Thin-layer chromatography of phospholipid components of normal and psoriatic epidermis

Genes involved in phosphatidylcholine biosynthesis correlate with nuclear factor-κB in biliary tract cancer patients: Evidence from 1H NMR and computational analyses

Gallbladder cancer (GBC) is an aggressive malignancy of gastrointestinal tract. Due to uncontrolled growth, GBC cells rapidly synthesize biomolecules including lipids. The lipids are integral component of cell membrane with a wide range of cellular functions. In this study, we measured the clinicopathological features in 40 cases of histologically confirmed GBC and 16 cases of chronic cholecystitis (CC). The female to male ratio in the GBC and CC groups were 3.44:1 and 2.2:1, respectively. The GBC patients exhibited well to poorly differentiated tumor. In the CC group, all patients showed cholecystitis with no evidence of dysplasia or malignancy. The majority of GBC and CC patients reported pain. Using 1H NMR spectroscopy, we observed 4-folds increase in the level of choline containing phospholipids (CCPLs) in the gallbladder of GBC patients as compared to CC patients. Other lipid metabolites such as cholesterol ester, C18-cholesterol and saturated fatty acids were insignificantly changed between GBC and CC patients. Moreover, the level of CCPLs in the GBC patients with BMI <25 kg/m2 was significantly higher as compared to CC patients. Further, a significant increase in the CCPLs level was observed in GBC female patients in comparison to CC patients. From the computational analyses, we observed that the genes involved in the biosynthesis of phosphatidylcholine (PtdCho) indirectly interact with the RELA, which encodes the NF-κB p65 subunit. The genes involved in the PtdCho biosynthesis were also correlated with the overall and disease-free survival of cholangiocarcinoma patients. The study opens new window for exploring the diagnostic and therapeutic potential of CCPLs in GBC patients.

Skin lipids in health and disease: A review

Our skin is the interface between us and our environment - a flexible barrier that has evolved for protection, immunity, regulation and sensation. Once regarded as inert, we now know that it is a dynamic environment. Skin lipids are crucial to the structure and function of skin. From deep in the hypodermis, through the ceramide-rich epidermis, to the lipids of the skin surface, there are a vast array of different lipids with important roles to play. This review firstly discusses the lipid composition of human skin and secondly, changes that have been found in skin lipid composition in different skin diseases. Further research into skin lipids facilitated by ever-improving methodologies will no doubt generate new knowledge, paving the way for diagnosis, prevention and treatment of skin disorders and diseases.

Investigation of psoriasis skin tissue by label-free multi-modal imaging: a case study on a phototherapy-treated patient

Background: Psoriasis is a systemic inflammatory disease characterized by epidermal proliferation in the skin. Altered lipid metabolism is considered to be a central factor in the psoriatic etiopathogenesis. Thus, it is necessary to visualize chemical specificity of the samples for better medical diagnosis and treatment. Here, we investigate its role in the development of psoriatic lesions, before and after ultraviolet phototherapy, in a case study.

Methods: The distribution and morphology of different lipids and fibrous proteins in psoriatic (lesional) tissues were visualized by two complementary label-free imaging techniques: 1) non-linear microscopy (NLM), providing images of lipids/proteins throughout the skin layers at submicrometer resolution; and 2) mass spectrometry imaging (MSI), offering high chemical specificity and hence the detection of different lipid species in the epidermal and dermal regions. A conventional method of histological evaluation was performed on the tissues, with no direct comparison with NLM and MSI.

Results: Psoriatic tissues had a higher lipid content, mainly in cholesterol, in both the epidermal and dermal regions, compared to healthy tissues. Moreover, the collagen and elastin fibers in the psoriatic tissues had a tendency to assemble as larger bundles, while healthy tissues showed smaller fibers more homogeneously spread. Although phototherapy significantly reduced the cholesterol content, it also increased the amounts of collagen in both lesional and non-lesional tissues.

Conclusion: This study introduces NLM and MSI as two complementary techniques which are chemical specific and can be used to assess and visualize the distribution of lipids, collagen, and elastin in a non-invasive and label-free manner.

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Sebaceous-immunobiology is orchestrated by sebum lipids

The major role of sebaceous glands in mammals is to produce sebum, which coats the epidermis and the hair providing waterproofing, thermoregulation and photoprotection. However, as the need for these functions decreased along the evolutionary changes in humans, a relevant question has been raised: are sebaceous glands and sebum the remnants of our mammalian heritage or do they have overtaken a far more complex role in human skin biology? Trying to provide answers to this question, this review introduces the evolving field of sebaceous immunobiology and puts into the focus the pathways that sebum lipids use to influence the immune milieu of the skin. By introducing possible modifiers of sebaceous lipogenesis and discussing the – human-specific – alterations in composition and amount of sebum, the attribute of sebum as a sensitive tool, which is capable of translating multiple signalling pathways into the dermal micro environment is presented. Further their interaction with macrophages and keratinocytes involves sebum lipid fractions into disease pathogenesis, which could lead – on the other side – to the development of novel sebum-based therapeutic strategies.

