Chikungunya virus (CHIKV) is an arthritogenic alphavirus transmitted primarily via Aedes aegypti and Aedes albopictus mosquitoes. Since its identification, CHIKV remained confined to parts of Africa and Asia until the early 2000s, when it expanded to other continents, causing epidemics. Structurally, it is an enveloped virus with a positive-single-stranded RNA genome, which encodes four non-structural proteins (nsP1-nsP4), responsible for viral replication, and five structural proteins (C, E3, E2, 6K, and E1), which form the capsid and envelope. Of these proteins, glycoproteins E1 and E2 are essential for cell recognition and membrane fusion, determining infectivity and viral tropism. CHIKV replication occurs in the cytosol of different cell types, triggering an intense inflammatory and immune response, which manifests clinically as Chikungunya fever (CHIKF). Despite its epidemiological impact, current treatment is limited to symptomatic approaches, including the use of analgesics and anti-inflammatories, as no specific antiviral therapies are available. In response, promising advances are being made, including the development of vaccines, targeted antivirals, and immunotherapies. This article aims to review the main aspects of viral biology, epidemiology, and immunopathogenesis of CHIKV infection, in addition to discussing the main advances in the development of new therapeutic approaches for its control.

Neuropathic pain arises from injuries to the nervous system in diseases such as diabetes, infections, toxicity, and traumas. The underlying mechanism of neuropathic pain involves peripheral and central pathological modifications. Peripheral mechanisms entail nerve damage, leading to neuronal hypersensitivity and ectopic action potentials. Central sensitization involves a neuropathological process with increased responsiveness of the nociceptive neurons in the central nervous system (CNS) to their normal or subthreshold input due to persistent stimuli, leading to sustained electrical discharge, synaptic plasticity, and aberrant processing in the CNS. Current treatments, both pharmacological and non-pharmacological, aim to alleviate symptoms but often face challenges due to the complexity of neuropathic pain. Neuromodulation is emerging as an important therapeutic approach for the treatment of neuropathic pain in patients unresponsive to common therapies, by promoting the normalization of neuronal and/or glial activity and by targeting cerebral cortical regions, spinal cord, dorsal root ganglia, and nerve endings. Having a better understanding of the efficacy, adverse events and applicability of neuromodulation through pre-clinical studies is of great importance. Unveiling the mechanisms and characteristics of neuromodulation to manage neuropathic pain is essential to understand how to use it. In the present article, we review the current understanding supporting dorsal root ganglia and spinal cord neuromodulation as a therapeutic approach for neuropathic pain.

Introduction: Chikungunya Virus (CHIKV), an enveloped RNA virus transmitted by Aedes mosquitoes, has become an increasing global health concern, particularly in South America, where cases and fatalities have risen (PAHO, 2023). This review focuses on therapeutic strategies targeting the CHIKV E2 protein, including vaccines, antibodies, and antiviral approaches tested in vitro and in vivo. Methods: Literature reporting on the E2 protein, including studies on viral structure, host interactions, symptoms, and treatments under development, was analyzed. Results: The E2 protein, a major structural component of CHIKV, is critical for viral entry and virulence, mediating interactions with host factors (Glycosaminoglycans (GAGs) and C-type lectins) and receptors (Matrix Remodeling-Associated Protein 8 (Mxra8) and Prohibitin-1 (PHB1)). It also elicits robust antibody responses, making it a key target for therapeutic intervention. Discussion: The E2 protein is essential for CHIKV entry and virulence, making it a key target for vaccines, antibodies, and antivirals. While preclinical studies show promise, efficacy varies and clinical translation remains limited. Challenges include viral diversity, immune escape, and the need for integrated strategies combining different therapeutic approaches. Conclusion: Given the absence of licensed vaccines and antivirals for alphaviruses, the E2 protein represents a promising therapeutic target while inhibiting E2 could block viral entry and infection. However, current strategies show variable efficacy and inconclusive results, highlighting the need for further research to validate and optimize E2-targeted therapies.

Background/Objectives: Fructose-1,6-bisphosphate (FBP) is an intermediate product of the glycolytic pathway with analgesic effect in acute inflammatory pain model via the production of adenosine. However, whether FBP is active in neuropathic pain is unknown. Therefore, we reason that it would be suitable to investigate the analgesic effect and mechanism of action of FBP in a model of chronic constriction injury (CCI) of sciatic nerve-induced neuropathic pain in mice. Methods: After CCI induction, mice received FBP, adenosine, A1 and/or A2A receptor antagonists, and/or inhibitors of the nitric oxide (NO)/cyclic guanosine monophosphate (cGMP)/protein kinase G (PKG)/ATP sensitive K channels (KATP) signaling pathway. Results: FBP (up to 85%) and adenosine (up to 84%) inhibited the mechanical hyperalgesia (electronic aesthesiometer) induced by CCI with similar profiles. FBP analgesia was dependent on adenosine because adenosine A1 and A2A receptors antagonists diminished FPB activity (100% and 79%, respectively). FBP analgesia was also dependent on activating the NO/cGMP/PKG/KATP signaling pathway. Furthermore, FBP treatment increased the production of NO in cultured dorsal root ganglia (DRG) neurons (100% increase), whereas neuronal nitric oxide synthase (nNOS) inhibition decreased (up to 70%) the analgesic effect of FBP. We also observed that FBP reduced the calcium levels of transient receptor potential ankyrin 1 (TRPA1)⁺ DRG neurons (85%) and paw-flinching triggered by TRPA1 activation (38%). Conclusions: FBP reduced neuropathic pain by reducing DRG neuron activation. The mechanisms involved the activation of adenosine A1 and A2A receptors to trigger the analgesic NO/cGMP/PKG/KATP signaling pathway and reducing TRPA1⁺ DRG neuron activity.

Satellite glial cells (SGCs) are specialized glial cells found in peripheral ganglia, including the dorsal root ganglia (DRG), where they tightly envelop sensory neuronal somata. Through this intimate bidirectional communication, SGCs actively regulate neuronal homeostasis and excitability and contribute to pain. This review discusses the physiological functions of SGCs in the DRG and the mechanisms underlying their contribution to pain across different conditions, as well as their neuroimmune and reparative roles and their potential as therapeutic targets. The literature reviewed indicates that SGCs contribute to neuronal homeostasis through structural and metabolic support and regulation of neuronal excitability. However, these functions can become altered under pathological conditions, involving changes in gap junction communication, purinergic and glutamatergic signaling, and inflammatory mediator production that are associated with SGC activation, neuronal sensitization and pain initiation and persistence. These alterations have been described across inflammatory, neuropathic, diabetic, chemotherapy-induced, and cancer-associated pain. Recent transcriptomic studies further indicate substantial SGC heterogeneity, suggesting distinct cellular states and functions and highlighting the importance of associated markers for their characterization. Beyond pain, SGCs participate in neuroimmune interactions, immune-related responses, and neuronal repair within the DRG microenvironment. Experimental interventions targeting SGC-associated pathways, including nutraceuticals, have produced analgesic effects in several preclinical models. Overall, SGCs are multifunctional components of the DRG, spanning physiological neuronal support and homeostasis to pathological pain and neuroimmune responses. Further investigation of SGC heterogeneity, functional states, and associated pathways may clarify their contribution to pain and support the development of SGC-associated therapeutic strategies for pain management.