Approach to hypohidrosis

Transcriptome profiling of anhidrotic eccrine sweat glands reveals that olfactory receptors on eccrine sweat glands regulate perspiration in a ligand-dependent manner

Sweat maintains systemic homeostasis in humans. Although sweating disorders may cause multifaceted health problems, therapeutic options for sweat disorders have not yet been established. To gain new insight into the mechanism underlying the regulation of perspiration, we compared eccrine sweat gland transcriptomes from hidrotic and anhidrotic lesions from patients with anhidrosis and found out that olfactory receptors were expressed differentially in anhidrotic and hidrotic eccrine sweat glands. We then confirmed OR51A7 and OR51E2 expression in human eccrine sweat glands by in situ hybridization and immunohistochemistry. An alkaline phosphatase-TGFα shedding assay revealed that β-ionone activates G-proteins through OR51A7 or OR51E2. The effect of topically applied β-ionone on sweating was examined with the quantitative sudomotor axon reflex test, which showed that responses to β-ionone differed between sexes. Topical β-ionone attenuated female sweating and augmented male sweating. Taken together, this study suggests that olfactory receptors expressed in eccrine sweat glands may regulate sweating in response to odorous ligands on the basis of sex. These unexpected results indicate that olfactory receptors may modulate sweating and that olfactory receptor modulators may contribute to the management of sweat disorders.

A simple non-contact optical method to quantify in-vivo sweat gland activity and pulsation

OBJECTIVE

Most methods for monitoring sweat gland activity use simple gravimetric methods, which merely measure the average sweat rate of multiple sweat glands over a region of skin. It would be extremely useful to have a method which could quantify individual gland activity in order to improve the treatment of conditions which use sweat tests as a diagnostic tool, such as hyperhidrosis, cystic fibrosis, and peripheral nerve degeneration.

METHODS

An optical method using an infrared camera to monitor the skin surface temperature was developed. A thermodynamics computer model was then implemented to utilize these skin temperature values along with other environmental parameters, such as ambient temperature and relative humidity, to calculate the sweat rates of individual glands using chemically stimulated and unstimulated sweating. The optical method was also used to monitor sweat pulsation patterns of individual sweat glands.

RESULTS

In this preliminary study, the feasibility of the optical approach was demonstrated by measuring sweat rates of individual glands at various bodily locations. Calculated values from this method agree with expected sweat rates given values found in literature. In addition, a lack of pulsatile sweat expulsion was observed during chemically stimulated sweating, and a potential explanation for this phenomenon was proposed.

CONCLUSION

A simple, non-contact optical method to quantify sweat gland activity in-vivo was presented.

SIGNIFICANCE

This method allows researchers and clinicians to investigate several sweat glands simultaneously, which has the potential to provide more accurate diagnoses and treatment as well as increase the potential utility for wearable sweat sensors.

Case Report: Analysis of Preserved Umbilical Cord Clarified X-Linked Anhidrotic Ectodermal Dysplasia With Immunodeficiency in Deceased, Undiagnosed Uncles

Family history is one key in diagnosing inborn errors of immunity (IEI); however, disease status is difficult to determine in deceased relatives. X-linked anhidrotic ectodermal dysplasia with immunodeficiency is one of the hyper IgM syndromes that is caused by a hypomorphic variant in the nuclear factor kappa beta essential modulator. We identified a novel IKBKG variant in a 7-month-old boy with pneumococcal rib osteomyelitis and later found that his mother has incontinentia pigmenti. Genetic analysis of preserved umbilical cords revealed the same variant in two of his deceased maternal uncles. Analysis of preserved umbilical cord tissue from deceased relatives can provide important information for diagnosing IEI in their descendants.

Objective Quantitation of Focal Sweating Areas Using a Mouse Sweat-assay Model

In vivo sweat quantitation assays are required for the development of drugs for the management of focal hyperhidrosis before clinical trials; however, in vivo assays, particularly mouse models, are rare. Even in sweat assays using mice, sweating is quantitated by manually counting the number of sweating spots, which can contribute to various errors owing to arbitrary judgment. In this study, we developed a mouse sweat-assay model and a method for quantitating the amount of sweating to remove possible errors. The use of the iodine-starch test in the castor oil-covered hind footpad skin of anesthetized mice resulted in the sweating area being stained blue-black. After the anesthesia and treatment with drugs (pilocarpine, glycopyrrolate, botulinum neurotoxin, myricetin, and myricetin-loaded lipid nanoparticles), the remaining area of the footpad skin was eliminated from the acquired footpad images using ImageJ. Blue pixels extracted from the footpad image are automatically adjusted using the Phansalkar method, where the percentage of the blue area was determined based on the whole hind footpad skin area, finally indicating the percentage of the sweating area. Using this mouse model and analysis for sweat assays, a clear difference between the control group and antiperspirant-administered group was observed with respect to the sweating area % with no error. In conclusion, this assay can be used as a preclinical tool to screen potential antiperspirant drugs. Graphic abstract: Overview of the mouse-model sweat assay and objective quantitation of the focal sweating area.

