Chloroquine -induced hair depigmentation

A Comprehensive Review of Mammalian Pigmentation: Paving the Way for Innovative Hair Colour-Changing Cosmetics

The natural colour of hair shafts is formed at the bulb of hair follicles, and it is coupled to the hair growth cycle. Three critical processes must happen for efficient pigmentation: (1) melanosome biogenesis in neural crest-derived melanocytes, (2) the biochemical synthesis of melanins (melanogenesis) inside melanosomes, and (3) the transfer of melanin granules to surrounding pre-cortical keratinocytes for their incorporation into nascent hair fibres. All these steps are under complex genetic control. The array of natural hair colour shades are ascribed to polymorphisms in several pigmentary genes. A myriad of factors acting via autocrine, paracrine, and endocrine mechanisms also contributes for hair colour diversity. Given the enormous social and cosmetic importance attributed to hair colour, hair dyeing is today a common practice. Nonetheless, the adverse effects of the long-term usage of such cosmetic procedures demand the development of new methods for colour change. In this context, case reports of hair lightening, darkening and repigmentation as a side-effect of the therapeutic usage of many drugs substantiate the possibility to tune hair colour by interfering with the biology of follicular pigmentary units. By scrutinizing mammalian pigmentation, this review pinpoints key targetable processes for the development of innovative cosmetics that can safely change the hair colour from the inside out.

Systemic toxicity of chloroquine and hydroxychloroquine: prevalence, mechanisms, risk factors, prognostic and screening possibilities

Chloroquine (CQ) and its hydroxylated analog, hydroxychloroquine (HCQ), are 4-aminoquinoline initially used as an antimalarial treatment. CQ and HCQ (4-aminoquinoline, 4-AQ) are today used in rheumatology, especially to treat rheumatoid arthritis and systemic lupus erythematosus. Their mechanism of action revolves around a singular triptych: 4-AQ acts as alkalizing agents, ionized amphiphilic molecules, and by binding to numerous targets. 4-AQ have so pleiotropic and original mechanisms of action, providing them an effect at the heart of the regulation of several physiological functions. However, this broad spectrum of action is also at the origin of various and original side effects, notably a remarkable chronic systemic toxicity. We describe here the 4-AQ-induced lesions on the eye, the heart, muscle, the nerves, the inner ear, and the kidney. We also describe their prevalence, their pathophysiological mechanisms, their risk factors, their potential severity, and the means to detect them early. Most of these side effects are reversible if treatment is stopped promptly. This 4-AQ-induced toxicity must be known to prescribing physicians, to closely monitor its appearance and stop treatment in time if necessary.

Three Streams for the Mechanism of Hair Graying

Hair graying is an obvious sign of human aging. Although graying has been investigated extensively, the mechanism remains unclear. Here, we reviewed previous studies on the mechanism of graying and seek to offer some new insights. The traditional view is that hair graying is caused by exhaustion of the pigmentary potential of the melanocytes of hair bulbs. Melanocyte dysfunction may be attributable to the effects of toxic reactive oxygen species on melanocyte nuclei and mitochondria. A recent study suggests that bulge melanocyte stem cells (MSCs) are the key cells in play. Graying may be caused by defective MSC self-maintenance, not by any deficiency in bulbar melanocytes. Our previous study suggested that graying may be principally attributable to active hair growth. Active hair growth may produce oxidative or genotoxic stress in hair bulge. These internal stress may cause eventually depletion of MSC in the hair follicles. Taken together, hair graying may be caused by MSC depletion by genotoxic stress in the hair bulge. Hair graying may also be sometimes caused by dysfunction of the melanocytes by oxidative stress in the hair bulb. In addition, hair graying may be attributable to MSC depletion by active hair growth.

Premature Graying of Hair: Review with Updates

Premature graying of hair (PGH) is defined as graying of hair before the age of 20 years in Caucasians and before 30 years in African American population. It can severely affect the self-esteem of an individual. The exact etiopathogenesis remains unknown, although it has been associated with premature aging disorders, atopy, and autoimmune diseases. Patients, who present with PGH, should be assessed for syndromes and metabolism diseases. Hair dyes remain the main modality of the treatment for cosmetic concerns after nutritional supplementation.

The role of antimalarial agents in the treatment of SLE and lupus nephritis

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease that affects various organs. Lupus nephritis is one of the most common, and most important, serious manifestations of SLE. Antimalarial agents are part of the immunomodulatory regimen used to treat patients with SLE; however, their role in the treatment of patients with lupus nephritis in particular is less well recognized, especially by nephrologists. Not all antimalarial agents have been used in the treatment of lupus; this Review will focus on studies using chloroquine and hydroxychloroquine. In addition, this Review will briefly describe the history of antimalarial drug use in patients with SLE, the theorized mechanisms of action of the agents chloroquine and hydroxychloroquine, their efficacy in patients with SLE and those with lupus nephritis, their use in pregnancy, and potential adverse effects. The Review will also cover the latest recommendations regarding monitoring for hydroxychloroquine-associated or chloroquine-associated retinopathy. Overall, antimalarial drugs have numerous beneficial effects in patients with SLE and lupus nephritis, and have a good safety profile.