Influence of caffeine on the protective activity of gabapentin and topiramate in a mouse model of generalized tonic-clonic seizures.

BACKGROUND: Caffeine may interact with classical antiepileptic drugs (AEDs), reducing their anticonvulsant effects in basic seizure models. The aim of the present study was to ascertain whether intraperitoneal caffeine (acute or chronic for 15 days) could attenuate the anticonvulsant effect of some newer AEDs: gabapentin (GBP) and topiramate (TPM) against electroconvulsions in mice. METHODS: Maximal electroshock (MES)-induced mouse seizure model was used for the estimation of the anticonvulsant activity of TPM whilst the protective activity of GBP was evaluated in the threshold test for maximal (tonic) convulsions. Adverse effects were evaluated by measurement of long-term memory (the step-through passive avoidance task) and motor coordination (chimney test). Plasma AED concentrations were also measured to determinate any pharmacokinetic contribution to the observed effects. RESULTS: Caffeine (both acute and chronic at 23.1 and 46.2mg/kg) significantly reduced the protective effects of TPM against MES. As regards GBP, caffeine (acutely at 46.2mg/kg and chronically at 23.1 or 46.2mg/kg) significantly diminished the GBP-induced increases in the electroconvulsive threshold. In addition, caffeine did not affect the free plasma concentrations of TPM or GBP. Acute and chronic caffeine (23.1 and 46.2mg/kg) enhanced the impairment of motor coordination in mice pretreated with GBP whilst an opposite effect was observed in TPM injected mice and pretreated with chronic caffeine at 46.2mg/kg. CONCLUSION: The results indicate that newer AEDs, GBP or TPM behave in the exactly same way as classical antiepileptics in mice challenged with caffeine. This hazardous effect of caffeine is not subject to tolerance.

IL-6, IL-10, c-Jun and STAT3 expression in B-CLL.

Chronic lymphocytic leukemia is characterized by the accumulation of functionally abnormal, monoclonal B lymphocytes in the peripheral blood, bone marrow, lymph nodes and spleen, resulting in a reduction count of normal immunocompetent cells and their impaired immune function. The defect in transmission of signals from various types of extracellular receptors, leading to aberrant cytokines and transcription factors gene expression, may underlie the basis of immune failure in B-CLL. The aim of the study was to assess of IL-6, IL-10, c-Jun, and STAT3 expression. In response to antigenic stimulation IL-6, IL-10, c-Jun, and STAT3 proteins induce mutual activity. The subject of the study was subpopulations of leukemic lymphocytes (CD5+ CD19+) and CD19+ B cells from healthy donors (control group). Our results provide evidence that the regulation of IL-6, IL-10, c-Jun, and STAT3 gene expression in CLL B cells is clearly different from normal B lymphocytes. In B-CLL STAT3 expression in unstimulated lymphocytes is significantly higher (p<0.0001) compared with normal subpopulation of B cell. In contrast, IL-6, IL-10, and c-Jun mRNA expressions are statistically lower in B-CLL in comparison with the control group, in all cases (p<0.0001). When analyzing the relationship between c-Jun expression and B-CLL stage according Rai we revealed decreasing c-Jun expression, both at the mRNA and protein levels, along with advancing stage of disease.

Aberrant TIRAP and MyD88 expression in B-cell chronic lymphocytic leukemia.