Lipid profiling of cancerous and benign gallbladder tissues by 1H NMR spectroscopy

Qualitative and quantitative (1) H NMR analysis of lipid extracts of gallbladder tissue in chronic cholecystitis (CC, benign) (n = 14), xanthogranulomatous cholecystitis (XGC, intermediate) (n = 9) and gallbladder cancer (GBC, malignant) (n = 8) was carried out to understand the mechanisms involved in the transformation of benign gallbladder tissue to intermediate and malignant tissue. The results revealed alterations in various tissue lipid components in gallbladder in CC, XGC and GBC. The difference in the nature of lipid components in benign and malignant disease may aid in the identification of the biological pathways involved in the etiopathogenesis of GBC. This is the first study on lipid profiling of gallbladder tissue by (1) H NMR spectroscopy, and has possible implications for the development of future diagnostic approaches.

Lipid disturbances in psoriasis: an update

Psoriasis is a common disease with the population prevalence ranging from 2% to 3%. Its prevalence in the population is affected by genetic, environmental, viral, infectious, immunological, biochemical, endocrinological, and psychological factors, as well as alcohol and drug abuse. In the recent years, psoriasis has been recognised as a systemic disease associated with numerous multiorgan abnormalities and complications. Dyslipidemia is one of comorbidities in psoriatic patients. Lipid metabolism studies in psoriasis have been started at the beginning of the 20th century and are concentrated on skin surface lipids, stratum corneum lipids and epidermal phospholipids, serum lipids, dermal low-density lipoproteins in the psoriatic skin, lipid metabolism, oxidative stress and correlations between inflammatory parameters, lipid parameters and clinical symptoms of the disease. On the basis of the literature data, psoriasis can be described as an immunometabolic disease.

Epidermal enzymes as penetration enhancers in transdermal drug delivery?

Epidermal enzymes play an important role in the process of differentiation of keratinocytes. The present preliminary in vitro study was undertaken to observe if topical enzyme treatment influenced permeation of compounds across the skin. Due to the noted function and importance of phosphatidylcholine metabolism during maturation of the barrier lipids, the effects of topical application of the phosphatidylcholine dependent phospholipase C enzyme (not present in epidermis) on skin penetration of three model drugs, viz. benzoic acid, mannitol and testosterone, were studied. Similar studies were also carried out using epidermal enzymes like triacylglycerol hydrolase, acid phosphatase, and phospholipase A2 (present in epidermis). Pretreatment of skin with phospholipase C significantly enhanced permeation of benzoic acid, mannitol, and testosterone relative to untreated skin. Triacylglycerol hydrolase (neutral) increased the penetration of mannitol 3-fold and had no effect on benzoic acid penetration. Topical application of acid phosphatase did not alter the permeation of any of these compounds. Phospholipase A2 significantly enhanced permeation of benzoic acid and mannitol while it did not have any effect on the penetration of testosterone. These results for the first time demonstrate that enzymes may remarkably affect and/or regulate the permeation of topically applied compounds.

Antimicrobial activity of stratum corneum lipids from normal and essential fatty acid-deficient mice

Among the cutaneous effects of an essential fatty acid deficient (EFAD) diet are hyperdesquamation, increased transepidermal water loss (TEWL), and altered lipid profiles, characteristics also common to inflammatory dermatoses. Because fatty acids are antimicrobial, we examined the indigenous skin flora of normal and EFAD hairless mice, and compared the antimicrobial efficacy of lipids extracted from their stratum corneum. EFAD mice supported 100-fold more bacteria than normal mice, and were the only group from which Staphylococcus aureus were routinely isolated. Despite this greater carriage, in vitro experiments demonstrated that EFAD lipids are more lethal than normal lipids against Streptococcus pyogenes, S. aureus, S. epidermidis, Micrococcus sp., and a coryneform. Skin fungi were equally susceptible to both extracts. After thin layer chromatography, the most active fractions were found to be glycosphingolipids and phospholipids. EFAD extracts had 35% more free fatty acids and 75% more glycosphingolipids; normal extracts had more triglycerides and phospholipids. S. aureus strain 502A survived equally well on EFAD as on normal mice. Normal lipids applied on EFAD mice had no additional effect, but EFAD lipids on normal mice brought about a 35% reduction of the inoculated bacteria. If the mice were pretreated with alcohol, carriage of strain 502A was reduced by 71%. If instead the mice were previously washed with acetone to increase TEWL, a 97% reduction of the staphylococcus occurred. The application of normal flora to such acetone-washed mice decreased the efficacy to 76%. EFAD and normal lipids on human subjects were equally ineffective in eliminating strain 502A.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultraviolet radiation alters choline phospholipid metabolism in human keratinocytes

Ultraviolet radiation B (UVB-290-320 nm) induces inflammation and hyperproliferation in human epidermis. This response is associated with the recovery from irradiated skin of inflammatory mediators derived from membrane phospholipids. We have previously reported that UVB stimulates the production of such mediators by human keratinocytes (HK) in culture. In these studies we examined the effect of UVB on the metabolism of choline containing phospholipids in HK prelabeled with [3H] choline. UVB (400-1600J/m2) stimulated a dose dependent release of [3H] choline from HK within minutes of irradiation. Examination of media extracts by paper chromatography revealed that the released [3H] choline was predominately in the form of glycerophosphorylcholine. Examination of label remaining in membranes of cells after irradiation by acid precipitation and HPLC revealed that the origin of the released [3H] choline was the membrane phosphatidylcholine/lysophosphatidylcholine. These data support a concept of UVB stimulation of both a phospholipase A (1 or 2) and a lysophospholipase. These UVB induced alterations of HK membrane phospholipid metabolism likely have profound effects on UVB-induced inflammation and control of cell growth in human skin.

