Interleukin-10 reduces hyperalgesia and the level of Interleukin-1β in BALB/c mice infected with Leishmania major with no major effect on the level of Interleukin-6

Nitric-oxide releasing chitosan nanoparticles towards effective treatment of cutaneous leishmaniasis

Cutaneous leishmaniasis (CL) is a major public health problem caused by Leishmania parasites that produce destructive and disfiguring skin conditions. There is an urgent need for alternative topical therapies due to the limitations of current systemic treatments. Recently, we have synthesized nitric oxide-releasing chitosan nanoparticles (NONPs) and shown their potential in vitro against Leishmania amazonensis. Herein we evaluated the application of NONPs for the treatment of CL on infected BALB/c mice. Mice were treated with topical administration of increasing concentrations of NONPs and disease progression was investigated regarding parasite load, lesion thickness, and pain score. As a result, we observed a dose-dependent NONPs effect. Parasite burden and lesion thickness were substantially lower on animals receiving NONPs at a 2 mM concentration compared to untreated control. Moreover, the clinical presentation of the lesions did not show any visible signs of ulcer, suggesting clinical healing in these animals. This successful outcome was sustained for at least 21 days after therapy even in one single dose. Thus, we demonstrate that NONPs are suitable for topical administration, and represent an attractive approach to treat CL.

Cytokines: Key Determinants of Resistance or Disease Progression in Visceral Leishmaniasis: Opportunities for Novel Diagnostics and Immunotherapy

Leishmaniasis is a parasitic disease of humans, highly prevalent in parts of the tropics, subtropics, and southern Europe. The disease mainly occurs in three different clinical forms namely cutaneous, mucocutaneous, and visceral leishmaniasis (VL). The VL affects several internal organs and is the deadliest form of the disease. Epidemiology and clinical manifestations of VL are variable based on the vector, parasite (e.g., species, strains, and antigen diversity), host (e.g., genetic background, nutrition, diversity in antigen presentation and immunity) and the environment (e.g., temperature, humidity, and hygiene). Chemotherapy of VL is limited to a few drugs which is expensive and associated with profound toxicity, and could become ineffective due to the parasites developing resistance. Till date, there are no licensed vaccines for humans against leishmaniasis. Recently, immunotherapy has become an attractive strategy as it is cost-effective, causes limited side-effects and do not suffer from the downside of pathogens developing resistance. Among various immunotherapeutic approaches, cytokines (produced by helper T-lymphocytes) based immunotherapy has received great attention especially for drug refractive cases of human VL. Therefore, a comprehensive knowledge on the molecular interactions of immune cells or components and on cytokines interplay in the host defense or pathogenesis is important to determine appropriate immunotherapies for leishmaniasis. Here, we summarized the current understanding of a wide-spectrum of cytokines and their interaction with immune cells that determine the clinical outcome of leishmaniasis. We have also highlighted opportunities for the development of novel diagnostics and intervention therapies for VL.

Glucantime reduces mechanical hyperalgesia in cutaneous leishmaniasis and complete Freund's adjuvant models of chronic inflammatory pain

OBJECTIVES

To evaluate the analgesic effect of Glucantime (antimoniate N-methylglucamine) in Leishmania amazonensis infection and complete Freund's adjuvant (CFA), chronic paw inflammation model, in BALB/c mice.

METHODS

Two models of chronic inflammatory pain in BALB/c mice paw were used: infection with L. amazonensis and CFA stimulation. Both animals models received daily treatment with Glucantime (10 mg/kg, i.p.) and during the treatment was measured the mechanical hyperalgesia with electronic version of von Frey filaments. After the treatment, the paw skin sample was collected for analysis of myeloperoxidase (MPO) and N-acetyl-β-glucosaminidase (NAG) activity, and IL-1β, TNF-α, IL-6, IFN-γ and IL-10 cytokines production by ELISA.

