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Annemieke Kavelaars

Publications and source records attributed to Annemieke Kavelaars.

At least 19 recordsLinked to original sources
PubMed2007

G protein-coupled receptor kinase 6 controls chronicity and severity of dextran sodium sulphate-induced colitis in mice.

BACKGROUND: Infiltration of inflammatory cells into the colon plays an important role in the onset and course of inflammatory bowel disease. G-protein-coupled receptor kinase 6 (GRK6) is an intracellular kinase that regulates the sensitivity of certain G-protein-coupled receptors, including those involved in the migration of inflammatory cells. Therefore, it is hypothesised that GRK6 plays a role in determining the course of inflammation. AIM: To analyse the role of GRK6 in the course of dextran sodium sulphate (DSS)-induced colitis. METHODS: Colitis was induced by administering 1% DSS in drinking water to GRK6(-/-), GRK6(+/-) and wild-type (WT) mice for 6 days. The severity of colitis was assessed on the basis of clinical signs, colon length and histology. Moreover, keratinocyte-derived chemokine (KC) levels, granulocyte infiltration, interleukin 1beta (IL1beta), CD4, CD8 and forkhead box protein P3 (FoxP3) expression in the colon were determined. In addition, regulatory T cell function in WT and GRK6(-/-) mice was analysed. The chemotactic response of granulocytes to colon culture supernatants was assessed using a transendothelial migration assay. RESULTS: The severity of colitis was increased in GRK6(-/-) and GRK6(+/-) mice and was accompanied by increased KC levels and increased granulocyte infiltration. Moreover, the chemotactic response of GRK6(-/-) granulocytes to supernatants of colon cultures was enhanced. Interestingly, the WT mice completely recovered from colitis, whereas the GRK6(-/-) and GRK6(+/-) mice developed chronic colitis, which was accompanied by increased IL1beta and CD4 expression and decreased FoxP3 expression. Moreover, regulatory T cell function was impaired in the GRK6(-/-) mice. CONCLUSIONS: The intracellular level of GRK6 is an important factor in determining the onset, severity and chronicity of DSS-induced colitis.

Acute Disease↗
PubMed2007

Reduced life expectancy in rats after neonatal dexamethasone treatment.

The glucocorticoid dexamethasone (Dex) is widely used in preterm infants for the prevention of chronic lung disease. However, major concern has arisen about the long-term sequelae of this therapy. Here we report that neonatal treatment with dexamethasone significantly shortens the lifespan by 25% of male rats (28.6 +/- 1.1 to 21.3 +/- 0.8 mo) and by 18% of female rats (26.9 +/- 1.8 to 22.0 +/- 0.7 mo). Histopathological examination indicated end-stage cardiac and renal failure as the cause of premature death. Furthermore, Dex-treated rats showed symptoms of hypertension at young adult age, which worsened with increasing age. Thus, a brief period of glucocorticoid treatment during early life results in untimely death presumably due to cardiovascular and renal disease later in life. These serious, adverse long-term consequences call for prudence with glucocorticoid treatment of human preterm infants and careful follow-up of young adults with a history of neonatal glucocorticoid treatment.

Animals↗
PubMed2006

Immune and endocrine function in burnout syndrome.

OBJECTIVE: Burnout is a stress-induced work-related syndrome. It is associated with a higher incidence of infections possibly pointing to a compromised immune system. In the present study, endocrine and ex vivo immune function of severe cases of burnout were investigated. METHODS: Endocrine and immune variables were compared in 56 persons with burnout and 38 healthy control subjects. Cortisol after awakening, after a low-dose dexamethasone, and dehydroepiandrosterone-sulphate (DHEAS) were analyzed from saliva. Peripheral blood was analyzed for T, B, and NK cell number and in vitro mitogen-induced pro- and antiinflammatory cytokine release. The capacity of dexamethasone to regulate cytokine release was compared between the groups. RESULTS: The burnout group showed an increased production of the antiinflammatory cytokine interleukin-10 (IL-10) by monocytes after lipopolysaccharide stimulation. No differences were observed in IL-10 release induced by the T-cell mitogen PHA nor in the proinflammatory cytokines gamma interferon and tumor necrosis factor alpha. The capacity of dexamethasone to regulate cytokine release did not differ between the groups. The number of peripheral blood T cells, B cells, or NK cells was not different either. The burnout group showed higher DHEAS levels but no difference in cortisol levels after awakening or after dexamethasone intake in comparison to controls. CONCLUSION: Production of the antiinflammatory cytokine IL-10 by monocytes was increased in individuals with burnout syndrome. It seems unlikely that glucocorticoids or changes in glucocorticoid receptor function play a role in this higher IL-10 production.

