1 alpha,25-Dihydroxyvitamin D3 and a novel vitamin D analogue MC 903 are potent inhibitors of human interleukin 1 in vitro

IL-1α, IL-6 and TNF-α in Cutaneous Lesions of Lupus Erythematosus are Inhibited by Topical Application of Calcipotriol

Lupus Erythematosus (LE) is an autoimmune disorder with an unknown etiology and pathogenesis. Skin lesions of LE express several cytokines which correlate to histological findings such as IL-1 and IL-6 which are mediators of epidermal growth and proliferation. Skin lesions of LE are generally treated with immunosuppressive agents such as oral or topically applied corticosteroids. Recently a new drug, calcipotriol, a vitamin D3 analogue has been useful in treatment of psoriasis with no ad verse effect on calcium metabolism. This drug shares immunomodulatory effects with vit. D3 by inhibiting several cytokines produced by keratinocytes.

In order to test the clinical effectiveness of calcipotriol in cutaneous lesions of LE we have investigated several proinflammatory cytokines such as: IL-1α, IL-1β, IL-4, IL-5, IL-6, IL-8, MCP-1, TNF-α. Using an avidin-biotin immunoperoxidase system we have found IL-1 in both forms, IL-6 and TNF-α in basal keratinocytes in patients affected with LE, after treatment they were reverted to normal. This inhibition is induced at a molecular level as demostrated by reduced IL-1, IL-6 and TNFα mRNA expression. This is the first report showing that calcipotriol is effective in cutaneous lesions of LE and suggesting that this action is due to an inhibition of protein synthesis and mRNA expression for IL-1α, IL-6 and TNFα.

A comparison of the effects of topical treatment of calcipotriol, camptothecin, clobetasol and tazarotene on an imiquimod-induced psoriasis-like mouse model

The interleukin-23/interleukin 17A (IL-23/IL-17A) cytokine axis plays a critical role in the pathogenesis of psoriasis. In this study, we report the effects of topical calcipotriol, camptothecin, clobetasol and tazarotene on the treatment of imiquimod (IMQ)-induced psoriasis-like inflammation, the development of which is dependent on the IL-23/IL-17A axis. IMQ-induced epidermal hyperplasia and inflammation in the BALB/c mouse ear were significantly inhibited following clobetasol treatment but not calcipotriol, camptothecin or tazarotene treatments. Real-time polymerase chain reaction showed that the mRNA levels of IL-17A, IL-17F, IL-22, IL-1β, IL-6 and TNF-α in ear skin were significantly decreased by clobetasol. In addition, we observed that calcipotriol, camptothecin and tazarotene failed to show any inhibitory effects on the IL-23/IL-17A/IL-22 axis. We also found that clobetasol treatment inhibited the proliferation of γδ T cells and C-C chemokine receptor type 6 (CCR6) expression induced by IMQ. Calcipotriol, camptothecin and tazarotene not only failed to inhibit this proliferation but also enhanced retinoic acid-related orphan receptor γ (RORγ) expression in IMQ-induced psoriasis-like inflammation. In conclusion, we suggest that clobetasol induces the relief of IMQ-induced psoriasis-like inflammation in a mouse model but that calcipotriol, camptothecin and tazarotene cannot. Therefore, we suggest that more in-depth studies on pharmacological effects of tazarotene, camptothecin and calcipotriol should be carried out.

Circulating IL-6, IL-17 and vitamin D in hepatocellular carcinoma: potential biomarkers for a more favorable prognosis?

Hepatitis C virus (HCV) infects primarily hepatocytes, leads to development of fibrosis and/or cirrhosis of the liver and is a significant factor for developing hepatocellular carcinoma (HCC). Evidence indicates that liver fibrosis contains uncontrolled inflammation as a part of its etiology. Normal cell-mediated immunity plays a central role in the mechanisms involved in viral clearance/persistence in the liver. In this context, cytokines modulate the immune system and exert direct anti-viral activity. To this end, this study investigated potential associations of serum IL-17 and IL-6 with exacerbation of hepatic damage in chronic HCV patients to determine their utility as prognostic markers for potential development of HCC. Chronic HCV-patients were recruited, divided into groups according to degree of liver damage, i.e. patients with peri-hepatic fibrosis, hepatic cirrhosis, or HCC, and had their blood collected for analysis of liver function and serum IL-6 and IL-17 levels. Interestingly, increases in serum IL-17 levels in the study groups were associated with aggravation of the clinical state from HCV to cirrhosis and then to HCC. Serum IL-6 levels followed a similar pattern. The association of both cytokines with progressive exacerbation of the initial HCV-induced liver damage was further confirmed by correlation analysis that revealed positive correlations between HCV RNA titer and IL-17 (+0.951, p < 0.05) and IL-6 (+0.85, p < 0.05). A receiver operating characteristics (ROC) analysis revealed their beneficial addition as promising biomarkers for a better prognostic profile of HCC. Interestingly, a significant progressive decline in the active vitamin D status was noted in all three clinical states, and these too were associated with progressive liver disease. This study confirms the necessity of adding screening for IL-6 and IL-17 and vitamin D to that of the classic marker AFP for patients with HCV and cirrhosis to hopefully permit clinicians to initiate measures that ultimately might mitigate/delay development of HCC in these infected patients.

Relationship between vitamin D and IL-23, IL-17 and macrophage chemoattractant protein-1 as markers of fibrosis in hepatitis C virus Egyptians

AIM

To assess vitamin D in hepatitis C patients and its relationship to interleukin (IL)-23, IL-17, and macrophage chemoattractant protein-1 (MCP-1).

METHODS

The study was conducted on 50 Egyptian hepatitis C virus (HCV) genotype number IV-infected patients and 25 age- and gender-matched healthy subjects. Venous blood samples were obtained. Samples were allowed to clot and sera were separated by centrifugation and stored at -20 °C. A 25 hydroxy vitamin D assay was carried out using solid phase RIA. A 1,25 dihydroxy vitamin D assay was carried out using a commercial kit purchased from Incstar Corporation. IL-17 and -23 and MCP-1 were assayed by an enzyme immunoassay. Quantitative and qualitative polymerase chain reaction for HCV virus were done by TaqMan technology. Only HCV genotype IV-infected subjects were included in the study. The mean ± SD were determined, a t-test for comparison of means of different parameters was used. Correlation analysis was done using Pearson's correlation. Differences among different groups were determined using the Kruskal-Wallis test.