KEY FINDINGS

Leishmania amazonensis-induced chronic inflammation with significant increase in mechanical hyperalgesia, MPO and NAG activity, and IL-1β, TNF-α and IL-6 production in the paw skin. Glucantime (10 mg/kg, i.p.) inhibited L. amazonensis-induced mechanical hyperalgesia and IL-1β and IL-6 cytokines productions. In chronic inflammatory model induced by CFA, Glucantime treatment during 7 days inhibited CFA-induced mechanical hyperalgesia, MPO and NAG activity, and IL-1β, TNF-α, IL-6 and IFN-γ production as well as increased IL-10 production.

CONCLUSIONS

Our data demonstrated that Glucantime reduced the chronic inflammatory pain induced by L. amazonensis and CFA stimuli by inhibiting the hyperalgesic cytokines production.

Leishmania infection: painful or painless?

The complex life cycle and immunopathological features underpinning the interaction of Leishmania parasites and their mammalian hosts poses frequent poorly explored and inconclusively resolved questions. The altered nociceptive signals over the course of leishmaniasis remain an intriguing issue for nociceptive and parasitology researchers. Experimental investigations have utilized behavioral, morphological, and neuro-immune approaches in the study of experimental cutaneous leishmaniasis (CL). The data generated indicates new venues for the study of the pathological characteristics of nociceptive processing in this parasitic disease. Leishmania-induced pain may be easily observed in mice and rats. However, nociceptive data is more complex in human investigations, including the occurrence of painless lesions in mucocutaneous and cutaneous leishmaniasis. Data from recent decades indicate that humans can also be affected by pain-related symptoms, often distinct from the region of body infection. The molecular and cellular mechanisms underlying such variable nociceptive states in humans during the course of leishmaniasis are an active area of research. The present article reviews nociception in leishmaniasis, including in experimental models of CL and clinical reports.

Atenolol Reduces Leishmania major-Induced Hyperalgesia and TNF-α Without Affecting IL-1β or Keratinocyte Derived Chemokines (KC)

Infection with a high dose of the intracellular parasitic protozoan Leishmania major induces a sustained hyperalgesia in susceptible BALB/c mice accompanied by up-regulation of the pro-inflammatory cytokines IL-1β and IL-6. Interleukin-13 (IL-13) has been shown to reduce this hyperalgesia (despite increased levels of IL-6) and the levels of IL-1β during and after the treatment period. These findings favor the cytokine cascade leading to the production of sympathetic amines (involving TNF-α and KC) over prostaglandins (involving IL-lβ and IL-6) as the final mediators of hyperalgesia. The aim of this study was to investigate the effect of daily treatment with the β-blockers atenolol on L. major-induced inflammation in mice with respect to hyperalgesia as well as the levels of TNF-α and KC (the analog of IL-8 in mice). Our data demonstrates that atenolol is able to reduce the L. major induced sustained peripheral hyperalgesia, which does not seem to involve a direct role for neither IL-lβ nor KC. Moreover, our results show that TNF-α may play a pivotal and direct role in sensitizing the peripheral nerve endings (nociceptors) since its level was reduced during the period of atenolol treatment, which correlates well with the reduction of the observed peripheral, but not central, hyperalgesia. These findings contribute to a better understanding of the cytokine cascade leading to hyperalgesia and may lead to the development of new and more efficient medications for many types of pain.

Anti-inflammatory effects of carvacrol: evidence for a key role of interleukin-10