Adult↗
PubMed2006

Differences in behavioral outcome and motor development at school age after neonatal treatment for chronic lung disease with dexamethasone versus hydrocortisone.

Neonatal dexamethasone (DEX) for chronic lung disease is associated with adverse outcome. We compared behavioral and motor development at school age of children who neonatally received DEX to children neonatally treated with hydrocortisone (HC) in a retrospective matched cohort study. DEX- and HC-treated groups matched for gestational age, birth weight and year, gender, and severity of respiratory distress syndrome were compared with a reference group (REF) and a group treated only antenatally with betamethasone (BMETH). REF and BMETH groups had a higher gestational age and less severe respiratory distress syndrome. From 192 children (DEX, n = 46; HC, n = 52; REF, n = 43; BMETH, n = 51), the Child Behavioral Checklists from parents and teachers (Teacher's Report Form) and the Movement Assessment Battery for Children to assess neuromotor function were analyzed. DEX girls had a poorer performance on nearly all behavioral scales of the Teacher's Report Form compared with HC girls. DEX boys did not differ from HC boys. The HC boys or girls did not differ from the REF or BMETH groups. Neuromotor development was poorer in DEX than the BMETH and REF groups. The HC group did not differ from REF and BMETH groups. We suggest that neonatal HC may be a "safer" alternative for DEX for the treatment of CLD.

Anti-Inflammatory Agents↗
PubMed2006

Knock-out mice reveal the contributions of P2Y and P2X receptors to nucleotide-induced Ca2+ signaling in macrophages.

Immune cell function is modulated by changes in extracellular nucleotide levels. Here we used reverse transcription-PCR analyses, single cell Ca2+ imaging, and knock-out mice to define the receptors mediating nucleotide-induced Ca2+ signaling in resident peritoneal macrophages. In Ca2+-free buffer, the potent (K0.5<1 microm) stimulatory effect of UTP (or ATP) on endoplasmic reticulum (ER) Ca2+ release was abolished in cells isolated from P2Y2/P2Y4 double knock-out mice. Moreover, P2Y4(0/-), but not P2Y2-/-, macrophages responded to UTP. In P2Y2-/- macrophages, we could elicit Ca2+ responses to "pure" P2X receptor activation by applying ATP in buffer containing Ca2+. Purified UDP and ADP were ineffective agonists, although modest UDP-induced Ca2+ responses could be elicited in macrophages after "activation" with lipopolysaccharide and interferon-gamma. Notably, in Ca2+-free buffer, UTP-induced Ca2+ transients decayed within 1 min, and there was no response to repeated agonist challenge. Measurements of ER [Ca2+] with mag-fluo-4 showed that ER Ca2+ stores were depleted under these conditions. When extracellular Ca2+ was available, ER Ca2+ stores refilled, but Ca2+ increased to only approximately 40% of the initial value upon repeated UTP challenge. This apparent receptor desensitization persisted in GRK2+/- and GRK6-/- macrophages and after inhibition of candidate kinases protein kinase C and calmodulin-dependent kinase II. Initial challenge with UTP also reduced Ca2+ mobilization by complement component C5a (and vice versa). In conclusion, homologous receptor desensitization is not the major mechanism that rapidly dampens Ca2+ signaling mediated by P2Y2, the sole Gq-coupled receptor for UTP or ATP in macrophages. UDP responsiveness (P2Y6 receptor expression) increases following macrophage activation.

Adenosine Diphosphate↗
PubMed2006

Public speaking stress-induced neuroendocrine responses and circulating immune cell redistribution in irritable bowel syndrome.

