Morphological and Physiological Monitoring of Gouty Arthritis Response to Low-Level Light Therapy

Abstract

Gouty arthritis (GA), induced by deposition of monosodium urate (MSU) crystals in joints, presents as intermittent episodes of acute inflammation along with chronic inflammation which can lead to irreversible erosive joint damage. Though widespread with a major negative impact on patients, there is no nonradiative and noninvasive method to monitor the inflammation quantitatively. By taking advantages of dual-wavelength optical-resolution photoacoustic microscopy (PAM), we monitored morphological and physiological features of vasculature in GA joint of rats in vivo. We showed that a hyperoxia period was followed by a hypoxia state in GA joints for the first time. Aiming at symptom control and recurrence prevention, we designed a ring-shape low-level light therapy (LLLT) device to treat the GA rats daily. We find that LLLT was able to reduce swelling, alleviate pain and accelerate dissolution of MSU crystals, which shortened the recovering time to half. Specifically, we observed that LLLT modulated the oxygen saturation level in joints with a less hyperoxia state at the beginning of GA and healed it to a normal level without experiencing hypoxia. Our result provided a non-invasive monitoring method and a drug-free treatment choice for GA, which revealed important aspects of the disease development and treatment mechanism.