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It is assumed that in mammals the circadian rhythms of peripheral clocks are synchronized to the environment via neural, humoral and/or behavioral outputs of the central pacemaker in the suprachiasmatic nucleus of the hypothalamus (SCN). With regard to the humoral outputs, the daily rhythm of the adrenal hormone corticosterone is considered as an important candidate. To examine whether adrenal hormones are necessary for the maintenance of daily rhythms in gene expression in white adipose tissue (WAT), we used RT-PCR to check rhythmic as well as 24 h mean gene expression in WAT from adrenalectomized (ADX) and sham-operated rats. In addition, we investigated the effect of adrenalectomy on gene expression in the hypothalamic SCN and paraventricular nucleus (PVN). Adrenalectomy hardly affected daily rhythms of clock gene expression in WAT. On the other hand, >80% of the rhythmic metabolic/adipokine genes in WAT lost their daily rhythmicity in ADX rats. Likewise, in the hypothalamus adrenalectomy had no major effects on daily rhythms in gene expression, but it did change the expression level of some of the neuropeptide genes. Together, these data indicate that adrenal hormones are important for the maintenance of daily rhythms in metabolic/adipokine gene expression in WAT, without playing a major role in clock gene expression in either WAT or hypothalamus.

Illness induces major modifications in central and peripheral thyroid hormone (TH) metabolism, so-called nonthyroidal illness syndrome (NTIS). As a result, organ-specific changes in local TH availability occur depending on the type and severity of illness. Local TH availability is of importance for the regulation of the tissue-specific TH target genes and determined by the interplay between deiodinating enzymes, TH transport and TH receptor (TR) expression. In the present study, we evaluated changes in TH transport, deiodination and TR expression, the resulting tissue TH concentrations and the expression of TH target genes in liver and muscle in three animal models of illness. We induced (1) acute systemic inflammation by intraperitoneal injection of bacterial endotoxin (LPS), (2) chronic local inflammation by a turpentine injection in the hind limb and (3) severe pneumonia and sepsis by intranasal inoculation with Streptococcus pneumoniae. We found that all aspects of peripheral TH metabolism are differentially regulated during illness, depending on the organ studied and severity of illness. In addition, tissue TH concentrations are not equally affected by the decrease in serum TH concentrations. For example, the decrease in muscle TH concentrations is less severe than the decrease observed in liver. In addition, despite lower TH concentrations in muscle in all three models, muscle T3 action is differentially affected. These observations help to understand the complex nature of the nonthyroidal illness syndrome.

Thyrostimulin, a putative glycoprotein hormone, comprises the subunits GPA2 and GPB5 and activates the TSH receptor (TSHR). The observation that proinflammatory cytokines stimulate GPB5 transcription suggested a role for thyrostimulin in the pathogenesis of nonthyroidal illness syndrome (NTIS). In the present study, we induced acute inflammation by LPS administration to GPB5−/−and WT mice to evaluate the role of thyrostimulin in peripheral thyroid hormone metabolism during NTIS. In addition to serum thyroid hormone concentrations, we studied mRNA expression and activity of deiodinase types I, II, and III (D1, D2, and D3) in peripheral T3target tissues, including liver, muscle, and white and brown adipose tissue (WAT and BAT), of which the latter three express the TSHR. LPS decreased serum free (f)T4and fT3indexes to a similar extent in GPB5−/−and WT mice. Serum reverse (r)T3did not change following LPS administration. LPS also induced significant alterations in tissue D1, D2, and D3 mRNA and activity levels, but only the LPS-induced increase in WAT D2 mRNA expression differed between GPB5−/−and WT mice. In conclusion, lacking GPB5 during acute illness does not affect the LPS-induced decrease of serum thyroid hormones while resulting in subtle changes in tissue D2 expression that are unlikely to be mediated via the TSHR.

Deiodinase type 2 (D2) is a thyroid hormone-activating enzyme converting the prohormone T-4 into the active hormone T-3. In the present study, we show for the first time that D2 is up-regulated in the mouse liver during acute and chronic inflammation, in close correlation with the proinflammatory cytokine IL-1 beta and independently of serum T-3. Inflammation-induced D2 expression was confirmed in macrophages, in conjunction with selective thyroid hormone transporter (monocarboxylate transporter 10) and thyroid hormone receptor (TR)alpha 1 stimulation, and was absent in hepatocytes. Moreover, D2 knockdown in macrophages resulted in a clear attenuation of the lipopolysaccharide (LPS)-induced IL-1 beta and GM-CSF expression, in addition to aberrant phagocytosis. Locally produced T-3, acting via the TR alpha, may be instrumental in this novel inflammatory response, because LPS-treated TR alpha(0/0) mice showed a markedly decreased LPS-induced GM-CSF mRNA expression. We now propose that hepatic D2 favors the innate immune response by specifically regulating cellular thyroid hormone levels in macrophages

