1 may represent a valuable strategy to be considered for the treatment of autoimmune hepatitis in humans.

Identification of novel targets for the diagnosis and treatment of liver fibrosis

Liver fibrosis is characterized by the excessive deposition of extracellular matrix (ECM) in the hepatic parenchyma and represents an intrinsic response to chronic injury, maintaining organ integrity when extensive necrosis or apoptosis occurs. Hepatic stellate cells (HSCs) are the major cell type responsible for liver fibrosis. Following liver injury, HSCs become activated and transdifferentiate into myofibroblasts (MFBs) that lead to intrahepatic ECM accumulation. In the present study, we performed a meta‑analysis of datasets which included whole-genome transcriptional data on HSCs in the quiescent and activated state from two different rodent species and identified commonly regulated genes. Several of the genes identified, including ECM components, metalloproteinases and growth factors, were found to be well‑known markers for HSC activation. However, other significant genes also appeared to play important roles in hepatic fibrosis. The elucidation of the molecular events underlying HSC activation may be key to the identification of potential novel pharmacological targets for the prevention and treatment of liver fibrosis.

Overexpression of Macrophage Migration Inhibitory Factor and Its Homologue D-Dopachrome Tautomerase as Negative Prognostic Factor in Neuroblastoma

Neuroblastoma (NB) represents one of the most frequent pediatric solid tumors. Macrophage migration inhibitory factor (MIF) is a cytokine exerting multiple biological functions. More recently, a second member of the MIF family of cytokine has been identified, the D-dopachrome tautomerase (DDT), that exerts several overlapping functions with MIF. Growing evidence suggests a key role for MIF and DDT in the development of cancer. The aim of this study is to characterize the prognostic value of MIF and DDT in NB. We show that higher expression levels of MIF and DDT in Stage 4 NB samples are associated with a poorer prognosis, independently of the presence of MYCN amplification. Moreover, higher levels of MIF are mostly enriched by Th1 cells, while lower levels of MIF are associated with an increased proportion of B cells, Cytotoxic T cells, Dendritic cells and Natural Killer T cells. We also show that treatment with the histone deacetylase (HDAC) inhibitor, vorinostat, of the NB cell line, SH-SY5Y, determines a significant reduction in the expression of both MIF and DDT. Finally, MIF and DDT inhibition by short interfering RNA is able to revert vincristine sensitivity in vitro. Overall, our data suggest that MIF exert pro-tumorigenic properties in NB, likely by dampening antigen presentation and cytotoxic immune responses, and we propose the HDAC inhibitors as a potential therapeutic strategy for NB patients.

Prevention of clinical and histological signs of MOG-induced experimental allergic encephalomyelitis by prolonged treatment with recombinant human EGF

Epidermal growth factor (EGF) represents the prototype of the group I EGF family. The pleiotropic effects of the EGF have attracted attention to the possibility that it could be implicated in autoimmune diseases, such as Multiple Sclerosis (MS). We show here that treatment with EGF, as a late prophylactic regime, improved the clinical and histological features of EAE, a preclinical model of MS. In silico analysis further corroborated these findings by demonstrating that EGF receptors are less expressed in CNS from patients with MS as compared to controls. Taken together these data provide clear-cut in vivo proof of concept for a beneficial role of exogenously administered EGF in MS, that may, therefore, represent a novel therapeutic approach.

Identification of CD4+ T cell biomarkers for predicting the response of patients with relapsing‑remitting multiple sclerosis to natalizumab treatment

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system of autoimmune etiopathogenesis, and is characterized by various neurological symptoms. Glatiramer acetate and interferon-β are administered as first-line treatments for this disease. In non-responsive patients, several second-line therapies are available, including natalizumab; however, a percentage of MS patients does not respond, or respond partially. Therefore, it is of the utmost importance to develop a diagnostic test for the prediction of drug response in patients suffering from complex diseases, such as MS, where several therapeutic options are already available. By a machine learning approach, the UnCorrelated Shrunken Centroid algorithm was applied to identify a subset of genes of CD4⁺ T cells that may predict the pharmacological response of relapsing-remitting MS patients to natalizumab, before the initiation of therapy. The results from the present study may provide a basis for the design of personalized therapeutic strategies for patients with MS.

