Mechanisms and Preventative Strategies for Persistent Pain following Knee and Hip Joint Replacement Surgery: A Narrative Review.

Chronic postsurgical pain (CPSP) following total knee arthroplasty (TKA) and total hip arthroplasty (THA) is a prevalent complication of joint replacement surgery which has the potential to decrease patient satisfaction, increase financial burden, and lead to long-term disability. The identification of risk factors for CPSP following TKA and THA is challenging but essential for targeted preventative therapy. Recent meta-analyses and individual studies highlight associations between elevated state anxiety, depression scores, preoperative pain, diabetes, sleep disturbances, and various other factors with an increased risk of CPSP, with differences observed in prevalence between TKA and THA. While the etiology of CPSP is not fully understood, several factors such as chronic inflammation and preoperative central sensitization have been identified. Other potential mechanisms include genetic factors (e.g., catechol-O-methyltransferase (COMT) and potassium inwardly rectifying channel subfamily J member 6 (KCNJ6) genes), lipid markers, and psychological risk factors (anxiety and depression). With regards to therapeutics and prevention, multimodal pharmacological analgesia, emphasizing nonopioid analgesics like acetaminophen and non-steroidal anti-inflammatory drugs (NSAIDs), has gained prominence over epidural analgesia. Nerve blocks and local infiltrative anesthesia have shown mixed results in preventing CPSP. Ketamine, an N-methyl-D-aspartate (NMDA)-receptor antagonist, exhibits antihyperalgesic properties, but its efficacy in reducing CPSP is inconclusive. Lidocaine, an amide-type local anesthetic, shows tentative positive effects on CPSP. Selective serotonin reuptake inhibitors (SSRIs) and serotonin norepinephrine reuptake inhibitors (SNRIs) have mixed results, while gabapentinoids, like gabapentin and pregabalin, present hopeful data but require further research, especially in the context of TKA and THA, to justify their use for CPSP prevention.

Optimized APEX2 peroxidase-mediated proximity labeling in fast- and slow-growing mycobacteria.

Proximity labeling is a technology for tagging proteins and other biomolecules in living cells. These methods use enzymes that generate reactive species whose properties afford high spatial resolution for the localization of proteins to subcellular compartments and the identification of endogenous interaction partners. Here we present the adaptation of the engineered peroxidase APEX2 to proximity labeling in mycobacteria, including the human pathogen Mycobacterium tuberculosis. APEX2 is uniquely suited for general use in bacteria because unlike other proximity labeling enzymes, it does not depend on metabolites like ATP that are found in the cytoplasm, but are absent from the bacterial periplasm. Importantly, we found that in slow-growing mycobacteria like M. tuberculosis, codon usage optimization is required for APEX2 export into the periplasm via fusion to an N-terminal secretion signal. APEX2 expressed from codon-optimized genes affords robust, compartment-specific protein labeling in the cytoplasm and the periplasm of both fast- and slow-growing species. Here we detail these updated constructs and provide an optimized protocol for APEX2-mediated protein labeling in mycobacteria. We expect this approach to be broadly useful for determining the localization of specific proteins, cataloging subcellular proteomes, and identifying interaction partners of 'bait' proteins expressed as fusions to APEX2.