The enzyme type 2 deiodinase (D2) is a major determinant of T3 production in the central nervous system. It is highly expressed in tanycytes, a specialized cell type lining the wall of the third ventricle. During acute inflammation, the expression of D2 in tanycytes is up-regulated by a mechanism that is poorly understood at present, but we hypothesized that cJun N-terminal kinase 1 (JNK1) and v-rel avian reticuloendotheliosis viral oncogene homolog A (RelA) (the 65 kD subunit of NFκB) inflammatory signal transduction pathways are involved. In a mouse model for acute inflammation, we studied the effects of lipopolysaccharide (LPS) on mRNA expression of D2, JNK1, and RelA in the periventricular area (PE) and the arcuate nucleus-median eminence of the hypothalamus. We next investigated LPS-induced D2 expression in primary tanycyte cell cultures. In the PE, the expression of D2 was increased by LPS. In the arcuate nucleus, but not in the PE, we found increased RelA mRNA expression. Likewise, LPS increased D2 and RelA mRNA expression in primary tanycyte cell cultures, whereas JNK1 mRNA expression did not change. Phosphorylation of RelA and JNK1 was increased in tanycyte cell cultures 15–60 minutes after LPS stimulation, confirming activation of these pathways. Finally, inhibition of RelA with the chemical inhibitors sulfasalazine and 4-Methyl-N1-(3-phenylpropyl)benzene-1,2-diamine (JSH-23) in tanycyte cell cultures prevented the LPS-induced D2 increase. We conclude that NFκB signaling is essential for the up-regulation of D2 in tanycytes during inflammation.

DNA damage contributes to the process of aging, as underscored by premature aging syndromes caused by defective DNA repair. Thyroid state changes during aging, but underlying mechanisms remain elusive. Since thyroid hormone (TH) is a key regulator of metabolism, changes in TH signaling have widespread effects. Here, we reveal a significant common transcriptomic signature in livers from hypothyroid mice, DNA repair-deficient mice with severe (Csbm/m/Xpa-/-) or intermediate (Ercc1-/Δ-7) progeria and naturally aged mice. A strong induction of TH-inactivating deiodinase D3 and decrease of TH-activating D1 activities are observed in Csbm/m/Xpa-/- livers. Similar findings are noticed in Ercc1-/Δ-7, in naturally aged animals and in wild-type mice exposed to a chronic subtoxic dose of DNA-damaging agents. In contrast, TH signaling in muscle, heart and brain appears unaltered. These data show a strong suppression of TH signaling in specific peripheral organs in premature and normal aging, probably lowering metabolism, while other tissues appear to preserve metabolism. D3-mediated TH inactivation is unexpected, given its expression mainly in fetal tissues. Our studies highlight the importance of DNA damage as the underlying mechanism of changes in thyroid state. Tissue-specific regulation of deiodinase activities, ensuring diminished TH signaling, may contribute importantly to the protective metabolic response in aging. ispartof: PLoS One vol:11 issue:3 pages:1-25 ispartof: location:United States status: published

Excessive secretion of triglyceride-rich very low-density lipoproteins (VLDL-TG) contributes to diabetic dyslipidemia. Earlier studies have indicated a possible role for the hypothalamus and autonomic nervous system in the regulation of VLDL-TG. In the current study, we investigated whether the autonomic nervous system and hypothalamic neuropeptide Y (NPY) release during fasting regulates hepatic VLDL-TG secretion. We report that, in fasted rats, an intact hypothalamic arcuate nucleus and hepatic sympathetic innervation are necessary to maintain VLDL-TG secretion. Furthermore, the hepatic sympathetic innervation is necessary to mediate the stimulatory effect of intracerebroventricular administration of NPY on VLDL-TG secretion. Since the intracerebroventricular administration of NPY increases VLDL-TG secretion by the liver without affecting lipolysis, its effect on lipid metabolism appears to be selective to the liver. Together, our findings indicate that the increased release of NPY during fasting stimulates the sympathetic nervous system to maintain VLDL-TG secretion at a postprandial level.

