Treatment with an inhibitor of matrix metalloproteinase 9 or cathepsin K lengthens embryonic lower jaw bone

Abstract

Objectives Skeletal malocclusions are common, and severe malocclusions are treated by invasive surgeries. Recently, jaw bone length has been shown to be developmentally controlled by osteoclasts. Our objective was to determine the effect of inhibiting osteoclast‐secreted proteolytic enzymes on lower jaw bone length of avian embryos by pharmacologically inhibiting matrix metalloproteinase‐9 (MMP9) or cathepsin K (CTSK). Methods Quail (Coturnix coturnix japonica) embryos were given a single dose of an inhibitor of MMP9 (iMMP9), an inhibitor CTSK (iCTSK), or vehicle at a developmental stage when bone deposition is beginning to occur. At a developmental stage when the viscerocranium is largely calcified, the heads were scanned via micro‐computed tomography and reproducible landmarks were placed on 3D‐reconstructed skulls; the landmark coordinates were used to quantify facial bone dimensions. Results Approximately half of the quail given either iMMP9 or iCTSK demonstrated an overt lower jaw phenotype, characterized by longer lower jaw bones and a greater lower to upper jaw ratio than control embryos. Additionally, iMMP9‐treated embryos exhibited a significant change in midface length and iCTSK‐treated embryos had significant change in nasal bone length. Conclusion MMP9 and CTSK play a role in osteoclast‐mediated determination of lower jaw bone length. Pharmacological inhibition of MMP9 or CTSK may be a promising therapeutic alternative to surgery for treating skeletal jaw malocclusions, but more preclinical research is needed prior to clinical translation.

A novel qPCR-based technique for identifying avian sex: an illustration within embryonic craniofacial bone

“…Primer-BLAST was also used to create four of the jaw bone development-related genes analyzed in Figures 3 and 4: RANK , MEPE , FGF23 , and OPN. The RT-qPCR primers for CTSK originate from Houchen et al 2023, the primers for MMP13 and COL1A1 originate from Ealba et al 2015, and the RUNX2 primers originate from Ealba et al 2013. Primer sequences, predicted amplicon sizes, species, and primer sources are listed in Table 1.…”

“…Having established sex of all quail and duck individuals using lower jaw mRNA, expression of genes relevant to jaw development were then analyzed and compared across sexes. Multiple cell types contribute to bone formation and lower jaw bone length in quail and duck, including osteoclasts, osteocytes, and osteoblasts (Ealba et al, 2015; Houchen et al, 2023). Osteoclasts resorb bone and express genes such as receptor activator of nuclear factor κ B ( RANK ) and cathepsin K ( CTSK ).…”

“…We analyzed expression of genes related to bone development in lower jaw tissue at Hamburger-Hamilton (HH) stage 39, when the jaw is largely calcified and there is active bone resorption by osteoclasts, relative to expression at stage HH33, when bone deposition by osteoblasts is just beginning and there are no active osteoclasts in the lower jaw bone (Ealba et al, 2015; Hamburger, 1951; Houchen et al, 2023). Osteoclast RANK expression was mildly but significantly higher in male duck compared to female duck (n=3-4/stage/sex, p=0.03; Figure 3A).…”

A novel qPCR‐based technique for identifying avian sex: An illustration within embryonic craniofacial bone

“…Primer‐BLAST was also used to create four of the jaw bone development‐related genes analyzed in Figures 3 and 4: RANK , MEPE , FGF23 , and OPN . The RT‐qPCR primers for CTSK originate from Houchen et al (2023), the primers for MMP9 , MMP13 , and COL1A1 originate from Ealba et al (2015), and the RUNX2 primers originate from Ealba and Schneider (2013). Primer sequences, predicted amplicon sizes, species, and primer sources are listed in Table 1.…”

“…We analyzed expression of genes related to bone development in lower jaw tissue at Hamburger and Hamilton (HH) Stage 39, when the jaw is largely calcified and there is active bone resorption by osteoclasts, relative to expression at stage HH33, when bone mineralization is just beginning and there are no active osteoclasts in the lower jaw bone (Ealba et al, 2015; Hamburger & Hamilton, 1951; Houchen et al, 2023). Osteoclast RANK expression was mildly but significantly higher in male duck compared to female duck ( n = 3–4/stage/sex, p = .03; Figure 3a).…”