Anti-tumor necrosis factor properties of non-peptide drugs in acute-phase responses

Clindamycin inhibits nociceptive response by reducing tumor necrosis factor-α and CXCL-1 production and activating opioidergic mechanisms

Clindamycin, a bacteriostatic semisynthetic lincosamide, is useful in the management of infections caused by aerobic and anaerobic Gram-positive cocci, including bacteremic pneumonia, streptococcal toxic shock syndrome and sepsis. It has been recently demonstrated that clindamycin inhibits in vitro and in vivo inflammatory cytokine production. In the present study, we investigated the effects of clindamycin in acute and chronic models of pain and inflammation in mice and the underlying mechanisms. Intraperitoneal (i.p.) administration of clindamycin (400 mg/kg) increased the animal's latency to exhibit the nociceptive behavior induced by noxious heat (hot plate model). Intrathecal injection of clindamycin (2, 10 and 50 µg) also increased the animals' latency to exhibit the nociceptive behavior. Tactile hypersensitivity and paw edema induced by intraplantar (i.pl.) injection of carrageenan were attenuated by previous administration of clindamycin (200 and 400 mg/kg, i.p.). Clindamycin (100, 200 and 400 mg/kg, i.p.) also attenuated ongoing tactile hypersensitivity and paw edema induced by i.pl. injection of complete Freund's adjuvant (CFA). The antinociceptive activity of clindamycin (400 mg/kg, i.p.) in the hot plate model was attenuated by previous administration of naltrexone (5 and 10 mg/kg, i.p.), but not glibenclamide or AM251. CFA-induced production of TNF-α and CXCL-1 was reduced by clindamycin (400 mg/kg, i.p.). Concluding, clindamycin exhibits activities in acute and chronic models of pain and inflammation. These effects are associated with reduced production of TNF-α and CXCL-1 and activation of opioidergic mechanisms. Altogether, these results indicate that the clindamycin's immunomodulatory effects may contribute to a pharmacological potential beyond its antibiotic property.

Dihydrotestosterone Increases Cytotoxic Activity of Macrophages on Prostate Cancer Cells via TRAIL

Although androgen deprivation therapy (ADT) and immunotherapy are potential treatment options in men with metastatic prostate cancer (CaP), androgen has conventionally been proposed to be a suppressor of the immune response. However, we herein report that DHT activates macrophages. When the murine macrophage cell line (RAW 264.7), human monocyte cell line (THP-1), and human peripheral blood monocytes were cultured with androgen-resistant CaP cell lines, DHT increased cytotoxicity of macrophages in a concentration-dependent manner. Further studies revealed that DHT induced M1 polarization and increased the expression levels of TNF-related apoptosis-inducing ligand (TRAIL) in macrophages and that this effect was abrogated when TRAIL was neutralized with a blocking antibody or small interfering RNA. Subsequent experiments demonstrated that induction of TRAIL expression was regulated by direct binding of androgen receptor to the TRAIL promoter region. Finally, an in vivo mouse study demonstrated that castration enhanced the growth of an androgen-resistant murine CaP tumor and that this protumorigenic effect of castration was blocked when macrophages were removed with clodronate liposomes. Collectively, these results demonstrate that DHT activates the cytotoxic activity of macrophages and suggest that immunotherapy may not be optimal when combined with ADT in CaP.

Pentamidine Inhibits Titanium Particle-Induced Osteolysis In Vivo and Receptor Activator of Nuclear Factor-κB Ligand-Mediated Osteoclast Differentiation In Vitro

Background

Wear debris-induced osteolysis leads to periprosthetic loosening and subsequent prosthetic failure. Since excessive osteoclast formation is closely implicated in periprosthetic osteolysis, identification of agents to suppress osteoclast formation and/or function is crucial for the treatment and prevention of wear particle-induced bone destruction. In this study, we examined the potential effect of pentamidine treatment on titanium (Ti) particle-induced osteolysis, and receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis.

Methods

The effect of pentamidine treatment on bone destruction was examined in Ti particle-induced osteolysis mouse model. Ti particles were implanted onto mouse calvaria, and vehicle or pentamidine was administered for 10 days. Then, calvarial bone tissue was analyzed using micro-computed tomography and histology. We performed in vitro osteoclastogenesis assay using bone marrow-derived macrophages (BMMs) to determine the effect of pentamidine on osteoclast formation. BMMs were treated with 20 ng/mL RANKL and 10 ng/mL macrophage colony-stimulating factor in the presence or absence of pentamidine. Osteoclast differentiation was determined by tartrate-resistant acid phosphatase staining, real-time polymerase chain reaction, and immunofluorescence staining.

