Advanced glycation end products cause RAGE‐dependent annulus fibrosus collagen disruption and loss identified using in situ second harmonic generation imaging in mice intervertebral disk in vivo and in organ culture models

Abstract

Aging and diabetes are associated with increased low-back pain and intervertebral disk (IVD) degeneration yet causal mechanisms remain uncertain. Advanced glycation end products (AGEs), which accumulate in IVDs from aging and are implicated in diabetes-related disorders, alter collagen and induce proinflammatory conditions. A need exists for methods that assess IVD collagen quality and degradation in order to better characterize specific structural changes in IVDs due to AGE accumulation and to identify roles for the receptor for AGEs (RAGE). We used multiphoton microscopy with second harmonic generation (SHG), collagen-hybridizing peptide (CHP), and image analysis methods to characterize effects of AGEs and RAGE on collagen quality and quantity in IVD annulus fibrosus (AF). First, we used SHG imaging on thin sections with an in vivo dietary mouse model and determined that high-AGE (H-AGE) diets increased AF fibril disruption and collagen degradation resulting in decreased total collagen content, suggesting an early degenerative cascade. Next, we used in situ SHG imaging with an ex vivo IVD organ culture model of AGE challenge on wild type and RAGE-knockout (RAGE-KO) mice and determined that early degenerative changes to collagen quality and degradation were RAGE dependent. We conclude that AGE accumulation leads to RAGE-dependent collagen disruption in the AF and can initiate molecular and tissue level collagen disruption. Furthermore, SHG and CHP analyzes were sensitive to collagenous alterations at multiple hierarchical levels due to AGE and may be useful in identifying additional contributors to collagen damage in IVD degeneration processes.

Advanced Glycation End Product Inhibitor Pyridoxamine Attenuates IVD Degeneration in Type 2 Diabetic Rats

“…The destructive effect of AGEs on IVD extracellular matrix proteins was recently reported by Hoy et al [46]. In their study, the authors demonstrated a receptor for AGE (RAGE)-dependent AF collagen disruption in mice fed a high-dose AGE diet, which they suggest induced early degenerative changes in the disc [46]. Therefore, the reduced aggrecan levels detected in our study might have been a consequence of the increase in AGE compounds detected in the degenerated IVD.…”

“…We also detected a decrease in aggrecan levels in injured versus uninjured IVDs in SD rats ( Figure 4 B). The destructive effect of AGEs on IVD extracellular matrix proteins was recently reported by Hoy et al [ 46 ]. In their study, the authors demonstrated a receptor for AGE (RAGE)—dependent AF collagen disruption in mice fed a high-dose AGE diet, which they suggest induced early degenerative changes in the disc [ 46 ].…”

Diet-induced obesity leads to behavioral indicators of pain preceding structural joint damage in wild-type mice

“…Dietary composition also impacts IVD health. Diets rich in advanced glycation endproducts (AGE) precursors accelerate IVD degeneration in mice in parallel with insulin resistance [72][73][74].…”

Advancing basic and preclinical spine research: Highlights from the ORS PSRS 5th International Spine Research Symposium

“…Interestingly, they showed that diminished IGF‐I bioavailability confers both the beneficial effects of decreased disc cell senescence and extracellular matrix catabolism, whilst at the same time negatively impacting proteoglycan production. Hoy et al used second harmonic generation and collagen‐hybridizing peptide imaging to assess compositional changes in mouse intervertebral discs associated with high dietary intake of advanced glycation end‐products (AGEs) 7 . Their results showed receptor‐dependent collagen disruption associated with AGE accumulation at multiple hierarchical levels.…”