Sweat in the pathogenesis of atopic dermatitis

Sweat is a transparent hypotonic body fluid made from eccrine sweat glands. Various ingredients contained in sweat are involved in a broad sense in skin homeostasis including temperature regulation, skin moisture, and immune functions. Thus, sweat plays a major role in maintaining skin homeostasis. Therefore, abnormal sweating easily compromises human health. For example, in atopic dermatitis (AD), perspiration stagnation accompanying sweat tube or sweat pore blockage, leakage of perspiration from the sweat gland to the outside tissue, and impaired secretion of sweat from the sweat gland are confirmed. In recent years, the hypothesis that atopic dermatitis is a sweat stasis syndrome has been clarified by the establishment of a sweat and sweat gland dynamic analysis technique. Secretion of sweat and leakage into tissues is caused by dermatitis and is thought to promote itching. Furthermore, from the metabolomic analysis of sweat of patients with atopic dermatitis, it was confirmed that the glucose concentration in AD sweat increased according to severity and skin phenotype, suggesting that elevated glucose affected the homeostasis of the skin. Multifaceted analyses of sweat from subjects with AD have revealed new aspects of the pathology, and appropriate measures to treat sweat can be expected to contribute to long-term control of AD.

Neural control of sweat secretion: a review

BACKGROUND

Humans have 4 million exocrine sweat glands, which can be classified into two types: eccrine and apocrine glands. Sweat secretion, a constitutive feature, is directly involved in thermoregulation and metabolism, and is regulated by both the central nervous system (CNS) and autonomic nervous system (ANS).

OBJECTIVES

To explore how sweat secretion is controlled by both the CNS and the ANS and the mechanisms behind the neural control of sweat secretion.

METHODS

We conducted a literature search on PubMed for reports in English from 1 January 1950 to 31 December 2016.

RESULTS AND CONCLUSIONS

Acetylcholine acts as a potent stimulator for sweat secretion, which is released by sympathetic nerves. β-adrenoceptors are found in adipocytes as well as apocrine glands, and these receptors may mediate lipid secretion from apocrine glands for sweat secretion. The activation of β-adrenoceptors could increase sweat secretion through opening of Ca²⁺ channels to elevate intracellular Ca²⁺ concentration. Ca²⁺ and cyclic adenosine monophosphate play a part in the secretion of lipids and proteins from apocrine glands for sweat secretion. The translocation of aquaporin 5 plays an important role in sweat secretion from eccrine glands. Dysfunction of the ANS, especially the sympathetic nervous system, may cause sweating disorders, such as hypohidrosis and hyperhidrosis.

Environmental Neurologic Injuries

PURPOSE OF REVIEW

This article discusses neurologic complications resulting from environmental injuries and the treatment modalities for these conditions.

RECENT FINDINGS

Recent advances include improved management of altitude sickness. Relatively uncommon conditions, such as keraunoparalysis (lightning-induced paralysis) and high-pressure neurologic syndrome, are areas of ongoing study.

SUMMARY

Environmental injuries may be associated with serious neurologic sequelae. This article reviews thermal and electrical injuries as well as injuries related to aviation, altitude, and diving. Recognition of signs and symptoms of such complex injuries and exposures will permit accurate diagnoses and improved outcomes.

Serum carcinoembryonic antigen specifically increases among various serum markers of adenocarcinoma in hypohidrosis or conditions related to hypohidrosis

Anhidrosis/hypohidrosis are conditions presenting various level of sweating dysfunction. Among them, acquired idiopathic generalized anhidrosis (AIGA) presents inadequate decrease or loss of sweating without apparent neurological and dermatological symptoms except cholinergic urticaria. Recently, serum level of carcinoembryonic antigen (CEA), one of the most well-known tumor markers, has been proposed as a clinical marker reflecting activity of AIGA. This study was performed to verify the specificity and independence of serum CEA level from the other serum tumor markers especially related to adenocarcinoma. The expression of various tumor markers in the serum collected from three healthy control subjects, four AIGA cases, and a cholinergic urticaria (CU) case with elevation of serum CEA level and history of hyperthermia was analyzed using a membrane-based antibody array. In all AIGA and CU cases, the intensity of CEA was significantly increased (7.60-15.9 times compared with that of control), relatively well-reflecting the serum CEA level, and the mean intensity of CEA was 11.8 times higher than the control subjects (P = 0.0011). On the other hand, the ratio of carbohydrate antigen (CA)125 and CA19-9 was 1.93 and 0.23 times compared with the mean intensity of the control subjects, respectively, and there was no statistical significance. Immunohistochemistry on 10 AIGA cases showed increased expression of CEA but not CA19-9 and CA125 in the eccrine sweat glands. In conclusion, the elevation of serum CEA level was independent from the other tumor markers in hypohidrotic condition represented by AIGA.

