Decreased β2-adrenergic receptor-mRNA and Ioricrin-mRNA, and increased involucrin-mRNA transcripts in psoriatic epidermis: analysis by reverse transcription–polymerase chain reaction

Sympathetic Nerve Hyperactivity in the Spleen: Causal for Nonpathogenic-Driven Chronic Immune-Mediated Inflammatory Diseases (IMIDs)?

Immune-Mediated Inflammatory Diseases (IMIDs) is a descriptive term coined for an eclectic group of diseases or conditions that share common inflammatory pathways, and for which there is no definitive etiology. IMIDs affect the elderly most severely, with many older individuals having two or more IMIDs. These diseases include, but are not limited to, type-1 diabetes, obesity, hypertension, chronic pulmonary disease, coronary heart disease, inflammatory bowel disease, and autoimmunity, such as rheumatoid arthritis (RA), Sjőgren's syndrome, systemic lupus erythematosus, psoriasis, psoriatic arthritis, and multiple sclerosis. These diseases are ostensibly unrelated mechanistically, but increase in frequency with age and share chronic systemic inflammation, implicating major roles for the spleen. Chronic systemic and regional inflammation underlies the disease manifestations of IMIDs. Regional inflammation and immune dysfunction promotes targeted end organ tissue damage, whereas systemic inflammation increases morbidity and mortality by affecting multiple organ systems. Chronic inflammation and skewed dysregulated cell-mediated immune responses drive many of these age-related medical disorders. IMIDs are commonly autoimmune-mediated or suspected to be autoimmune diseases. Another shared feature is dysregulation of the autonomic nervous system and hypothalamic pituitary adrenal (HPA) axis. Here, we focus on dysautonomia. In many IMIDs, dysautonomia manifests as an imbalance in activity/reactivity of the sympathetic and parasympathetic divisions of the autonomic nervous system (ANS). These major autonomic pathways are essential for allostasis of the immune system, and regulating inflammatory processes and innate and adaptive immunity. Pathology in ANS is a hallmark and causal feature of all IMIDs. Chronic systemic inflammation comorbid with stress pathway dysregulation implicate neural-immune cross-talk in the etiology and pathophysiology of IMIDs. Using a rodent model of inflammatory arthritis as an IMID model, we report disease-specific maladaptive changes in β₂-adrenergic receptor (AR) signaling from protein kinase A (PKA) to mitogen activated protein kinase (MAPK) pathways in the spleen. Beta₂-AR signal "shutdown" in the spleen and switching from PKA to G-coupled protein receptor kinase (GRK) pathways in lymph node cells drives inflammation and disease advancement. Based on these findings and the existing literature in other IMIDs, we present and discuss relevant literature that support the hypothesis that unresolvable immune stimulation from chronic inflammation leads to a maladaptive disease-inducing and perpetuating sympathetic response in an attempt to maintain allostasis. Since the role of sympathetic dysfunction in IMIDs is best studied in RA and rodent models of RA, this IMID is the primary one used to evaluate data relevant to our hypothesis. Here, we review the relevant literature and discuss sympathetic dysfunction as a significant contributor to the pathophysiology of IMIDs, and then discuss a novel target for treatment. Based on our findings in inflammatory arthritis and our understanding of common inflammatory process that are used by the immune system across all IMIDs, novel strategies to restore SNS homeostasis are expected to provide safe, cost-effective approaches to treat IMIDs, lower comorbidities, and increase longevity.