Carvacrol, a phenolic monoterpene, has been reported to possess anti-inflammatory properties. However, the mechanisms involved in its pharmacological properties are currently not well understood. In the present study, the contribution of cytokine modulation to the anti-inflammatory effects of carvacrol was investigated in a classical inflammation model: the complete Freund's adjuvant (CFA)-induced paw inflammation in mice. The paw edema was measured using a plesthismometer. Paw tissue was removed 2h after the inflammatory stimulus to determine the levels of prostaglandin E(2) (PGE(2)) by enzyme immunoassay, the levels of interleukin-1 β (IL-1β), tumor necrosis factor-α (TNF-α), and interleukin-10 (IL-10) by ELISA or the mRNA expression of cyclooxygenase-2 (COX-2), IL-1β, TNF-α, and IL-10 by real-time PCR. Administration of carvacrol produced anti-inflammatory effects against CFA-induced inflammation in mice. Treatment of mice with carvacrol at 50 and 100mg/kg attenuated the paw edema and reduced the IL-1β and PGE(2), but not TNF-α, local levels. Similarly, carvacrol (100mg/kg) reduced the COX-2 and IL-1β mRNA expression. The levels of IL-10, an anti-inflammatory cytokine, and the IL-10 mRNA expression in the inflamed paw were enhanced by carvacrol. In addition, the treatment with carvacrol did not reduce the CFA-induced paw edema in IL-10 knockout mice. The present results suggest that carvacrol causes anti-inflammatory effects by reducing the production of inflammatory mediators, such as IL-1β and prostanoids, possibly through the induction of IL-10 release.

Interleukin-10 of red nucleus plays anti-allodynia effect in neuropathic pain rats with spared nerve injury

Our previous studies have shown that pro-inflammatory cytokines tumor necrosis factor-alpha (TNF-α) and interleukin-1beta (IL-1β) in red nucleus (RN) are involved in the development of neuropathic pain and play facilitated roles on the mechanical allodynia induced by peripheral nerve injury. The current study was designed to evaluate the expression and effect of IL-10, an anti-inflammatory cytokine, in the RN of rats with spared nerve injury (SNI). Immunohistochemical staining results demonstrated when 3 weeks after SNI, the expression level of IL-10 in the contralateral RN of SNI rats was apparently higher than those of sham-operated and normal rats. To further study the effect of IL-10 in the development of neuropathic pain, different doses of IL-10 (1.0, 0.5 and 0.1 μg/μl) were microinjected respectively into the RN contralateral to the nerve injury side of SNI rats. Results demonstrated that higher doses of IL-10 (1.0 and 0.5 μg/μl) significantly attenuated the mechanical allodynia of neuropathic rats, while 0.1 μg/μl of IL-10 did not show any analgesic effect. These results suggest that IL-10 of RN participates in the development of neuropathic pain and plays inhibitory roles on the mechanical allodynia induced by SNI.

The intrathecally administered kappa-2 opioid agonist GR89696 and interleukin-10 attenuate bone cancer-induced pain through synergistic interaction

BACKGROUND

Although bone cancer-related pain is one of the most disruptive symptoms in patients with advanced cancer, patients are often refractory to pharmacological treatments; thus, more effective treatments for bone cancer pain are needed. We evaluated the analgesic efficacy of and interaction between intrathecal GR89696, a κ(2)-opioid receptor agonist, and interleukin (IL)-10 in a rat model of bone cancer pain.

METHODS

The rat model of bone cancer pain was produced by right tibia intramedullary injection of rat breast cancer cells, and an intrathecal catheterization was performed. Ten days later, a paw-withdrawal threshold to mechanical stimulus by von Frey hairs was measured using the up-down method, after intrathecal administration of GR89696 and IL-10. The interaction between the 2 drugs was also evaluated using an isobolographic analysis.

RESULTS

Intrathecal GR89696 and IL-10 significantly increased the paw withdrawal threshold of the cancer cell-implanted rat, in a dose-dependent manner, with 50% effective dose values (95% confidence interval) of 50.78 μg (31.80-80.07μg) and 0.83 μg (0.59-1.15 μg), respectively. Isobolographic analysis revealed a synergistic interaction between intrathecal GR89696 and IL-10.

CONCLUSIONS

Intrathecally administered GR89696 and IL-10 attenuated bone cancer-induced pain, and the 2 drugs interacted synergistically in the spinal cord. These results raise the intriguing possibility of κ(2)-opioid receptor agonists and IL-10 as a new therapeutic approach for the management of bone cancer-associated pain.

