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.

Arthroplasty is an orthopedic surgical procedure that replaces a dysfunctional joint by an orthopedic prosthesis, thereby restoring joint function. Upon the use of the joint prosthesis, a wearing process begins, which releases components such as titanium dioxide (TiO₂) that trigger an immune response in the periprosthetic tissue, leading to arthritis, arthroplasty failure, and the need for revision. Flavonoids belong to a class of natural polyphenolic compounds that possess antioxidant and anti-inflammatory activities. Hesperidin methyl chalcone’s (HMC) analgesic, anti-inflammatory, and antioxidant effects have been investigated in some models, but its activity against the arthritis caused by prosthesis-wearing molecules, such as TiO₂, has not been investigated. Mice were treated with HMC (100 mg/kg, intraperitoneally (i.p.)) 24 h after intra-articular injection of 3 mg/joint of TiO₂, which was used to induce chronic arthritis. HMC inhibited mechanical hyperalgesia, thermal hyperalgesia, joint edema, leukocyte recruitment, and oxidative stress in the knee joint (alterations in gp91^phox, GSH, superoxide anion, and lipid peroxidation) and in recruited leukocytes (total reactive oxygen species and GSH); reduced patellar proteoglycan degradation; and decreased pro-inflammatory cytokine production. HMC also reduced the activation of nociceptor-sensory TRPV1⁺ and TRPA1⁺ neurons. These effects occurred without renal, hepatic, or gastric damage. Thus, HMC reduces arthritis triggered by TiO₂, a component released upon wearing of prosthesis.

Reactive oxygen species (ROS) are formed by the incomplete reduction of oxygen and play a crucial role in both physiological function and pathological process, being controlled by enzymatic and non-enzymatic antioxidant systems. However, excessive ROS production can exceed the body’s antioxidant capacity, resulting in oxidative stress and causing cell death and oxidation of important biomolecules. In this context, the inhibition and/or modulation of ROS has been shown to be effective in reducing pain, oxidative stress, and inflammation. Among ROS, superoxide anion (O₂^•−) is the first free radical to be formed through the mitochondrial electron transport chain (ETC) or by specific enzymes systems, such as the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) complex. O₂^•− plays a significant role in the development and maintenance of pain associated with inflammatory conditions through direct or indirect activation of primary nociceptive neurons and, consequently, peripheral and central sensitization. Experimentally, potassium superoxide (KO₂, a O₂^●− donor) is used to initiate O₂^●− mediated inflammatory and nociceptive responses, making it important for studying the mechanisms associated with ROS-induced pain and evaluating potential therapeutic molecules. This review addresses the production and regulation of O₂^•−, highlighting its biosynthesis, redox control, and its physiological and pathological roles in the development of inflammatory pain, as well as the pharmacological therapies under development aimed at its generation and/or action.

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.

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.