Paolo Ferrario

Increased tumor necrosis factor-alpha and prostaglandin E2 concentrations in the cerebrospinal fluid of rats with inflammatory hyperalgesia: the effects of analgesic drugs.

BACKGROUND:We examined the changes in cerebrospinal fluid (CSF) concentrations of prostaglandin E2 (PGE2) and tumor necrosis factor-α (TNF-α) after intraplantar administration of complete Freund’s adjuvant (CFA) in rats. In addition, we investigated whether different analgesic drugs orally administered at antihyperalgesic doses were able to prevent the changes in PGE2 and TNF-α spinal levels associated with hindpaw inflammation. METHODS:The Randall–Selitto paw-withdrawal test was used to measure inflammatory hyperalgesia. Tramadol (7.5 mg/kg), paracetamol (65 mg/kg), tramadol plus paracetamol and nimesulide (5 mg/kg) were administered orally twice a day, starting from the first day after the CFA injection. PGE2 in the CSF was measured by enzyme immunoassay, and TNF-α by ELISA. Behavioral and biochemical parameters were measured on Day 7 after intraplantar injection of CFA or saline. RESULTS:Withdrawal thresholds to mechanical stimuli decreased markedly in the CFA-treated paw. In these animals the quantification of proinflammatory mediators in the CSF revealed a significant increase in both PGE2 and TNF-α concentrations. All the pharmacological treatments prevented the development of the hyperalgesia as well as the PGE2 increase in the CSF. Conversely, a prevention of the increase in TNF-α levels was observed only in rats treated with nimesulide or tramadol and paracetamol in combination. CONCLUSIONS:Our results demonstrate that peripheral inflammatory hyperalgesia is associated with significant changes of proinflammatory mediators in the CSF. It is important to note, however, that spinal PGE2 and TNF-α proved to be differently affected by pharmacological treatments able to fully abolish the hyperalgesia.

Silent cardiovascular involvement in patients with diffuse systemic sclerosis: a controlled cross-sectional study.

An association between systemic autoimmune diseases and atherosclerosis has been described in many connective tissue diseases, and this association is known to lead to increased cardiovascular morbidity and mortality. Systemic sclerosis (SSc) is characterized by multisystem organ inflammation, endothelial wall damage, and vasculopathy. There are many markers of endothelial dysfunction and/or atherosclerotic risk, such as asymmetric dimethylarginine (ADMA), arterial stiffness parameters, carotid intima‐media thickness (CIMT), and coronary flow reserve (CFR) assessed by transthoracic echocardiography. The aim of this pilot study was to use various endothelial and atherosclerosis markers to identify early cardiovascular involvement in a group of SSc patients.

Effects of the bisphosphonate ibandronate on hyperalgesia, substance P, and cytokine levels in a rat model of persistent inflammatory pain

The anti‐inflammatory and analgesic properties of different bisphosphonates have been demonstrated in both animal and human studies. Ibandronate is a third‐generation bisphosphonate effective in managing different types of bone pain. In this study we investigated its effects in a standard pre‐clinical model of inflammatory pain. We evaluated the effects of a single injection of different doses (0.5, 1.0, and 2.0mg/kg i.p.) of ibandronate on inflammatory oedema and cutaneous hyperalgesia produced by the intraplantar injection of complete Freunds adjuvant (CFA) in the rat hind‐paw. In addition, we measured the effects of this drug (1.0mg/kg i.p.) on hind‐paw levels of different pro‐inflammatory mediators (PGE‐2, SP, TNF‐α, and IL‐1β). We also measured the levels of SP protein and of its mRNA in the ipsilateral dorsal root ganglia (DRG). Ibandronate proved able to reduce the inflammatory oedema, the hyperalgesia to mechanical stimulation, and the levels of SP in the inflamed tissue as measured 3 and 7 days following CFA‐injection. This drug significantly reduced the levels of TNF‐α and IL‐1β only on day 7. On the other hand, the levels of PGE‐2 in the inflamed hind‐paw were unaffected by the administration of this bisphosphonate. Finally, ibandronate blocked the overexpression of SP mRNA in DRG induced by CFA‐injection in the hind‐paw.

In vivo and in vitro effects of bromelain on PGE(2) and SP concentrations in the inflammatory exudate in rats.

The effects of bromelain were examined in rats with subcutaneous carrageenin-induced inflammation. After oral in vivo administration, bromelain (10 and 20 mg/kg p.o.) induced a significant decrease of both PGE2 and substance P concentrations in the exudate. When added to the inflammatory exudate in vitro, the drug (25, 50, 100 µg/ml) did not affect PGE2 concentrations and induced an increase in the substance P levels. Our data indicate that bromelain reduces the production of two key mediators of inflammation. This effect does not seem to be related to a direct action of the drug on PGE2 and SP released in the exudate in response to the inflammatory stimulus.

Increased substance P and tumor necrosis factor-α level in the paws following formalin injection in rat tail

We previously described a rat model where the injection of formalin in the tail induced a facilitation of the hindpaw withdrawal reflexes (hyperalgesia). In the present work, after injecting formalin in the tail, we measured the levels of pro-nociceptive mediators tumor necrosis factor-alpha (TNF) and substance P (SP) in the rat paws. A significant increase of SP levels was evident in the hindpaw, whereas no changes in SP were observed in the forepaw. Both in the hindpaw and in the forepaw the TNF levels were higher than normal at each stage of measurement. Our results indicate that a prolonged neuronal activation induced by formalin injection is associated with a change in nociceptive and inflammatory mediators in distal sites of the body. The fact that SP levels are changed in the hindpaw but not in the forepaw might point to the activation of a mechanism of retrograde signaling from central synapses to paw afferent nerves.