Increased prevalence of early repolarization in electrocardiograms of psoriatic patients

Psoriasis (Ps) is a chronic-relapsing, inflammatory, and proliferative condition of the skin: prior studies hypothesized a link between Ps and anomalies in β-adrenergic tone. We therefore aimed to ascertain the prevalence of early repolarization pattern (ERP) in resting electrocardiograms (ECGs) of psoriatic patients compared with an appropriate control group. We performed a retrospective study of resting ECGs of 100 consecutive psoriatic patients and 100 healthy controls. The presence of ERP in at least two contiguous leads at rest ECG was recorded, and findings were also categorized according to the lead group where ERP was detected (anterior, lateral, inferior). An ERP in ≥ 2 contiguous leads occurred in 40 % of psoriatic patients, compared with 14 % of control subjects (p < 0.001). (36 vs 10 % in anterior leads, p < 0.001; 6 vs 3 % in inferior leads, p n.s.; 10 vs 2 % in lateral leads). After adjustment for sex, age, heart rate, and level of physical activity, the odds ratios for the presence of ERP were 8.6 (95 % CI, 2.1-35.2, p < 0.01), and 7.1 (95 % CI, 1.6-31.8, p < 0.05) in anterior leads. In a small case/control study, increased rates of ECGs showing ERP have been observed among psoriatic patients. Clinical significance of such finding needs to be assessed in further observational studies.

Beta adrenergic receptors in keratinocytes

Beta2 adrenergic receptors were identified in keratinocytes more than 30 years ago, but their function in the epidermis continues to be elucidated. Abnormalities in their expression, signaling pathway, or in the generation of endogenous catecholamine agonists by keratinocytes have been implicated in the pathogenesis of cutaneous diseases such as atopic dermatitis, vitiligo, and psoriasis. New studies also indicate that the beta2AR also modulates keratinocyte migration, and thus can function to regulate wound reepithelialization. This review focuses on the function of these receptors in keratinocytes and their contribution to cutaneous physiology and disease.

Cystatin A suppresses ultraviolet B-induced apoptosis of keratinocytes

BACKGROUND

Cystatin A is a cysteine proteinase inhibitor abundantly expressed in keratinocytes. Although cystatin A is one of the cornified cell envelope constituents and expressed in the upper epidermis, its precise function is still unknown. Ultraviolet B irradiation (UVB) induces apoptosis accompanied with the activation of cysteine proteinases, caspases.

OBJECTIVE

We investigated the effect of cystatin A on UVB-induced apoptosis of keratinocytes.

METHODS

We assessed the caspase activities and apoptotic cell numbers induced by UVB ittadiation in cystatin A gene transfected keratinocytes.

RESULTS

UVB-induced pro-caspase 3 cleavage and caspase 3 activation were suppressed in cystatin A expression vector-transfected SV40-transformed human keratinocytes (SVHK). Furthermore, the transfected SVHK cells were resistant to UVB-induced apoptosis. In contrast neither caspase 8 nor caspase 9 activities were affected by UVB irradiation in cystatin A-transfected SVHK cells. The effects were also observed in cystatin A expression adenovirus vector-transfected cultured normal human keratinocytes (NHK). Conversely knockdown of cystatin A by si-RNA induced marked apoptosis of NHK cells following UVB irradiation accompanied with increased caspase 3 activity. In order to confirm the antiapoptotic effect of cystatin A in vivo UVB irradiation was performed on cystatin A transgenic mice (cystatin A-tg). The epidermis from cystatin A-tg was resistant to UVB-induced apoptosis compared to control mice epidermis.

CONCLUSION

These results indicate that cystatin A suppresses UVB-induced apoptosis of keratinocytes by the inhibition of caspase 3 activation.

Effect of psychological stress on salivary interleukin-1beta in psoriasis

BACKGROUND

Psoriasis is a chronic inflammatory skin disease in which several Th1 cytokines such as interleukin-1 beta (IL-beta) have been shown to play a pivotal role. Psychological stress has also been implicated in triggering or exacerbating the disease.

METHODS

Salivary IL-1beta and cortisol levels of 25 patients with psoriasis were compared with those of 50 age- and sex-matched healthy controls under basal conditions and after a standardized stressful procedure including mental arithmetics and the Stroop Color-Word Naming Test.

