The human tripeptide GHK-Cu in prevention of oxidative stress and degenerative conditions of aging: implications for cognitive health

Natural Tripeptide-Based Inhibitor of Multifaceted Amyloid β Toxicity

Accumulation of amyloid beta (Aβ) peptide and its aggregates in the human brain is considered as one of the hallmarks of Alzheimer's disease (AD). The polymorphic oligomers and fully grown fibrillar aggregates of Aβ exhibit different levels of neuronal toxicity. Moreover, aggregation of Aβ in the presence of redox-active metal ions like Cu(2+) is responsible for the additional trait of cellular toxicity induced by the generation of reactive oxygen species (ROS). Herein, a multifunctional peptidomimetic inhibitor (P6) has been presented, based on a naturally occurring metal chelating tripeptide (GHK) and the inhibitor of Aβ aggregation. It was shown by employing various biophysical studies that P6 interact with Aβ and prevent the formation of toxic Aβ forms like oligomeric species and fibrillar aggregates. Further, P6 successfully sequestered Cu(2+) from the Aβ-Cu(2+) complex and maintained it in a redox-dormant state to prevent the generation of ROS. P6 inhibited membrane disruption by Aβ oligomers and efficiently prevented DNA damage caused by the Aβ-Cu(2+) complex. PC12 cells were rescued from multifaceted Aβ toxicity when treated with P6, and the amount of ROS generated in cells was reduced. These attributes make P6 a potential therapeutic candidate to ameliorate the multifaceted Aβ toxicity in AD.

Regulation of RANKL-Induced Osteoclastogenesis by 635-nm Light-Emitting Diode Irradiation Via HSP27 in Bone Marrow-Derived Macrophages

OBJECTIVE

This study was designed to investigate the effect of 635-nm irradiation from a light-emitting diode (LED) on osteoclastogenesis in receptor activator of nuclear factor kappa-B (NF-κB) ligand (RANKL)-stimulated mouse bone marrow-derived macrophages (BMMs). We determined whether 635-nm irradiation modulated the RANKL-induced osteoclastic signaling pathway in heat shock protein-27 (HSP27)-silenced cells and analyzed the functional cross talk between these factors in osteoclastic differentiation and activation.

BACKGROUND

HSP27, a member of the small HSP family, regulates oxidative stress. Clinical reports suggest that low-level laser therapy or LED therapy (LEDT) could be an effective alternative treatment for osteolytic bone disease.

METHODS

In control or HSP27-siRNA-treated BMMs, the effects of LED irradiation with 635 nm and 5 mW/cm² on RANKL-induced osteoclastic differentiation and activity were assessed by measuring tartrate-resistant acid phosphatase (TRAP) and resorption pit formation. Quantitative real-time polymerase chain reaction and western blot assays were carried out to assess the mRNA expression of osteoclastogenesis-related genes and phosphorylation of c-Jun-N-terminal kinase (JNK), extracellular signal-regulated kinase 1/2 (ERK1/2), AKT, and p38, respectively. Intracellular reactive oxygen species (ROS) generation was measured using the 2',7'-dichlorodihydrofluorescein diacetate (H₂DCF-DA) detection method.

RESULTS

The 635-nm irradiation treatment significantly increased HSP27 expression and decreased intracellular ROS generation, as well as p38 and AKT phosphorylation, leading to reductions in the expression of c-fos, NFATc1, and DC-STAMP and TRAP activation and osteoclastic bone resorption in RANKL-induced BMMs. However, in HSP27-silenced BMMs, no change was observed.

CONCLUSIONS

Thus, 635-nm irradiation modulates RANKL-induced osteoclastogenesis via HSP27 in BMMs. Thus, HSP27 may play a role in regulating the osteoclastic response to LEDT.

Skin rejuvenation using cosmetic products containing growth factors, cytokines, and matrikines: a review of the literature

Skin aging is primarily due to alterations in the dermal extracellular matrix, especially a decrease in collagen I content, fragmentation of collagen fibrils, and accumulation of amorphous elastin material, also known as elastosis. Growth factors and cytokines are included in several cosmetic products intended for skin rejuvenation because of their ability to promote collagen synthesis. Matrikines and matrikine-like peptides offer the advantage of growth factor-like activities but better skin penetration due to their much smaller molecular size. In this review, we summarize the commercially available products containing growth factors, cytokines, and matrikines for which there is evidence that they promote skin rejuvenation.

Tripeptide-copper complex GHK-Cu (II) transiently improved healing outcome in a rat model of ACL reconstruction

After anterior cruciate ligament reconstruction (ACLR), the biological healing of the graft is a rate-limiting step which can contribute to graft failure. The tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu(II) (GHK-Cu) is a well-known activator of tissue remodeling. We investigated whether GHK-Cu can improve graft healing following ACLR. Seventy-two rats underwent unilateral ACLR were randomized to saline, 0.3 or 3 mg/ml GHK-Cu groups (n = 24). Post-operational intra-articular injections were given from week 2, once a week, for 4 weeks. Gait analysis was performed pre-injury and at harvesting time. At 6 or 12 weeks post-operation, knee specimens were harvested for knee laxity test, graft pull-out test, and histology. At 6 weeks post-ACLR, GHK-Cu groups resulted in a smaller side-to-side difference in knee laxity as compared to the saline group (p = 0.009), but there was no significant difference at 12 weeks post-operation. The graft complex in the 0.3 mg/ml GHK-Cu group had higher stiffness than saline group at 6 weeks post-operation (p = 0.026), but there was no significant difference in ultimate load, gait parameters, and histological scores among treatment groups. All grafts failed mid-substance during pull-out test. Intra-articular supplementation with a bioactive small molecule GHK-Cu improved graft healing following ACLR in rat, but the beneficial effects could not last as treatment discontinued.

Role of micronutrients in skin health and function

Skin is the first line of defense for protecting our bodies against external perturbations, including ultraviolet (UV) irradiation, mechanical/chemical stress, and bacterial infection. Nutrition is one of many factors required for the maintenance of overall skin health. An impaired nutritional status alters the structural integrity and biological function of skin, resulting in an abnormal skin barrier. In particular, the importance of micronutrients (such as certain vitamins and minerals) for skin health has been highlighted in cell culture, animal, and clinical studies. These micronutrients are employed not only as active compounds in therapeutic agents for treating certain skin diseases, but also as ingredients in cosmetic products. Here, the author describes the barrier function of the skin and the general nutritional requirements for skin health. The goal of this review is to discuss the potential roles and current knowledge of selected micronutrients in skin health and function.