Assessment of rat antigen-induced arthritis and its suppression during glucocorticoid therapy by use of hemicyanine dye probes with different molecular weight in near-infrared fluorescence optical imaging

Activatable fluorescent probes for imaging and diagnosis of rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease that is primarily manifested as synovitis and polyarticular opacity and typically leads to serious joint damage and irreversible disability, thus adversely affecting locomotion ability and life quality. Consequently, good prognosis heavily relies on the early diagnosis and effective therapeutic monitoring of RA. Activatable fluorescent probes play vital roles in the detection and imaging of biomarkers for disease diagnosis and in vivo imaging. Herein, we review the fluorescent probes developed for the detection and imaging of RA biomarkers, namely reactive oxygen/nitrogen species (hypochlorous acid, peroxynitrite, hydroxyl radical, nitroxyl), pH, and cysteine, and address the related challenges and prospects to inspire the design of novel fluorescent probes and the improvement of their performance in RA studies.

Clinical Use and Molecular Action of Corticosteroids in the Pediatric Age

Corticosteroids are the mainstay of therapy for many pediatric disorders and sometimes are life-saving. Both endogenous and synthetic derivatives diffuse across the cell membrane and, by binding to their cognate glucocorticoid receptor, modulate a variety of physiological functions, such as glucose metabolism, immune homeostasis, organ development, and the endocrine system. However, despite their proved and known efficacy, corticosteroids show a lot of side effects, among which growth retardation is of particular concern and specific for pediatric age. The aim of this review is to discuss the mechanism of action of corticosteroids, and how their genomic effects have both beneficial and adverse consequences. We will focus on the use of corticosteroids in different pediatric subspecialties and most common diseases, analyzing the most recent evidence.

[(18)]F FDG PET/CT imaging to monitor the therapeutic effect of liposome-encapsulated prednisolone in experimental rheumatoid arthritis

Current treatment of rheumatoid arthritis includes systemic administration of glucocorticoids. To improve joint targeting and anti-inflammatory efficacy these glucocorticoids are encapsulated in long-circulating liposomes. The present study aimed to monitor therapeutic effects of prednisolone (PLP)-containing PEG-liposomes in murine antigen-induced arthritis (AIA) using [(18)F]FDG PET/CT. Mono-articular arthritis was induced in male C57Bl6/J mice. At 0, 3, 7 and 12 days after arthritis induction, inflamed joints were macroscopically scored (0 = unaffected to 4 = immobile) and [(18)F]FDG PET/CT images were acquired. In a second experiment, to study the feasibility to monitor therapeutic effects of PLP encapsulating PEG-liposomes, mice were treated with a single i.v. injection of PLP-containing PEG-liposomes (10 mg/kg) or empty PEG-liposomes 3 days after arthritis induction. Inflamed joints were macroscopically scored and images were acquired at -3, 0, 4 and 9 days after treatment. PET images were analyzed quantitatively, and mice were dissected to allow histological analysis of the joints. With progression of arthritis, [(18)F]FDG uptake in inflamed joints increased significantly (day 0: 2.5 ± 0.9%ID/ml, day 7: 4.4 ± 0.4%ID/ml, p = 0.0159), while no changes were observed in unaffected paws (day 0: 2.5 ± 1.1%ID/ml, day 7: 2.7 ± 0.8%ID/ml, p = 0.3466). In the second experiment, macroscopic scoring revealed suppression of joint swelling after treatment with PLP-containing PEG-liposomes. In line with that, [(18)F]FDG uptake did not change in the treated mice (day -3: 1.9 ± 0.3%ID/ml, day 4: 2.2 ± 0.2%ID/ml, p = 0.3466), while it increased in mice that developed arthritis (day -3: 2.0 ± 0.2%ID/ml, day 4: 3.1 ± 0.6%ID/ml, p = 0.0225). Histological analysis confirmed therapeutic efficacy, which showed less inflammation (p = 0.0354) and bone erosion (p = 0.0298) in treated mice. These data show that [(18)F]FDG PET/CT could be used to monitor the progression of AIA and confirmed rapid and profound anti-inflammatory effects of PLP-containing PEG-liposomes that were also observed macroscopically and microscopically.

Long-term prevalence of NIRF-labeled magnetic nanoparticles for the diagnostic and intraoperative imaging of inflammation

Inflammation is a very common disease worldwide. In severe cases, surgery is often the method of choice. Today, there is a general need for the implementation of image-based guidance methodologies for reliable target resection. We investigated new near infrared fluorescence (NIRF)-nanoparticles (NPs) as a simple but effective bimodal magnetic resonance imaging (MRI) and optical contrast agent for diagnosis and intraoperative imaging of inflammation. Physicochemical analysis revealed that these NPs were highly fluorescent with similar characteristics like unlabeled NPs (hydrodynamic diameter about 130 nm and zeta potential about −10 mV). NP-uptake and NIR-dye labeling was biocompatible to macrophages (no impact on cellular ATP and reactive oxygen species production). These cells could successfully be tracked with MRI and NIRF-optical imaging. I.v. injection of fluorescent NPs into mice led to highly specific T₂-weighted signal of edema due to uptake by phagocytic cells and subsequent migration to the site of inflammation. NIRF signals of the edema region were well detectable for up to 4 weeks, underlining the potential of the NPs for systematic planning and flexible time scheduling in intraoperative applications. NPs were degraded over a time period of 12 weeks, which was not altered due to inflammation. Redistribution of iron might be primarily due to inflammation and not to the presence of NPs per se in a concentration suitable for imaging. Our findings highlight the potential of the NPs to be used as a suitable tool for pre- and intraoperative imaging of inflammation.