RESULTS

At baseline, mean IL-1beta levels were higher in patients with psoriasis than controls (p <0.001), whereas mean cortisol levels did not differ significantly between groups. Although IL-1beta levels increased after stress among controls, they did not increase among patients with psoriasis, with a significant group-by-time interaction (p <0.01). After stress, cortisol levels were significantly increased in both groups as compared with baseline (p < or =0.001), without any group-by-time interaction. Perceived stress was similar among psoriatic patients and controls. There was no significant correlation between changes in IL-1beta and changes in cortisol.

CONCLUSIONS

The higher basal IL-1beta levels among psoriatic patients suggest that its production is increased. Changes in proinflammatory cytokine activity in psoriatic skin may play an important role in propagating inflammation. The blunted response of IL-1beta to stress observed in psoriatic patients may reflect a "ceiling effect", or be ascribed to a defective response of the immune system to adrenergic stimuli.

ATX-S10(Na)-PDT shows more potent effect on collagen metabolism of human normal and scleroderma dermal fibroblasts than ALA-PDT

Recent study revealed that photodynamic therapy (PDT) with a novel photosensitizer (ATX-S10(Na)) shows more potent effects for various skin diseases than ALA-PDT. The effect of ATX-S10(Na)-PDT on dermal fibroblasts is still unknown. Using dermal fibroblasts derived from normal and scleroderma patients, and mouse skin in vivo, we compared the effects of ATX-S10(Na)-PDT and ALA-PDT. Fibroblasts from normal, scleroderma patients or mice skin were treated with ATX-S10(Na)-PDT or ALA-PDT. After the PDT treatments, the expression of matrix metalloproteinases (MMPs) Tissue inhibitors of metalloproteinases (TIMPs) and collagen synthesis was assayed using ELISA and reverse transcription-PCR (RT-PCR). The expression of MMP-1 and MMP-3 was slightly decreased and collagen I mRNA was significantly increased in scleroderma fibroblasts compared with normal fibroblasts. Both ATX-S10(Na)-PDT and ALA-PDT increased the expression of MMP-1 and MMP-3 in protein and mRNA levels in both normal and scleroderma fibroblasts with more potent effect by ATX-S10(N)-PDT. Collagen I synthesis was markedly decreased by ATX-S10(Na)-PDT and by ALA-PDT again with more potent effect by ATX-S10(Na)-PDT in both normal and scleroderma fibroblasts. In mice skin the effect of PDT for MMPs and collagen I was also detected and the effect was more potent in ATX-S10(Na)-PDT. In contrast, MMP-2, TIMP-1, TIMP-2, and collagen III expression was not affected by the ATX-S10(Na)-PDT or ALA-PDT treatment. ATX-S10(Na)-PDT is more potent modulator for dermal matrix components than ALA-PDT and might be useful for scleroderma patients.

Characterization of the loricrin (LOR) gene as a positional candidate for the PSORS4 psoriasis susceptibility locus

Psoriasis is a chronic inflammatory disease of the skin with both genetic and environmental risk factors. Non-parametric linkage analyses have mapped many susceptibility loci on different chromosomes. We mapped one of these loci, PSORS4, on human chromosome 1q21. Using the linkage disequilibrium approach, we refined the critical region to a specific genomic interval of about 100 Kb which contains only the loricrin (LOR) gene. Here we report a genetic and functional study of this gene to verify its involvement in psoriasis pathogenesis. We document low expression of LOR in psoriatic skin of patients selected from families in which the disease was segregating with the PSORS4 locus. Re-sequencing of the entire gene in a subset of patients revealed the existence of novel polymorphisms able to influence the protein structure, as shown by molecular modelling studies. However, no evidence for genetic association was detected in a large cohort of Italian nuclear families. This rules out the LOR gene as a candidate for the PSORS4 locus.

Roxithromycin suppresses involucrin expression by modulation of activator protein-1 and nuclear factor-kappaB activities of keratinocytes

BACKGROUND

Roxithromycin (RXM), a new 14-member macrolide antibiotic, is effective for chronic airway diseases such as diffuse panbronchiolitis and bronchial asthma. Recent study disclosed that RXM inhibits nuclear factor-kappaB (NF-kappaB)-mediated inflammation. Involucrin is one of the precursor proteins of the cornified cell envelope (CE) and is markedly increased in inflammatory skin diseases such as psoriasis. However, its molecular mechanism of action remains unknown.

