Prostaglandin D2 Uses Components of ROS Signaling to Enhance Testosterone Production in Keratinocytes

Nanodrug Delivery Strategies to Signaling Pathways in Alopecia

Over 50% of the global population suffers from hair loss. The mixed results in the treatment of hair loss reveal the limitations of conventional commercial topical drugs. One the one hand, the definite pathogenesis of hair loss is still an enigma. On the other hand, targeted drug carriers ensure the drug therapeutic effect and low side effects. This review highlights the organization and overview of nine crucial signaling pathways associated with hair loss, as well as the development of nanobased topical delivery systems loading the clinical drugs, which will fuel emerging hair loss treatment strategies.

The physiological and pharmacological roles of prostaglandins in hair growth

Hair loss is a common status found among people of all ages. Since the role of hair is much more related to culture and individual identity, hair loss can have a great influence on well-being and quality of life. It is a disorder that is observed in only scalp patients with androgenetic alopecia (AGA) or alopecia areata caused by stress or immune response abnormalities. Food and Drug Administration (FDA)-approved therapeutic medicines such as finasteride, and minoxidil improve hair loss temporarily, but when they stop, they have a limitation in that hair loss occurs again. As an alternative strategy for improving hair growth, many studies reported that there is a relationship between the expression levels of prostaglandins (PGs) and hair growth. Four major PGs such as prostaglandin D2 (PGD₂), prostaglandin I2 (PGI₂), prostaglandin E2 (PGE₂), and prostaglandin F2 alpha (PGF₂α) are spatiotemporally expressed in hair follicles and are implicated in hair loss. This review investigated the physiological roles and pharmacological interventions of the PGs in the pathogenesis of hair loss and provided these novel insights for clinical therapeutics for patients suffering from alopecia.

A peripheral lipid sensor GPR120 remotely contributes to suppression of PGD2-microglia-provoked neuroinflammation and neurodegeneration in the mouse hippocampus

BACKGROUND

Neuroinflammation is a key pathological component of neurodegenerative disease and is characterized by microglial activation and the secretion of proinflammatory mediators. We previously reported that a surge in prostaglandin D₂ (PGD₂) production and PGD₂-induced microglial activation could provoke neuroinflammation. We also reported that a lipid sensor GPR120 (free fatty acid receptor 4), which is expressed in intestine, could be activated by polyunsaturated fatty acids (PUFA), thereby mediating secretion of glucagon-like peptide-1 (GLP-1). Dysfunction of GPR120 results in obesity in both mice and humans.

METHODS

To reveal the relationship between PGD₂-microglia-provoked neuroinflammation and intestinal PUFA/GPR120 signaling, we investigated neuroinflammation and neuronal function with gene and protein expression, histological, and behavioral analysis in GPR120 knockout (KO) mice.

RESULTS

In the current study, we discovered notable neuroinflammation (increased PGD₂ production and microglial activation) and neurodegeneration (declines in neurogenesis, hippocampal volume, and cognitive function) in GPR120 KO mice. We also found that Hematopoietic-prostaglandin D synthase (H-PGDS) was expressed in microglia, microglia were activated by PGD₂, H-PGDS expression was upregulated in GPR120 KO hippocampus, and inhibition of PGD₂ production attenuated this neuroinflammation. GPR120 KO mice exhibited reduced intestinal, plasma, and intracerebral GLP-1 contents. Peripheral administration of a GLP-1 analogue, liraglutide, reduced PGD₂-microglia-provoked neuroinflammation and further neurodegeneration in GPR120 KO mice.

CONCLUSIONS

Our results suggest that neurological phenotypes in GPR120 KO mice are probably caused by dysfunction of intestinal GPR120. These observations raise the possibility that intestinal GLP-1 secretion, stimulated by intestinal GPR120, may remotely contributed to suppress PGD₂-microglia-provoked neuroinflammation in the hippocampus.

The role of prostaglandins in androgenetic alopecia

BACKGROUND

Though androgenetic alopecia (AGA) is one of the most common diseases affecting both sexes and all races, its pathogenesis is not completely clarified. The aim of this study was to investigate the role of the four major prostaglandins (PGs) (PGE₂ , PGD₂ , PGF_2α , and PI₂ or prostacyclin) in the pathogenesis of AGA in males and females.

METHODS

Human scalp biopsies were obtained from 30 adults (17 males and 13 females) suffering from AGA and from 30 healthy adults (18 males and 12 females). In each subject, two skin biopsies were performed, one from the frontal bald area and another one from the occipital area with normal hair growth. In the healthy group, biopsies were taken from both areas too. In each sample, all four PGs were measured.

