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

Influence of Apis mellifera syriaca Bee Venom on Nociception and Inflammatory Cytokine Profiles in Experimental Hyperalgesia

Hyperalgesia is a condition marked by an abnormal increase in pain sensitivity, often occurring in response to tissue injury, inflammation, or prolonged exposure to certain medications. Inflammatory mediators, such as cytokines IL-1β, IL-6, and TNF-α, play a central role in this process, amplifying pain perception. Developing effective treatments that address the underlying mechanisms of hyperalgesia is an active field of research. Apis mellifera syriaca venom demonstrated potential immunomodulatory activity associated with cytokine release in vivo. Therefore, the aim of this study is to evaluate the effect of Apis mellifera syriaca bee venom (AmsBV) on pain sensitivity in a formalin-induced hyperalgesia mice model and to evaluate the potential role of cytokines associated with the nociception of pain. The hotplate test, used to measure pain latency, showed that hypersensitivity to pain was induced in formalin-injected male mice only, with no changes in females, suggesting a sex-based response to formalin. When applied, AmsBV reduced pain sensitivity in males, suggesting pain relief potential. At the molecular level, AmsBV was able to reduce pro-inflammatory interleukin IL-4 and cytokine IFN-γ, emphasizing its immunomodulatory potential. Interestingly, the venom restored anti-inflammatory IL-10 levels that were significantly decreased in hyperalgesia males. Together, these findings highlight the therapeutic potential for AmsBV in managing inflammation and reducing pain, particularly hyperalgesia.

The role of NF-κB transcription factor in the regulation of cytokine induced thermal hyperalgesia in a Leishmania major model in BALB/c mice

Cutaneous leishmaniasis caused mainly by Leishmania major (L. major) is one of the trending models used to investigate induced hyperalgesia and the involved cytokines. Previous studies approached the role of several cytokines in the observed hyperalgesia, but the molecular mechanisms orchestrating such a response still needed to be addressed. In this study, we inspect the role of the NF-κB in the modulation of L. major-prompted hyperalgesia and cytokine expression in BALB/c mice by administering celastrol, a potent blocker of this transcription factor. Intraperitoneal injection of 0.5 mg/kg and 1 mg/kg of celastrol attenuated the L. major-induced thermal hyperalgesia in BALB/c mice for 15 days and 21 days, respectively, as detected by hot plate and tail flick behavioral assessments. Cytokine levels were quantified in the infected paws of BALB/c mice using Sandwich ELISA. The administration of 1 mg/kg celastrol decreased TNF-α levels in L. major infected mice for 23 days, and IL-1β expression declined significantly for 23 days using both celastrol dosages. However, no significant change was observed in the levels of IL-10 in our experimental groups. The activation of NF-κB was detected by observing the phosphorylation levels of the p65 subunit using PathScan phospho-ELISA. The level of NF-κB phosphorylation was elevated in L. major infected BALB/c mice. Only administering 1 mg/kg celastrol suppressed the phosphorylation of p65, thus inactivating NF-kB. In conclusion, our results provide new insights into the correlation between the activation of NF-kB, the induction of thermal hyperalgesia, and the expression of TNF-α and IL-1β in the L. major-induced hyperalgesia model.

Tuina alleviates neuropathic pain through regulate the activation of microglia and the secretion of inflammatory cytokine in spinal cord

OBJECTIVE

To observe the analgesic effects of Tuina on neuropathic pain (NPP) and the underlying mechanisms.

METHODS

Forty-eight Sprague-Dawley (SD) rats were assigned by random into three treatment groups: sham, chronic constriction injury (CCI), and Tuina. Each group contained sixteen rats. CCI model was generated by ligating the right sciatic nerve. Behavioral changes of CCI were assessed by the paw withdrawal threshold (PWT) and paw withdrawal latency (PWL). In addition, biochemical techniques such as immunofluorescence staining, enzyme-linked immunosorbent assay (ELISA) and Western blotting were used to profile levels of microglia activation and inflammatory factors in the spinal dorsal horn (SDH) of rats. Tuina (clockwise pressing and rubbing) was performed at Chengshan (BL57) to observe the analgesic effects on CCI rats and the underlying mechanisms.

RESULTS

Rats with CCI experienced significant reduction in the PWT and PWL of the right hind paw relative to CCI group at day 3. Tuina treatment rescued this situation significantly on days 10 and 14. Besides, Iba-1, microglia M1 receptor CD68, tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) were higher in the right SDH for CCI group compared to the sham group on day 14. As expected, Tuina partially downregulated the CCI-induced overexpressed Iba-1, CD68, TNF-α, and IL-1β in the SDH of CCI model.

CONCLUSION

Tuina induces a time-dependent cumulative analgesic effect in CCI rats by inhibiting the activation of microglia and the secretion of IL-1β and TNF-α in SDH.

Contribution of spinal cord glial cells to L. amazonensis experimental infection-induced pain in BALB/c mice

Background

The cellular and molecular pathophysiological mecha\nisms of pain processing in neglected parasitic infections such as leishmaniasis remain unknown. The present study evaluated the participation of spinal cord glial cells in the pathophysiology of pain induced by Leishmania amazonensis infection in BALB/c mice.