Interleukin-13 reduces hyperalgesia and the level of interleukin-1β in BALB/c mice infected with Leishmania major with an up-regulation of interleukin-6

The anti-inflammatory cytokines interleukin-10 (IL-10) and interleukin-13 (IL-13) were shown to reduce hyperalgesia in some models such as rats exposed to UV rays. In addition, IL-10 was also shown to reduce hyperalgesia in high dose of Leishmania major-induced inflammation in BALB/c mice accompanied by a significant decrease in the levels of interleukin-1β (IL-1β) in the paws of infected mice, while no effect on the levels of IL-6 was observed. In this study, we injected BALB/c mice with a high dose of L. major and treated them with IL-13 (15 ng/animal) for twelve days (excluding the weekends) and hyperalgesia was assessed using thermal pain tests. Furthermore, the levels of IL-1β and IL-6 were also assessed at different post-infection days. Our results show that IL-6 and more importantly IL-1β don't play a direct role in the L. major-induced hyperalgesia and that IL-13 induces this hyperalgesia through the down-regulation of IL-1β and another proinflammatory cytokine (most probably TNF-α). Furthermore, our data show that IL-13 leads to the upregulation of the level IL-6 which initially seems to have no direct role in the induced hyperalgesia. Therefore, we suggest that the L. major-induced hyperalgesia is mainly mediated by the cytokine cascade leading to the production of sympathetic amines.

Nitric oxide synthase modulates CFA-induced thermal hyperalgesia through cytokine regulation in mice

Background

Although it has been largely demonstrated that nitric oxide synthase (NOS), a key enzyme for nitric oxide (NO) production, modulates inflammatory pain, the molecular mechanisms underlying these effects remain to be clarified. Here we asked whether cytokines, which have well-described roles in inflammatory pain, are downstream targets of NO in inflammatory pain and which of the isoforms of NOS are involved in this process.

Results

Intraperitoneal (i.p.) pretreatment with 7-nitroindazole sodium salt (7-NINA, a selective neuronal NOS inhibitor), aminoguanidine hydrochloride (AG, a selective inducible NOS inhibitor), L-N(G)-nitroarginine methyl ester (L-NAME, a non-selective NOS inhibitor), but not L-N(5)-(1-iminoethyl)-ornithine (L-NIO, a selective endothelial NOS inhibitor), significantly attenuated thermal hyperalgesia induced by intraplantar (i.pl.) injection of complete Freund's adjuvant (CFA). Real-time reverse transcription-polymerase chain reaction (RT-PCR) revealed a significant increase of nNOS, iNOS, and eNOS gene expression, as well as tumor necrosis factor-alpha (TNF), interleukin-1 beta (IL-1β), and interleukin-10 (IL-10) gene expression in plantar skin, following CFA. Pretreatment with the NOS inhibitors prevented the CFA-induced increase of the pro-inflammatory cytokines TNF and IL-1β. The increase of the anti-inflammatory cytokine IL-10 was augmented in mice pretreated with 7-NINA or L-NAME, but reduced in mice receiving AG or L-NIO. NNOS-, iNOS- or eNOS-knockout (KO) mice had lower gene expression of TNF, IL-1β, and IL-10 following CFA, overall corroborating the inhibitor data.

Conclusion

These findings lead us to propose that inhibition of NOS modulates inflammatory thermal hyperalgesia by regulating cytokine expression.

Accelerated control of visceral Leishmania donovani infection in interleukin-6-deficient mice

In patients with visceral leishmaniasis, increased levels of circulating interleukin-6 (IL-6) regularly accompany fully expressed, progressive infections (kala-azar). To experimentally test the role of IL-6, responses to an intracellular Leishmania donovani infection in the livers of IL-6(-/-) and wild-type mice were compared. IL-6(-/-) mice showed an enhanced control of the infection and earlier, rapid parasite killing along with additional evidence of a stimulated antileishmanial Th1-cell-type response: increased levels of circulating gamma interferon, accelerated granuloma assembly, and heightened responsiveness to chemotherapy. In this model of visceral leishmaniasis, IL-6 appears to act in a suppressive, macrophage-deactivating fashion, which identifies it as a potential target for therapeutic blockade.