Interleukin 1 stimulation of the hypothalamic-pituitary-adrenal axis

More than just teeth: How oral health can affect the heart

Epidemiological evidence has revealed a potential relationship between periodontal disease and cardiovascular disease (CVD). Consensus regarding a link between these pathologies remains elusive, however, largely secondary to the considerable overlap between risk factors and comorbidities common to both disease processes. This review article aims to update the evidence for an association by summarizing the evidence for causality between periodontitis and comorbidities linked to CVD, including endocarditis, hypertension (HTN), atrial fibrillation (AF), coronary artery disease (CAD), diabetes mellitus (DM) and hyperlipidemia (HLD). This article additionally discusses the role for periodontal therapy to improved management of the comorbidities, with the larger goal of examining the value of periodontal therapy on reduction of CVD risk. In doing so, we endeavor to further the understanding of the commonality between periodontitis, and CVD.

[Alexithymia in Multiple Sclerosis - Narrative Review]

Alexithymia is a multidimensional construct of personality implicating difficulties in identifying and describing another's feelings, and externally oriented thinking. It is broadly reported in psychiatric patients but has gained little attention regarding its occurrence and pathophysiology in multiple sclerosis (MS). This narrative review aims to address prevalence, etiology, neurobiological, and clinical findings of alexithymia. The prevalence of alexithymia in MS ranges from 10 to 53%. There seems to be an association with anxiety, depression, fatigue, and some aspects of social cognition, while the relationship with clinical and classical cognitive variables was rarely evaluated. Only a few studies referred to its pathophysiology assuming an aberrant interhemispheric transfer or regional cerebral abnormalities. The prevalence of alexithymia in MS and the potential negative impact on quality of life and interpersonal communication could severely impact clinical MS management and a screnning for these factors should be mandatory. Thus, further evaluation is needed concerning its relationship with clinical, emotional, and cognitive confounders. Large-scale studies employing neuroimaging techniques are needed for a better understanding of the neural underpinnings of this MS feature.

The systemic-level repercussions of cancer-associated inflammation mediators produced in the tumor microenvironment

The tumor microenvironment is a dynamic, complex, and redundant network of interactions between tumor, immune, and stromal cells. In this intricate environment, cells communicate through membrane-membrane, ligand-receptor, exosome, soluble factors, and transporter interactions that govern cell fate. These interactions activate the diverse and superfluous signaling pathways involved in tumor promotion and progression and induce subtle changes in the functional activity of infiltrating immune cells. The immune response participates as a selective pressure in tumor development. In the early stages of tumor development, the immune response exerts anti-tumor activity, whereas during the advanced stages, the tumor establishes mechanisms to evade the immune response, eliciting a chronic inflammation process that shows a pro-tumor effect. The deregulated inflammatory state, in addition to acting locally, also triggers systemic inflammation that has repercussions in various organs and tissues that are distant from the tumor site, causing the emergence of various symptoms designated as paraneoplastic syndromes, which compromise the response to treatment, quality of life, and survival of cancer patients. Considering the tumor-host relationship as an integral and dynamic biological system, the chronic inflammation generated by the tumor is a communication mechanism among tissues and organs that is primarily orchestrated through different signals, such as cytokines, chemokines, growth factors, and exosomes, to provide the tumor with energetic components that allow it to continue proliferating. In this review, we aim to provide a succinct overview of the involvement of cancer-related inflammation at the local and systemic level throughout tumor development and the emergence of some paraneoplastic syndromes and their main clinical manifestations. In addition, the involvement of these signals throughout tumor development will be discussed based on the physiological/biological activities of innate and adaptive immune cells. These cellular interactions require a metabolic reprogramming program for the full activation of the various cells; thus, these requirements and the by-products released into the microenvironment will be considered. In addition, the systemic impact of cancer-related proinflammatory cytokines on the liver-as a critical organ that produces the leading inflammatory markers described to date-will be summarized. Finally, the contribution of cancer-related inflammation to the development of two paraneoplastic syndromes, myelopoiesis and cachexia, will be discussed.

Critical Appraisal of Bidirectional Relationship between Periodontitis and Hyperlipidemia

Periodontal disease and hyperlipidemia are both multifactorial disease with a high prevalence Worldwide. Cross-sectional and longitudinal prospective clinical studies show some evidence for a bidirectional relationship. Periodontitis and hyperlipidemia share some common risk factors and there exist a mechanistic link between both. Studies have found a positive response to periodontal therapy among hyperlipidemic patients, and statin use by hyperlipidemic patients has shown to influence the periodontal health. However, in spite of the rising prevalence of both diseases, many people remain unaware of their association with each other. Hence, this article summarizes the cyclic relationship between periodontal disease and hyperlipidemia.