Background: Decreased serum leptin has been proposed as a critical signal initiating the neuroendocrine response to fasting. Leptin administration partially reverses the fasting-induced suppression of the hypothalamus-pituitary-thyroid axis at the central level. It is, however, unknown to what extent leptin affects peripheral thyroid hormone metabolism. The aim of this study was to evaluate the effect of leptin administration on starvation-induced alterations of peripheral thyroid hormone metabolism in mice. Methods: Three types of experiments were performed: (i) mice were fasted for 24 hours while leptin was administered twice (at 0 and 8 hours, 1 mu g/g body weight [BW]), (ii) mice were fasted for 24 hours and, subsequently, leptin was given once at 24 hours (killed at 28 and 32 hours), and (iii) mice were fasted for 48 hours. All groups had appropriate controls. Serum triiodothyronine and thyroxine, liver type 1 deiodinase (D1), type 3 deiodinase (D3), thyroid hormone receptor (TR)beta 1, TR alpha 1 and alpha 2 mRNA expression, and liver D1 and D3 activity were measured. Results: Twenty-four hours of fasting decreased liver TR beta 1 mRNA expression, while liver TR alpha 1, TR alpha 2, and D1 mRNA expression and activity did not change. In contrast, 24 hours of fasting increased liver D3 mRNA. Leptin administration after fasting restored liver D3 expression, while serum thyroid hormone levels and liver TR beta 1 expression remained low. Conclusion: Leptin administration selectively restores starvation-induced increased hepatic D3 expression independently of serum thyroid hormone concentrations. The present study shows that fasting-induced changes in mRNA expression of genes involved in hepatic hormone metabolism are influenced not only by decreased serum thyroid hormone levels but also by serum leptin

Background: The iodine-containing drug amiodarone (Amio) and its noniodine containing analogue dronedarone (Dron) are potent antiarrhythmic drugs. Previous in vivo and in vitro studies have shown that the major metabolite of Amio, desethylamiodarone, acts as a thyroid hormone receptor (TR) alpha(1) and beta(1) antagonist, whereas the major metabolite of Dron debutyldronedarone acts as a selective TR alpha(1) antagonist. In the present study, Amio and Dron were used as tools to discriminate between TR alpha(1) or TR beta(1) regulated genes in central and peripheral thyroid hormone metabolism. Methods: Three groups of male rats received either Amio, Dron, or vehicle by daily intragastric administration for 2 weeks. We assessed the effects of treatment on triiodothyronine (T-3) and thyroxine (T-4) plasma and tissue concentrations, deiodinase type 1, 2, and 3 mRNA expressions and activities, and thyroid hormone transporters monocarboxylate transporter 8 (MCT8), monocarboxylate transporter 10 (MCT10), and organic anion transporter 1C1 (OATP1C1). Results: Amio treatment decreased serum T-3, while serum T-4 and thyrotropin (TSH) increased compared to Dron-treated and control rats. At the central level of the hypothalamus-pituitary-thyroid axis, Amio treatment decreased hypothalamic thyrotropin releasing hormone (TRH) expression, while increasing pituitary TSH beta and MCT10 mRNA expression. Amio decreased the pituitary D2 activity. By contrast, Dron treatment resulted in decreased hypothalamic TRH mRNA expression only. Upon Amio treatment, liver T3 concentration decreased substantially compared to Dron and control rats (50%, p

Decreased serum thyroid hormone concentrations in severely ill patients were first reported in the 1970s, but the functional meaning of the observed changes in thyroid hormone levels, together known as nonthyroidal illness syndrome (NTIS), remains enigmatic. Although the common view was that NTIS results in overall down-regulation of metabolism in order to save energy, recent work has shown a more complex picture. NTIS comprises marked variation in transcriptional and translational activity of genes involved in thyroid hormone metabolism, ranging from inhibition to activation, dependent on the organ or tissue studied. Illness-induced changes in each of these organs appear to be very different during acute or chronic inflammation, adding an additional level of complexity. Organ- and timing-specific changes in the activity of thyroid hormone deiodinating enzymes (deiodinase types 1, 2, and 3) highlight deiodinases as proactive players in the response to illness, whereas the granulocyte is a novel and potentially important cell type involved in NTIS during bacterial infection. Although acute NTIS can be seen as an adaptive response to support the immune response, NTIS may turn disadvantageous when critical illness enters a chronic phase necessitating prolonged life support. For instance, changes in thyroid hormone metabolism in muscle during critical illness may be relevant for the pathogenesis of myopathy associated with prolonged ventilator dependence. This review focuses on NTIS as a timing-related and organ-specific response to illness, occurring independently from the decrease in serum thyroid hormone levels and potentially relevant for disease progression.

