Protective Effects of Melatonin against Severe Burn-Induced Distant Organ Injury: A Systematic Review and Meta-Analysis of Experimental Studies

Assessment of functional roles and therapeutic potential of integrin receptors in osteoarthritis: A systematic review and meta-analysis of preclinical studies

BACKGROUND

Integrins are heterodimeric transmembrane receptors that mediate a variety of biological function and plays a critical role in osteoarthritis (OA) pathogenesis, which may provide new targets for the development of OA therapies. However, the roles of integrins in different stages of OA remain elusive.

OBJECTIVES

This study aimed to synthesize all published preclinical evidence on the roles of integrin receptors in different stages of OA to identify the potential target for drug development in alleviating OA pathogenesis.

METHODS

Major electronic databases were used to identify related original articles. The methodological quality of all included studies was appraised using the SYRCLE risk of bias tool. We used the generic inverse variance with random effects model to calculate standardized mean differences (SMDs) and 95% confidence interval (CI).

RESULTS

Seventeen studies were included in this systematic review. Integrin α5β1 activation increases the histopathological score both in early [SMD, 6.39; 95%CI (2.90, 9.87); p = 0.0003] and late [SMD, 3.41; 95%CI (2.44, 4.38); p < 0.00001] stage of OA. Integrin α5β1 also increased the core catabolic factors like MMP-3, IL-1β, and TNF-α. Interestingly, the inactivation of α5β1 integrin did not change the histopathological score (p = 0.84). Similarly, β1 integrin notably increased histopathological score at both stages of OA [early; SMD, 7.13; 95%CI (2.01, 12.24); p = 0.006]; [late; SMD, 10.25; 95%CI (5.11, 15.39); p < 0.0001], and increased the MMP-13 levels. However, integrin β1 was upregulated at the early stage and downregulated at the late stage of OA. Furthermore, α2β1 integrin significantly increased histopathological score [SMD, 3.14; 95%CI (2.18, 4.10); p < 0.00001] and MMP-13 [SMD, 2.24; 95%CI (0.07, 4.41); p = 0.04]. Deactivating integrin α1β1 increased histopathological score in late [SMD, 1.53; 95%CI (0.80, 2.26); p < 0.0001], but not in early [SMD, 0.90; 95%CI (-1.65, 3.45); p = 0.49] stage of OA.

CONCLUSION

This study provides evidence that α5β1, α2β1, and α1β1 integrin might be the potential target for future drug development in alleviating OA pathogenesis. Further work is required to establish our findings through activating/deactivating these receptors in different stages of OA.

How We Can Change Clinical Practice Using Antioxidant Molecules?

The collection of studies in this Special Issue, “The Role of Antioxidant Molecules and Melatonin in Cellular Protection”, published in Antioxidants (accessed on 30 April 2021; https://www [...]

Efficacy of extracts from cryopreserved placenta on third-degree burns in rats

Human placenta extracts have anti-inflammatory, antioxidant and wound-healing properties, so they are promising drugs for the treatment of wounds of various origins, including burns. Cryopreservation methods are widely used to preserve the biological activity of placental drugs for a long time. The aim of this work was to study the effect of low-temperature storage of the placenta on the regenerative properties of its extracts. Fragments of freshly obtained placentas were cooled by immersion in liquid nitrogen and stored at –196 °C for 6 months. The placenta was warmed in a water bath at 37 °C. The effect of low-temperature preservation of the placenta on the ability of its extracts to positively affect the wound healing process was studied in a model of thermal burn of III B degree in rats. The effectiveness of wound treatment with extracts from cryopreserved placenta was evaluated by planimetric and histological methods at 3, 7, 14, 21 and 28 days after the burn. The activity of antioxidant enzymes in the serum of animals was also determined. superoxide dismutase activity was assessed by inhibition of adrenaline autooxidation in carbonate buffer, catalase activity was assessed by the degree of inhibition of ammonium peroxide formation. It has been shown that the treatment of burns with extracts from cryopreserved placenta helped to accelerate the regeneration processes and the rate of wound healing. The formation of granulation tissue was detected on the 7th day of treatment with extracts, and on the 14th day in the control. The area of burn wounds during treatment with extracts probably differed from the control starting from 14 days after application of the burn. It was found that the dynamics of recovery of catalase activity after burns is probably higher on the 7th day of treatment with extracts. The obtained data testify to the high efficiency of application of placenta stored at low-temperature for the purpose of obtaining extracts from it with preservation of regenerative properties.