Tumour necrosis factor (TNF) and interleukin-1 (IL-1) induce muscle proteolysis through different mechanisms

The purpose of this study was to test the hypothesis that muscle proteolysis induced by TNF or IL-1 is mediated by glucocorticoids. Rats were treated with 300 mug kg(-1) of recombinant human preparations of IL-1alpha (rIL-1alpha) or TNFalpha (rTNFalpha) divided into three equal intraperitoneal doses given over 16 h. Two hours before each cytokine injection, rats were given 5 mg kg(-1) of the glucocorticoid receptor blocker mifepristone RU 38486, by gavage or were gavaged with the vehicle. Eighteen hours after the first cytokine injection, total and myofibrillar protein breakdown rates were determined in incubated extensor digitorum longus muscles as release of tyrosine and 3-methylhistidine, respectively. Total and myofibrillar proteolytic rates were increased following injection of rIL-1alpha or rTNFalpha. Proteolysis induced by rIL-1alpha was not altered by treatment with RU 38486. In contrast, the glucocorticoid receptor blocker inhibited the proteolytic effect of rTNFalpha. The results suggest that the proteolytic effect of TNF is mediated by glucocorticoids and that IL-1 induces muscle proteolysis through a glucocorticoid independent pathway.

Brown fat UCP1 is not involved in the febrile and thermogenic responses to IL-1beta in mice

The activity of brown adipose tissue (BAT), a site of nonshivering metabolic thermogenesis, has been reported to increase after interleukin (IL)-1beta/lipopolysaccharide injection. To clarify the possible contribution of BAT thermogenesis to whole body febrile response, we investigated febrile and thermogenic response to IL-1beta using mice deficient in uncoupling protein-1 (UCP1), a key molecule for BAT thermogenesis. In wild-type (WT) mice, IL-1beta injection (5 microg/kg ip) increased body temperature (+1.82 degrees C at 20 min), decreased physical activity (-37% at 1 h), and produced a slight and insignificant rise (+15% at 1 h) in oxygen consumption (Vo(2)). Vo(2) dependent on metabolic thermogenesis (DeltaVO2 thermogenesis) calculated by correcting the effect of physical activity was increased after IL-1beta injection (726 +/- 200 ml x h(-1) x kg(-1) at 1 h). Almost the same responses were observed in UCP1-deficient mice, showing 638 +/- 87 ml x h(-1) x kg(-1) of DeltaVO2 thermogenesis at 1 h. In contrast, CL316,243, a selective activator of BAT thermogenesis, increased body temperature, decreased physical activity, and produced a significant rise in Vo2 in WT mice, showing 1,229 +/- 35 ml x h(-1) x kg(-1) of DeltaVO2 thermogenesis at 1 h. These changes were not observed in UCP1-deficient mice. These results, conflicting with a previously proposed idea of a role of BAT in fever, suggest a minor contribution of BAT thermogenesis to IL-1beta-induced fever. In support of this, we found no effect of IL-1beta on triglyceride content and UCP1 mRNA level in BAT, in contrast with apparent effects of CL316,243.

Immune modulation of the hypothalamic-pituitary-adrenal (HPA) axis during viral infection

Compelling data has been amassed indicating that soluble factors, or cytokines, emanating from the immune system can have profound effects on the neuroendocrine system, in particular the hypothalamic- pituitary-adrenal (HPA) axis. HPA activation by cytokines (via the release of glucocorticoids), in turn, has been found to play a critical role in restraining and shaping immune responses. Thus, cytokine-HPA interactions represent a fundamental consideration regarding the maintenance of homeostasis and the development of disease during viral infection. Although reviews exist that focus on the bi-directional communication between the immune system and the HPA axis during viral infection (188,235), others have focused on the immunomodulatory effects of glucocorticoids during viral infection (14,225). This review, however, concentrates on the other side of the bi-directional loop of neuroendocrine-immune interactions, namely, the characterization of HPA axis activity during viral infection and the mechanisms employed by cytokines to stimulate glucocorticoid release.