KCNMA1 Expression is Downregulated in Colorectal Cancer via Epigenetic Mechanisms

KCNMA1 is a gene located at 10q22 that encodes the pore-forming α-subunit of the large-conductance Ca²⁺-activated K⁺ channel. KCNMA1 is down-regulated in gastric carcinoma tumors, through hypermethylation of its promoter. In the present study, we have evaluated the expression levels of KCNMA1 both in a mouse model of Colorectal Cancer (CRC) and in human CRC samples. Additionally, epigenetic mechanisms of KCNMA1 gene regulation were investigated. We observed a significant down-regulation of KCNMA1 both in a human and mouse model of CRC. No differences in KCNMA1 levels were, however, observed at different TNM stages. We also wanted to determine whether the modulation in KCNMA1 was dependent on epigenetic mechanisms. A statistically significant inverse correlation between KCNMA1 expression and mir-17-5p levels was observed in patients with CRC. Furthermore, in the tumor samples, we found a significant hypermethylation of the promoter, in the loci cg24113782 and cg25655799, compared to healthy tissue. Overall, our data suggest the possible use of KCNMA1 as a therapeutic target in the early stages of CRC.

In Silico and In Vivo Analysis of IL37 in Multiple Sclerosis Reveals Its Probable Homeostatic Role on the Clinical Activity, Disability, and Treatment with Fingolimod

We evaluated the in silico expression and circulating levels of interleukin (IL)37 in patients with different forms of multiple sclerosis (MS) and also upon treatment with different disease-modifying drugs. The combined interpretation of the resulting data strengthens and extends the current emerging concept that endogenous IL37 plays an important role in determining onset and progression of MS. The in silico analysis revealed that production of IL37 from cluster of differentiation (CD)4+ T cells from MS patients was reduced in vitro as compared to healthy controls. The analysis of the datasets also demonstrated that “higher” levels of IL37 production from PBMC entailed significant protection from MS relapses. In addition, the in vivo part of the study showed that IL37 was selectively augmented in the sera of MS patients during a relapse and that treatment with the high potency disease-modifying drug fingolimod significantly increased the frequency of patients with circulating blood levels of IL37 (6/9, 66%) as compared to patients receiving no treatment (n = 48) or platform therapy (n = 59) who had levels of IL37 below the limit of the sensitivity of the assay. This finding therefore anticipates that fingolimod may at least partially exert its beneficial effects in MS by upregulating the production of IL37.

Effects of NO-Hybridization on the Immunomodulatory Properties of the HIV Protease Inhibitors Lopinavir and Ritonavir

HIV protease inhibitors (PIs) are antiretroviral agents, which have been found to also affect several cellular processes, such as inflammation and cell progression. In studies on non-steroidal, anti-inflammatory drugs, the addition of a nitric oxide (NO) moiety has been shown to both reduce their toxicity and enhance their pharmacological efficacy. Along this line of research, several derivatives of PIs have been synthesized by covalent attachment of NO moiety to the parental molecules. Previous work has indicated that NO-hybridization of the prototypical PI, Saquinavir leads to a derivative named Saquinavir-NO that while retaining the antiretroviral effect, acquires antitumoural and immunomodulatory properties along with reduced toxicity in vitro and in vivo. These data prompted us to evaluate the effects of NO-hybridization on two other PIs, Lopinavir and Ritonavir. The two NO-derivatives were compared head to head with their parental compounds on human primary peripheral blood mononuclear cells as well as on human primary macrophages. Lopinavir-NO and Lopinavir were also screened in an in vivo model of autoimmune hepatitis. Our results prove that Lopinavir-NO exerts markedly superior effects as compared to the parental compound both in vitro and in vivo. On the contrary, Ritonavir-NO effects overlapped those of Ritonavir. These data demonstrate that NO-hybridization of Lopinavir generates a derivative with significantly stronger immunomodulatory effects that are apparently related to an action of the compound on T-cell secretory capacity. Lopinavir-NO deserves additional studies for its possible use in T-cell-mediated autoimmune diseases including, but not limited to autoimmune hepatitis.