OBJECTIVES: Augmented neuroendocrine stress responses and altered immune functions may play a role in the manifestation of functional gastrointestinal (GI) disorders. We tested the hypothesis that IBS patients would demonstrate enhanced psychological and endocrine responses, as well as altered stress-induced redistribution of circulating leukocytes and lymphocytes, in response to an acute psychosocial stressor when compared with healthy controls. METHODS: Responses to public speaking stress were analyzed in N = 17 IBS patients without concurrent psychiatric conditions and N = 12 healthy controls. At baseline, immediately following public speaking, and after a recovery period, state anxiety, acute GI symptoms, cardiovascular responses, serum cortisol and plasma adrenocorticotropic hormone (ACTH) were measured, and numbers of circulating leukocytes and lymphocyte subpopulations were analyzed by flow cytometry. RESULTS: Public speaking led to significant cardiovascular activation, a significant increase in ACTH, and a redistribution of circulating leukocytes and lymphocyte subpopulations, including significant increases in natural killer cells and cytotoxic/suppressor T cells. IBS patients demonstrated significantly greater state anxiety both at baseline and following public speaking. However, cardiovascular and endocrine responses, as well as the redistribution of circulating leukocytes and lymphocyte subpopulations after public speaking stress, did not differ for IBS patients compared with controls. CONCLUSIONS: In IBS patients without psychiatric comorbidity, the endocrine response as well as the circulation pattern of leukocyte subpopulations to acute psychosocial stress do not differ from healthy controls in spite of enhanced emotional responses. Future studies should discern the role of psychopathology in psychological and biological stress responses in IBS.

Adrenocorticotropic Hormone↗
PubMed2006

GRKs and arrestins: regulators of migration and inflammation.

In the immune system, signaling by G protein-coupled receptors (GPCRs) is crucial for the activity of multiple mediators, including chemokines, leukotrienes, and neurotransmitters. GPCR kinases (GRKs) and arrestins control GPCR signaling by mediating desensitization and thus, regulating further signal propagation through G proteins. Recent evidence suggests that the GRK-arrestin desensitization machinery fulfills a vital role in regulating inflammatory processes. First, GRK/arrestin levels in immune cells are dynamically regulated in response to inflammation. Second, in animals with targeted deletion of GRKs or arrestins, the progression of various acute and chronic inflammatory disorders, including autoimmunity and allergy, is profoundly affected. Third, chemokine receptor signaling in vitro is known to be tightly regulated by the GRK/arrestin machinery, and even small changes in GRK/arrestin expression can have a marked effect on cellular responses to chemokines. This review integrates data about the role of GRKs and arrestins in inflammation, with results on the molecular mechanism of action of GRKs/arrestins, and describes the pivotal role of GRKs/arrestins in inflammatory processes, with a special emphasis on regulation of chemokine responsiveness.

Acute Disease↗
PubMed2006

Gender-specific neuroprotection by 2-iminobiotin after hypoxia-ischemia in the neonatal rat via a nitric oxide independent pathway.

We have shown earlier that 2-iminobiotin (2-IB) reduces hypoxia-ischemia (HI)-induced brain damage in neonatal rats, and presumed that inhibition of nitric oxide synthases (NOS) was the underlying mechanism. We now investigated the effect of 2-IB treatment in P7 rat pups to determine the role of gender and the neuroprotective mechanism. Pups were subjected to HI (occlusion of right carotid artery and 120 mins FiO(2) 0.08) and received subcutaneous (s.c.) 10 mg/kg 2-IB at 0, 12 and 24 h after hypoxia. After 6 weeks, neuronal damage was assessed histologically. We determined cerebral nitrite and nitrate (NO(x)) and nitrotyrosine, heat-shock protein 70, cytosolic cytochrome c, cleaved caspase 3, nuclear translocation of apoptosis-inducing factor (AIF) and the effect of 2-IB on NOS activity in cultured cells. 2-Iminobiotin treatment reduced long-term brain damage in female but not male rats. Unexpectedly, 2-IB treatment did not reduce cerebral NO(x) or nitrotyrosine levels, and did not inhibit NOS activity in vitro. The gender-dependent neuroprotective effect of 2-IB was reflected in inhibition of the HI-induced increase in cytosolic cytochrome c and cleaved caspase 3 in females only. Hypoxia-ischemia-induced activation of AIF was observed in males only and was not affected by 2-IB. Post-HI treatment with 2-IB provides gender-specific long- and short-term neuroprotection in female P7 rats via inhibition of the cytochrome c-caspase 3 neuronal death pathway. 2-Iminobiotin did not alter cerebral NO(x) nor inhibited NOS in intact cells. Therefore, we conclude that it is highly unlikely that the neuroprotective effect of 2-IB involves NOS inhibition.