OBJECTIVE

To determine the effect of RXM on involucrin expression of keratinocytes.

METHODS

We constructed chloramphenicol acetyltransferase (CAT)-involucrin promoter expression vector and CAT assay was performed. Furthermore, western blot and RT-PCR were performed to examine the expression of involucrin in RXM-treated cultured human keratinocytes.

RESULTS

The increased involucrin expression by 12-O-tetradecanoylphorbol acetate (TPA) was suppressed by 10(-6) M RXM and the maximal inhibitory effect was observed at 48 h. RXM suppressed increased CAT activity by TPA and the effect was not inhibited by H-7 or cafferic acid phenethyl ester (CAPE). Deletion of T1 region (-119 to -113) of involucrin promoter completely abolished TPA-dependent stimulatory and RXM-dependent inhibitory promoter activity. Gel shift assay showed that c-Jun (but not p65) selectively binds to the T1 region. The assay of activator protein-1 (AP-1) and NF-kappaB activities revealed that RXM decreased both transcriptional activities. Co-transfection of c-jun and c-fos expression vectors, or p65 and p50 expression vectors, rescued decreased CAT activity by RXM, respectively.

CONCLUSION

Our study demonstrated for the first time that involucrin expression of keratinocytes is suppressed by RXM through direct inhibition of AP-1 and indirect inhibition of NF-kappaB.

Similarly potent action of 1,25-dihydroxyvitamin D3 and its analogues, tacalcitol, calcipotriol, and maxacalcitol on normal human keratinocyte proliferation and differentiation

BACKGROUND

The active vitamin D3 regulates proliferation and differentiation of epidermal keratinocytes. Recently topical vitamin D3, tacalcitol, calcipotriol, and maxacalcitol are widely used for psoriasis.

OBJECTIVE

To examine the effect of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) on cultured normal keratinocytes (NHK) and compared its effect with those of various vitamin D3 analogues.

METHODS

Cell proliferation of NHK cells was analyzed by MTS, BrdU and 3H-thymidine incorporation. The expression of involucrin, transglutaminase 1, keratin 5 and keratin 1 was investigated by western blot and PCR amplification and quantitative assay. Furthermore, we performed cornified cell envelope (CE) formation assay.

RESULTS

1,25(OH)2D3, tacalcitol, calcipotriol, and maxacalcitol decreased NHK cell proliferation in a concentration-dependent manner and the maximal effect was observed at 10(-7) M. There was no significant difference in the anti-proliferative effect among the active vitamin D3 analogues. The expression of involucrin and transglutaminase 1 were induced by 1,25(OH)2D3 and its analogues in mRNA and protein levels. CE formation was also induced by 1,25(OH)2D3 and its analogues. There was no significant difference in the potency among these chemicals. Keratin 5 and 1 expression was not altered by these active vitamin D3 analogues.

CONCLUSIONS

The present study demonstrated that active vitamin D3 analogues, tacalcitol, calcipotriol, and maxacalcitol, suppress keratinocyte proliferation and induce differentiation with similar potency.

Aberrant expression of apoptosis-related molecules in psoriatic epidermis

Apoptosis is a physiological form of cell death that is responsible for the deletion of cells. Epidermal keratinocytes are supposed to be regulated by cell proliferation and cell death leading to structural homeostasis. Psoriatic skin shows marked thickening of the epidermis, suggesting the imbalance of the homeostasis, which might be related to abnormal apoptotic process. We investigated the expression of various apoptosis-related molecules in the psoriatic hyperproliferative epidermis. Real time quantitative RT-PCR analyses revealed that mRNAs of Fas, Bcl-xL, Bax and ICAD (inhibitor of caspase 3-related DNase) of the psoriatic involved epidermis were increased by 4.2-, 2.8-, 2.6- and 5.6-fold, respectively, compared with the uninvolved epidermis. In contrast, Bcl-2 expression in the involved epidermis was one-third suppressed compared with the uninvolved epidermis. No significant difference in the expression of mRNAs of Fas ligand or CAD (caspase 3-related DNase) was detected between the involved and uninvolved epidermis. Western blot analysis and immunohistochemical studies showed compatible results obtained by RT-PCR analyses. Although active caspase 3 was slightly increased in the involved epidermis, apoptotic cells were marginally detected. These results indicate that psoriatic epidermis shows aberrant expression of apoptosis-related molecules representing suppressed apoptotic process, which might be related to characteristic histopathology.

