Andrea Dovio

The overtraining syndrome in athletes: A stress-related disorder

Physical exercise is a type of allostatic load for several endocrine systems, notably the hypothalamic-pituitary-adrenal (HPA) axis. Athletes undergoing a strenuous training schedule can develop a significant decrease in performance associated with systemic symptoms or signs: the overtraining syndrome (OTS). This is a stress-related condition that consists of alteration of physiological functions and adaptation to performance, impairment of psychological processing, immunological dysfunction and biochemical abnormalities. Universally agreed diagnostic criteria for OTS are lacking. The pituitary-adrenal response to a standardized exercise test is usually reduced in overtrained athletes. This HPA dysfunction could reflect the exhaustion stage of Selye’s general adaptation syndrome. The most attractive hypothesis that accounts for the observed neuro-endocrine-immune dysregulation is the Smith’s cytokine hypothesis of OTS. It assumes that physical training can produce muscle and skeletal trauma, thus generating a local inflammatory reaction. With the excessive repetition of the training stimulus the local inflammation can generate a systemic inflammatory response. The main actors of these processes are the cytokines, polypeptides that modulate HPA function in and outside the brain at nearly every level of activity. It is hoped that future research will focus on endogenous risk factors for morbidities related to the neuro-endocrine-immune adaptation to exercise.

Modulation by cytokines of glucocorticoid action.

ABSTRACT: Glucocorticoids (GC) are potent modulators of the inflammatory response. Their effects serve to down‐regulate the inflammatory response and are mediated by genomic pathways that follow the interaction with specific receptors (glucocorticoid receptors, GR). Interleukin (IL)‐1, IL‐2, and IL‐6 are able to increase GC secretion by enhancing synthesis and release of CRH and ACTH. Cytokine effects upon steroidogenesis also occur at the adrenal level. The role of cytokines as modulators of GR has received scarce attention. IL‐1 has been shown to up‐regulate GR mRNA expression in hypothalamic CRH secreting cells. On the other hand, macrophage migration inhibitory factor (MIF), a T‐cell product inducible by inflammatory substances including other cytokines, counterregulates GC action within the immune system. Besides immunocytes and neurons, bone cells are a sensitive target for GC and cytokines. We have found that IL‐2 and IL‐6 up‐regulate remarkably the number of GR binding sites and the expression of GR mRNA in peripheral blood mononuclear cells and in osteoblast‐like Saos‐2 cells. Available data suggest that inflammatory cytokines have both direct and indirect effects on GC action at the target level. Autocrine‐induced transcription of GR in immunocytes and/or osteoblasts could be a mechanism that restrains excess cytokine production.

Differential responses of serum and salivary interleukin-6 to acute strenuous exercise

Physical exercise is associated with elevation of serum levels of interleukin-6 (IL-6) because of its production in the muscles. The use of IL-6 measurements in saliva has been proposed in the field of immunopathology, mainly involving salivary gland disease. We evaluated the responses of serum and salivary IL-6 in two different groups of athletes submitted to different types of controlled strenuous exercise (spinning activity and maximal isokinetic test). Serum and salivary samples for IL-6 measurements, and serum samples for lactate and myoglobin determination before and after exercise, were obtained. Salivary IL-6 was measured by ELISA after dilution experiments and compared with results obtained by immunoradiometric assay. Spinning activity elicited significant increases in all the variables, and no correlation was found among the respective variations. A significant response to the isokinetic exercise was observed for serum IL-6, lactate and myoglobin only; no correlation was found between serum and salivary IL-6. Our study demonstrated that serum and salivary IL-6 responses to exercise are dissociated, possibly in relation to the lack of relationships between the systemic/muscular and the salivary routes of IL-6 production. Analytical issues that concern IL-6 measurement in saliva deserve attention, notably regarding the collection method used to absorb saliva. Concomitant monitoring of serum markers of inflammation, muscle metabolism and damage can provide information about muscle function properties and adaptations to physical effort in different types of athletes.

Interactions between Glucocorticoids and Cytokines in the Bone Microenvironment

Abstract: Cytokines belonging to the so‐called interleukin‐6 (IL‐6) or gp130 cytokine family, notably IL‐6 and IL‐11, are known as pro‐resorptive cytokines, in that they promote osteoclastogenesis. Glucocorticoid (GC)‐induced osteoporosis is admittedly the most frequent secondary osteoporosis. The pathogenesis still has many unresolved issues. Although the effects of GCs on cytokine production and recognition have been extensively studied, little is known about the effects of cytokines on GC action at the target level. We have focused on the effects of IL‐6 and IL‐11 on specific binding by type II GC receptors (GRs) in two human osteoblast‐like cell lines (Saos‐2 and MG‐63) that have remarkably different constitutive expression of these cytokines and GRs as well. We have provided evidence that IL‐6 upregulates GR binding sites, while IL‐11 downregulates these sites, as determined by radioligand binding assay and Scatchard analysis. GR affinity (Kd) did not change after exposure to both cytokines. A number of experiments were consistent with the view that in human osteoblast‐like cells, cytokines of the IL‐6 family have autocrine modulatory effects on GRα (GRβ is a variant that does not bind specifically in our method). Complex effects of GCs on the system(s) of proinflammatory/anti‐inflammatory cytokines and conversely of these cytokines on GC action could account for the dynamics of bone loss in patients given GCs and conceivably having high concentrations of these cytokines in the bone microenvironment.