Animals↗
PubMed2006

Respiratory distress syndrome-associated inflammation is related to early but not late peri/intraventricular hemorrhage in preterm infants.

OBJECTIVE: To investigate whether or not peri/intraventricular hemorrhages (PIVHs) occurring in the first 12 hours of life (early PIVHs) are related to respiratory distress syndrome (RDS)-associated inflammatory factors in contrast to PIVHs developing after 12 hours of life (late PIVHs). STUDY DESIGN: Blood samples obtained at 0 to 12 hours, 48 to 72 hours, and 168 hours of life were evaluated for determination of the proinflammatory cytokines interleukin (IL)-8 and IL-6, tumor necrosis factor (TNF)-alpha, and malondialdehyde (MDA) as measures of lipid peroxidation. Simultaneously, cranial ultrasonography was performed in 114 neonates under 32 weeks gestational age. RESULTS: Out of the total study group of 114 neonates, 67 (59%) had RDS. Early PIVH occurred in 16 neonates, 14 of whom (88%) had RDS. Late PIVHs occurred in 12 neonates. Neonates with RDS had higher IL-8 and IL-6 levels at 0 to 12 hours (P < .0001; < .0001) and at 48 to 72 hours (P < .001; < .01) than those without RDS. Neonates with early PIVH had higher IL-8 (P < .02), IL-6 (P < .02), and MDA (P < .01) levels at 0 to 12 hours than those with late PIVH or no PIVH. Those with early PIVH had higher IL-8 levels at 48 to 72 hours than those without PIVH (P < .02). Multiple linear regression revealed an association between RDS/early PIVH and IL-8, IL-6, and MDA levels. CONCLUSIONS: An RDS-associated increase in proinflammatory cytokine and MDA levels was associated with early PIVHs, but not with late PIVHs, suggesting a different etiopathogenesis in early versus late PIVHs.

Age Factors↗
PubMed2006

Selective inhibition of nuclear factor-kappaB activation after hypoxia/ischemia in neonatal rats is not neuroprotective.

Activated nuclear factor-kappaB (NFkappaB) has been shown to increase transcription of several genes that could potentially contribute to neuronal damage, such as proinflammatory cytokines, chemokines, and inducible nitric oxide synthase. The aim of our study was to investigate whether inhibition of NFkappaB activation could prevent hypoxia/ischemia (HI)-induced cerebral damage in neonatal rats. We used a cell permeable peptide (NEMO binding domain [NBD] peptide) that is known to prevent the association of the regulatory protein NEMO with IKK, the kinase that activates NFkappaB. Via this mechanism, the NBD peptide can specifically block the activation of NFkappaB, without inhibiting basal NFkappaB activity. Cerebral HI was induced in neonatal rats by occlusion of the right carotid artery followed by 90 min of hypoxia (Fio(2) = 0.08). Immediately upon reoxygenation, as well as 6 and 12 h later, rats were treated with vehicle or NBD peptide (20 mg/kg i.p.). Histologic analysis of brain damage was performed at 6 wk after HI. To assess NFkappaB activation, electromobility shift assays (EMSAs) were performed on brain nuclear extracts obtained 6 h after reoxygenation. Increased NFkappaB activity could be shown at 6 h after HI in both hemispheres. Peripheral administration of NBD peptide prevented this HI-induced increase in NFkappaB activity in both hemispheres. Histologic analysis of long-term cerebral damage revealed that inhibition of NFkappaB activation by administration of NBD peptide at 0, 6, and 12 h after HI resulted in an increment of neuronal damage. In conclusion, our data suggest that inhibition of NFkappaB activation using NBD peptide early after HI increases brain damage in neonatal rats.

Animals↗
PubMed2006

Bilateral molecular changes in a neonatal rat model of unilateral hypoxic-ischemic brain damage.