RESULTS

The mean vitamin D level in HCV patients (group I) was 15 ± 5.2 ng/mL while in control (group II) was 39.7 ± 10.8. For active vitamin D in group I as 16.6 ± 4.8 ng/mL while in group II was 41.9 ± 7.9. IL-23 was 154 ± 97.8 in group I and 6.7 ± 2.17 in group II. IL-17 was 70.7 ± 72.5 in cases and 1.2 ± 0.4 in control. MCP-1 was 1582 ± 794.4 in group I and 216.1 ± 5.38 in group II. Vitamin D deficiency affected 72% of HCV-infected patients and 0% of the control group. Vitamin D insufficiency existed in 28% of HCV-infected patients and 12% of the control group. One hundred percent of the cirrhotic patients and 40% of non cirrhotic HCV-infected patients had vitamin D deficiency. IL-23, IL-17, and MCP-1 were markedly increased in HCV-infected patients in comparison to controls.A significant negative correlation between vitamin D and IL-17 and -23 and MCP-1 was detected. HCV-infected males and females showed no differences with respect to viral load, vitamin D levels, IL-17, IL-23 and MCP-1. The viral load was negatively correlated with vitamin D and active vitamin D (P = 0.0001 and P = 0.001, respectively), while positively correlated with IL-23, IL-17, and MCP-1. We classified the patients according to sonar findings into four groups. Group Ia with bright hepatomegaly and included 14 patients. Group Ib with perihepatic fibrosis and included 11 patients. Group Ic with liver cirrhosis and included 11 patients. Group Id with hepatocellular carcinoma (HCC) and included 14 patients. Vitamin D and active vitamin D were shown to be lower in cirrhotic patients and much lower in patients with HCC, and this difference was highly significant (P = 0.0001). IL-17 and -23 and MCP-1 were higher in advanced liver disease) and the differences were highly significant (P = 0.0001).

CONCLUSION

Whether the deficiency of vitamin D is related to HCV-induced chronic liver disease or predisposing factor for higher viral load is a matter of debate.

Vitamin D deficiency: Correlation to interleukin-17, interleukin-23 and PIIINP in hepatitis C virus genotype 4

AIM: To assess vitamin D (Vit D) abnormalities in hepatitis C infected patients and their relationship with interleukin (IL)-17, IL-23 and N-terminal propeptide of type III pro-collagen (PIIINP) as immune response mediators.

METHODS: The study was conducted on 50 Egyptian patients (36 male, 14 female) with hepatitis C virus (HCV) infection, who visited the Hepatology Outpatient Clinic in the Endemic Disease Hospital at Cairo University. Patients were compared with 25 age- and sex-matched healthy individuals. Inclusion criteria were based on a history of liver disease with HCV genotype 4 (HCV-4) infection (as new patients or under follow-up). Based on ultrasonography, patients were classified into four subgroups; 14 with bright hepatomegaly; 11 with perihepatic fibrosis; 11 with hepatic cirrhosis; and 14 with cirrhosis and hepatocellular carcinoma (HCC). Total Vit D (i.e., 25-OH-Vit D) and active Vit D [i.e., 1,25-(OH)₂-Vit D] assays were carried out using commercial kits. IL-17, IL-23 and PIIINP levels were assayed using enzyme linked immunosorbent assay kits, while HCV virus was measured by quantitative and qualitative polymerase chain reaction.

RESULTS: Levels of Vit D and its active form were significantly lower in advanced liver disease (hepatic cirrhosis and/or carcinoma) patients, compared to those with bright hepatomegaly and perihepatic fibrosis. IL-17, IL-23 and PIIINP levels were markedly increased in HCV patients and correlated with the progression of hepatic damage. The decrease in Vit D and active Vit D was concomitant with an increase in viral load, as well as levels of IL-17, IL-23 and PIIINP among all subgroups of HCV-infected patients, compared to normal healthy controls. A significant negative correlation was evident between active Vit D and each of IL-17, IL-23 and PIIINP (r = -0.679, -0.801 and -0.920 at P < 0.001, respectively). HCV-infected men and women showed no differences with respect to Vit D levels. The viral load was negatively correlated with Vit D and active Vit D (r = -0.084 and -0.846 at P < 0.001, respectively), and positively correlated with IL-17, IL-23 and PIIINP (r = 0.951, 0.922 and 0.94 at P < 0.001, respectively). Whether the deficiency in Vit D was related to HCV-induced chronic liver disease or was a predisposing factor for a higher viral load remains to be elucidated.

CONCLUSION: The negative correlations between Vit D and IL-17, IL-23 and PIIINP highlight their involvement in the immune response in patients with HCV-4-related liver diseases in Egypt.

Calcipotriol/betamethasone dipropionate in the treatment of psoriasis vulgaris

Psoriasis is one of the most common skin diseases. The mainstay of treatment for the vast majority of patients is topical therapy. A rising first-line treatment modality for psoriasis vulgaris is the two-compound ointment containing calcipotriol 50 mug/g plus betamethasone dipropionate 0.5 mg/g (Dovobet((R)), Daivobet((R)), Taclonex((R))), which combines a vitamin D analog and a corticosteroid. This innovative formulation preserves the activity and bioavailability of the two components and many clinical studies have demonstrated that it has a greater efficacy, tolerability, and a rapid onset of action compared with its individual ingredients or tacalcitol.

Calcipotriol/betamethasone dipropionate for the treatment of psoriasis

The two-compound product calcipotriol/betamethasone dipropionate is arising as a first-line treatment for mild-to-moderate plaque psoriasis. Its beneficial action is attributed to the synergistic effect of its components on keratinocyte proliferation and differentiation, and on inflammation. The good tolerability of the two-compound product is thought to be due to the anti-inflammatory effect of betamethasone. Evidence from short-term (4-12 weeks) and long-term use (> 1 year) has shown a good safety profile. Areas such as the face or skin folds, which are sensitive to the components of the combination, should be avoided. Finally, it is unsuitable for use in unstable psoriasis, in which potent steroids may lead to an increased inflammatory response.

Tazarotene: a review of its pharmacological profile and potential for clinical use in psoriasis

Psoriasis appears to be a T-cell-mediated, HLA-associated genetic skin disease that profoundly alters epidermal differentiation in a reversible manner. The topical treatment of mild-to-moderate stable plaque psoriasis is limited by side-effects, cosmetic problems, and often by unsatisfactory efficacy, while systemic therapy is usually not warranted because of safety concerns. Tazarotene is the first member of a novel acetylenic and non-isomerisable class of retinoids to undergo extensive clinical testing. Tazarotene therapy regulates gene transcription via interaction with specific nuclear retinoic acid receptors (RARs), thereby modulating the three key pathogenic factors in psoriasis. Systemic absorption is minimal and, in contrast to some other retinoids, elimination is rapid. The results of Phase II and Phase III controlled clinical studies have shown tazarotene to be an effective treatment for psoriasis. The clinical response is rapid, and in many patients was sustained for several weeks following discontinuation of therapy. Adverse effects are generally limited to mild-to-moderate local effects, as seen with other topical retinoid therapies. Convenient once-daily application of tazarotene gel is effective first-line monotherapy for mild-to-moderate plaque psoriasis, providing rapid and sustained benefits, while minimal systemic absorption and rapid elimination appear to limit the potential for systemic side-effects.