Metabolism and function of skin lipids

It is apparent from this review that the skin is an organ displaying a highly active metabolism of PUFA's. It possesses the capacity to biosynthesize, metabolize and interconvert a variety of lipids as outlined in the review. Its inability to desaturate the essential fatty acids underscores the significance of these PUFAs in cutaneous biology. For instance, increases in the concentrations of 20:4n6 as well as certain autacoids are associated with many inflammatory-hyperproliferative dermatoses. However, the origin of 20:4n6, which is found complexed to skin phospholipids, has until recently remained a mystery. Studies undertaken in our laboratory designed to delineate the origin of epidermal 20:4n6, and to elucidate the effects of EFA deficiency and crossover replenishment with dietary oils on epidermal lipid metabolism have demonstrated: (i) that microsomal preparations from rat and guinea pig epidermis lack the capacity to transform 18:2n6 into 18:3n6 (catalyzed by the enzyme delta 6 desaturase) and 20:3n6 into 20:4n6 (catalyzed by the enzyme delta 5 desaturase). This observation implies that 20:4n6, a component of epidermal phospholipids, is biosynthesized elsewhere endogenously and transported to the epidermis for esterification into the phospholipids. In an extension of this work, epidermal microsomal preparations from normal human and diseased human epidermis (clinically uninvolved and involved psoriatic epidermis) were examined in order to determine the activities of the delta 6 and the delta 5 desaturases as well as the elongase, respectively. Our data revealed that normal, uninvolved and involved human epidermal preparations lack the capacity to desaturate 18:2n6 to 18:3n6 and 20:3n6 to 20:4n6. These results are interesting in view of the fact that 20:4n6 metabolites participate in the phlogistic and hyperproliferative processes in psoriasis. It is likely that the increases in the 20:4n6-derived eicosanoids, which are prominent in uninvolved and involved psoriatic skin, are the result of an enhanced epidermal phospholipase A2 activity. The heightened lipase activity would lead to an elevated concentration of free 20:4n6 which, in turn, would result in the reported increase of epidermal eicosanoid levels. (ii) Incubation of 18:3n6 with microsomal preparations from skin specimens from normal, uninvolved and involved psoriatic epidermis revealed the presence of elongase activity capable of converting 18:3n6 into 20:3n6. This activity was markedly elevated (5-fold) in involved hyperproliferative psoriatic preparations.(ABSTRACT TRUNCATED AT 250 WORDS)

A unique phospholipase A2 in human epidermis: its physiologic function and its level in certain dermatoses

It is now well established that epidermis, like many other tissues, contains a phospholipase A2 that is responsible for the initiation of the arachidonic acid cascade. Here we report that human epidermis also contains a second, quite distinct enzyme of the phospholipase A2 group, which is unique in its extreme activity against phospholipids in true solution. It also differs from the classic cutaneous enzyme in that (a) its activity is not reduced by pretreatment of the skin with corticosteroids in vivo nor by treatment of the epidermal homogenate with alkaline phosphatase in vitro, and (b) its activity is reduced, rather than increased, in the lesions of inflammatory diseases such as psoriasis. The enzyme seems to occur mainly in fully differentiated keratinocytes, its level being low in the basal cell layer of epidermis and in keratinocytes cultured in vitro. On the basis of these observations, we suggest that this new phospholipase A2 is responsible for the degradation of phospholipids that accompanies the terminal keratinization process.

Elevated phosphorus in psoriatic skin determined by energy dispersive x-ray micro-analysis

Scanning electron-microscopy in combination with secondary electron imaging and x-ray energy spectrometry (electron-probe micro-analysis) was performed on the stratum corneum of involved and uninvolved, psoriatic skin. The significant, elemental alterations included an increase in phosphorus and calcium in the involved skin regions. A composite, chemical, elemental profile of normal and uninvolved, psoriatic stratum corneum is presented.

The phospholipid pattern in the involved and the uninvolved psoriatic epidermis

The phospholipid pattern of the involved and the uninvolved epidermis from 48 psoriatic patients and of the normal epidermis from 23 healthy controls was determined by thin-layer chromatography. A higher amount of total phospholipids was found only in the involved psoriatic epidermis, whereas significant alterations in the phospholipid pattern were observed in the psoriatic lesion and in the lesion-free epidermis. Namely, the decrease of phosphatidylserine and the increase of phosphatidylinositol were identically present in both the involved and the uninvolved psoriatic epidermis. It seems likely that these alterations in the phospholipid pattern in psoriasis may be related to subclinical alterations of the epidermis in this disease.