Acute inflammation is characterized by low serum T-3 and T-4 levels accompanied by changes in liver type 1 deiodinase (D1), liver D3, muscle D2, and muscle D3 expression. It is unknown at present whether thyroid hormone receptor alpha (TR alpha) plays a role in altered peripheral thyroid hormone metabolism during acute illness in vivo. We induced acute illness in TR alpha-deficient (TR alpha(0/0)) mice by administration of a sublethal dose of LPS. Compared with wild-type, TR alpha(0/0) mice have lower basal serum T-4 and lower liver D1 activity and muscle D3 mRNA expression, whereas liver D3 activity is higher. These changes are gender specific. The inflammatory response to LPS was similar in WT and TR alpha(0/0) mice. The decrease in serum thyroid hormones and liver D1 was attenuated in TR alpha(0/0) mice, whereas the LPS induced fall in liver D3 mRNA was more pronounced in TR alpha(0/0) mice. Muscle D2 mRNA increased similarly in both strains, whereas muscle D3 mRNA decreased less pronounced in TR alpha(0/0) mice. We conclude that alterations in peripheral thyroid hormone metabolism induced by LPS administration are partly regulated via TR alpha. (Endocrinology 151: 1959-1969, 2010)

The activation of type 3 deiodinase (D3) has been postulated to play a role in the reduction of thyroid hormone levels during illness. Using a mouse model of acute bacterial infection, we have recently demonstrated marked D3 immunostaining in neutrophils infiltrating infected organs. These observations suggest a possible additional role for this enzyme in the innate immune response. To further assess the role of D3 in the response to acute bacterial infection, we used null D3 [D3 knockout (D3KO)] and wild type (WT) mice and infected them with Streptococcus pneumoniae. Marked reductions in serum thyroid hormone levels were observed both in D3KO and WT mice. Infection resulted also in a decrease in liver D1 activity in WT, but not in infected D3KO mice. Upon infection, pulmonary neutrophilic influx (measured by myeloperoxidase levels) and IL-6 and TNF concentrations increased equally in D3KO and WT mice, and histological examination of infected mice showed similar pulmonary inflammation in both strains. However, D3KO animals demonstrated significantly higher bacterial load in blood, lung, and spleen compared with WT mice. We conclude that 1) D3 is not required to generate the systemic manifestations of the nonthyroidal illness syndrome in this model; 2) the lack of D3 does not affect the extent of pulmonary inflammation; and 3) bacterial outgrowth in blood, spleen, and lung of D3KO mice is significantly higher than in WT mice. Our results suggest a protective role for D3 in the defense against acute bacterial infection, probably by reinforcing the microbial killing capacity of neutrophils.

During illness, changes in thyroid hormone metabolism occur, known as nonthyroidal illness and characterised by decreased serum triiodothyronine (T3) and thyroxine (T4) without an increase in TSH. A mouse model of chronic illness is local inflammation, induced by a turpentine injection in each hind limb. Although serum T3 and T4 are markedly decreased in this model, it is unknown whether turpentine administration affects the central part of the hypothalamus–pituitary–thyroid axis (HPT-axis). We therefore studied thyroid hormone metabolism in hypothalamus and pituitary of mice during chronic inflammation induced by turpentine injection. Using pair-fed controls, we could differentiate between the effects of chronic inflammation per se and the effects of restricted food intake as a result of illness. Chronic inflammation increased interleukin (IL)-1β mRNA expression in the hypothalamus more rapidly than in the pituitary. This hypothalamic cytokine response was associated with a rapid increase in local D2 mRNA expression. By contrast, no changes were present in pituitary D2 expression. TSHβ mRNA expression was altered compared with controls. Comparing chronic inflamed mice with pair-fed controls, both preproTSH releasing hormone (TRH) and D3 mRNA expression in the paraventricular nucleus were significantly lower 48 h after turpentine administration. The timecourse of TSHβ mRNA expression was completely different in inflamed mice compared with pair-fed mice. Turpentine administration resulted in significantly decreased TSHβ mRNA expression only after 24 h while later in time it was lower in pair-fed controls. In conclusion, central thyroid hormone metabolism is altered during chronic inflammation and this cannot solely be attributed to diminished food intake.

Profound changes in thyroid hormone metabolism occur in the central part of the hypothalamus–pituitary–thyroid (HPT) axis during fasting. Hypothalamic changes are partly reversed by leptin administration, which decreases during fasting. It is unknown to what extent leptin affects the HPT axis at the level of the pituitary. We, therefore, studied fasting-induced alterations in pituitary thyroid hormone metabolism, as well as effects of leptin administration on these changes. Because refeeding rapidly increased serum leptin, the same parameters were studied after fasting followed by refeeding. Fasting for 24 h decreased serum T3 and T4 and pituitary TSHβ, type 2deiodinase (D2), and thyroid hormone receptor β2 (TRβ2) mRNA expression. The decrease in D2 and TRβ2 mRNA expression was prevented when 20 μg leptin was administered twice during fasting. By contrast, the decrease in TSHβ mRNA expression was unaffected. A single dose of leptin given after 24 h fasting did not affect decreased TSHβ, D2, and TRβ2 mRNA expression, while 4 h refeeding resulted in pituitary D2 and TRβ2 mRNA expression as observed in control mice. Serum leptin, T3, and T4 after refeeding were similar compared with leptin administration. We conclude that fasting decreases pituitary TSHβ, D2, and TRβ2 mRNA expression, which (with the exception of TSHβ) can be prevented by leptin administration during fasting. Following 24 h fasting, 4 h refeeding completely restores pituitary D2 and TRβ2 mRNA expression, while a single leptin dose is ineffective. This indicates that other postingestion signals may be necessary to modulate rapidly the fasting-induced decrease in pituitary D2 and TRβ2 mRNA expression.

