Emerging Approaches for the Management of Chemotherapy-Induced Peripheral Neuropathy (CIPN): Therapeutic Potential of the C5a/C5aR Axis

The role and treatment potential of the complement pathway in chronic pain

The role of the complement system in pain syndromes has garnered attention on the back of preclinical and clinical evidence supporting its potential as a target for new analgesic pharmacotherapies. Of the components that make up the complement system, component 5a (C5a) and component 3a (C3a) are most strongly and consistently associated with pain. Receptors for C5a are widely found in immune resident cells (microglia, astrocytes, sensory neuron-associated macrophages (sNAMs)) in the central nervous system (CNS) as well as hematogenous immune cells (mast cells, macrophages, T-lymphocytes, etc.). When active, as is often observed in chronic pain conditions, these cells produce various inflammatory mediators including pro-inflammatory cytokines. These events can trigger nervous tissue inflammation (neuroinflammation) which coexists with and potentially maintains peripheral and central sensitization. C5a has a likely critical role in initiating this process highlighting its potential as a promising non-opioid target for treating pain. This review summarizes the most up-to-date research on the role of the complement system in pain with emphasis on the C5 pathway in peripheral tissue, dorsal root ganglia (DRG) and the CNS, and explores advances in complement-targeted drug development and sex differences. A perspective on the optimal application of different C5a inhibitors for different types (e.g., neuropathic, post-surgical and chemotherapy-induced pain, osteoarthritis pain) and stages (e.g., acute, subacute, chronic) of pain is also provided to help guide future clinical trials. PERSPECTIVE: This review highlights the role and mechanisms of complement components and their receptors in physiological and pathological pain. The potential of complement-targeted therapeutics for the treatment of chronic pain is also explored with a focus on C5a inhibitors to help guide future clinical trials.

Multitargeting Pt(IV) Derivatives of Cisplatin or Oxaliplatin Inhibit Tumor Growth in Mice without Inducing Neuropathic Pain

Cisplatin and oxaliplatin are Pt(II) anticancer agents that are used to treat several cancers, usually in combination with other drugs. Their efficacy is diminished by dose-limiting peripheral neuropathy (PN) that affects ∼70% of patients. PN is caused by selective accumulation of the platinum drugs in the dorsal root ganglia (DRG), which overexpress transporters for cisplatin and oxaliplatin. To date, no drug is recommended for the prevention of PN. We report that Pt(IV) prodrugs of cisplatin or oxaliplatin do not induce neuropathic pain in mice, likely due to the lower accumulation of platinum in the DRG compared with Pt(II) drugs. Moreover, the multitargeting prodrug that combines cisplatin with paclitaxel, both strong inducers of PN, efficiently inhibited tumor growth in vivo without inducing neuropathic pain. The high antitumor efficacy of Pt(IV) prodrugs and their micellar counterparts and the low level of neuropathic pain associated with them make them ideal candidates for clinical use in cancer therapy.

Oral Neuropathy Associated with Commonly used Chemotherapeutic Agents: A Narrative Review

PURPOSE OF REVIEW

Chemotherapy-induced peripheral neuropathy (CIPN) is a frequent complication of cytotoxic chemotherapeutic agents; its incidence largely varies, depending on type, dose, agent and preexisting risk factors. Oral-and-perioral-CIPN (OCIPN) is underreported. Neurotoxic agents can cause jaw pain or numbness. This review aims to present available data on OCIPN RECENT FINDINGS: A narrative literature review, following SANRA guidelines was conducted. PubMed and Cochrane databases were searched until September 2023. Articles referring to neuropathy or neuropathic pain due to head and neck cancer, head and neck radiotherapy, oropharyngeal mucositis, infection or post-surgical pain were excluded. Platinum-based chemotherapeutics, taxanes, vinca alkaloids, immunomodulatory and alkylating agents can cause OCIPN. Platinum-based chemotherapeutics can cause orofacial cold sensitivity, orofacial and jaw pain, oral cavity tingling and teeth hypersensitivity. Taxanes may induce oral cavity and tongue numbness and tingling as well as hot hypersensitivity. Vinca alkaloids may cause jaw, teeth and lips pain and oral mucosa hyperalgesia. Immunomodulatory drugs can cause lips, tongue and perioral numbness, while alkylating agents induce tongue and lips tingling and teeth cold-hypersensitivity. Chemotherapy may cause OCIPN due to changes in cellular structure and function, like alterations in membrane receptors and neurotransmission. OCIPN should be documented and physicians, dentists and health care providers should be alerted.