First case of congenital idiopathic hypohidrosis in China

A 43-year-old Chinese man presented with generalized hypohidrosis, which he had had since birth, without obvious abnormalities of other skin appendages except a sparse beard and axillary hairs. The sweat test revealed localized sweating on the face, axillae and palms. Histopathologic examination showed that the sweat glands were absent in the forearm and thigh, but some eccrine and apocrine sweat glands were present in the right axilla. S-100 was expressed in the nerve terminals surrounding the acini and ducts of the eccrine sweat glands, while PGP9.5 was positive in the acini of apocrine glands and the nerve terminals surrounding the eccrine glands in the axilla. To our knowledge, this is the first case of congenital idiopathic hypohidrosis in China.

Hypohidrosis in Individuals with Exertional Heat Injury: A Prospective Open Cohort Study

BACKGROUND

Hypohidrosis is a risk factor for developing heat-related illnesses.

OBJECTIVE

To determine the prevalence of hypohidrosis in heat injury.

METHODS

Soldiers from the Singapore Armed Forces who developed heat injury between January 1, 2012 and December 31, 2013 were invited to participate in the study. Subjects were induced to sweat through exercising in a temperature- and humidity-regulated room, and then atomized starch-iodine powder was administered over their whole body to detect hypohidrosis. If this was found to be present, investigations to elucidate the cause of anhidrosis were performed.

RESULTS

Out of 65 males, 30 consented to participation. One was excluded because an exogenous cause resulted in heat injury. Nine (31%) demonstrated hypohidrosis. Of these, 1 (11%) had miliaria profunda, 2 (22%) had acquired idiopathic generalized anhidrosis and 6 (67%) manifested a new phenotype which we termed acquired symmetrical hypohidrosis (ASH).

CONCLUSION

Thirty-one percent of healthy soldiers who developed heat injury had hypohidrosis. Concurrently, a new clinical phenotype of ASH was identified.

Photoletter to the editor: Acquired idiopathic generalized anhidrosis

Anhidrosis is a failure in sweat production in response to physiological thermal or chemical stimuli. Acquired idiopathic generalized anhidrosis is a rare disorder without sweat gland pathology and without neurologic symptoms. Most cases have been reported from Far East. We report a case of a 58-year-old Caucasian male who suffered from heat intolerance, heat-induced cutaneous burning and failed to sweat even in sauna for five years. A skin biopsy disclosed no pathologies. He had no neurologic disorders. The diagnosis of acquired idiopathic generalized anhidrosis was confirmed and treatment with methylprednisolone initiated. This led to improvement of heat tolerance, remission of burning and partial remission of sweating.

Sweat, the driving force behind normal skin: an emerging perspective on functional biology and regulatory mechanisms

The various symptoms associated with excessive or insufficient perspiration can significantly reduce a patient's quality of life. If a versatile and minimally invasive method could be established for returning sweat activity to normalcy, there is no question that it could be used in the treatment of many diseases that are believed to involve perspiration. For this reason, based on an understanding of the sweat-gland control function and sweat activity, it was necessary to conduct a comprehensive search for the factors that control sweating, such as the central and peripheral nerves that control sweat-gland function, the microenvironment surrounding the sweat glands, and lifestyle. We focused on the mechanism by which atopic dermatitis leads to hypohidrosis and confirmed that histamine inhibits acetylcholinergic sweating. Acetylcholine promotes the phosphorylation of glycogen synthesis kinase 3β (GSK3β) in the sweat-gland secretory cells and leads to sensible perspiration. By suppressing the phosphorylation of GSK3β, histamine inhibits the movement of sweat from the sweat-gland secretory cells through the sweat ducts, which could presumably be demonstrated by dynamic observations of the sweat glands using two-photon microscopy. It is expected that the discovery of new factors that control sweat-gland function can contribute to the treatment of diseases associated with dyshidrosis.

Skin manifestations in CDG

The group of congenital disorders of glycosylation (CDG) has expanded tremendously since its first description in 1980, with around 70 distinct disorders described to date. A great phenotypic variability exists, ranging from multisystem disease to single organ involvement. Skin manifestations, although inconsistently present, are part of this broad clinical spectrum. Indeed, the presence of inverted nipples, fat pads and orange peel skin in a patient with developmental delay are considered as a hallmark of CDG, particularly seen in PMM2 deficiency. However, over the years many more dermatological findings have been observed (e.g., ichthyosis, cutis laxa, tumoral calcinosis…). In this review we will discuss the variety of skin manifestations reported in CDG. Moreover, we will explore the possible mechanisms that link a certain glycosylation deficiency to its skin phenotype.