One of the hallmarks of the sick euthyroid syndrome or non-thyroidal illness is a decrease of serum triiodothyronine, caused mainly by a decrease in liver deiodinase type 1 (D1) mRNA and activity. Proinflammatory cytokines like interleukin (IL)-1beta are likely involved in this disease, but are also known to inhibit thyroid hormone receptor (TR)-beta1 gene expression, which is of interest as the D1 promoter contains TREs. The aim of the present study was to evaluate whether the IL-1beta-induced decrease of D1 and TRbeta1 mRNA is mediated by the same cytokine signalling pathways in a human hepatoma cell line (HepG2). We observed a downregulation of both D1 and TRbeta1 mRNA after 4 h of incubating the cells with IL-1beta. Sulfasalazine was used to inhibit the nuclear factor-kappaB (NFkappaB) pathway and SP600125, a chemical inhibitor of the c-Jun N-terminal kinase, was used as an inhibitor of the activator protein-1 (AP-1) pathway. AP-1 inhibition did not affect the decrease of D1 and TRbeta1 mRNA, but the TRbeta1 mRNA decrease was completely abolished after inhibiting NFkappaB, while D1 mRNA was unaffected. Only simultaneous inhibition of both the NFkappaB and AP-1 pathways abolished the D1 mRNA decrease. We concluded that IL-1beta stimulation of HepG2 cells results in a marked decrease of D1 and TRbeta1 mRNA. The decrease of TRbeta1 mRNA is exclusively mediated by the NFkappaB pathway, while the decrease of D1 mRNA requires inhibition of both the AP-1 and the NFkappaB pathways.

T helper 1 driven immune responses facilitate host defence during viral infections. Because interleukin-18 (IL-18) mediates T helper 1 driven immune responses, and since mature IL-18 is up-regulated in human macrophages after influenza virus infection in vitro, it has been suggested that IL-18 plays an important role in the immune response to influenza. To determine the role of IL-18 in respiratory tract infection with influenza, IL-18 gene-deficient (IL-18(-/-)) and normal wildtype mice were intranasally inoculated with influenza A virus. Influenza resulted in an increase in constitutively expressed IL-18 in the lungs of wildtype mice. The clearance of influenza A was inhibited by IL-18, as indicated by reduced viral loads on day 8 and day 12 after infection in IL-18(-/-) mice. This enhanced viral clearance correlated with increased CD4(+) T-cell activation in the lungs as reflected by CD69 expression on the cell surface. Surprisingly, interferon-gamma (IFN-gamma) levels were similar in the lungs of IL-18(-/-) mice and wildtype mice. Intracellular IFN-gamma staining revealed similar expression levels in lung-derived natural killer cells, CD4(+) and CD8(+) T cells, indicating that IFN-gamma production is IL-18-independent during influenza virus infection. Tumour necrosis factor-alpha production by CD4(+) T cells was significantly lower in IL-18(-/-) mice than in wildtype mice. Our data indicate that endogenous IL-18 impairs viral clearance during influenza A infection.

In mice, respiratory syncytial virus (RSV) infection during allergic provocation aggravates the allergic Th2 immune response, characterised by production of interleukin (IL)-4, IL-5, and IL-13, and eosinophilic inflammation. This enhancement of the Th2 response occurs simultaneously with a strong RSV-induced Th1 cytokine response (IL-12 and IFN-γ). The present study investigated whether IFN-γ and IL-12 are critically involved in this RSV-enhanced OVA allergy. Therefore, IFN-γR- and IL-12-deficient mice (both on a 129/Sv/Ev background) were sensitised and challenged with ovalbumin (OVA) and infected with RSV during the OVA challenge period. Neither gene deletion affected the development of ovalbumin-induced allergic inflammation in mice. However, when OVA-allergic IFN-γR deficient mice were infected with RSV, an increased pulmonary eosinophilic infiltrate and increased IL-4 and IL-13 mRNA expression in lung tissue were observed compared with identically treated wild-type mice. In contrast, deficiency of IL-12 did not aggravate the Th2 immune and inflammatory response in OVA/RSV-treated mice, compared with wild-type. In conclusion, the virus-induced IFN-γ response diminishes the Th2 inflammatory response during OVA allergy but fails to prevent totally the enhancement of the OVA allergy by RSV. In contrast, IL-12 is not involved in inhibiting nor increasing the RSV-enhanced allergy in 129/Sv/Ev mice. J. Med. Virol. 69:156–162, 2003. © 2003 Wiley-Liss, Inc.

