Syed S. Asghar

Prolonged Increase of cis-Urocanic Acid Levels in Human Skin and Urine after Single Total-body Ultraviolet Exposures

Cis-urocanic acid (cis-UCA), a mediator of immunosuppression, is formed from trans-UCA upon UV-exposure of the skin. This study describes a liquid chromatographic method for the simultaneous quantification of cis- and trans-UCA in skin, urine and plasma of nonirradiated volunteers. It also describes cis- and trans-UCA kinetics in UV-irradiated volunteers. New procedures to remove interfering substances from urine and plasma are reported. Normal levels of cis-UCA in skin, urine and plasma of nonirradiated volunteers were 0.5 nmol/cm2, 0.03 mumol/mmol creatinine (median 0.00) and undetectable and those of trans-UCA were 17.1 nmol/cm2, 1.36 mumol/ mmol creatinine and 0.5 microM, respectively. Upon single total body UVB (290-320 nm) exposures of 250 J/m2, epidermal cis-UCA levels immediately reached a maximum and returned to basic levels 3 weeks later. The cis-UCA levels in urine reached a maximum in 5-12 h postirradiation and reached baseline values in 8-12 days. Additionally, a single total body UVA (320-400 nm) irradiation of 200 kJ/m2 yielded a similar pattern. The kinetics of cis-UCA in plasma could not be followed due to low concentrations; however, that of skin and urine was informative in relation to solar exposures and phototherapy.

HLA associations in vitiligo patients in the dutch population

This study characterizes the HLA class I and class II antigens in a group of patients with vitiligo and a control group, both of Dutch descent. Earlier reports had shown a significant positive association with DR4 and a significant negative association with DR3. We found that, after correction for the broad antigens studied, only Cw7 and DR6 were significantly associated with vitiligo. The significant positive association of DR6 with vitiligo is interesting since vitiligo has an autoimmune component in its pathogenesis and DR6 may be a marker for high immune responsiveness.

Transforming growth factor-β isoforms regulate the surface expression on membrane cofactor protein (CD46) and CD59 on human keratinocytes

We studied the regulation of the expression of complement regulatory proteins, membrane cofactor protein (MCP), decay accelerating factor (DAF) and CD59, on human keratinocytes by supernatant of activated mononuclear cells and by some individual cytokines present therein. Cultured keratinocytes expressed MCP, DAF and CD59. Supernatant of activated mononuclear cells and recombinant forms of transforming growth factor (TGF)‐β variants (β1, β2 and β3) up‐regulated MCP and CD59 but not DAF. Recombinant IL‐1α, IL‐2, IL‐6, TNF‐α and IFN‐γ had no influence. TGF‐β present in the supernatant was likely responsible for up‐regulation of MCP and CD59. A monoclonal anti‐TGF‐β antibody, which neutralized TGF‐β1, ‐β2 and ‐β3, did not inhibit the up‐regulation of MCP and CD59 by the supernatant. These results indicated that TGF‐β and an additional factor(s) present in the supernatant may be responsible for up‐regulating the expression of MCP and CD59 on keratinocytes; both may be acting non‐synergistically.

Defensins and complement systems from the perspective of skin immunity and autoimmunity