1alpha,25-dihydroxyvitamin D3 inhibits anti-CD40 plus IL-4-mediated IgE production in vitro

In the present study, we examined whether anti-CD40+IL-4-mediated B cell proliferation and immunoglobulin synthesis is affected by vitamin D (VD) and its low-hypercalcemic analogue EB1089 in Bcells from healthy donors. Analysis of vitamin D receptor (VDR) expression showed that only anti-CD40+IL-4-stimulated, but not resting B cells express VDR. Studies on B cell proliferation revealed that anti-CD40+IL-4-mediated proliferation of B cells was not affected by VD or EB1089. By contrast, IgE synthesis was markedly inhibited by both, VD and EB1089, starting at concentrations from 10(-10) M for VD and 10(-12) M for EB1089, with maximal inhibition at 10(-6) M (VD 85.5+/-9.7%; EB1089 77.3+/-10.8%). The production of the other Ig (IgA and IgG) was not significantly inhibited by VD after anti-CD40+IL-4 stimulation, and IgM production was only slightly reduced (18.7+/-7.9%). These observations were confirmed by intracellular staining of the different isotypes in B cells after anti-CD40+IL-4 stimulation, which showed a strong reduction of IgE(+) cells in the presence of VD. Analyses of molecules that are known to affect IgE production (CD23 and IL-6) revealed that these are not involved in VD-dependent inhibition of IgE production. By contrast, epsilon germ-line transcription was inhibited by VD (41.2+/-26.1%; n=5), as was NF-kappaB (p50 and p65) protein expression in stimulated cells. These data show that VD and its analogue EB1089 inhibit IgE production of anti-CD40+IL-4-stimulated B cells in vitro. The involved mechanism includes epsilon germ-line transcription, NF-kappaB activation and switch recombination suggesting that complex mechanisms of VD action in anti-CD40+IL-4-stimulated B cells are responsible.

Calcipotriol ointment. A review of its use in the management of psoriasis

Calcipotriol, a vitamin D3 analog, acts not only to inhibit cell proliferation and enhance cell differentiation in the skin of patients with psoriasis, but also appears to have effects on immunologic markers that are thought to play a role in the etiology of the disease. In several well designed, short term studies in adults, calcipotriol ointment 50 micrograms/g twice daily provided similar or superior efficacy to several other antipsoriatic agents in adult patients with mild to moderate psoriasis. In patients with nonscalp psoriasis, the drug provided superior efficacy to twice daily placebo (vehicle ointment), twice daily fluocinonide 500 micrograms/g, once daily tacalcitol 4 micrograms/g and twice daily coal tar 5% plus allantoin 2% and hydrocortisone 0.5%. Furthermore, calcipotriol therapy generally provided superior efficacy to twice daily betamethasone valerate 1 to 1.2 mg/g or once daily dithranol 1 to 20 mg/g, and similar efficacy to twice daily betamethasone dipropionate plus salicylic acid or once daily maxacalcitol 6 to 50 micrograms/g. Limited data indicated that calcipotriol ointment 50 micrograms/g also improved overall disease severity in children. In combination with other antipsoriatic agents [acitretin, cyclosporine, betamethasone valerate, halobetasol (ulobetasol)], ultraviolet B or psoralen ultraviolet A (PUVA) phototherapy, calcipotriol ointment 50 micrograms/g twice daily improved the beneficial effects of these drugs on overall disease severity in adult patients with moderate to severe psoriasis. Furthermore, in separate trials, calcipotriol combination therapy reduced the dosage of acitretin required to achieve clearance of psoriasis and the duration of PUVA and dosage of UVA phototherapy, potentially improving the benefit/risk ratio for these other antipsoriatic treatments. Calcipotriol was generally well tolerated in short and long term studies in adult patients, with the majority of adverse events being mild to moderate in intensity and transient. The most common adverse events associated with calcipotriol therapy were dermatologic in nature and included lesional or perilesional irritations, face and scalp irritations, worsening of psoriasis and miscellaneous dermatologic events. Notably, there have been very few reports of patients developing hypercalcemia or hypercalciuria during calcipotriol therapy, with most occurring in patients who exceeded the recommended dosage of 100 g/week. Although data in children are limited, the drug was well tolerated with the nature and incidence of adverse effects similar to those observed in adult patients.

CONCLUSIONS

Extensive clinical experience, along with several short and long term clinical trials, has shown calcipotriol ointment to be an effective and well tolerated topical agent in adult patients with psoriasis. In addition, calcipotriol ointment proved beneficial in combination with other topical, phototherapy or systemic antipsoriatic treatments, reducing the dosage and/or duration of some of these treatments and potentially improving their benefit/risk ratio. Calcipotriol ointment is valuable as a first- or second-line therapy option for the management of mild to moderate psoriasis and in combination with other antipsoriatic agents for more severe psoriasis.

Vitamin D(3) and its synthetic analogs inhibit the spontaneous in vitro immunoglobulin production by SLE-derived PBMC

The production of high-affinity pathogenic autoantibodies in systemic lupus erythematosus (SLE) may result from aberrant immune regulation. Since 1,25 dihydroxy vitamin D(3) (1,25 D(3)) has immunoregulatory activity, we examined effects of 1,25 D(3) and its analogs HM, V, MC1288, and KH1060 on autoantibody production and proliferation of SLE PBMC. We found, in SLE, a higher percentage of T, B, and NK expressing vitamin D(3) receptors (VDRs) (P = 0.034, 0.006, 0.012, respectively). Incubating SLE PBMC with 1,25 D(3) compounds significantly reduced proliferation, polyclonal and anti-dsDNA IgG production, and the percentages of CD3(+)/DR(+) T and B (CD19(+)) cells, while elevating NK (CD16(+)) cells (P < 0.001). 1,25 D(3) analogs were more potent than the natural compound: KH1060 up-regulated CD14 expression by SLE monocytes (P < 0.001), inhibited polyclonal and anti-dsDNA IgG production by SLE-derived B lymphoblasts, and induced apoptosis of activated B lymphoblasts. These data suggest that 1,25 D(3) compounds can offer novel approaches to the clinical management of SLE.

1alpha,25-dihydroxycholecalciferol and cyclosporine suppress induction and promote resolution of psoriasis in human skin grafts transplanted on to SCID mice

Accumulating evidence has emphasized the importance of immunocompetent cells in determining the psoriatic phenotype. We have investigated the effect of 1alpha,25-dihydroxycholecalciferol, the naturally occurring active form of vitamin D3, cyclosporine A, and interleukin-10 on the phenotype of human psoriatic skin xenotransplants. First, psoriatic skin transplants were injected with either 1alpha,25-dihydroxy- cholecalciferol, cyclosporine A, or interleukin-10. Second, we determined the ability of autologous lymphocytes, activated in vitro using staphylococcal enterotoxin B and interleukin-2 and then exposed to either 1alpha, 25-dihydroxycholecalciferol or cyclosporine A, to induce psoriatic lesions if they were injected into the dermis of uninvolved skin grafts. We found that injections into transplanted psoriatic plaques of either 1alpha,25-dihydroxycholecalciferol or cyclosporine A, but not interleukin-10, resulted in a consistent reduction in the clinical and histologic score of psoriasis with remission towards uninvolved psoriatic skin. Injection of activated immunocytes into symptomless psoriatic skin grafts, changed the grafts towards plaque-type psoriasis with silvery scale, parakeratosis, elongated rete pegs, acanthosis, and dermal angiogenic reaction. In contrast, if activated immunocytes were exposed to 1alpha, 25-dihydroxycholecalciferol or cyclosporine A prior to injection, only minimal changes occurred. It was determined that neither staphylococcal enterotoxin B and interleukin-2 activation by itself, nor the drugs investigated, changed the CD4/CD8 ratio of activated (CD25 + ) cells. Our results are consistent with the hypothesis that psoriasis may be induced by activated T lymphocytes, and indicate that novel immunomodulatory drugs can serve to inhibit the pathogenetic ability of immunocytes in psoriasis.