Perinatal hypoxia ischemia (HI) is a frequent cause of neonatal brain injury. This study aimed at describing molecular changes during the first 48 h after exposure of the neonatal rat brain to HI. Twelve-day-old rats were subjected to unilateral carotid artery occlusion and 90 min of 8% O2, leading to neuronal damage in the ipsilateral hemisphere only. Phosphorylated-Akt levels were decreased from 0.5 to 6 h post-HI, whereas the level of phosphorylated extracellular signal-related kinases (ERK)1/2 increased during this time frame. Hypoxia-inducible factor (HIF)-1alpha protein increased with a peak at 3 h after HI. mRNA expression for IL-beta and tumor necrosis factor-alpha and -beta started to increase at 6 h with a peak at 24 h post-HI. Expression of heat shock protein 70 was increased from 12 h after HI onwards in the ipsilateral hemisphere only. Surprisingly, HI changed the expression of cytokines, HIF1-alpha ,and P-Akt to the same extent in both the ipsi- as well as the contralateral hemisphere, although neuronal damage was unilateral. Exposure of animals to hypoxia without carotid artery occlusion induced similar changes in cytokines, HIF-1alpha, and P-Akt. We conclude that during HI, hypoxia is sufficient to regulate multiple molecular mediators that may contribute, but are not sufficient, to induce long-term neuronal damage.

Animals↗
PubMed2006

Severe fatigue in adolescents: a common phenomenon?

OBJECTIVE: The purpose of this study was to determine the prevalence of severe fatigue in adolescent boys and girls, to explore the role of lifestyle factors in fatigue, and to investigate whether severe fatigue in a healthy population is associated with depression, anxiety, and comorbid factors also observed in chronic fatigue syndrome patients. METHODS: In a sample of 1718 boys and 1749 girls, fatigue severity and duration were measured using a multidimensional questionnaire (Checklist Individual Strength). In addition, self-reports of depressive symptoms, anxiety, chronic fatigue syndrome-related symptoms, and lifestyle characteristics were assessed by means of questionnaires. Prevalence rates of severe fatigue and severe fatigue for > or =1 month, based on a clinical cutoff score of the Checklist Individual Strength, were determined for boys and girls separately, and gender-specific predictors of fatigue were identified by multiple regression analysis. RESULTS: The data showed high prevalence rates of severe fatigue in adolescents. Remarkable differences between boys and girls were observed: 20.5% of girls and 6.5% of the boys scored above the clinical cutoff score on the Checklist Individual Strength. Of these subjects 80.0% of the girls and 61.5% of the boys reported severe fatigue for > or =1 month. Of the examined lifestyle characteristics, only sleep characteristics and the participation in sports played a role in predicting fatigue in both genders. Moreover, in girls, fatigue was associated with higher age, an early menarche, medication use, and the absence of an additional job. Overall, girls scored higher on depression, anxiety, and chronic fatigue syndrome-related symptoms. However, the relation between fatigue and these comorbid symptoms did not differ between genders. In both girls and boys, the duration of fatigue was positively related to fatigue severity, severity of depression and anxiety, and the number of chronic fatigue syndrome-related symptoms. CONCLUSIONS: Fatigue prevalence among adolescents is high, especially in girls. Adolescent girls seem to be more vulnerable to symptoms of fatigue and comorbidity than boys. Interestingly, despite a female predominance in complaints, the relation between fatigue and depression, anxiety, and chronic fatigue syndrome-related symptoms was not gender specific and emerged as a cluster. In both genders, fatigue duration was associated with the severity of fatigue and the level of psychological comorbidity and chronic fatigue syndrome-related symptoms, and we, therefore, hypothesize that enduring severe fatigue may form a risk factor for the development of chronic fatigue syndrome.

Adolescent↗
PubMed2005

Effects of paroxetine and venlafaxine on immune parameters in patients with obsessive compulsive disorder.

BACKGROUND: Obsessive-compulsive disorder (OCD) has been associated with an altered activity of the immune system. This study was carried out to investigate whether treatment with paroxetine and venlafaxine modifies the immune function in OCD and whether this modification is related to treatment outcome. METHODS: Ex vivo production of TNF-alpha, IL-4, IL-6, IL-10, and IFN-gamma in whole blood cultures, and NK-cell activity and peripheral blood NK-cell-, monocytes-, T-cell-, and B-cell- percentages were measured in 42 outpatients with OCD who participated in a 12-week, double-blind SRI trial. RESULTS: Paroxetine and venlafaxine treatment did not affect immune parameters and clinical response was not directly related to altered activity of the immune system. Responders, defined as having a >or=25% decrease on the Y-BOCS, differed from non-responders with regard to the change of TNF-alpha values. CONCLUSIONS: The present results suggest that paroxetine and venlafaxine do not affect immune parameters and that clinical response is not related to altered activity of the immune system in OCD. Nonetheless, our data yielded interesting preliminary results that warrant further discussion and investigation.