Senescence as a main mechanism of Ritonavir and Ritonavir-NO action against melanoma

The main focus of this study is exploring the effect and mechanism of two HIV-protease inhibitors: Ritonavir and Ritonavir-nitric oxide (Ritonavir-NO) on in vitro growth of melanoma cell lines. NO modification significantly improved the antitumor potential of Ritonavir, as the IC₅₀ values of Ritonavir-NO were approximately two times lower than IC₅₀ values of the parental compound. Our results showed for the first time, that both compounds induced senescence in primary and metastatic melanoma cell lines. This transformation was manifested as a change in cell morphology, enlargement of nuclei, increased cellular granulation, upregulation of β-galactosidase activity, lipofuscin granules appearance, higher production of reactive oxygen species and persistent inhibition of proliferation. The expression of p53, as one of the key regulators of senescence, was upregulated after 48 hours of Ritonavir-NO treatment only in metastatic B16F10 cells, ranking it as a late-response event. The development of senescent phenotype was consistent with the alteration of the cytoskeleton-as we observed diminished expression of vinculin, α-actin, and β-tubulin. Permanent inhibition of S6 protein by Ritonavir-NO, but not Ritonavir, could be responsible for a stronger antiproliferative potential of the NO-modified compound. Taken together, induction of senescent phenotype may provide an excellent platform for developing therapeutic approaches based on selective killing of senescent cells.

Comparative study of rapamycin and temsirolimus demonstrates superimposable anti-tumour potency on prostate cancer cells

Rapamycin is a macrocyclic lactone currently used for the treatment of cancer and for the prevention of transplant rejection. The primary pharmacological mode of action of rapamycin occurs through the inhibition (blocking) of the mammalian target of rapamycin (mTOR). By doing so, rapamycin interferes with the phosphoinositide 3-kinase (PI3K)-Akt-mTOR axis that controls several cellular functions involving cell growth, proliferation and angiogenesis. The frequent activation of the phosphoinositide 3-kinase (PI3K)/AKT pathway in advanced prostate cancer has provided a rationale for the use of mTOR inhibitors in this setting. We carried out a comparative study on the effects of rapamycin and temsirolimus on the in vitro and in vivo growth of the prostate cancer cell lines, LnCap and PC3. Our results demonstrate that rapamycin and temsirolimus exert similar in vitro and in vivo anti-proliferative effects against prostate cancer cells.

N-Acetylcysteine causes analgesia in a mouse model of painful diabetic neuropathy

N-Acetylcysteine, one of the most prescribed antioxidant drugs, enhances pain threshold in rodents and humans by activating mGlu2 metabotropic glutamate receptors. Here, we assessed the analgesic activity of N-acetylcysteine in the streptozotocin model of painful diabetic neuropathy and examined the effect of N-acetylcysteine on proteins that are involved in mechanisms of nociceptive sensitization. Mice with blood glucose levels ≥250 mg/dl in response to a single intraperitoneal (i.p.) injection of streptozotocin (200 mg/kg) were used for the assessment of mechanical pain thresholds. Systemic treatment with N-acetylcysteine (100 mg/kg, i.p., either single injection or daily injections for seven days) caused analgesia in diabetic mice. N-acetylcysteine-induced analgesia was abrogated by the Sxc− inhibitors, sulfasalazine (8 mg/kg, i.p.), erastin (30 mg/kg, i.p.), and sorafenib (10 mg/kg, i.p.), or by the mGlu2/3 receptor antagonist, LY341495 (1 mg/kg, i.p.). Repeated administrations of N-acetylcysteine in diabetic mice reduced ERK1/2 phosphorylation in the dorsal region of the lumbar spinal cord. The analgesic activity of N-acetylcysteine was occluded by the MEK inhibitor, PD0325901 (25 mg/kg, i.p.), the TRPV1 channel blocker, capsazepine (40 mg/kg, i.p.), or by a cocktail of NMDA and mGlu5 metabotropic glutamate receptor antagonists (memantine, 25 mg/kg, plus MTEP, 5 mg/kg, both i.p.). These findings offer the first demonstration that N-acetylcysteine relieves pain associated with diabetic neuropathy and holds promise for the use of N-acetylcysteine as an add-on drug in diabetic patients.