Ultraviolet B irradiation induces apoptosis of keratinocytes by direct activation of Fas antigen

Ultraviolet B (UVB) irradiation induces apoptosis of keratinocytes, where p53 has been suggested to play an important role. Recently we have shown that UVB irradiation induces apoptosis of SV40-transformed human keratinocytes (SVHK cells). Because p53 function is impaired in SVHK cells by large T antigen, a UVB-induced p53-independent apoptotic pathway was suggested. We investigated the UVB-induced apoptotic pathway using various keratinocytes. Cultured mouse keratinocytes of homozygous p53 deficient mice (p53(-/-)) were markedly resistant to UVB-induced apoptosis compared with keratinocytes from wild or heterozygous p53 deficient mice (p53(-/+)). Twenty per cent of keratinocytes derived from p53 (-/-) mice, however, induced apoptosis following UVB irradiation. Analysis using caspase inhibitors disclosed activation of caspase 8 and 3 in UVB-irradiated SVHK cells. Keratinocytes derived from MRL/lpr mice, which have mutated Fas antigen, showed diminished UVB-induced apoptosis suggesting that Fas antigen is significantly involved in UVB-induced apoptosis. Immunohistochemical analysis revealed that UVB irradiation induces aggregation of Fas antigen showing a dense dot-like staining, which was also observed in SVHK cells treated with agonistic anti-Fas antibody, CH11. Pretreatment of antagonistic anti-Fas antibody, ZB4, inhibited CH11-induced but not UVB-induced multimerization of Fas antigen. Furthemore, UVB irradiation did not affect the basal expression of Fas ligand mRNA, protein and soluble Fas ligand. These results indicate that UVB irradiation induces multimerization of Fas antigen that results in apoptosis without the Fas ligand.

Functional alteration of guanine nucleotide binding proteins (Gs and Gi) in psoriatic epidermis

Psoriatic involved epidermis has been characterized by a defective beta-adrenergic adenylate cyclase response. It is also characterized by increased cholera toxin- and forskolin-induced cyclic AMP accumulations. Due to the fact that receptor signals are transduced to adenylate cyclase through guanine nucleotides binding proteins (G-proteins), that affect cholera toxin- and forskolin-induced cyclic AMP accumulations, possible alterations of G-proteins of psoriatic involved and perilesional uninvolved epidermis by using toxin-catalyzed ADP-ribosylation and immunoblot analyses was investigated. Cholera toxin catalyzes ADP-ribosylation of stimulatory guanine nucleotides binding protein (Gs) in either trimeric (inactive) or monomeric (active) form, while islet activating protein (IAP) catalyzes ADP ribosylation of inhibitory guanine nucleotide binding protein (Gi) in only trimeric (inactive) form. Results indicate that although the psoriatic involved epidermis shows increased cholera toxin- and IAP-catalyzed ADP-ribosylations, the amounts of immunoreactive Gs alpha or Gi alpha are not significantly altered. The increase in IAP-catalyzed ADP-ribosylation indicates increased inactive Gi, explaining the increased forskolin-induced cyclic AMP accumulation. The increase in cholera toxin-catalyzed ADP-ribosylation of Gs explains the increased cholera toxin-induced cyclic AMP accumulation in the psoriatic involved epidermis.