Calcifying disorders of the skin

Calcium is vital to many biologic processes. In skin, it has a profound effect on keratinocyte proliferation, differentiation, and cell-cell adhesion. Serum calcium is tightly regulated by parathyroid hormone and 1,25(OH)2D3. Despite this careful regulation, calcification and ossification of cutaneous and subcutaneous tissues may occur. Cutaneous calcification may be divided into four major categories: dystrophic, metastatic, idiopathic, and iatrogenic. Dystrophic calcification occurs as a result of local tissue injury or abnormalities. Metastatic calcification results from abnormal calcium and/or phosphate metabolism. Virtually any process that calcifies may secondarily ossify. Primary ossification may rarely occur.

Vitamin D3 metabolism in patients with rheumatic diseases: low serum levels of 25-hydroxyvitamin D3 in patients with systemic lupus erythematosus

1,25-dihydroxyvitamin D3 (1,25(OH)2 D3) has been shown to modulate lymphocyte activation in vitro. Through binding to specific receptors 1,25-(OH)2 D3 inhibits proliferation, immunoglobulin production and the release of cytokines. Moreover, 1,25-(OH)2 D3 is efficiently produced by activated monocytes. These findings suggest that 1,25-(OH)2 D3 may play a role as a regulator of immunological activation. Consequently, we found it of interest to study the serum levels of the two major metabolites of vitamin D3 in patients with systemic lupus erythematosus (SLE) (n = 21), rheumatoid arthritis (RA) (n = 29) and osteoarthritis (n = 12). In patients with SLE the levels of 25-OH D3 were below those of the healthy controls (p = 0.0008) and OA (p = 0.0168). The levels 1,25-(OH)2 D3 corresponded to normal levels. There were no significant correlations between 25-OH D3 levels and clinical or paraclinical disease manifestations. Further, the phenotypic distribution of Gc-globulin, which binds vitamin D3 metabolites in circulation, was normal. The serum concentrations of 1,25-(OH)2 D3 and 25-OH D3 in patients with RA and OA corresponded to those of the controls. Although the cause of the reduced 25-OH D3 levels in SLE patients is unclear, possible beneficial effects of administration of vitamin D to these patients should be considered.

A novel therapeutic approach to psoriasis with combination calcipotriol ointment and very low-dose cyclosporine: results of a multicenter placebo-controlled study

BACKGROUND

Recent advances in the treatment of psoriasis include both the topical vitamin D analogue calcipotriol and cyclosporine. Combined treatments have been sought to decrease the incidence of side effects while maintaining efficacy in the treatment of severe chronic plaque psoriasis.

OBJECTIVE

The objective of this study was to evaluate the efficacy and safety of the combination of 2 mg/kg/day of cyclosporine with calcipotriol ointment (50 micrograms/gm) in the treatment of severe plaque psoriasis.

METHODS

Sixty-nine patients were randomly selected for this double-blind, multicenter study to receive cyclosporine (2 mg/kg/day) combined with calcipotriol ointment (50 micrograms/gm) or cyclosporine (2 mg/kg/day) combined with placebo ointment (vehicle of calcipotriol) for a 6-week period.

RESULTS

Complete clearing or 90% improvement in Psoriasis Area and Severity Index score occurred in 50.0% of patients in the calcipotriol/cyclosporine group in comparison with 11.8% of patients treated with placebo/cyclosporine (p = 0.0019). The confidence interval for the difference ranged from 17.8% to 58.7%. No difference was found between the two groups with respect to side effects.

CONCLUSION

The calcipotriol/cyclosporine combination was more effective than placebo/cyclosporine. Further studies are needed to establish the long-term efficacy and safety profile of this combination therapy.

Effects of 1,25-dihydroxyvitamin D3 and the analogues MC903 and KH1060 on interleukin-1 beta-induced inhibition of rat pancreatic islet beta-cell function in vitro

The cytokine interleukin-1 beta (IL-1 beta) has been proposed to be involved in pancreatic beta-cell destruction during the development of autoimmune insulin-dependent diabetes mellitus. It has been demonstrated that 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) inhibits T-lymphocyte and monocyte functions in vitro, probably through an effect on cytokine actions, and that in vivo treatment with vitamin D can prevent pancreatic insulitis in diabetes-prone NOD mice. In this study isolated rat pancreatic islets were exposed to human IL-1 beta (25 U/ml) in the absence or presence of 1,25-(OH)2D3 or the analogues MC903 and KH1060 for 48-72 h in tissue culture, whereupon medium insulin accumulation, islet DNA and insulin contents, glucose-stimulated insulin secretion and glucose oxidation rates were assessed. All three vitamin D derivatives counteracted the suppressive effect of IL-1 beta on medium insulin accumulation, 1,25-(OH)2D3 being active at concentrations down to 0.1 nM, i.e., 1-2 orders of magnitude more efficacious than the analogues. However, only KH1060 opposed the suppressive effect of IL-1 beta on islet glucose-stimulated insulin secretion and glucose oxidation rate despite the fact that KH1060 itself reduced the islet DNA and insulin content by approximately 10% and 30%, respectively. The protective effect observed against IL-1 beta-induced beta-cell dysfunction might be related to a beneficial action of vitamin D3 on the mitochondrial calcium metabolism of the beta-cells.

Topical treatment of pityriasis rubra pilaris with calcipotriol

From a clinical, histological and therapeutic point of view, psoriasis and pityriasis rubra pilaris share important characteristics. Recently, calcipotriol has been shown to be an effective treatment in psoriasis, and we report three patients with pityriasis rubra pilaris who showed a favourable response to topical therapy with calcipotriol. In one case, analysis of markers for epidermal growth, differentiation and inflammation revealed reduction of suprabasal expression of keratin 16, and the number of T lymphocytes, monocytes and macrophages. It is of interest that a reduction of the recruitment of cycling epidermal cells, which is a consistent response pattern during treatment of psoriasis, was not observed during treatment of pityriasis rubra pilaris.

Immunosuppressive effects of 1,25-dihydroxyvitamin D3 and its analogue calcipotriol on epidermal cells

1,25-Dihydroxyvitamin D3 (1,25(OH)2D3; calcitriol) is the biologically active form of vitamin D. This hormone is a potent immunoregulatory agent. Calcipotriol is a synthetic analogue of 1,25(OH)2D3, with similar receptor binding, and comparable effects on cell proliferation and differentiation, but less potent effects on calcium metabolism. As a step towards understanding the mechanisms by which vitamin D compounds affect T-cell activation by epidermal cells (EC), we assessed the effects of 1,25(OH)2D3 and calcipotriol on the human allogeneic mixed epidermal cell-lymphocyte reaction. All experiments were performed both with 1,25(OH)2D3, and calcipotriol, with similar results. Both compounds had potent immunoinhibitory properties on this model, and enhanced the immunosuppressive effects of cyclosporin A. Using preincubation experiments, we found that pretreatment of EC with 1,25(OH)2D3 resulted in a more pronounced inhibition than preincubation of lymphoid cells. The epidermal targets of this inhibitory effect have been further investigated, using cultures with freshly isolated Langerhans cells (LC) or LC-depleted keratinocytes, separated by an immunomagnetic particle technique. Pretreatment of LC induced a 30% decrease of proliferation, compared with vehicle-treated LC. These calcitriol-pulsed LC did not decrease the proliferation induced by unmodified autologous EC. As expected, LC-depleted keratinocytes failed to stimulate allogenic lymphocytes. When added to autologous unmodified EC, however, calcitriol-pulsed keratinocytes induced an 85% decrease of proliferation, compared with vehicle-treated keratinocytes. The phenotypic expression of HLA-DR, -DQ, and -DP antigens on EC, assessed by immunoalkaline phosphatase staining, was not modified after a 2-h or 24-h pulse with 1,25(OH)2D3 or calcipotriol.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulatory effects of 1,25-dihydroxyvitamin D3 and a novel vitamin D3 analogue MC903 on secretion of interleukin-1 alpha (IL-1 alpha) and IL-8 by normal human keratinocytes and a human squamous cell carcinoma cell line (HSC-1)