The skin is the largest and most visible of all organs. It is the largest peripheral outpost of the nervous system, packed with neurons and specialized organelles that discern pressure, temperature, movement, and pain. In addition to those apparent features, the major function of skin is perhaps that is serves as a barrier between the outer world and the body, and vice versa. It must be emphasized that the barrier organ skin is not something between the environment and the body, a shell that is not really part of ourselves. The skin is an essential and living part of us. Part of the barrier function is physical in nature, part biological, and a major aspect of the biological barrier function of the skin is immunological in nature. The skin serves a major role in discerning self from nonself, the primary characteristic of the immune system. The extremely variable and large number of exogenous substances and microorganisms to which the skin is exposed indeed makes it logical to assume that the immune system has developed a special subsystem in the skin, to bind them, present them, and if necessary, to eliminate them. The skin immune system (SIS), first brought forward as a perception of the skin as an organ of defense in 1986,1 is not a primary or secondary immune organ. In the primary immune organs bone marrow and thymus, the basic cellular components of the immune system are formed and selected, after which they start percolating the different tissues of the body through a complex system of arterial, venous, and lymphatic routings. The secondary immune organs, lymphoid tissues in spleen, lymph nodes, and gastrointestinal tract, are involved in maintaining memory, both in cellular and humoral immunity. In addition to adhesion molecules on endothelial cells and their counterstructures on immune cells (addressins), the individual chemokine status of a particular tissue or organ is of main importance in the redistribution of bone marrow-derived cells. The skin must be seen as a tertiary immune organ, in which the expression of acquired immunity is a daily event, percolated as it is by clouds of lymphocytes migrating in and out, as well as antibodies washing the interstitial space of especially the dermal compartment of skin. But then we must observe that the distinction between primary, secondary, and tertiary tissues is not entirely satisfying. One reason to be dissatisfied with the concept of primary, secondary, and tertiary immune organs is that local tissue factors are instrumental in directing acquired immunity into the set of action. An example is the complex interplay between chemokines and proinflammatory cytokines produced in the skin after injury, with profound effects on endothelial cells and cell immigration from the peripheral circulation. Another point is that innate immunity is to a large extent guaranteed by factors produced locally, or by cells that have homed into the tertiary organ and reproduce themselves there. Keratinocytes, for example, which are the major cellular constituent of epidermis and epithelial lining of mucosa, have been found to be a production source for different innate immunity-related humoral compounds, such as defensins, complement factors, and complement regulatory proteins.

Hereditary deficiency of C5 in association with discoid lupus erythematosus

A 29-year-old woman with discoid lupus erythematosus had undetectable classic pathway complement activity. Hypocomplementemia was due to selective deficiency of C5. One of her children was also deficient. To our knowledge this is the first documented case of an association between discoid lupus erythematosus and C5 deficiency.

Comparison of immunofluorescence and immunoperoxidase techniques for detection of tissue antigen.

SummaryA comparison of immunofluorescence and immunoperoxidase techniques as regards to their sensitivities to demonstrates the patterns of IgG located in the skin sections of discoid lupus erythematosus was made. Biopsies with loosely as well as densely packed IgG deposits at the dermal-epidermal junction were selected for these studies. Using the immunoperoxidase method, densely packed IgG deposits in the skin lesions could easily be detected but the technique was found to be insensitive in case IgG deposits were loosely arranged. The direct immunofluorescence technique appeared to be superior to the direct immunoperoxidase technique. The possible reason for the differences in sensitivities of the two methods is discussed.ZusammenfassungDie Empfindlichkeit des Immunfluorescenzverfahrens und der Peroxydasetechnik zum Nachweis von IgG in Hautschnitten von discoidem Lupus erythematodes wurde verglichen. Für diese Untersuchung wurden Hautschnitte mit leichter als auch mit sehr starker IgG-Bindung an die dermo-epidermale Verbundzone verwendet. Bei der Immunperoxydasemethode konnten dicht gepackte IgG-Komplexe in den Hautveränderungen nachgewiesen werden, jedoch erwies sich die Technik als unempfindlich bei Fällen, in denen die Immunkomplexe nur in geringerer Menge vorhanden waren. Die direkte Immunfluorescenztechnik erwies sich als brauchbarer gegenüber der Immunperoxydasetechnik. Die Gründe für die unterschiedlichen Empfindlichkeiten beider Methoden werden besprochen.