Adult↗
PubMed2005

G protein-coupled receptor kinase 2 negatively regulates chemokine signaling at a level downstream from G protein subunits.

The G protein-coupled receptor kinase 2 (GRK2) phosphorylates and desensitizes ligand-activated G protein-coupled-receptors. Here, evidence is shown for a novel role of GRK2 in regulating chemokine-mediated signals. The presence of increased levels of GRK2 in human embryonic kidney (HEK) 293 cells produced a significant reduction of the extracellular signal-regulated kinase (ERK) response to CCL2. This effect is independent of its role in receptor phosphorylation because the kinase-deficient mutant GRK2K220R was able to reduce this response, and ERK activation by CCR2BIX, a phosphorylation-defective receptor mutant, was also inhibited by GRK2. Constructs containing the Galpha(q)-binding RGS-like RH domain of GRK2 or its Gbetagamma-binding domain could not reproduce the inhibition, thus revealing that GRK2 acts downstream of G proteins. Interestingly, chemokine-driven mitogen-activated protein kinase kinase (MEK) stimulation is not affected in cells overexpressing GRK2 or GRK2K220R or in splenocytes from heterozygous GRK2 mice, where reduced kinase levels correlate with enhanced ERK activation by chemokines. We find GRK2 and MEK in the same multimolecular complex, thus suggesting a mechanism for GRK2 regulation of ERK activity that involves a direct or coordinate interaction with MEK. These results suggest an important role for GRK2 in the control of chemokine induction of ERK activation at the level of the MEK-ERK interface.

Animals↗
PubMed2005

Tumour necrosis factor-alpha stimulates dehydroepiandrosterone metabolism in human fibroblast-like synoviocytes: a role for nuclear factor-kappaB and activator protein-1 in the regulation of expression of cytochrome p450 enzyme 7b.

Glucocorticoids have successfully been used in the treatment of rheumatoid arthritis. Data suggest that 7alpha-hydroxy-dehydroepiandrosterone (7alpha-OH-DHEA), an immunostimulating metabolite of dehydroepiandrosterone, can block glucocorticoid-induced immune suppression. Formation of 7alpha-OH-DHEA is catalyzed by activity of cytochrome p450 enzyme 7b (Cyp7b). Recently, we reported that tumour necrosis factor (TNF)-alpha, IL-1alpha, IL-1beta and IL-17 enhance Cyp7b mRNA expression and induce a concomitant increase in the formation of 7alpha-OH-DHEA by fibroblast-like synoviocytes (FLS) from rheumatoid arthritis patients. The aim of this study was to elucidate which signal transduction pathway is involved in the TNF-alpha-mediated induction of Cyp7b activity in FLS. We studied the effects of inhibitors of different signal transduction pathways on Cyp7b activity in FLS by measuring Cyp7b mRNA expression using reverse transcription PCR and by measuring the formation of 7alpha-OH-DHEA. We applied SN50, an inhibitor of nuclear translocation of transcription factors (i.e. activator protein-1 [AP-1] and nuclear factor-kappaB [NF-kappaB]); PSI, a proteasome inhibitor that prevents IkappaB degradation and thereby NF-kappaB release; SP600125, a c-Jun N-terminal kinase (JNK) inhibitor; and the mitogen-activated protein kinase inhibitors PD98059 (extracellular signal-regulated kinase) and SB203580 (p38). Cyp7b is constitutively expressed in RA FLS and can be activated in response to TNF-alpha. SN50 and PSI prevented the TNF-alpha-induced increase in Cyp7b activity, whereas the mitogen-activated protein kinase inhibitors PD98059 and SB203580 had no effect. In addition, inhibition of Cyp7b mRNA expression and activity was observed with SN50, PSI and SP600125, suggesting that NF-kappaB and AP-1 induce Cyp7b transcription. These findings suggest that NF-kappaB and AP-1 are involved in the TNF-alpha-enhanced formation of the dehydroepiandrosterone metabolite 7alpha-OH-DHEA. Our results are in accordance with presence of AP-1 and NF-kappaB binding sites in the Cyp7b promoter.