Methods

Mice received intra-plantar (i.pl.) injection of L. amazonensis (1 × 10⁵) and hyperalgesia, and paw edema were evaluated bilaterally for 40 days. The levels of TNF-α and IL-1β, MPO activity, and histopathology were assessed on the 40th day. ATF3 mRNA expression was assessed in DRG cells at the 30th day post-infection. Blood TNF-α and IL-1β levels and systemic parasite burden were evaluated 5–40 days after the infection. At the 30th day post-infection L. amazonensis, the effects of intrathecal (i.t.) treatments with neutralizing antibody anti-CX₃CL1, etanercept (soluble TNFR2 receptor), and interleukin-1 receptor antagonist (IL-1ra) on infection-induced hyperalgesia and paw edema were assessed. In another set of experiments, we performed a time course analysis of spinal cord GFAP and Iba-1 (astrocytes and microglia markers, respectively) and used confocal immunofluorescence and Western blot to confirm the expression at the protein level. Selective astrocyte (α-aminoadipate) and microglia (minocycline) inhibitors were injected i.t. to determine the contribution of these cells to hyperalgesia and paw edema. The effects of i.t. treatments with glial and NFκB (PDTC) inhibitors on spinal glial activation, TNF-α, IL-1β, CX₃CR1 and CX₃CL1 mRNA expression, and NFκB activation were also evaluated. Finally, the contribution of TNF-α and IL-1β to CX₃CL1 mRNA expression was investigated.

Results

L. amazonensis infection induced chronic mechanical and thermal hyperalgesia and paw edema in the infected paw. Mechanical hyperalgesia was also observed in the contralateral paw. TNF-α, IL-1β, MPO activity, and epidermal/dermal thickness increased in the infected paw, which confirmed the peripheral inflammation at the primary foci of this infection. ATF3 mRNA expression at the ipsilateral DRG of the infected paw was unaltered 30 days post-infection. TNF-α and IL-1β blood levels were not changed over the time course of disease, and parasitism increased in a time-dependent manner in the ipsilateral draining lymph node. Treatments targeting CX₃CL1, TNF-α, and IL-1β inhibited L. amazonensis-induced ongoing mechanical and thermal hyperalgesia, but not paw edema. A time course of GFAP, Iba-1, and CX₃CR1 mRNA expression indicated spinal activation of astrocytes and microglia, which was confirmed at the GFAP and Iba-1 protein level at the peak of mRNA expression (30th day). Selective astrocyte and microglia inhibition diminished infection-induced ipsilateral mechanical hyperalgesia and thermal hyperalgesia, and contralateral mechanical hyperalgesia, but not ipsilateral paw edema. Targeting astrocytes, microglia and NFκB diminished L. amazonensis-induced GFAP, Iba-1, TNF-α, IL-1β, CX₃CR1 and CX₃CL1 mRNA expression, and NFκB activation in the spinal cord at the peak of spinal cord glial cells activation. CX₃CL1 mRNA expression was also detected in the ipsilateral DRG of infected mice at the 30th day post-infection, and the i.t. injection of TNF-α or IL-1β in naïve animals induced CX₃CL1 mRNA expression in the spinal cord and ipsilateral DRG.

Conclusions

L. amazonensis skin infection produces chronic pain by central mechanisms involving spinal cord astrocytes and microglia-related production of cytokines and chemokines, and NFκB activation contributes to L. amazonensis infection-induced hyperalgesia and neuroinflammation.

Electronic supplementary material

The online version of this article (10.1186/s12974-019-1496-2) contains supplementary material, which is available to authorized users.

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.

Evaluation of interleukin 8 +2767 A/T polymorphism in visceral leishmaniasis

OBJECTIVE

To evaluated the relationship between the genetic variations at IL-8 +2767 position with VL pathogenesis among Iranian patients.

METHODS

Three groups including patients with VL clinical presentation and leishmania seropositive (n = 124), patients seropositive but without clinical presentation (n = 82) and healthy controls (n = 63) were selected to conduct this cross-sectional study. Polymorphism at +2767 position of IL-8 was investigated using PCR-RFLP techniques. Anti-leishmania antibody titration was evaluated by the immunoflorescence technique.

RESULTS

We observed higher significant frequencies +2767 A/A and A/T genotypes in Group 1 compared to Group 2 and healthy controls (P = 0.001). Also, patients in Group 1 carrying A/A genotype showed higher titer of anti-leishmania antibody than patients with A/T and T/T genotypes (P = 0.05). The validity of the data was analyzed using Hardy-Weinberg equilibrium and one way analysis of variance (ANOVA), as well as χ² tests.

CONCLUSIONS

Our findings indicate that the IL-8 +2767 polymorphism is significantly involved in impaired immune responses against VL and it could be considered as a risk factor for the VL progress.

The Effect of Repeated Electroacupuncture Analgesia on Neurotrophic and Cytokine Factors in Neuropathic Pain Rats

Chronic pain is a common disability influencing quality of life. Results of previous studies showed that acupuncture has a cumulative analgesic effect, but the relationship with spinal cytokines neurotrophic factors released by astrocytes remains unknown. The present study was designed to observe the effect of electroacupuncture (EA) treatment on spinal cytokines neurotrophic factors in chronic neuropathic pain rats. The chronic neuropathic pain was established by chronic constrictive injury (CCI). EA treatment was applied at Zusanli (ST36) and Yanglingquan (GB34) (both bilateral) once a day, for 30 min. IL-1β mRNA, TNF-α mRNA, and IL-1 mRNA were detected by quantitative real-time PCR, and the proteins of BDNF, NGF, and NT3/4 were detected by Western blot. The expression levels of cytokines such as IL-1β mRNA, TNF-α mRNA, IL-6 mRNA, and neurotrophic factors such as BDNF, NGF, and NT3/4 in the spinal cord were increased significantly after CCI. The astrocytes released more IL-1β and BDNF after CCI. Repeated EA treatment could suppress the elevated expression of IL-1β mRNA, TNFα mRNA, and BDNF, NGF, and NT3/4 but had no effect on IL-6 mRNA. It is suggested that cytokines and neurotrophic factors which may be closely associated with astrocytes participated in the process of EA relieving chronic pain.