RESULTS

In the patient group, PGD₂ and prostacyclin or PGI₂ levels were increased in bald compared to haired scalp. On the contrary, measurements of PGE₂ and PGF_2α showed that they were diminished in bald areas compared to haired areas. PG levels in healthy samples were comparable to the haired areas.

CONCLUSION

These results support that there is a fine balance between these four proteins in scalp hair follicles, and its maintenance may be crucial for hair growth. Furthermore, their receptors could be potential targets for treatment of AGA.

Systemic dexpanthenol as a novel treatment for female pattern hair loss

BACKGROUND

There are only a few drugs that have been used for the treatment of female pattern hair loss (FPHL).

AIMS

Through use of the Dermatologic Life Quality Index (DLQI) and a modified hair growth questionnaire, we aimed to evaluate the effect of dexpanthenol (DXP) as a new option for FPHL.

METHODS

Women who received 500 mg intramuscular DXP weekly for FPHL were included in this study. They were evaluated in terms of DLQI and laboratory characteristics, before and after DXP treatment, and were examined with a modified hair growth questionnaire.

RESULTS

Overall satisfaction with the appearance of the hair was described by the patients as 57.1% " I am satisfied," 28.6% "I am very satisfied," and 14.3% "I am neutral (neither satisfied nor dissatisfied)." There was a statistical difference between the mean DLQI scores before and after DXP treatment (P < .001). No statistical difference was found in the laboratory characteristics of the patients before and after DXP treatment (P > 0.05). No side effect was reported during DXP treatment.

CONCLUSION

Dexpanthenol is a safe and novel drug that may increase the quality of life in patients with FPHL.

Androgenetic alopecia: combing the hair follicle signaling pathways for new therapeutic targets and more effective treatment options

Introduction: In the past 30 years, only two drugs have received FDA approval for the treatment of androgenetic alopecia reflecting a lack of success in unraveling novel targets for pharmacological intervention. However, as our knowledge of hair biology improves, new signaling pathways and organogenesis processes are being uncovered which have the potential to yield more effective therapeutic modalities. Areas covered: This review focuses on potential targets for drug development to treat hair loss. The physiological processes underlying the promise of regenerative medicine to recreate new functional hair follicles in bald scalp are also examined. Expert opinion: The discovery of promising new targets may soon enable treatment options that modulate the hair cycle to preserve or extend the growth phase of the hair follicle. These new targets could also be leveraged to stimulate progenitor cells and morphogenic pathways to reactivate miniaturized follicles in bald scalp or to harness the potential of wound healing and embryogenic development as an emerging paradigm to generate new hair follicles in barren skin.

Maternal perinatal calorie restriction temporally regulates the hepatic autophagy and redox status in male rat

Intrauterine growth restriction (IUGR) leads to adult obesity, cardiovascular disease, and non-alcoholic fatty liver disease/steatohepatitis. Animal models have shown that combined intrauterine and early postnatal calorie restriction (IPCR) ameliorates these sequelae in adult life. The mechanism by which IPCR protects against adult onset disease is not understood. Autophagy, a lysosomal degradative process, recycles cellular constituents and eliminates damaged organelles, proteins, and oxidants. In this study, we hypothesized that IPCR could regulate autophagy in the liver of male rat offspring. At birth (d1) of male IUGR rat offspring and on day 21 (p21) of life, IPCR male rat offspring had a profound decrease in hepatic autophagy in all three stages of development: initiation, elongation, and maturation. However, upon receiving a normal diet ad-lib throughout adulthood, aged IPCR rats (day 450 of life (p450)), had increased hepatic autophagy, in direct contrast to what was seen in early life. The decreased autophagy at d21 led to the accumulation of ubiquitinated proteins and lipid oxidative products, whereas the increased autophagy in late life had the opposite effect. Oxidized lipids were unchanged at d1 by IUGR treatment indicating that decreased autophagy precedes oxidative stress in early life. When cellular signaling pathways regulating autophagy were examined, the 5' adenosine monophosphate-activated protein kinase pathway (AMPK), and not endoplasmic stress pathways, was found to be altered, suggesting that autophagy is regulated through AMPK signaling pathway in IPCR rats. Taken together, this study reveals that the perinatal nutritional status establishes a nutritionally sensitive memory that enhances hepatic autophagy in late life, a process that perhaps acts as a protective mechanism to limited nutrition.