Arthritis, Rheumatoid↗
PubMed2005

G protein-coupled receptor kinase 2 in multiple sclerosis and experimental autoimmune encephalomyelitis.

Many modulators of inflammation, including chemokines, neuropeptides, and neurotransmitters signal via G protein-coupled receptors (GPCR). GPCR kinases (GRK) can phosphorylate agonist-activated GPCR thereby promoting receptor desensitization. Here we describe that in leukocytes from patients with active relapsing-remitting multiple sclerosis (MS) or with secondary progressive MS, GRK2 levels are significantly reduced. Unexpectedly, cells from patients during remission express even lower levels of GRK2. The level of GRK2 in leukocytes of patients after stroke, a neurological disorder with paralysis but without an autoimmune component, was similar to GRK2 levels in cells from healthy individuals. In addition, we demonstrate that the course of recombinant myelin oligodendrocyte glycoprotein (1-125)-induced experimental autoimmune encephalomyelitis (EAE), an animal model for MS, is markedly different in GRK2(+/-) mice that express 50% of the GRK2 protein in comparison with wild-type mice. Onset of EAE was significantly advanced by 5 days in GRK2(+/-) mice. The earlier onset of EAE was associated with increased early infiltration of the CNS by T cells and macrophages. Although disease scores in the first phase of EAE were similar in both groups, GRK2(+/-) animals did not develop relapses, whereas wild-type animals did. The absence of relapses in GRK2(+/-) mice was associated with a marked reduction in inflammatory infiltrates in the CNS. Recombinant myelin oligodendrocyte glycoprotein-induced T cell proliferation and cytokine production were normal in GRK2(+/-) animals. We conclude that down-regulation of GRK2 expression may have important consequences for the onset and progression of MS.

Animals↗
PubMed2005

CYP7B expression and activity in fibroblast-like synoviocytes from patients with rheumatoid arthritis: regulation by proinflammatory cytokines.

OBJECTIVE: The cytochrome P450 enzyme CYP7B catalyzes the conversion of dehydroepiandrosterone (DHEA) into 7alpha-hydroxy-DHEA (7alpha-OH-DHEA). This metabolite can stimulate the immune response. We previously reported that the severity of murine collagen-induced arthritis is correlated with CYP7B messenger RNA (mRNA) expression and activity in the arthritic joint. The purpose of this study was to investigate the presence of 7alpha-OH-DHEA in synovial samples and the cytokine regulation of CYP7B activity in fibroblast-like synoviocytes (FLS) from patients with rheumatoid arthritis (RA). METHODS: The presence of 7alpha-OH-DHEA was examined in synovial biopsy tissues, synovial fluid, and serum by radioimmunoassay. The effect of cytokines on CYP7B mRNA expression and CYP7B activity in FLS was examined by determining the formation of the CYP7B enzyme product 7alpha-OH-DHEA with the use of high-performance liquid chromatography. RESULTS: The CYP7B enzyme product 7alpha-OH-DHEA was found in synovial biopsy tissues, synovial fluid, and serum from RA patients. The proinflammatory cytokines tumor necrosis factor alpha (TNFalpha), interleukin-1alpha (IL-1alpha), IL-1beta, and IL-17 up-regulated CYP7B activity in an FLS cell line 2-10-fold. Enhanced CYP7B activity was correlated with an increase in CYP7B mRNA. The cytokine transforming growth factor beta inhibited CYP7B activity. Moreover, CYP7B activity was detected in 10 of 13 unstimulated synovial fibroblast cell lines. Stimulation with TNFalpha increased CYP7B activity in all cell lines tested. CONCLUSION: Exposure to the proinflammatory cytokines TNFalpha, IL-1alpha, IL-1beta, and IL-17 increases CYP7B activity in synovial tissue. Increased CYP7B activity leads to higher levels of the DHEA metabolite 7alpha-OH-DHEA in synovial fluid, which may contribute to the maintenance of the chronic inflammation observed in RA patients.

Arthritis, Rheumatoid↗