Results

Pentamidine administration decreased Ti particle-induced osteoclast formation significantly and prevented bone destruction compared to the Ti particle group in vivo. Pentamidine also suppressed RANKL-induced osteoclast differentiation and actin ring formation markedly, and inhibited the expression of nuclear factor of activated T cell c1 and osteoclast-specific genes in vitro. Additionally, pentamidine also attenuated RANKL-mediated phosphorylation of IκBα in BMMs.

Conclusion

These results indicate that pentamidine is effective in inhibiting osteoclast formation and significantly attenuates wear debris-induced bone loss in mice.

Pentamidine blocks hepatotoxic injury in mice

Toxin-induced liver diseases lack effective therapies despite increased understanding of the role factors such as an overactive innate immune response play in the pathogenesis of this form of hepatic injury. Pentamidine is an effective antimicrobial agent against several human pathogens, but studies have also suggested that this drug inhibits inflammation. This potential anti-inflammatory mechanism of action, together with the development of a new oral form of pentamidine isethionate VLX103, led to investigations of the effectiveness of this drug in the prevention and treatment of hepatotoxic liver injury. Pretreatment with a single injection of VLX103 in the d-galactosamine (GalN) and lipopolysaccharide (LPS) model of acute, fulminant liver injury dramatically decreased serum alanine aminotransferase levels, histological injury, the number of terminal deoxynucleotide transferase-mediated deoxyuridine triphosphate nick end-labeling (TUNEL)-positive cells and mortality compared with vehicle-injected controls. VLX103 decreased GalN/LPS induction of tumor necrosis factor (TNF) but had no effect on other proinflammatory cytokines. VLX103 prevented the proinflammatory activation of cultured hepatic macrophages and partially blocked liver injury from GalN/TNF. In GalN/LPS-treated mice, VLX103 decreased activation of both the mitochondrial death pathway and downstream effector caspases 3 and 7, which resulted from reduced c-Jun N-terminal kinase activation and initiator caspase 8 cleavage. Delaying VLX103 treatment for up to 3 hours after GalN/LPS administration was still remarkably effective in blocking liver injury in this model. Oral administration of VLX103 also decreased hepatotoxic injury in a second more chronic model of alcohol-induced liver injury, as demonstrated by decreased serum alanine and aspartate aminotransferase levels and numbers of TUNEL-positive cells.

CONCLUSION

VLX103 effectively decreases toxin-induced liver injury in mice and may be an effective therapy for this and other forms of human liver disease. (Hepatology 2017;66:922-935).

A novel zebrafish model to provide mechanistic insights into the inflammatory events in carrageenan-induced abdominal edema

A suitable small animal model may help in the screening and evaluation of new drugs, especially those from natural products, which can be administered at lower dosages, fulfilling an urgent worldwide need. In this study, we explore whether zebrafish could be a model organism for carrageenan-induced abdominal edema. The research results showed that intraperitoneal (i.p.) administration of 1.5% λ-carrageenan in a volume of 20 µL significantly increased abdominal edema in adult zebrafish. Levels of the proinflammatory proteins tumor necrosis factor-α (TNF-α) and inducible nitric oxide synthase (iNOS) were increased in carrageenan-injected adult zebrafish during the development of abdominal edema. An associated enhancement was also observed in the leukocyte marker, myeloperoxidase (MPO). To support these results, we further observed that i.p. methylprednisolone (MP; 1 µg), a positive control, significantly inhibited carrageenan-induced inflammation 24 h after carrageenan administration. Furthermore, i.p. pretreatment with either an anti-TNF-α antibody (1∶5 dilution in a volume of 20 µL) or the iNOS-selective inhibitor aminoguanidine (AG; 1 µg) inhibited carrageenan-induced abdominal edema in adult zebrafish. This new animal model is uncomplicated, easy to develop, and involves a straightforward inducement of inflammatory edema for the evaluation of small volumes of drugs or test compounds.

Activities of 2-phthalimidethanol and 2-phthalimidethyl nitrate, phthalimide analogs devoid of the glutarimide moiety, in experimental models of inflammatory pain and edema