Background Th2 lymphocyte responses are associated with inflammation and disease during allergic responses. Exposure to particular environmental factors during the expression of allergy could result in more pronounced Th2-like immune responses and more severe disease. One factor might be a respiratory virus infection. Objective The aim of our study was to investigate the influence of respiratory syncytial virus (RSV) infection on the expression of ovalbumin (OVA)-induced allergy in BALB/c mice. Methods We determined OVA-specific IgE in serum, cytokine profiles and histopathological lesions in lungs of OVA-allergic mice after RSV infection. Results OVA sensitization and challenge induced OVA-specific IgE in serum, Th2 cytokine mRNA expression, and mononuclear and eosinophilic inflammation in the lungs. RSV inoculation during the challenge period enhanced OVA-induced IL-4 and IL-5 mRNA expression in lung tissue. RSV further enhanced the OVA-induced hypertrophy of mucous cells and eosinophilic infiltration in lung tissue. Surprisingly, RSV infection decreased Th2 cytokine secretion and eosinophilic influx in bronchoalveolar lavage of OVA-allergic mice. Because inactivated RSV did not influence these responses, replication of RSV appeared essential for the modification of OVA-induced Th2 cytokine expression. RSV did not change OVA-specific IgE levels in serum. Furthermore, the RSV-induced IL-12 mRNA expression in lung tissue of OVA-allergic mice was diminished, but IFN-γ mRNA expression was not affected. Conclusion RSV infection enhanced particular OVA-induced Th2 cytokine mRNA responses and pulmonary lesions in allergic mice and thus aggravated allergic respiratory disease.

Respiratory syncytial virus (RSV) is the most important cause of bronchiolitis and pneumonia in infants and young children. Immunopathology may play a role in RSV-induced disease and a severe RSV infection may also be associated with an increased risk of developing asthma. Vaccination with formalin-inactivated RSV (FI-RSV) prior to infection resulted both in human and in the mouse model in extensive lung pathology. In the mouse model, it has been shown that this aggravation of disease was associated with a shift in the balance between Th1 and Th2 cytokines towards a Th2-type response. The aim of the present study was to characterise the immunological and inflammatory responses in BALB/c mice upon RSV infection with or without prior vaccination with aluminium-adjuvanted FI-RSV or control antigens (FI-Mock). As previously reported by others, we also observed that a primary RSV infection in BALB/c mice resulted in a predominant Th1-type cytokine response, which was associated with slight bronchiolitis and alveolitis. FI-RSV vaccination prior to RSV challenge prevented virus replication and was associated with an aggravation of pulmonary histopathology and a shift towards a Th2-type response. Vaccination with FI-Mock did not prevent RSV replication in the lung but resulted in an even more pronounced Th2 response after infection while these mice were not sensitised to specific viral antigens. Thus, viral replication in a Th2 responding animal (induced by aluminium-adjuvanted mock vaccine) appears to boost the Th2 response upon RSV infection.

The hypothalamus is a major target for glucocorticoids and a key structure for hypothalamic-pituitary-adrenal (HPA) axis setpoint regulation. The enzyme 11β hydroxysteroid dehydrogenase type 1 (11βHSD1) modulates glucocorticoid signalling in various tissues at the prereceptor level by converting biologically inactive cortisone to its active form cortisol. The present study aimed to assess 11βHSD1 expression in the human hypothalamus. We studied 11βHSD1 expression in five frozen and four formalin-fixed, paraffin-embedded human hypothalami (obtained from the Netherlands Brain Bank) by the polymerase chain reaction and immunocytochemistry, respectively. 11βHSD1 mRNA was expressed in the area of the suprachiasmatic nucleus, which is the biological clock of the brain, in the supraoptic nucleus and paraventricular nucleus (PVN), and in the infundibular nucleus, which is the human homologue of the rodent arcuate nucleus. 11βHSD1 was detected by immunocytochemistry in the same nuclei. In the PVN, neuronal 11βHSD1 immunoreactivity colocalised with corticotrophin-releasing hormone (CRH), arginine vasopressin and oxytocin, as shown by dual fluorescence staining. Our data demonstrate that 11βHSD1 is widely expressed in the human hypothalamus. Its colocalisation with CRH in the PVN suggests a role in modulation of glucocorticoid feedback of the HPA axis, whereas the expression of 11βHSD1 in additional and functionally diverse hypothalamic nuclei points to a role for the enzyme in the regulation of metabolism, appetite and circadian rhythms.