Pro-inflammatory cytokines mediate their biological functions after they are secreted or released from intracellular to extracellular milieu. Keratinocytes have proven to be able to produce various cytokines including IL-1 and IL-8. Dysregulations of IL-1 and IL-8 were found in psoriatic lesions. Recently, vitamin D3 (VD3) was found to be an effective and safe therapy for psoriasis. In the present study, we investigated the effects of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) and its analogue MC903 on IL-1 alpha and IL-8 secretion by human keratinocytes in vitro. Cultured normal human keratinocytes (NHKs) produced considerable amounts of IL-1 alpha but secreted less. In contrast, they produced less IL-8 and almost all molecules were secreted to the culture supernatants. Treatment of unstimulated NHKs with 1,25(OH)2D3 or MC903 showed little effects on IL-1 alpha production and secretion though they slightly enhanced IL-8. When NHKs were stimulated with tumour necrosis factor-alpha (TNF alpha), both IL-1 alpha and IL-8 secretions were enhanced and these enhancements were inhibited by 1,25(OH)2D3 or MC903. Stimulation of NHKs with phorbol 12-myristate 13-acetate(PMA) and lipopolysaccharide(LPS) resulted in an increase of IL-8 and decrease of IL-1 alpha in the culture supernatants. Addition of 1,25(OH)2D3 or MC903 inhibited the increased secretion of IL-8 but restored decreased secretion of IL-1 alpha from stimulated NHKs dose dependently. Hydrocortisone and cyclosporin A showed similar inhibitory effects on PMA/LPS-increased IL-8 secretion from NHKs but had little effect of restoring IL-1 alpha.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytokine system as potential target for antipsoriatic therapy

Cytokines are produced by a variety of cells and have numerous of overlapping activities. There is increasing evidence that cytokines play a crucial role in the pathogenesis of psoriasis and of other dermatologic diseases. This review summarizes current knowledge as to how the altered cytokine network is involved in the accumulation of inflammatory cells in lesional skin, and how the cytokines are involved in epidermal hyperproliferation. The actions of the most important therapeutic compounds, such as corticosteroids, dithranol, cyclosporine, retinoids, vitamin D3 analogues and ultraviolet radiation, on the cytokine system are also discussed. Consideration is given as to how the effects on the production of cytokines and/or cytokine receptors contribute to their therapeutic action.

Interaction of liposomal incorporated vitamin D3-analogues and human keratinocytes

The influence of different liposomal qualities, loaded with a variety of vitamin D3-analogues, on the proliferation and interleucine 1 alpha-release (IL-1 alpha) of human keratinocytes was examined by fluorimetric and colorimetric measurements to optimize their use for psoriasis treatment. In comparison, the effects of the free drugs, as 25-hydroxyvitamin D3, calcipotriol, and calcitriol, as well as of empty liposomes have been studied. At the interaction between empty liposomes (< 200 nm) and HaCaT-cells has been looked by electron microscopy. Empty liposomes, made of DMPC as well as of egg-PC, can be used as drug carrier without any inhibiting effect on the proliferation of human keratinocytes at lipid concentrations of < 10(-4) M. Under the influence of the free drugs investigated an inhibition of cell growth as well as of the IL 1 alpha-release was measured at drug concentrations of > or = 10(-8) M. In comparison the related liposomal drug formulations didn't show any diminishing in the proliferation effects caused by the free drugs. A significant improvement, however, was only found in the action of DMPC-incorporated 25-hydroxyvitamin D3 at drug concentration of 10(-7) M. These results suggest that there is no remarkable improvement in the action of liposomal incorporated vitamin D3-analogues neither related to their proliferation nor their IL1 alpha-releasing effects. The influence of liposomal incorporated vitamin D3-analogues in keeping small their negative side effects has to be investigated at a more relevant model.

1,25-Dihydroxyvitamin D3 increases type 1 interleukin-1 receptor expression in a murine T cell line

The biologically active metabolite of vitamin D3, 1,25 (OH)2 D3, exerts important immunoregulatory effects in addition to being a central mediator of calcium/phosphate metabolism. Utilizing an interleukin 1 responsive murine T cell line and 125I-interleukin 1 alpha, we show that 1,25 (OH)2 D3 (5,50 nM) enhanced 125I-interleukin 1 alpha binding up to almost 2-fold over control. This 1,25 (OH)2 D3 effect occurred in a dose-dependent manner and was detectable after 24 h but not before 7 h of culture. Scatchard analysis of 125I-interleukin 1 alpha binding data demonstrated that 1,25 (OH)2 D3 enhanced interleukin 1 receptor number without a significant change in affinity. The biologically less potent metabolite of vitamin D3, 25 (OH) D3, also augmented 125I-interleukin 1 alpha binding but at steroid levels 2-3 log orders greater than 1,25 (OH)2 D3. This observation, combined with the presence of high-affinity 3H-1,25 (OH)2 D3 receptors (88 sites/cell, K = 0.45 nM) in cytosolic extracts, strongly suggests that the nuclear vitamin D receptor mediates this steroid's effect on interleukin 1 receptor expression. Based on the capacity of an anti-type 1 interleukin 1 receptor monoclonal antibody (35F5) to block 1,25 (OH)2 D3-enhanced 125I-interleukin 1 alpha binding, we conclude that this steroid augments type 1 interleukin 1 receptor expression. When combined with interleukin 1, a cytokine that also impacts MD10 interleukin 1 receptor expression, 1,25 (OH)2 D3 enhanced interleukin 1 receptor expression. Northern blots hybridized with a 32P-type 1 interleukin 1 receptor cDNA probe show that 1,25 (OH)2 D3 enhanced type 1 interleukin 1 receptor steady state mRNA levels. Functionally, 1,25 (OH)2 D3 pretreatment augmented the MD10 proliferative response to suboptimal levels of interleukin 1 (< 100 fM interleukin 1 alpha). These findings further support 1,25 (OH)2 D3's role as an immunoregulatory molecule and provides a possible mechanism by which this steroid could potentiate certain immune activities.