The reintroduction of thalidomide in the pharmacotherapy greatly stimulated the interest in the synthesis and pharmacological evaluation of phthalimide analogs with new and improved activities and also greater safety. In the present study, we evaluated the activities of two phthalimide analogs devoid of the glutarimide ring, namely 2-phthalimidethanol (PTD-OH) and 2-phthalimidethyl nitrate (PTD-NO), in experimental models of inflammatory pain and edema in male C57BL/6J mice. Intraplantar (i.pl.) injection of carrageenan (300 μg) induced mechanical allodynia and this response was inhibited by previous per os (p.o.) administration of PTD-OH and PTD-NO (750 mg/kg) and also by thalidomide (500 or 750 mg/kg). The edema induced by carrageenan was also inhibited by previous p.o. administration of PTD-OH (500 and 750 mg/kg) and PTD-NO (125, 250, 500 or 750 mg/kg), but not by thalidomide. Carrageenan increased tumor necrosis factor (TNF)-α and CXCL1 concentrations and also the number of neutrophils in the paw tissue. Previous p.o. administration of PTD-NO (500 mg/kg) reduced all the parameters, while PTD-OH (500 mg/kg) reduced only the accumulation of neutrophils. Thalidomide, on the other hand, was devoid of effect on these biochemical parameters. Plasma concentrations of nitrite were increased after p.o. administration of the phthalimide analog coupled to a NO donor, PTD-NO (500 mg/kg), but not after administration of PTD-OH or thalidomide. In conclusion, our results show that small molecules, structurally much simpler than thalidomide or many of its analogs under investigation, exhibit similar activities in experimental models of pain and inflammation. Finally, as there is evidence that the glutarimide moiety contributes to the teratogenic effect of many thalidomide analogs, our results indicate that phthalimide analogs devoid of this functional group could represent a new class of analgesic and anti-inflammatory candidates with potential greater safety.

In vivo effects of pentoxifylline on enzyme and non-enzyme antioxidant levels in rat liver after carrageenan-induced paw inflammation

The present study aimed to investigate the effects of pentoxifylline (PTX) on the carrageenan (CG)-induced paw oedema and on the endogenous levels of cell enzyme and non-enzyme antioxidants in rat liver, 4 and 24 h after CG injection. PTX (50 mg kg(-1) , i.p.), administered 30 min before CG, decreased the paw oedema, 2-4 h after CG administration. The drug protected CG-induced decrease of glutathione (non-enzyme antioxidant) and had no effect on CG-unchanged activities of superoxide dismutase, glutathione peroxidase (enzyme antioxidants) and glucose-6-phosphate dehydrogenase (enzyme, important for the activity of GSH-conjugated antioxidant enzymes). The drug showed a good antioxidant capacity in chemical systems, generating reactive oxygen species. The present results suggest that the antioxidant activity of PTX might contribute to its beneficial effects in liver injuries.

Characterization of the antinociceptive and anti-inflammatory activities of riboflavin in different experimental models

Riboflavin, similar to other vitamins of the B complex, presents anti-inflammatory activity but its full characterization has not yet been carried out. Therefore, we aimed to investigate the effect of this vitamin in different models of nociception, edema, fever and formation of fibrovascular tissue. Riboflavin (25, 50 or 100 mg/kg, i.p.) did not alter the motor activity of mice in the rota-rod or the open field models. The second phase of the nociceptive response induced by formalin in mice was inhibited by riboflavin (50 or 100 mg/kg). The first phase of this response and the nociceptive behavior in the hot-plate model were inhibited only by the highest dose of this vitamin. Riboflavin (25, 50 or 100 mg/kg, i.p.), administered immediately and 2 h after the injection of carrageenan, induced antiedema and antinociceptive effects. The antinociceptive effect was not inhibited by the pretreatment with cadmium sulfate (1 mg/kg), an inhibitor of flavokinase. Riboflavin (50 or 100 mg/kg, i.p., 0 and 2 h) also inhibited the fever induced by lipopolysaccharide (LPS) in rats. Moreover, the formation of fibrovascular tissue induced by s.c. implant of a cotton pellet was inhibited by riboflavin (50 or 100 mg/kg, i.p., twice a day for one week). Riboflavin (10 or 25 mg/kg, i.p.) also exacerbated the effect of morphine (2, 4 or 8 mg/kg, i.p.) in the mouse formalin test. In conclusion, the study demonstrates the antinociceptive and anti-inflammatory activities of riboflavin in different experimental models. These results, associated with the fact that riboflavin is a safe drug, is approved for clinical use and exacerbates the antinociceptive effect of morphine, may warrant clinical trials to assess its potential in the treatment of different painful or inflammatory conditions.