The alpha and eta isoforms of protein kinase C stimulate transcription of human involucrin gene

Involucrin is one of the precursor proteins of the cornified cell envelope that is formed beneath the cell membrane during terminal differentiation of keratinocytes. 12-O-tetradecanoylphorbol-13-acetate (TPA), which is a potent protein kinase C (PKC) activator, induces terminal differentiation of keratinocytes. We previously demonstrated that involucrin promoter activity is stimulated by TPA in cultured fetal rat skin keratinocytes. PKC is a large family of proteins and keratinocytes containing five PKC isozymes: alpha, delta, epsilon, eta, and zeta. In order to determine the role of the PKC isozyme(s) on involucrin gene expression, we constructed the chloramphenicol acetyl transferase (CAT)-involucrin promoter expression vector by connecting the 5'-upstream region of the human involucrin gene containing the untranslated first exon to the CAT reporter gene. The CAT-involucrin promoter expression vector was transfected with various PKC isozyme expression vectors into SV40-transformed human keratinocytes (SVHK cells). Transfection of the CAT-involucrin promoter expression vector with PKC-alpha or PKC-eta expression vectors resulted in a significant increase in the TPA-dependent involucrin promoter activity. The PKC inhibitor, 1-(5-isoquinoline-sulfonyl)-2-methyl piperazine dihydrochloride, inhibited the promoter activity stimulated by TPA. Transfection of PKC-delta, -epsilon, and -zeta had no effect on the involucrin-promoter activity. Although the promoter activity was stimulated by transfection of PKC-gamma, TPA did not enhance the promoter activity in the PKC-gamma-transfected SVHK cells. Previously we showed three AP-1 binding sites (AP1-1, -2, and -3) on the involucrin promoter region. Both the basal and the TPA-stimulated involucrin promoter activities were suppressed by deleting the AP1-1 site (-119 to -113) that is the most proximal to the transcription start site. The deletion of AP1-2 (-297 to -303) or AP1-3 (-447 to -453) did not affect the involucrin promoter activity. Gel retardation analyses disclosed that TPA stimulated the specific DNA binding of the nuclear protein(s) of control, PKC-alpha, or PKC-eta-transfected SVHK cells, but not of PKC-gamma-transfected cells. Addition of anti-c-Jun and anti-c-Fos antibodies decreased the specific protein-DNA complex band with a concomitant appearance of supershifted bands. These results indicate that PKC, specifically PKC-alpha and PKC-eta, mediates the TPA-dependent activation of involucrin gene expression of SVHK cells. PKC-gamma, which is not present in keratinocytes, also induces involucrin gene expression in a TPA-independent manner, when introduced into SVHK cells.

Interleukin-1beta-converting enzyme and CPP32 are involved in ultraviolet B-induced apoptosis of SV40-transformed human keratinocytes

Interleukin-1beta-converting enzyme (ICE) and CPP32 are cysteine proteinases, that are involved in apoptotic process in various cell systems. We investigated the effects of ICE on ultraviolet B (UVB) induced-apoptosis in SV40-transformed human keratinocytes (SVHK cells). The ICE inhibitor (Z-Val-Ala-Asp-CH2F) and CPP32 inhibitor (Z-Asp-Glu-Val-Asp-CH2F) blocked the apoptotic cell death caused by UVB irradiation. The addition of both ICE and CPP32 inhibitors to the incubation medium resulted in neither an additive nor a synergistic suppression of UVB-induced apoptosis. Reverse transcription and polymerase chain reaction (RT-PCR) analysis indicated that SVHK cells expressed ICE-alpha, and beta mRNAs. UVB irradiation increased the mRNA of both isoforms and Western blot analysis confirmed that UVB increased an active form of ICE protein, p20, that is generated by autoproteolytic cleavage of inactive 45 kDa proenzyme derived from both mRNAs. Transfection of ICE expression vector into SVHK cells resulted in apoptosis in a dose dependent manner and UVB-irradiation further augmented the ICE expression vector-induced apoptosis. These results indicate that ICE plays an important role in UVB-induced apoptosis of SVHK cells.