Interleukin-6 producing pheochromocytoma presenting with acute inflammatory syndrome

Pheochromocytomas are tumors able to produce catecholamines and a variety of biologically active neuropeptides. We report the case of a 36-yr-old female patient with pheochromocytoma exhibiting headache, intermittent fever, thrombocytosis, and marked inflammatory signs. Nonsteroidal anti-inflammatory drugs were ineffective in lowering the body temperature, while a corticosteroid agent obtained excellent results. IL-6 was found elevated (20 pg/ml); it fell to 4.5 pg/ml 3 weeks after the adrenalectomy, in parallel to normalization of other laboratory data. The interleukin-6 (IL-6) over-production can either be ascribed directly to the tumor (as confirmed by immunohistochemistry) or indirectly accounted for by tumoral production, as a consequence of the high levels of circulating norepinephrine. To our knowledge, our paper represents the 6th case report of IL-6 secreting pheochromocytoma associated with clinical markers of inflammatory response.

Metabolic effects of single-dose pamidronate administration in prostate cancer patients with bone metastases

BACKGROUND Increased osteolysis usually accompanies sclerotic bone metastases from prostate cancer. This provides a rationale for the use of bisphosphonates to treat bone pain and prevent skeletal complications. METHODS The fasting urinary levels of calcium, hydroxyproline (OHPRO), pyridinolines (PYD), deoxypyridinolines (DPYD), collagen cross-linked N-telopeptide (NTX) and the serum values of calcium, total alkaline phosphatase and relevant bone isoenzyme, bone gla protein (BGP), carboxy-telopeptide of type I collagen (ICTP) and parathyroid hormone (PTH) were determined at baseline and on the 15th, 30th, 60th and 90th days after single-dose (90 mg) pamidronate administration in 35 consecutive prostate cancer patients with bone metastases. These biochemical indices and serum interleukin 6 (IL-6) were also measured after four days in the last consecutive 17 cases. RESULTS PYD, DPYD and NTX showed a significant decrease lasting four weeks (p<0.01, <0.01 and <0.001, respectively). OHPRO and ICTP did not change significantly. The NTX decline was greater than that of PYD and DPYD (maximum percent decrease: -71.3, -23.1 and -28.2, respectively). Bone formation markers and serum calcium did not change significantly. Serum PTH showed a rapid initial increase followed by a slow decrease (p<0.001). DPYD and NTX patterns did not correlate with changes in bone pain. As observed in the last 17 cases, the maximum osteolysis inhibition after pamidronate occurred on the fourth day after drug infusion. Serum IL-6 levels showed a short-lived decrease preceded by a transient rise on the fourth day. CONCLUSIONS Pamidronate is able to induce a decrease in bone resorption without significantly influencing bone formation. The maximum decrease in bone resorption occurs very early. NTX is the most sensitive bone resorption marker in bisphosphonate therapy monitoring. Changes in IL-6 but not bone resorption markers may be useful in the prediction of symptomatic response.

Sport-related hyperhomocysteinaemia: a putative marker of muscular demand to be noted for cardiovascular risk

Objective: Regular physical activity is associated with a reduction of cardiovascular morbidity and mortality; however, evidence of unfortunate cardiovascular events accompanying elite sport involvement continues to accumulate. To date, no information is available on possible peculiarities of the cardiovascular risk profile in athletes. Design: The aim of this study was to evaluate plasma homocysteine levels in a group of athletes and to search for relationship with vitamin status and other metabolic variables in order to confirm the existence of a “sport-related hyperhomocysteinaemia” and to explain its clinical significance. The study population was composed of 82 athletes (59 male and 23 female) practising different sports and 70 healthy age-matched subjects (40 male and 30 female) as a control group. Besides the general clinical and analytical determinations, the assessed variables included homocysteine, folate, vitamin B12, total and high-density lipoprotein (HDL) cholesterol, lactate dehydrogenase (LDH), creatine kinase (CPK) and interleukin-6 (IL-6). Results: The prevalence of hyperhomocysteinaemia (>15 μmol/l) in athletes and controls was 47% and 15%, respectively. No correlation was found between homocysteine and any of the other investigated variables, in particular plasma folate, blood pressure, LDH, CPK, total and HDL cholesterol and IL-6. Conclusion: The results of this study confirm the existence of a sport-related hyperhomocysteinaemia which appears linked neither to the same variables found in the general population, nor to specific training-related variables. We suggest that it would represent an adaptation to training but the possibility of a secondary vascular damage cannot be excluded.

Differential expression of determinants of glucocorticoid sensitivity in androgen-dependent and androgen-independent human prostate cancer cell lines.