The role of cytokines in the psoriatic inflammation

Psoriasis represents an inflammatory skin disorder which is characterized by a marked hyperproliferation of keratinocytes in association with vascular expansion, fibroblast activation, leukocyte infiltration, alterations of eicosanoid metabolism and of cytokine production. However, it is unclear at present whether these changes may be a cause or a result of the significantly increased keratinocyte turnover. More than one mechanism is involved in triggering active psoriasis, particularly a genetic predisposition and environmental factors affecting the immune system. Most of the therapeutic regimes used for the treatment of psoriasis are immunosuppressive. Therefore, it is tempting to speculate that a specific defect of the immune system represents an important pathogenic principle in psoriasis. There are several lines of evidence that changes in cytokine production by keratinocytes and immunocompetent cells in the skin of the patients (particularly of interleukin-6 and TGF-alpha) may play an important role in the propagation of the inflammatory response in psoriasis. Further studies are required to reveal the role of a local T-cell activation as a basic mechanism for initiation and maintenance of the psoriatic inflammatory response. Accordingly, parameters, such as the evaluation of cytokine production in vitro and in vivo, as well as the measurement of cellular activation products, may be useful tools for diagnosis and monitoring of psoriasis.

Dietary vitamin D affects cell-mediated hypersensitivity but not resistance to experimental pulmonary tuberculosis in guinea pigs

Outbred, Hartley strain guinea pigs were fed purified diets varying only in their levels of vitamin D. The amounts of vitamin D in the diets were adjusted to represent 0, 25, 50, 100, or 200% of the recommended level (1,180 IU/kg of body weight) for guinea pigs. In some experiments, half of the animals in each diet group were vaccinated with Mycobacterium bovis BCG vaccine at the time the diets were introduced. Six weeks later, all guinea pigs were infected by the respiratory route with a low dose of virulent M. tuberculosis H37Rv. Vitamin D-deficient animals exhibited marked reductions in levels of the major vitamin D metabolite, 25-hydroxyvitamin D3, in plasma. Altered vitamin D intake was accompanied by changes in antigen (purified protein derivative)-induced, cell-mediated immune responses both in vivo (tuberculin hypersensitivity) and in vitro (lymphoproliferation). Dermal tuberculin reactivity developed more slowly in vitamin D-deficient guinea pigs but eventually achieved normal levels. The proliferation of splenocytes cultured with purified protein derivative was suppressed by both deficiency and excess of dietary vitamin D. Vitamin D status did not affect the abilities of naive guinea pigs to control primary, pulmonary tuberculosis, nor did it influence the protective efficacy of BCG vaccination. We conclude that changes in dietary vitamin D are associated with alterations in some cellular immune functions but may not be an important determinant of disease outcome in pulmonary tuberculosis, as has been suggested previously.

Inhibition of human T lymphocyte proliferation and cytokine production by 1,25-dihydroxyvitamin D3. Differential effects on CD45RA+ and CD45R0+ cells

1,25-dihydroxyvitamin D3 (1,25-(OH)2 D3), the biologically active form of vitamin D3, has been shown to modulate lymphocyte functions in vitro. These effects are exerted through binding to specific receptors that are expressed in activated, but not in resting lymphocytes. 1,25-(OH)2 D3 inhibits lymphocyte proliferation, immunoglobulin production and the release of cytokines including interleukin-2 (IL-2) and interferon gamma (IFN gamma) by mitogen driven blood mononuclear cells (MNC). A distinction between CD45RA+ and CD45R0+ subsets of T cells has, however, proven extremely relevant in terms of immunoactivation and immunopathology. The present study was undertaken to evaluate effects of 1,25-(OH)2 D3 on proliferation and cytokine production by purified CD45RA+ and CD45R0+ T cells. 1,25-(OH)2 D3 caused a dose- and time-dependent reduction in phytohemagglutinin-(PHA) and poke-weed mitogen (PWM)-driven proliferation of purified CD45R0+ T cells. In contrast, proliferation of the CD45RA+ subset was unaffected by this treatment. Comparable levels of lymphotoxin (LT), IFN gamma and IL-2 were obtained in cultures of both subsets. 1,25-(OH)2 D3 reduced these levels, but the suppressive effect of the hormone was delayed in cultures of CD45RA+ T cells. The results suggest that the CD45R0+ subset is relatively more sensitive than CD45RA+ subset to the inhibitory effects of 1,25-(OH)2 D3. This finding may be of pharmacological interest, because the CD45R0+ subset plays a key role in immune activation and because these cells have been associated with the pathogenesis of autoimmune diseases such as rheumatoid arthritis and multiple sclerosis.

Treatment of psoriasis with calcipotriol and other vitamin D analogues

The discovery of a high-affinity receptor for the bioactive form of vitamin D3, 1,25-dihydroxyvitamin D3 (1,25[OH]D3), in most skin cells has led to the finding of previously unknown effects of vitamin D on epidermal growth and on the skin immune system. 1,25(OH)2D3 inhibits epidermal proliferation and promotes epidermal differentiation. These properties provided the rationale for introducing 1,25(OH)2D3 in the treatment of psoriasis vulgaris. In addition to 1,25(OH)2D3, the synthetic vitamin D3 analogues 1 alpha(OH)D3, 1,24(OH)2D3, and calcipotriol have undergone clinical evaluation. Calcipotriol has been studied most extensively. Compared with 1,25(OH)2D3, calcipotriol is about 200 times less potent in its effects on calcium metabolism, although similar in receptor affinity. In double-blind, placebo-controlled, randomized studies, topical calcipotriol (50 micrograms/gm, up to 100 gm weekly) has been shown to be efficacious and safe for the treatment of psoriasis. A similar therapeutic profile has been seen in long-term studies. In comparative studies topical calcipotriol is slightly more efficacious than betamethasone 17-valerate and dithranol. The mode of action of calcipotriol and other vitamin D3 analogues in psoriasis is not known. Although vitamin D3 analogues affect epidermal growth, their immunosuppressive properties may be equally important for their antipsoriatic effect.

1,25-Dihydroxyvitamin D3 inhibits cytokine production by human blood monocytes at the post-transcriptional level

1,25-Dihydroxyvitamin D3 [1,25-(OH)2D3] inhibits lymphocyte proliferation and production of antibodies and lymphokines such as interleukin (IL)-2 and interferon gamma. These lymphocyte functions are dependent upon cytokines, including IL-1 alpha, IL-1 beta, IL-6 and tumour necrosis factor alpha (TNF-alpha), produced by the antigen presenting cells. In the present study we examined the effect of 1,25-(OH)2D3 on the production of these cytokines, as well as superoxide generation by freshly isolated mononuclear cells and partially purified monocytes. The immediate precursor of 1,25(OH)2D3, 25-OH D3, and the synthetic analogue MC 903 ('Calcipotriol') were examined in parallel. 1,25-(OH)2D3 dose-dependently inhibited the production of IL-alpha, IL-6 and TNF-alpha by Escherichia coli lipopolysaccharide (LPS)-stimulated monocytes, without affecting superoxide production. MC 903 had comparable effects while 25-OH D3 was ineffective. The inhibition caused by 1,25-(OH)2D3 was not abolished by supraoptimal concentrations of LPS or indomethacin. 1,25-(OH)2D3 had similar effects on secreted and cell-associated IL-alpha. Nuclear run-off analysis indicated that inhibition of these cytokines was not caused by impaired production of mRNA. Taken together, the study demonstrates a vitamin D-induced inhibitory effect of LPS-driven monokine production, which is most likely a vitamin D-receptor mediated phenomenon exerted at a post-transcriptional, presecretory level. Impaired monokine production may be of importance in 1,25-(OH)2D3-mediated inhibition of lymphocyte functions in vitro.