Evaluation of hyaluronic acid-P40 conjugated cream in a mouse model of dermatitis induced by oxazolone

P40 is a particulate fraction or fragment isolated from Corynebacterium granulosum, which exhibits a wide spectrum of pharmacological functions including antitumor, antibacterial, phagocytic, antiviral and cytokine induction effects. In the present study, the immunomodulatory potential of P40-conjugated with hyaluronic acid was assessed in a mouse model of dermatitis induced by oxazolone. Oxazolone-induced allergic contact dermatitis is a T cell-mediated Th2-like hypersensitivity reaction, which mimics the corresponding reaction in humans. Female cluster of differentiation-1 mice were sensitized on days 0 and 1 by the application of 2% oxazolone onto a shaved back. The disease was induced by re-challenge on day 7 using 15% oxazolone in the inner and outer of the left ears of the mice. Mice were topically treated with hyaluronic acid-P40 conjugate cream or with placebo to the inner and outer surface of the left ear for 7 consecutive days starting from 1 h after the sensitization. A significant reduction in ear thickness and weight and in edema and leukocyte recruitment were observed in the mice treated with hyaluronic-P40 conjugate cream compared with mice treated with the cream base alone (P<0.05). Thus, P40-conjugated with hyaluronic acid may constitute an innovative dermatitis treatment.

Acceleration of SLE-like syndrome development in NZBxNZW F1 mice by beta-glucan

Beta-glucans are naturally occurring polysaccharides that exert important immunostimulatory activities. In the present study, we evaluated whether beta-glucans could modulate the development and the course of systemic lupus erythematosus (SLE). To this aim, we employed the classical model of SLE represented by the F1 hybrid between the NZB and NZW mouse strains which develop severe lupus-like phenotypes comparable to that of SLE patients. The administration of beta-glucan was associated to a more aggressive development of the disease and a worse prognosis, as observed from the clinical, biochemical and histopathological data. This finding implies that restraint should be practised in the possible use of beta-glucans as immunomodulators in human therapy in the context of SLE.

Decitabine induces regulatory T cells, inhibits the production of IFN-gamma and IL-17 and exerts preventive and therapeutic efficacy in rodent experimental autoimmune neuritis

Guillain-Barré syndrome (GBS) is an immune-mediated acute disorder of the peripheral nervous system. Despite treatment, there is an associated mortality and severe disability in 9 to 17% of the cases. Decitabine (DAC) is a hypomethylating drug used in myelodisplastic syndrome, that has been shown to exert immunomodulatory effects. We have evaluated the effects of DAC in two rodent models of GBS, the Experimental Allergic Neuritis (EAN). Both prophylactic and therapeutic treatment with DAC ameliorated the clinical course of EAN, increasing the numbers of thymic regulatory T cells and reducing the production of proinflammmatory cytokines. Our data suggest the possible use of decitabine for the treatment of GBS.

Apotransferrin inhibits interleukin-2 expression and protects mice from experimental autoimmune encephalomyelitis

Transferrin (Tf) has a major role in T cell activation and proliferation. Here, we investigated whether Tf exerts immunomodulatory effects on T cells and in development of T-cell driven experimental autoimmune encephalomyelitis (EAE). While treatment of concanavalin A-stimulated splenocytes with apotransferrin (ApoTf) did not affect release of IL-1β, TNF, IFN-γ, IL-17, IL-4, and IL-10, it markedly and dose-dependently down-regulated synthesis of IL-2 in these cells. ApoTf also inhibited IL-2 generation in purified CD3+ T cells and the effect was accompanied with down-regulation of MAPK p44/42 and NFκB signaling. Despite impeded IL-2 release, proliferation of splenocytes was not inhibited by ApoTf. Importantly, ApoTf ameliorated EAE in mice and significantly reduced ex vivo IL-2 production in proteolipid protein-specific lymphocytes. Thus ApoTf may be a promising beneficial agent for multiple sclerosis.