The downregulation of liver deiodinase type 1 (D1) is supposed to be one of the mechanisms behind the decrease in serum tri-iodothyronine (T3) observed during non-thyroidal illness (NTI). Liver D1 mRNA expression is positively regulated by T3, mainly via the thyroid hormone receptor (TR)β1. One might thus expect that lacking the TRβ gene would result in diminished downregulation of liver D1 expression and a smaller decrease in serum T3 during illness. In this study, we used TRβ−/− mice to evaluate the role of TRβ in lipopolysaccharide (LPS, a bacterial endotoxin)-induced changes in thyroid hormone metabolism. Our results show that the LPS-induced serum T3 and thyroxine and liver D1 decrease takes place despite the absence of TRβ. Furthermore, we observed basal differences in liver D1 mRNA and activity between TRβ−/− and wild-type mice and TRβ−/− males and females, which did not result in differences in serum T3. Serum T3 decreased rapidly after LPS administration, followed by decreased liver D1, indicating that the contribution of liver D1 during NTI may be limited with respect to decreased serum T3 levels. Muscle D2 mRNA did not compensate for the low basal liver D1 observed in TRβ−/− mice and increased in response to LPS in TRβ−/− and WT mice. Other (TRβ independent) mechanisms like decreased thyroidal secretion and decreased binding to thyroid hormone-binding proteins probably play a role in the early decrease in serum T3 observed in this study.

Transcripts derived from the thyroid hormone receptor alpha (TRalpha) gene are alternatively spliced resulting in a functional receptor TRalpha1 and a non-T3-binding variant TRalpha2 that can exert a dominant negative effect on the transactivation functions of other TRs. There is evidence that the ratio of TRalpha isoform transcripts can be modulated and here, we investigate whether the PPARgamma co-activator alpha (PGC-1alpha) has an effect on this splicing process. PGC-1alpha was discovered not only as a transcriptional co-activator, but also has certain motifs characteristic of splicing factors. We demonstrate that PGC-1alpha alters the ratio of endogenously expressed TRalpha isoform transcripts in HepG2 cells, by decreasing TRalpha1 mRNA levels twofold. This change in isoform ratio is accompanied by a decrease in 5'-deiodinase expression, whereas no differences were found in TRbeta1 expression. Deletion of the RNA-processing domain of PGC-1alpha abrogated the effect on the TRalpha splicing, whereas expression of only the RNA-processing domain favored TRalpha1 expression. PGC-1alpha showed a similar effect on the splicing of a TRalpha minigene containing only the last four exons and introns of the TRalpha gene. These data suggest that PGC-1alpha is involved in the RNA processing of TRalpha transcripts.

During illness, changes in thyroid hormone metabolism occur, so-called nonthyroidal illness (NTI). NTI has been characterized by a fall of serum T(3) due to decreased extrathyroidal conversion of T(4) into T(3) by liver type 1 deiodinase (D1), without an increase in serum TSH. Type 3 deiodinase (D3) was thought not to play an important role during NTI, but recently it has been shown that D3 activity is up-regulated in liver and skeletal muscle of critically ill patients related to hypoxia. We studied D3 gene expression and activity in liver and muscle/subcutis of mice during illness, which was induced by two different stimuli: bacterial endotoxin (lipopolysaccharide) administration, resulting in an acute systemic response, and a turpentine injection in each hindlimb, resulting in a local sc abscess. Lipopolysaccharide induced a rapid decrease in liver D1 and D3 activity but not skeletal muscle of hindlimb. In contrast, local inflammation induced by turpentine did not decrease liver D1 and D3 activity but increased markedly D3 activity in the muscle/subcutis sample containing the abscess, associated with strongly increased IL-1beta and IL-6 mRNA expression. Inflammatory cells, surrounding the abscess showed D3 and T(3)-transporter monocarboxylate transporter-8 immunoreactivity, whereas muscle cells did not show any immunoreactivity. In conclusion, local inflammation strongly induces D3 activity in inflammatory cells, especially in invading polymorphonuclear granulocytes, suggesting enhanced local degradation of T(3).