Vitamin D analogues and psoriasis

Topical vitamin D analogues offer a new, effective, more convenient and generally well-tolerated option for the treatment of psoriasis. Only psoriasis vulgaris has been intensively studied, but other forms of the disease may also respond. Both calcitriol and calcipotriol have been shown to be effective in numerous clinical trials, and the latter has compared well with betamethasone valerate and short-contact dithranol in controlled studies. Their mechanism of action is not yet fully understood and may prove complex. The most important effect may be a direct regulation of keratinocyte proliferation and differentiation. However, these compounds also have potent immunological properties, and may act by inhibition of cytokine production by keratinocytes or lymphocytes. Topical application of vitamin D analogues appears generally to be remarkably safe, but hypercalcaemia and hypercalciuria may develop if large quantities are used.

Immunological properties of vitamin D analogues and metabolites

This commentary has attempted to describe some of the new aspects of our knowledge of the immunological properties of 1 alpha,25(OH)2D3, the physiologically active metabolite of vitamin D3, and its new analogues. These analogues will, in the future, serve as tools to increase our understanding of the role of vitamin D in immunobiology, not only in basal research but also, hopefully, in the therapy of immune-mediated diseases.

Epidermal cytokeratin and immunocyte responses during treatment of psoriasis with calcipotriol and betamethasone valerate

Changes in epidermal immunocytes and cytokeratins were investigated during treatment of psoriasis with calcipotriol and betamethasone valerate. Skin biopsies were obtained from 10 subjects on each treatment from lesional and non-lesional skin at baseline, and from treated lesions after 4 weeks. In each subject, changes in expression of cytokeratins K5, K10 and K16, and changes in epidermal immunocyte counts were assessed. Responses were compared with a separate histological parameter of improvement, epidermal thickness. Both treatments produced a marked normalization of cytokeratins. The reduction of K16 expression was similar on each treatment and correlated significantly with reduction in epidermal thickness. Expression of both K5 and K10 improved less than thickness with betamethasone valerate but more than thickness with calcipotriol, although these differences did not reach statistical significance. With calcipotriol there was an increase in K5 and K10 responses with increasing response of epidermal thickness, which was not seen with betamethasone valerate. T6+ cells, HLA-DR+ dendritic cells and T lymphocytes were all reduced by betamethasone valerate. There was a remarkable similarity in the level of normalization between cell types and also between cellular response and reduction in thickness. Calcipotriol produced a similar consistent reduction in cell numbers and in thickness, with the exception of T6+ cells which increased in some subjects during treatment. Only in subjects in whom thickness had virtually returned to normal was there a marked decrease in T6+ cells.

Vitamin D3 and skin diseases

The physiologically active metabolite of vitamin D3, 1 alpha,25-dihydroxycolicalciferol [1,25(OH)2D3, calcitriol] has achieved the status of a hormone. It is believed to mediate its effects by binding to a specific receptor which belongs to the family of nuclear receptors for glucocorticoids, estrogens, thyroxine, and retinoid acid. It has been discovered that 1,25(OH)2D3 has the ability to regulate growth and differentiation in many cell types, including cancer cells, epidermal keratinocytes, and activated lymphocytes. This has set the stage for the development of a new class of compounds with potential usefulness in hyperproliferative and immune-mediated diseases. Ideally, such agents should possess potent effects as regulators of cell proliferation and differentiation at concentrations well below those that may induce side effects related to the classical vitamin D activity on calcium absorption and bone mineralization. In addition to 1,25(OH)2D3, the synthetic vitamin D3 analogues 1 alpha-OH-D3, 1,24(OH)2D3, and calcipotriol have undergone clinical evaluation. Calcipotriol has been studied most extensively. Compared with 1,25(OH)2D3, calcipotriol is about 200 times less potent in its effect on calcium metabolism although similar in receptor affinity. In double-blind, placebo-controlled multicenter studies, topical calcipotriol has been shown to be both efficacious and safe for the short- and long-term treatment of plaque-type psoriasis. Because some of the novel vitamin D analogues are potent regulators of cell growth and immune responses, they may be of potential interest in the treatment of ichthyoses, cancer, and autoimmune diseases.

The weak calcemic vitamin D3 analogue 22-oxacalcitriol suppresses the production of tumor necrosis factor-alpha by peripheral mononuclear cells

The effect of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) and its analogue 22-oxacalcitriol (OCT), which was reported to have very weak bone resorbing activity, on the production of tumor necrosis factor (TNF)-alpha was investigated. Mononuclear cells (MNC; 10(6)/ml) were incubated in 5% FCS/RPMI-1640 medium containing 1 microgram/ml lipopolysaccharide (LPS) in the presence or absence of 10(-8) M 1,25(OH)2D3 or 10(-8) M OCT for up to 96 h. Both 1,25(OH)2D3 and OCT suppressed TNF-alpha release by LPS-stimulated mononuclear cells, from the early to late stage of the incubation period, while neither 1,25(OH)2D3 nor OCT shifted the peak time point of TNF-alpha release clearly. MNC (10(6)/ml) were incubated with 1 microgram of LPS in the presence of various concentrations of 1,25(OH)2D3 or 10(-8) M OCT for 48 h. 1,25(OH)2D3 reduced TNF-alpha levels of LPS-stimulated MNC culture supernatant at 48 h in a dose-dependent manner. The half-maximal dose (ED50) for this suppressive effect was 3.7 x 10(-9) M. OCT decreased TNF-alpha levels of culture supernatant at 48 h with a half-maximal dose of 7.8 x 10(-11) M, which indicates that it is approximately 50 times more potent than that of 1,25(OH)2D3. These results indicate that OCT may be applicable as an immunosuppressive agent with limited calcium metabolic activity.

20-epi-vitamin D3 analogues: a novel class of potent regulators of cell growth and immune responses

The 20-epi-vitamin D3 analogues are a novel class of vitamin D3 derivatives, structurally related to 1 alpha,25-dihydroxycholecalciferol (1 alpha,25(OH)2D3). They are characterized by an altered stereochemistry at carbon 20 in the side-chain. In vitro, these new analogues were found to be considerably more potent as regulators of growth and differentiation in the human histiocytic lymphoma cell line U 937 than 1 alpha,25(OH)2D3, despite a practically unchanged calcemic activity in vivo. The most potent analogue, KH 1060, inhibited cell proliferation by 50% at 10(-12) M (14,000 times more active than 1 alpha,25(OH)2D3). At the same time, KH 1060 induced cell differentiation at concentrations as low as 10(-14)M. In addition, the 20-epi-vitamin D3 analogues were found to be very potent inhibitors of T-lymphocyte proliferation induced by interleukin-1 or alloantigen. In this respect, they were several orders of magnitude more active than the potent immunosuppressive agent cyclosporin A (CyA). KH 1060, the most potent analogue, inhibited interleukin-1-induced mouse thymocyte proliferation by 50% at 3 x 10(-16) M and allogeneic stimulation of mouse spleen lymphocytes at 5 x 10(15) M. These effects were considered to be mediated by inhibition of interleukin-2 release from activated T-lymphocytes. The new analogues are of potential interest in the prevention of graft rejection and in the treatment of psoriasis, cancer and auto-immune diseases.