Glucocorticoids (GCs) are widely used for the treatment of hormone refractory prostate cancer. However, few data are available on the expression and regulation of glucocorticoid and mineralocorticoid receptors (GR and MR) and 11beta-hydroxysteroid dehydrogenase (11beta-HSD) 1 and -2 activities in prostate cancer cells. Here we show that GR is expressed in both the androgen-independent PC-3 cell line and, at very low levels, in the androgen-dependent LNCaP cells, and MR is expressed in both cell lines. IL-1beta increased GR expression in both cell lines. In LNCaP cells IL-1beta also increased MR expression. Significant 11beta-HSD oxidase activity and 11beta-HSD2 protein were found in LNCaP cells, but not in PC3 cells, and no ketoreductase activity was detected in either cell lines. GR function was assessed by measuring the inhibitory effect of dexamethasone on constitutive and IL-1beta-inducible IL-6 and osteoprotegerin (OPG) production. In PC-3 cells, IL-1beta stimulated IL-6 and OPG release, and dexamethasone dose-dependently inhibited IL-1beta-inducible IL-6 release, and constitutive and IL-1beta-inducible OPG release. In LNCaP cells, IL-1beta stimulated only OPG release. While dexamethasone was ineffective, cortisol dose-dependently inhibited IL-1beta-inducible OPG release. Eplerenone (Epl), a selective mineralocorticoid antagonist, reverted this effect. We conclude that different patterns of expression of receptors and 11beta-HSD activity were associated with different responsiveness to GCs in terms of regulated gene expression. GR and MR expression may vary as a function not only of the malignant phenotype, but also of local conditions such as the degree of inflammation. Inhibition of IL-6 and OPG release by GCs may contribute to the antitumor efficacy in prostate cancer.

Mental deterioration correlates with response of natural killer (NK) cell activity to physiological modifiers in patients with short history of Alzheimer's disease

Natural killer (NK) cell activity of peripheral blood mononuclear (PBM) cells was measured in 16 subjects with mild to moderate senile dementia of Alzheimers type (sDAT) chosen for short history of disease and no medication, and in 17 age- and sex-matched controls. Levels of cytotoxicity at baseline and after PBM cell exposure to modifiers either negative (cortisol 10(-6) M) or positive (rIL-2 650 IU/ml and rIFN-gamma 100 UI/ml, respectively) were related to indices of hypothalamic-pituitary-adrenal (HPA) function and Gottfries Bråne Rating Scale (GBS) score for mental deterioration. Spontaneous NK cell activity was not significantly different in sDAT subjects vs controls. In vitro inhibition by cortisol was lower in sDAT (P<0.05); cytokine-induced changes were greater (rIL-2, P<0.02; rIFN-gamma, P<0.05). Percent negative or positive variations from baseline significantly correlated with GBS scores (P<0.05 or less). Serum cortisol and cortisol/DHEAS molar ratio at 0800 h were significantly higher in sDAT (P<0.05 and P<0.02, respectively). Cortisol/DHEA ratio positively correlated with GBS scores (P<0.02). Moreover, the ratios of incremental area of response ACTH/cortisol and beta-endorphin/cortisol after 1 microg/kg ovine-corticotrophin-releasing hormone (o-CRH) positively correlated with percent increase of NK cell activity after rIL-2 (P<0.01). Data indicate that patients with mild cognitive impairment and short history of sDAT show abnormal responsiveness of NK cell activity to physiological modifiers while maintaining normal spontaneous activity. Furthermore, data are compatible with partial glucocorticoid resistance at the immune level. Progressing sDAT longitudinal studies are needed to address: i) the clinical applicability of these abnormalities as prognostic factors; ii) the role played by pro-opiomelanocortin (POMC)-derived peptides and adrenal androgens in the control of NK cell activity.

Autocrine Up-Regulation of Glucocorticoid Receptors by Interleukin-6 in Human Osteoblast-Like Cells

6 cells, respectively). We measured the expression of glucocorticoid receptor (GR) in terms of specific binding sites after exposure of cells to different amounts of IL-6. Incubation for 20 hours with IL-6 at increasing concentrations up to 2000 pg/ml yielded significant increase of GR binding sites in both cell lines. IL-6 was also able to revert the inhibitory effect of dexamethasone (1 μM) on GR in both cell lines. In MG-63 cells, that express higher concentrations of GR, IL-6 deprivation via a specific anti-IL-6 antibody (100 ng/ml) significantly decreased GR, as it was noticed, although to a lesser degree, using a specific anti-IL-6 receptor antibody. In Saos-2, cells that express lower concentrations of GR, a 40-hour treatment with human IL-1β (10 ng/ml) significantly increased both IL-6 production and GR. This latter effect was completely abolished by co-treating the cells with the anti-IL-6 antibody. Our data are consistent with an autocrine up-regulation of GR expression by IL-6 in human osteoblast-like cells. This phenomenon, which is also relevant to paracrine cell-to-cell communication, subserves a feedback loop in the bone microenvironment that restrains excess inducible IL-6 production. In patients having high levels of IL-6 and given GCs, it could offer an additional explanation for the biphasic pattern of bone loss in the course of therapy.