Changes in both central and peripheral thyroid hormone (TH) metabolism occur during illness. These changes, known collectively as non-thyroidal illness, are apparently mediated by the proinflammatory cytokines IL-6, TNFalpha and IFNgamma. IL-12 is involved in regulation of IFNgamma and TNFalpha. The aim of this study was to evaluate the role of IL-12 in TH metabolism during illness. We studied TH metabolism both centrally (in the pituitary) and peripherally (in the liver) in IL-12 knock-out (IL-12 (-/-)) and wild type (WT) mice during illness induced by administration of bacterial endotoxin (LPS). LPS induced a similar decrease in serum T (3), T (4) and liver 5'-DI mRNA expression in IL-12 (-/-) and WT mice with the exception of a smaller reduction of serum T (4) in IL-12 (-/-) mice. In the pituitary, the LPS-induced decline in 5'-DI activity in WT mice was not observed in IL-12 (-/-) mice (p < 0.001), whereas the decrease in DII activity tended to be smaller in IL-12 (-/-) mice (p = 0.066). The lower decrease in pituitary activity of both DI and DII in IL-12 (-/-) mice is possibly related to the lower LPS-induced T (4) decrease. In conclusion, IL-12 is involved in the central regulation of the HPT axis during illness but not in the peripheral regulation.

Objective: Proinflammatory cytokines are involved in the pathogenesis of non-thyroidal illness (NTI), its shown by studies with IL-6(-/-) and IL-12(-/-) mice. Interleukin (IL)-6 changes peripheral thyroid hormone metabolism, and IL-12 seems to be involved in the regulation of the central part of the hypothalamic-pituitary-thyroid (HPT) axis during illness. IL-18 is a proinflammatory cytokine which shares important biological properties with IL-12, such as interferon (IFN)-gamma-inducing activity. Design: By studying the changes in the HPT axis during bacterial lipopolysaccharide (LPS)-induced illness in IL-18(-/-), IFNgammaR(-/-) and wild-type (WT) mice, we wanted to unravel the putative role of IL-18 and IFNgamma in the pathogenesis of NTI. Results: LPS induced a decrease in pituitary type 1 deiodinase (D1) activity (P

During illness, major changes in thyroid hormone metabolism and regulation occur; these are collectively known as non-thyroidal illness and are characterized by decreased serum triiodothyronine (T(3)) and thyroxine (T(4)) without an increase in serum TSH. Whether alterations in the central part of the hypothalamus-pituitary-thyroid (HPT) axis precede changes in peripheral thyroid hormone metabolism instead of vice versa, or occur simultaneously, is presently unknown. We therefore studied the time-course of changes in thyroid hormone metabolism in the HPT axis of mice during acute illness induced by bacterial endotoxin (lipopolysaccharide; LPS).LPS rapidly induced interleukin-1beta mRNA expression in the hypothalamus, pituitary, thyroid and liver. This was followed by almost simultaneous changes in the pituitary (decreased expression of thyroid receptor (TR)-beta2, TSHbeta and 5'-deiodinase (D1) mRNAs), the thyroid (decreased TSH receptor mRNA) and the liver (decreased TRbeta1 and D1 mRNA). In the hypothalamus, type 2 deiodinase mRNA expression was strongly increased whereas preproTRH mRNA expression did not change after LPS. Serum T(3) and T(4) fell only after 24 h.Our results suggested almost simultaneous involvement of the whole HPT axis in the downregulation of thyroid hormone metabolism during acute illness.

Patienten met type 2 diabetes hebben een verhoogde leversecretie van triglyceriden in VLDL-partikels (VLDL-TG).1 VLDL-TG-secretie wordt onder andere gereguleerd door circulerende metabolieten (vrije vetzuren) en hormonen, zoals insuline. Recent onderzoek liet daarnaast ook een rol zien voor de hersenen en het autonome zenuwstelsel bij de regulatie van VLDL-TG-secretie.

RSV is an important cause of bronchiolitis in infants. Immunopathology may play a role in RSV-induced bronchiolitis and severe RSV-induced disease has been associated with a Th2 type immune response. The aim of the study was to identify cytokine pathways that are crucial in influencing RSV-induced disease. For that purpose we inoculated IFNgammaR-/-, IL-12-/-, IL-18-/-, or IL-4-/- mice with RSV. We observed that an RSV infection resulted in a predominant Th1 cytokine response associated with slight bronchiolitis and alveolitis. Pulmonary histopathology was only aggravated in IFN R-/- mice, characterised by eosinophilic influx around the bronchioles. Despite subtle changes in cytokine expression, no differences in histopathology were observed in IL-12-/- and IL-18-/- mice. Deficiency of IL-4 has no effect on RSV-induced Th1 cytokines and pulmonary histopathology. IFNgamma-receptor deficiency during primary RSV infection resulted in a disturbed Th1 response based on increased IL-4, IL-5, and IL-13 expression and the presence of eosinophils in the lungs. It is concluded that IFNgamma signalling is required for a pronounced Th1 response to RSV while IL-12 and IL-18 are not. A shift in the balance between Th1 and Th2 towards a Th2 response induced by missing IFNgamma signalling leads to aggravated pulmonary pathology. This is not caused by enhanced viral load.