Melatonin Maintains Anabolic-Catabolic Equilibrium and Regulates Circadian Rhythm During Osteoarthritis Development in Animal Models: A Systematic Review and Meta-analysis

Background: The driving force behind osteoarthritis (OA) pathogenesis is an anabolic-catabolic (a/c) imbalance. Melatonin (MT) is a key player in maintaining a/c stability and mitigates OA pathogenesis, but mechanisms underlying its effects remain poorly understood.

Objectives: We performed a systematic review analyzing the experimental data that support the clinical applicability of MT in the treatment of OA pathogenesis, placing particular emphasis on the regulation of circadian rhythms and a/c balance.

Methods: Major electronic databases and grey literature were used to identify related original articles. Methodological quality of all selected studies was evaluated using the SYRCLE risk of bias tool. Pooled mean differences (MDs)/standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated to estimate the effect size.

Results: Eleven trials were included in this systematic review. Compared with the control group, MT significantly decreased the levels of interleukin-1β (IL-1β; SMD = −5.45; 95% CI [−6.78, −4.12]; p < 0.00001, and histological grading scale (SMD = −3.46; 95% CI, [−5.24, −1.68]; p < 0.0001). MT significantly increased the transforming growth factor-β1 (TGF-β1; SMD = 1.17; 95% CI [0.31, 2.03]; p < 0.0007). Furthermore, core circadian clock genes Per2 and Cry1 mRNA levels were regulated by MT treatment in OA progression.

Conclusion: MT may maintain a/c balance and regulate circadian rhythms during OA development. MT could be used in as adjunct with other interventions to manage pain and OA severity.

Neurocognitive effects of melatonin treatment in healthy adults and individuals with Alzheimer's disease and insomnia: A systematic review and meta-analysis of randomized controlled trials

Endogenous melatonin levels are inversely associated with age and cognitive deficits. Although melatonin can improve psychopathological behavior disturbances in clinical trials, whether melatonin may also enhance cognitive function remains elusive. This study examined cognitive outcomes from randomized trials of melatonin treatment for Alzheimer's disease (AD), insomnia, and healthy-subjects. Twenty-two studies met the inclusion criteria (AD = 9, insomnia = 2, healthy-subjects = 11). AD patients receiving >12 weeks of melatonin treatment improved mini-mental state examination (MMSE) score [MD: 1.82 (1.01; 2.63) p < 0.0001]. Importantly, melatonin significantly improved MMSE score in mild stage of AD [MD: 1.89 (0.96; 2.82) p < 0.0001]. In healthy-subjects, although daytime melatonin treatment notably decreased in accuracy by correct responses [SMD: -0.74 (-1.03; -0.45) p < 0.00001], the reaction-time score on different stimuli (p = 0.37) did not increased. Additionally, by pooling of short-term, spatial, and visual memory scores, melatonin did not reduce memory function (p = 0.08). Meta-analysis of MMSE score suggested that melatonin is effective in treatment for mild stage of AD. Additionally, we propose that melatonin may be preferable to traditional hypnotics in management of insomnia.

Differential role of melatonin in healthy brain aging: a systematic review and meta-analysis of the SAMP8 model

The relationship between oxidative stress (OS) and cellular senescence (CS) is an important research topic because of the rapidly aging global population. Melatonin (MT) is associated with aging and plays a pivotal role in redox homeostasis, but its role in maintaining physiological stability in the brain (especially in OS-induced senescence) remains elusive. Here, we systematically reviewed the differential role of MT on OS-induced senescence in the SAMP8 mouse model. Major electronic databases were searched for relevant studies. Pooled mean differences (MDs)/standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated to estimate the effect size. Overall, 10 studies met the inclusion criteria. MT treatment was associated with the reduction of lipid peroxidation (SMD = -2.00, 95% CI [-2.91, -1.10]; p < 0.0001) and carbonylated protein (MD = -5.74, 95% CI [-11.03, -0.44]; p = 0.03), and with enhancement of the reduced-glutathione/oxidized-glutathione ratio (MD = 1.12, 95% CI [0.77, 1.47]; p < 0.00001). No differences were found in catalase and superoxide dismutase activities between MT-treated and vehicle-treated groups. Furthermore, nuclear-factor-κB, cyclin-dependent kinase-5, and p53 were regulated by MT administration. MT may improve physiological stability during aging by regulating interactions in brain senescence, but acts differentially on the antioxidant system.