1,25(OH)2-D3 is a potent regulator of interleukin-1 induced interleukin-8 expression and production

Interleukin 8 (IL-8) is a potent leukocyte chemotactic and activating cytokine produced by keratinocytes, fibroblasts, peripheral blood monocytes (PBMC) and endothelial cells. IL-8 is believed to play an important role in the development of inflammation and is thus an obvious target for therapeutical modulation. We studied the possible effect of an endogenous immune modulator 1,25(OH)2-cholecalciferol (1,25(OH)2-D3) on the IL-1-induced IL-8-production by several types of cells. 1,25(OH)2-D3 inhibited the IL-1-alpha induced IL-8 production and mRNA expression in keratinocytes, fibroblasts and PBMC, but not in endothelial cells. Optimal vitamin concentrations varied between 10(-10) and 10(-11) M. These results suggest a potential role of this hormone in the regulation of chemotactic cytokine production.

Inhibition of production and function of interleukin-6 by 1,25-dihydroxyvitamin D3

1,25-Dihydroxyvitamin D3 (1,25-(OH)2D3) has been shown to interfere with immunoglobulin production and lymphocyte proliferation in vitro. These lymphocyte functions are influenced by interleukin (IL)-6 produced by antigen presenting cells. Hence, the ability of 1,25-(OH)2D3 to interfere with the production and function of IL-6 was investigated. 1,25-(OH)2D3 and the analogue MC 903 inhibited IL-6 production by LPS-stimulated human mononuclear cells. The precursor 25-OH D3 was ineffective. Likewise, 1,25-(OH)2D3 but not 25-OH D3 inhibited rIL-6-driven as well as rIL-1 alpha/beta-driven proliferation of murine thymocytes. This effect of 1,25-(OH)2D3 was partially or totally overcome by larger concentrations of rIL-6 as well as by rIL-2 and ionomycin. Consistently, the production of IL-6 and IL-2 in rIL-1 driven thymocyte cultures were found to be reduced by 1,25-(OH)2D3. Inhibition of production and function of IL-6 may therefore be involved in 1,25-(OH)2D3-mediated regulation of lymphocyte functions in vitro.

The role of monocytes and T cells in 1,25-dihydroxyvitamin D3 mediated inhibition of B cell function in vitro

1,25-Dihydroxyvitamin D3 (1,25-(OH)2D3) inhibits immunoglobulin production by human mononuclear cells (MNC) in vitro. The present study was undertaken to evaluate the role of T cells and monocytes in 1,25-(OH)2D3 induced suppression of B cell functions. The synthetic vitamin D3 analogue MC 903 was examined in parallel. 1,25-(OH)2D3 and MC 903 showed a dose-related inhibition of IgM, IgG and IgA plaque-forming cells in poke-weed mitogen (PWM) activated cultures of MNC. This effect was most likely mediated through impairment of T cell and monocyte functions. First, the inhibitory effect was seen after PWM stimulation, but not after Epstein-Barr virus stimulation which activates B cells independently of T cells and monocytes. Second, 1,25-(OH)2D3 was not effective in T cell and monocyte-depleted cultures. Third, the effect of 1,25-(OH)2D3 on PWM driven MNC was reversed by addition of the recombinant monokines: interleukin (IL)-1 beta, tumour necrosis factor alpha (rTNF alpha), rIL-6, as well as the lymphokines: lymphotoxin (rLT) and rIL-2. This is consistent with the finding that 1,25-(OH)2D3 also inhibited IL-1 alpha, TNF alpha and LT production in these cultures. The assumption that B cells are not directly affected by 1,25-(OH)2D3 was further supported by the fact that 24 h of culture with 10(-8) M 1,25-(OH)2D3 failed to reduce immunoglobulin production by in vivo activated B cells.

Simultaneous assessment of inflammation and epidermal proliferation in psoriatic plaques during long-term treatment with the vitamin D3 analogue MC903: modulations and interrelations

The influence of topical application of MC903, an analogue of 1 alpha,25-dihydroxyvitamin D3, on psoriatic plaques was investigated during a long-term treatment study. The parameters for epidermal growth and for inflammation were assessed on frozen sections using immunohistochemical methods to elucidate their modulations in time and the interrelations between the different cell types involved during treatment with MC903. Biopsies were taken before and after 1, 2, 4 and 12 weeks of treatment. Monoclonal antibodies against the hyperproliferation-associated keratin 16, against cycling nuclei, and against T lymphocytes, B lymphocytes, Langerhans cells and CD14-positive cells were used in combination with a polyclonal antibody against polymorphonuclear leucocyte (PMN)-elastase. The earliest change was a statistically significant decrease in PMN after 1 week of treatment followed by a decline of cycling nuclei after 2 weeks. These changes preceded a decrease of T lymphocytes which occurred after 4 weeks. Keratin 16 content tended to diminish after 4 weeks of treatment. CD14+ cells decreased slightly during the observation period, whereas Langerhans cells tended to increase. No B lymphocytes were found. These results suggest that MC903 influences the number of PMN and epidermal growth rather than the number of T lymphocytes.

Down-regulation of monocyte functions by treatment of healthy adults with 1 alpha,25 dihydroxyvitamin D3

A number of in vitro studies suggest an immunoregulatory role of 1 alpha,25 Dihydroxyvitamin D3 (1,25-(OH)2D3). The hormone inhibits production of interleukin-2 and immunoglobulin, and it blocks lymphocyte proliferation. Diverse effects on monocyte functions have been reported. However, immunological effects of 1,25-(OH)2D3 have not been substantiated in vivo. Six healthy male volunteers, aged 28-45 yr, were treated orally with 1,25-(OH)2D3 (tabl. Rocaltrol), 1 microgram twice daily for 7 days. Blood and urine samples were collected before and 7 days after initiation of treatment. Blood mononuclear cells from individuals treated with 1,25-(OH)2D3 showed a significantly reduced production of both interleukin-1 alpha (45%) and tumor necrosis factor-alpha (58%) (both measured by ELISA). Interleukin-6, production, measured by the B9 cell assay, was reduced in five individuals (78%), and unchanged in one. There was no effect on the release of interleukin-1 beta. There was no measurable effect on interleukin-2, interferon gamma or immunoglobulin production, or on mitogen-induced proliferation of blood mononuclear cells. Serum-osteocalcin and urine excretion of calcium were increased to 131 and 173%, respectively. The serum-calcium and serum-phosphate levels were unchanged.

Abnormal vitamin D3 metabolism in patients with primary Sjögren's syndrome

Recent studies have suggested that vitamin D3 may have an immunoregulatory role in vitro. The vitamin D3 metabolism in 35 patients with primary Sjögren's syndrome was investigated by measuring blood concentrations of 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25-(OH)2D3) and 25-hydroxyvitamin D3 (25-OHD3), as well as phenotypes and blood concentrations of Gc globulin, the main vitamin D3 binding protein in the blood. 25-OHD3 concentrations were diminished, but those of 1 alpha,25-(OH)2D3 were normal. There was no significant difference between the distribution of Gc phenotypes in the patients with primary Sjögren's syndrome and normal controls. Likewise, blood concentrations of Gc globulin corresponded to normal values. Among patients with increased concentrations of IgM rheumatoid factor there was a significant negative correlation between the serum titres of IgM rheumatoid factor and 25-OHD3 concentrations.