Melatonin increases interleukin-1beta and decreases tumor necrosis factor alpha in the brain of mice infected with the Venezuelan equine encephalomyelitis virus

The effect of melatonin (MLT) on the brain levels of tumor necrosis factor alpha (TNF-alpha) and interleukin-1beta (IL-1beta) in Venezuelan equine encephalomyelitis (VEE) virus infection was determined. Brain homogenates from mice inoculated with 10 LD50 of VEE virus, untreated or treated with 500 microg MLT/kg body weight were assayed by ELISA to measure the levels of TNF-alpha and IL-1beta. MLT was injected daily starting 3 days before and continuing to 7 days after virus inoculation. Infected mice treated with MLT showed decreased levels of TNF-alpha when compared to the untreated infected mice on days 1, 3, 4, and 5 postinoculation (P < 0.001). In contrast, IL-1beta levels increased from days 1 to 5 in the infected mice treated with MLT when compared with the untreated infected animals (P < 0.01). The results suggest that the protective effect of MLT on the VEE virus infection could be due, among other factors, to a decrease in TNF-alpha synthesis along with an increase in the production of IL-1beta.

Intraamniotic interleukin-1 accelerates surfactant protein synthesis in fetal rabbits and improves lung stability after premature birth

Intraamniotic infection is associated with increased IL-1 activity in amniotic fluid, increased incidence of preterm labor, and with decreased incidence of respiratory distress syndrome in infants born prematurely. We hypothesized that an elevated IL-1 in amniotic fluid promotes fetal lung maturation. On day 23 or 25 of gestation (term 31 d), either IL-1alpha (150 or 1,500 ng per fetus) or its antagonist IL-1 receptor antagonist (IL-1ra, 20 microg) was injected to the amniotic fluid sacs in one uterine horn, whereas the contralateral amniotic sacs were injected with vehicle. Within 40 h, IL-1alpha caused a dose-dependent increase in surfactant protein-A (SP-A) and SP-B mRNAs (maximally, fivefold), without affecting lung growth or increasing inflammatory cells in the lung. Both genders, and upper and lower lung lobes were similarly affected. IL-1ra did not modify SP-A, -B, or -C mRNA. IL-1 increased the intensity of staining of alveolar type II cells for SP-B, and the concentrations of SP-B, -A, and disaturated phosphatidylcholine in bronchoalveolar lavage. The dynamic lung compliance and the postventilatory expansion of lungs were increased two- to fourfold after IL-1alpha treatment. In fetal lung explants, IL-1alpha increased the expression of SP-A mRNA. IL-1 in amniotic fluid in preterm labor may promote lung maturation and thus be part of a host-defense mechanism that prepares the fetus for extrauterine life.

Effects of pyrogenic immunomodulators on the release of corticotrophin-releasing factor-41 and prostaglandin E2 from the intact rat hypothalamus in vitro

1. The actions of the following pyrogens: lipopolysaccharide (LPS), polyinosinic:polycytidylic acid (Poly-I:C), human interleukin (IL)-1 alpha and IL-1 beta, human IL-6 and rat interferon (INF) on corticotrophin-releasing factor-41 (CRF-41) and prostaglandin E2 (PGE2) release from the intact rat hypothalamus in vitro have been studied. 2. Rat hypothalami were incubated in vitro in an artificial cerebrospinal fluid. Immunoreactive (ir)-CFR-41 and PGE2 released into the medium were measured by two-site enzyme amplified immunometric assay (EAIA) and radioimmunoassay (RIA) respectively. 3. Human IL-6 (1 to 10,000 IU ml-1) caused a dose-dependent release of irCRF-41, rising to a maximal 3-4 fold increase over basal at the highest dose tested. Human IL-1 alpha (1 to 1000 IU ml-1), human IL-1 beta (1 to 1000 IU ml-1), poly-I:C (10 pg ml-1 to 100 micrograms ml-1) and rat INF (1 to 10,000 IRu ml-1) all failed to alter irCRF-41 release. 4. LPS (1 mg ml-1) caused a 35% decrease in irCRF-41 release; however, over the dose-range of 0.1 microgram ml-1 to 100 micrograms ml-1, LPS failed to alter irCRF-41 release. The decreased irCRF-41 release in response to LPS (1 mg ml-1) was accompanied by a decrease in the subsequent 56 mM KCl stimulation of irCRF-41. 5. Human IL-1 alpha and IL-1 beta (1000 IU ml-1) were able to stimulate the release of irPGE2 from intact hypothalami, causing a 2 fold increase over basal release. Poly-I:C (100 microg ml-1), LPS (0.1 microg ml-1 to 1 mg ml-1), rat INF (10,000 IRu ml-1) and human IL-6 (1 to 10,000 iu ml-1) all failed to alter irPGE2release.6. In conclusion, these results suggest that the in vitro release of CRF-41 and PGE2, in response to pyrogens, are mediated via different cytokines. In view of this it is possible that different cytokines may mediate the temperature, prostaglandin and hypothalamo-pituitary-adrenocortical axis activation seen during pyrogenic stimulation in vivo.