Interleukin-6 affects scopolamine-induced amnesia, but not brain amino acid levels in mice

WE have previously shown that, after peripheral administration, different cytokines affect cognitive functions in mice. In this study, we evaluated the effects of mouse interleukin-6 (IL-6) on the classical behavioural test of scopolamine-induced amnesia for a passive avoidance response in the mouse. Pretraining i.p. administration of this cytokine (0.125 and 0.5 μg/mouse) significantly reduced the amnesic action of the muscarinic receptor antagonist. As it is well known that brain amino acids are deeply involved in the modulation of cognitive processes we measured the levels of glutamine, aspartic acid, glutamic acid and GABA in the hippocampus and hypothalamus of mice treated with IL-6. At both doses which affected the cognitive functions, this cytokine had no effect on brain levels of measured amino acids. Neither nociceptive thresholds to a thermal stimulus, nor spontaneous locomotor activity were modified by the acute administration of IL-6 (0.5μg/mouse). Our data confirm previous observations indicating that peripheral administration of cytokines affects some, but not other brain functions and suggest the involvement of IL-6 in the central modifications induced by the immune activation.

Effects of interleukin-1β and interleukin-2 on amino acids levels in mouse cortex and hippocampus

We measured the levels of glutamine, aspartic acid, glutamic acid and GABA in cortex and hippocampus of mice acutely treated with i.p. human recombinant interleukin-2 (IL-2) or human recombinant interleukin-1 beta (IL-1 beta). Administration of IL-2 (5.0 micrograms kg-1) induced a slight but statistically significant increase in glutamine concentrations in both brain areas, while similar administration of IL-1 beta (20 micrograms kg-1) significantly reduced the hippocampal levels of glutamine, glutamic acid and GABA. Our data suggest that brain amino acid pathways are involved in the central modifications induced by IL-1 beta.

GM-CSF affects hypothalamic neurotransmitter levels in mice: involvement of interleukin-1.

WE studied the effects of granulocyte-macrophage colony stimulating factor (GM-CSF) on the brain levels of several neurotransmitters in mice. Administration of GM-CSF (5.0 and 10 μg, i.p.) significantly reduced the hypothalamic levels of glutamine, glutamic acid, GABA and aspartic acid. GM-CSF (5.0 μg, i.p.) also induced a significant reduction of norepinephrine and serotonin levels in the hypothalamus, without affecting dopamine levels. The hippocampal levels of neurotransmitters were not modified by GM-CSF administration. The peripheral administration of a specific interleukin-1 receptor antagonist (IL-1ra, 50 μg, i.p.) blocked the effects of GM-CSF. These results confirm our previous behavioural data suggesting that GM-CSF is able to exert neuromodulatory actions.

Plasma and synovial fluid concentrations of nimesulide and its main metabolite after a single or repeated oral administration in patients with knee osteoarthritis.

The aim of this study was to evaluate plasma and synovial fluid concentrations of the non-steroidal anti-inflammatory drug nimesulide and its major metabolite (hydroxynimesulide, M1), after a single 100 mg dose of nimesulide and a repeated (14 day) administration, 100 mg twice a day, in patients with osteoarthritis of the knee and joint effusion. Nimesulide was rapidly absorbed in plasma and distributed in synovial fluid. On day 1, effective concentrations were present 30 min after the first dose and on day 14, the synovial fluid concentration of nimesulide was significantly higher than that measured on day 1; no accumulation was observed in plasma. After 14 days of treatment, both the plasma and synovial fluid concentrations of M1 were significantly higher than those measured on day 1. These data may help to explain the rapid onset of the analgesic effect of nimesulide demonstrated in several clinical conditions, including painful osteoarthritis.

L-arginine, asymmetric dimethylarginine, and symmetric dimethylarginine in plasma and synovial fluid of patients with knee osteoarthritis.

Background The aim of this study was to investigate the involvement of the nitric oxide (NO) pathway in osteoarthritis (OA). Material/Methods The study groups consisted of 32 patients with knee OA and 31 healthy controls. In peripheral venous blood samples (from the OA patients and the controls) and in synovial fluid samples (from the OA patients), the concentrations of L-arginine (ARN), asymmetric dimethylarginine (ADMA), and symmetric dimethylarginine (SDMA) were evaluated. In plasma samples, thiobarbituric acid reactive substances (TBARS) were also measured. Results Plasma ARN concentrations were lower in the OA patients than in controls (53.55±16.37 vs. 70.20±25.68 μmol/l) (P<0.05), while plasma ADMA concentrations were similar. Accordingly, the ARN/ADMA ratio was lower in the OA patients than in the control group (80.85±29.58 vs. 110.51±30.48, P<0.05). Plasma SDMA and TBARS concentrations were higher in the OA patients than in controls (0.69±0.15 vs. 0.60±0.10 μmol/l, P<0.05 and 1.21±0.29 vs. 0.55±0.12, respectively) (P<0.001). In the OA patients, ADMA concentrations were significantly higher in the synovial fluid than in plasma (0.75±0.09 vs. 0.69±0.14 μmol/l, P<0.05), as were ARN concentrations (76.96±16.73 vs. 53.55±16.73 μmol/l) (P<0.00001). Conclusions These results indicate a poor availability of NO in the synovial fluid of the OA patients, which may contribute to the progression of OA. The decreased ARN/ADMA ratio and the increased SDMA and TBARS in the plasma of the OA patients suggest an impairment of endothelial function in these subjects.