Role of 72-kDa Heat Shock Protein in Heat-stimulated Regeneration of Injured Muscle in RatKami, Katsuya; Ohira, Takashi; Oishi, Yasuharu; Nakajima, Takayuki; Goto, Katsumasa; Ohira, Yoshinobu
doi: 10.1369/0022155419859861pmid: 31233366
The regeneration of injured muscles is facilitated by intermittent heat stress. The 72-kDa heat shock protein (HSP72), the level of which is increased by heat stress, is likely involved in this effect, but the precise mechanism remains unclear. This study was conducted to investigate the localization and role(s) of HSP72 in the regenerating muscles in heat-stressed rats using immunohistochemistry. Heat stress was applied by immersion of the rat lower body into hot water (42C, 30 min, every other day) following injection of bupivacaine into the soleus muscles. After 1 week, we found that HSP72 was expressed at high levels not only in the surviving myofibers but also in the blood vessels of the regenerating muscles in heated rats. In addition, leukocytes, possibly granulocytes, expressing cluster of differentiation 43 within the blood capillaries surrounding the regenerating myofibers also highly expressed HSP72. In contrast, marked expression of HSP72 was not observed in the intact or regenerating muscles without heat stress. These results suggest that heat-stress-induced HSP72 within the myofibers, blood vessels, and circulating leukocytes may play important roles in enhancing regeneration of injured muscles by heat stress. Our findings would be useful to investigate cell-specific role(s) of HSP72 during skeletal muscle regeneration.
Elevated ATF4 Expression in Odontogenic Keratocysts Epithelia: Potential Involvement in Tissue Hypoxia and Stromal M2 Macrophage InfiltrationZhong, Wen-Qun; Li, Zhi-Zheng; Jiang, Hao; Zou, Yan-Ping; Wang, Hai-Tao; Cai, Yu; Zhao, Yi; Zhao, Ji-Hong
doi: 10.1369/0022155419871550pmid: 31424999
The aim of this study was to investigate the expression of the activating transcription factor 4 (ATF4) in odontogenic keratocysts (OKC), its association with hypoxia and M2-polarized macrophages infiltration, and its potential relationships with angiogenesis in OKC. The expression of ATF4, hypoxia-inducible factor 1α (HIF-1α), macrophage colony-stimulating factor (M-CSF), and receptor activator of nuclear factor κ-B ligand (RANKL) in OKC samples and normal oral mucosa (OM) was detected by immunohistochemistry. Meanwhile, microvessel density (MVD) was measured using antibody against CD31. M2-polarized macrophages were identified using double-staining for CD68+ and CD163+. The correlations of ATF4 with HIF-1α, M-CSF, and M2-polarized macrophages infiltration were determined by Spearman’s rank correlation test and hierarchical clustering. Human immortalized oral epithelial cells (HIOECs) were used in in vitro experiments. Our data showed that the expression of HIF-1α, ATF4, and M-CSF was significantly upregulated in the epithelium of OKC when compared with the OM. The expression of ATF4 was positively correlated with that of HIF-1α, M-CSF, MVD, and M2-polarized macrophages infiltration. Elevated expression of ATF4 in the epithelial lining of OKC may facilitate the M2 macrophages infiltration in response to hypoxia, leading to the development of OKC.
Marker Expression of Interstitial Cells in Human Skeletal Muscle: An Immunohistochemical StudyHejbøl, Eva K.; Hajjaj, Mohammad A.; Nielsen, Ole; Schrøder, Henrik D.
doi: 10.1369/0022155419871033pmid: 31411936
There is a growing recognition that myogenic stem cells are influenced by their microenvironment during regeneration. Several interstitial cell types have been described as supportive for myoblasts. In this role, both the pericyte as a possible progenitor for mesenchymal stem cells, and interstitial cells in the endomysium have been discussed. We have applied immunohistochemistry on normal and pathological human skeletal muscle using markers for pericytes, or progenitor cells and found a cell type co-expressing CD10, CD34, CD271, and platelet-derived growth factor receptor α omnipresent in the endomysium. The marker profile of these cells changed dynamically in response to muscle damage and atrophy, and they proliferated in response to damage. The cytology and expression profile of the CD10+ cells indicated a capacity to participate in myogenesis. Both morphology and indicated function of these cells matched properties of several previously described interstitial cell types. Our study suggests a limited number of cell types that could embrace many of these described cell types. Our study indicate that the CD10+, CD34+, CD271+, and platelet-derived growth factor receptor α+ cells could have a supportive role in human muscle regeneration, and thus the mechanisms by which they exert their influence could be implemented in stem cell therapy.