A Novel Therapy for Cisplatin-Induced Allodynia and Dysfunctional and Emotional Impairments in Male and Female Mice

Patients undergoing chemotherapy with cisplatin (CIS) develop neuropathy in addition to other symptoms such as, anxiety, depression, muscle wasting and body weight loss. This symptomatology greatly weakens patients and may even lead to adjournment of chemotherapy. The protecting actions of molecular hydrogen in many neurological illnesses have been described, but its effect on the functional and emotional deficiencies caused by CIS has not been assessed. In C57BL/6J male and female mice injected with CIS, we examined the impact of the prophylactic treatment with hydrogen-rich water (HRW) on: (i) the tactile and cold allodynia, (ii) the deficits of grip strength and weight loss, (iii) the anxiodepressive-like behaviors and (iv) the inflammatory and oxidative reactions incited by CIS in the dorsal root ganglia (DRG) and prefrontal cortex (PFC). The results demonstrate that the mechanical allodynia and the anxiodepressive-like comportment provoked by CIS were similarly manifested in both sexes, whereas the cold allodynia, grip strength deficits and body weight loss produced by this chemotherapeutic agent were greater in female mice. Nonetheless, the prophylactic treatment with HRW prevented the allodynia and the functional and emotional impairments resulting from CIS in both sexes. This treatment also inhibited the inflammatory and oxidative responses activated by CIS in the DRG and PFC in both sexes, which might explain the therapeutic actions of HRW in male and female mice. In conclusion, this study revealed the plausible use of HRW as a new therapy for the allodynia and physical and mental impairments linked with CIS and its possible mechanism of action.

Inhibition of C5aR1 as a promising approach to treat taxane-induced neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is a common side effect of several antitumor agents resulting in progressive and often irreversible damage of peripheral nerves. In addition to their known anticancer effects, taxanes, including paclitaxel, can also induce peripheral neuropathy by activating microglia and astrocytes, which release pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α), interleukin 1-beta (IL-1β), and chemokine (C-C motif) ligand 2 (CCL-2). All these events contribute to the maintenance of neuropathic or inflammatory response. Complement component 5a (C5a)/C5a receptor 1 (C5aR1) signaling was very recently shown to play a crucial role in paclitaxel-induced peripheral neuropathy. Our recent findings highlighted that taxanes have the previously unreported property of binding and activating C5aR1, and that C5aR1 inhibition by DF3966A is effective in preventing paclitaxel-induced peripheral neuropathy (PIPN) in animal models. Here, we investigated if C5aR1 inhibition maintains efficacy in reducing PIPN in a therapeutic setting. Furthermore, we characterized the role of C5aR1 activation by paclitaxel and the CIPN-associated activation of nod-like receptor (NLR) family pyrin domain containing 3 (NLRP3) inflammasome. Our results clearly show that administration of the C5aR1 inhibitor strongly reduced cold and mechanical allodynia in mice when given both during the onset of PIPN and when neuropathy is well established. C5aR1 activation by paclitaxel was found to be a key event in the induction of inflammatory factors in spinal cord, such as TNF-α, ionized calcium-binding adapter molecule 1 (Iba-1), and glial fibrillary acidic protein (GFAP). In addition, C5aR1 inhibition significantly mitigated paclitaxel-induced inflammation and inflammasome activation by reducing IL-1β and NLRP3 expression at both sciatic and dorsal root ganglia level, confirming the involvement of inflammasome in PIPN. Moreover, paclitaxel-induced upregulation of C5aR1 was significantly reduced by DF3966A treatment in central nervous system. Lastly, the antinociceptive effect of C5aR1 inhibition was confirmed in an in vitro model of sensory neurons in which we focused on receptor channels usually activated upon neuropathy. In conclusion, C5aR1 inhibition is proposed as a therapeutic option with the potential to exert long-term protective effect on PIPN-associated neuropathic pain and inflammation.

Ozone attenuates chemotherapy-induced peripheral neuropathy via upregulating the AMPK-SOCS3 axis

Background

Chemotherapy-induced peripheral neuropathy (CIPN) is a severe adverse reaction to chemotherapeutics, which seriously affects the outcome of chemotherapy and patients' quality of life. Although it is commonly seen, it lacks effective treatment. Our previous study found that ozone could alleviate neuropathic pain. Damage-associated molecular patterns (DAMPs) or Toll-like receptor 4 (TLR4) or tissue factor (TF)-mediated neuroinflammation and microcirculation disturbance is the main reason for CIPN. Suppressors of cytokine signaling (SOCS) 3 is an endogenous negative feedback regulator of inflammation via TLR4 inhibition.

Materials and Methods

Oxaliplatin (L-OHP) was used to establish mice's CIPN model. Nociceptive responses were assessed by observing the ICR mice's incidence of foot regression in mechanical indentation response experiments. Cell signaling assays were performed by Western blotting and immunohistochemistry. The mouse leukemia cells of monocyte-macrophage line RAW 264.7 were cultured to investigate the effects of ozone administration on macrophage.

Results

Ozone decreased the expression of TF in the blood and sciatic nerve. It upregulated the adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK)-SOCS3 axis to relieve CIPN and inhibit TF expression in vivo. SOCS3 expression was induced by ozone to inhibit the p38/TF signaling in RAW 246.7 cells. Ozone also prevented L-OHP-induced sciatic nerve demyelination. Microglia activation was inhibited, and c-Fos and calcitonin gene-related peptide (CGRP) expression was decreased in the spinal dorsal horn via ozone.

Conclusions

In this study, we demonstrated that ozone could alleviate CIPN by upregulating the AMPK-SOCS3 axis to inhibit TF expression, which is a potential treatment for CIPN.