In situ demonstration of CD40- and CD154-positive cells in psoriatic lesions and keratinocyte production of chemokines by CD40 ligation in vitro

In psoriatic lesions, T cells and keratinocytes are in an activated state. Ligation of CD40 expressed on activated keratinocytes with CD154 expressed on activated T cells is thought to be involved in the pathogenesis of psoriasis. However, the presence of CD40+ and CD154+ cells in psoriatic skin has not been thoroughly studied. The present study has therefore examined their presence by immunohistochemistry in the lesional and non‐lesional skin of ten patients. The influence of CD154–CD40 ligation on the release of chemokines (IL‐8, RANTES, and MCP‐1) and complement components (C3 and factor B) from keratinocytes was also investigated in vitro. Studies using single and double staining showed that clusters of CD40+ keratinocytes were present in both lesional and non‐lesional skin; CD40+CD1a+ Langerhans cells in lesional, non‐lesional, and normal skin; and numerous CD40+CD83+ cells in lesional skin. CD1a+ and CD83+ cells always expressed CD40 strongly. Numerous T cells were seen in lesional skin. A small number of T cells expressed CD154. CD154+ T cells were seen in the lesional epidermis of seven of ten patients—in six, in juxtaposition to CD40+ cells including keratinocytes. In non‐lesional epidermis, CD154+ T cells were seen in two patients—in one, in juxtaposition to CD40+ keratinocytes. In vitro studies showed that IFN‐γ‐treated keratinocytes released small amounts of IL‐8, RANTES, and MCP‐1; ligation of these cells with CD154‐transfected J558 cells or soluble CD154 greatly enhanced the release. This ligation did not enhance the release of C3 and factor B. These results warrant further studies on the role of CD40 ligation in the pathogenesis of psoriasis. Copyright

Morphoea lesions are associated with aberrant expression of membrane cofactor protein and decay accelerating factor in vascular endothelium

One of the main features of systemic and localized forms of scleroderma is vascular damage, the mechanism of which is not yet understood. Recently, we have shown undetectable or decreased expression of complement regulatory molecules, membrane cofactor protein (MCP) and decay‐accelerating factor (DAF), in cutaneous endothelium of patients with systemic sclerosis (SSc). In some patients. CD59 expression in endothelium was also altered. As these molecules protect endothelial cells from damage by autologous complement, their decreased expression could be part of the mechanism of vascular damage in SSc. In the present study, we investigated the expression of MCP, DAF and CD59 in the endothelium of lesional and non‐lesional skin of patients with localized morphoea. Normal skin and lesional skin from patients with systemic lupus erythematosus, and three inflammatory diseases, were included as relevant controls.

Suppression of the development of experimental allergic encephalomyelitis by suramin

Suramin was tested for its ability to suppress experimental allergic encephalomyelitis. Prophylactic administration caused significant reduction in the severity of the disease, incidence of paralysis and cellular infiltration in nervous tissue. Therapeutic treatment with suramin also caused a reduction in the severity of the disease, the incidence of paralysis and cellular infiltration, but to a lesser extent. Significantly fewer animals were paralysed for more than two days on therapeutic treatment.

Human plasma kallikreins and their inhibition by amidino compounds

Human plasma kallikreins (EC 3.4.21.8) were purified as three distinct enzyme entities which hydrolyzed arginine esters and were active in releasing kinin from heated human plasma as measured by guinea pig ileum contraction bio-assay. The three enzymatically active fractions were termed as 19 S, 7 S-I and 7 S-II kallikreins. They represented purifications of 262- 2200- and 110-fold, respectively. These enzyme activities showed differences in physicochemical and biochemical properties as it appears from their elution profile on Sephadex G-200 and DEAE-cellulose columns, affinity for substrates and susceptibility of inhibition by various protease inhibitors such as trasylol and soya bean trypsin inhibitor. The data suggest that all these three enzyme preparations were most likely kallikreins. All these three enzymes (19 S, 7 S-I and 7 S-II) were inhibited by a series of amidino compounds competitively. Diamidines consisting of two amidinophenyl residues linked in para position by molecular bridge were comparatively stronger inhibitors of all of three enzymes than those linked in meta position and those having single ring structure. The possibility that some of these amidino compounds might prove to be useful for treatment of disease states where the kallikrein-kinin system plays a role, is discussed.