TIRAP and Myd88 are adaptor proteins for Toll-like receptors-2 and -4 (TLR2/4) which are engaged in transducing the signal to downstream molecules. Several studies have shown the increased role of infection factors in pathogenesis of B cell chronic lymphocytic leukemia (B-CLL). This prompted us to test whether there is a correlation between MyD88-TIRAP dynamics before and after inflammatory stimuli. We determined the mRNA and protein expression of TIRAP and MyD88 in CD5(+)CD19(+) B-CLL cells and in a subpopulation of normal B CD19(+) lymphocytes. Additionally we determined the influence of lipopolysaccharide Escherichia coli - TLR4-ligand (LPS) and Staphylococcus aureus strain Cowan I - TLR2-ligand (SAC) on TIR-domain-containing adaptor protein, also called MyD88 adaptor-like (TIRAP) and myeloid differentiation primary response protein 88 (MyD88) expression. We have found that the mRNA and protein expression of TIRAP and MyD88 in B-CLL lymphocytes is lower compared with that in normal B lymphocytes. LPS and SAC stimulation in normal lymphocytes significantly altered neither TIRAP nor MyD88 mRNA expression, whereas TIRAP protein level substantially decreased after TLR agonist treatment. We did not observe any changes in MyD88 protein level after B lymphocyte stimulation. There was a significant increase in TIRAP mRNA expression after LPS and SAC stimulation of B-CLL cells. MyD88 mRNA expression levels in B-CLL lymphocytes slightly decreased upon treatment with either stimulator. Stimulation with TLR agonists did not cause changes in TIRAP and MyD88 expression at the protein level in B-CLL lymphocytes. The results of our study suggest that there may exist a, yet unknown, defect of TIRAP and MyD88 proteins in B-CLL lymphocytes.

TLR2 may influence the behavior of the malignant clone in B-CLL.

B-cell receptor (BCR) and Toll-like receptor (TLR) stimulation and integration with signals from the pathogen or immune cells and their products determine the B-cell antibody response. Low expression of BCR is the hallmark of B lymphocytes in CLL, however little is known about the expression and function of TLR in B-CLL. We studied TLR2, TLR4, IL-6 and mIL-6Rα expression on mRNA and protein level in CD19(+) subpopulation of normal lymphocytes and the CD19(+)CD5(+) subpopulation from B-CLL. Experiments were performed on unstimulated and stimulated lymphocytes [Staphylococcus aureus Cowan I (SAC) and lipopolysaccharide (LPS) from Escherichia coli - TLR2- and TLR4-specific agonists, respectively]. We showed undetectable or low IL-6 expression, which seems to be specific for B-CLL lymphocytes. Induction of TLR4 mRNA upon LPS stimulation affected the expression of IL-6, but not of mIL-6Rα. Increased expression of TLR2 (MFI) after LPS and SAC stimulation did not correlate with mIL-6Rα receptor expression. B-CLL CD19(+)CD5(+) lymphocytes showed a significant increase in TLR2 expression at the protein level after stimulation with SAC and LPS compared to normal CD19(+) lymphocytes. TLR2 may influence the behaviour of the malignant clone in B-CLL.

Caffeine and the anticonvulsant potency of antiepileptic drugs: experimental and clinical data.

Caffeine (1,3,7-trimethylxanthine) is the most commonly ingested stimulant in the world. The daily consumption of this methylxanthine in coffee, tea and soft drinks is approximately 200 mg per person, which yields a pharmacologically active blood concentration. Experimental data indicate that caffeine may either lower the convulsive threshold in experimental models of epilepsy or induce seizure activity in doses over 400 mg/kg in rodents. Interestingly, animal data have demonstrated that caffeine, at doses far below its convulsive potential, diminishes the protective effects of conventional antiepileptic drugs (AEDs--carbamazepine, phenobarbital, phenytoin, valproate) and the newer AED, topiramate against electroconvulsions in mice. However, in contrast to these AEDs, caffeine did not impair the anticonvulsant efficacy of other newer AEDs, lamotrigine, tiagabine, and oxcarbazepine in this experimental model of epileptic seizure. Although limited, the clinical data generally confirm the experimental findings, suggesting increased seizure frequency in epileptic patients who began ingesting caffeine in high quantities. Thus far, no analysis has been performed in epileptic patients to determine whether the hazardous effects of caffeine are dependent upon individual antiepileptic treatments. These data clearly indicate that methylxanthines should be avoided in epileptic patients.