Lipopolysaccharide-mediated regulation of hepatic transporter mRNA levels in rats

The function of hepatic transporters is to move organic substances across sinusoidal and canalicular membranes. During extrahepatic cholestasis, transporters involved in the movement of substances from blood to bile, such as sodium/taurocholate-cotransporting polypeptide (Ntcp) and multidrug resistance protein 2 (Mrp2), are down-regulated, whereas others that transport chemicals from liver to blood, such as Mrp3, are up-regulated. Unlike extrahepatic cholestasis, where transporter expression responds to the stress of accumulating bile constituents, lipopolysaccharide (LPS)-induced intrahepatic cholestasis may be directly caused by alterations in transporter expression. The aim of this study was to quantitatively determine the effect of LPS on transporter expression and study the mechanism(s) by which LPS alters mRNA levels of major hepatic transporters in Sprague-Dawley rats. Hepatic mRNA levels of Mrp2, Mrp6, multiple drug resistance protein 1a (Mdr1a), organic anion-transporting polypeptide 1 (Oatp1), Oatp2, Oatp4, Ntcp, bile salt export pump, organic cation transporter 1 (Oct1), and organic anion transporter 3 (Oat3) were dramatically decreased, beginning approximately 6 h after LPS administration, whereas Mrp5 and Oat2 levels were unchanged. In contrast, LPS increased mRNA levels of Mrp1, Mrp3, and Mdr1b concurrently with the down-regulated transporters. Pretreatment with dexamethasone, which decreases the release of cytokines, reversed the reduction of Mdr1a, Oatp1, Oatp2, Oct1, and Ntcp mRNA following LPS administration. Furthermore, dexamethasone pretreatment also prevented the LPS-mediated increase in Mrp1, Mrp3, and Mdr1b, whereas pretreatment with aminoguanidine or gadolinium chloride, an inhibitor of inducible nitric oxide synthetase and a Kupffer cell toxicant, respectively, had no effect on the LPS-induced changes. The concurrent repression and induction of various transporters, as well as dexamethasone abatement of both LPS-mediated repression and induction, indicates that these responses may be mediated through similar pathways.

Curative effects of sodium fusidate on the development of dinitrobenzenesulfonic acid-induced colitis in rats

Fusidic acid and sodium fusidate (fusidin) are antibiotics with low toxicity and powerful immunomodulatory activities in vitro and in vivo. In this study we have evaluated the effect of fusidin on the development of dinitrobenzenesulfonic acid (DNB)-induced colitis in rats that serves as a preclinical model of human inflammatory bowel disease (IBD). The data show that when administered orally at the dose of 80 (but not 40) mg/kg body wt under a "therapeutic" regimen soon after DNB application, fusidin significantly ameliorates clinical, histological, and seroimmunological signs of disease. These entailed a significant reduction in body weight loss, smaller increase in colon weights, milder macroscopic damage, and lower histological scores. In addition, when sacrificed at the end of the study, fusidin-treated rats had significantly lower blood levels of tumor necrosis factor alpha and interferon-gamma compared with untreated controls. The present findings concur with the beneficial actions of fusidin in a pilot study conducted in patients with Crohn's disease and warrant controlled studies in humans with IBD.

Shiga-like toxin II impairs hepatobiliary transport of doxorubicin in rats by down-regulation of hepatic P glycoprotein and multidrug resistance-associated protein Mrp2

We investigated the effect of Shiga-like toxin II (SLT-II), derived from Escherichia coli O157:H7, on the hepatobiliary excretion of doxorubicin, a substrate for P glycoprotein and the multidrug resistance-associated protein Mrp2, and on the expression of P glycoprotein and Mrp2 in rats. Histopathological examination did not show any liver injury in SLT-II-treated rats. A significant delay in the disappearance of doxorubicin from plasma after its intravenous administration (5 mg/kg of body weight) was observed in rats treated 24 h earlier with SLT-II (2 micro g/animal). When rats received an infusion of doxorubicin (2.6 micro g/min) 24 h after intravenous injection of SLT-II, the steady-state concentration of doxorubicin in plasma increased and the bile flow decreased, whereas the concentration in liver did not alter. SLT-II significantly increased the unbound fraction of doxorubicin in plasma but did not alter the concentration in liver tissue. SLT-II significantly decreased the biliary excretion rate and biliary clearance of doxorubicin based on the total concentration and concentration of the unbound fraction in plasma and liver. Western blot analysis revealed that SLT-II down-regulated P glycoprotein and Mrp2 in the liver, which could explain the observed decrease in the biliary excretion of doxorubicin by SLT-II. A tumor necrosis factor alpha (TNF-alpha) production inhibitor, pentoxifylline, could not protect SLT-II-induced decreases in the biliary clearance of doxorubicin and down-regulation of both transporters. It is unlikely that TNF-alpha plays a major role in the SLT-II-induced decrease in the hepatobiliary transport of doxorubicin and the down-regulation of both transporters.

Shiga-like toxin II modifies brain distribution of a P-glycoprotein substrate, doxorubicin, and P-glycoprotein expression in mice

The effect of Shiga-like toxin II (SLT-II), which was derived from Escherichia coli O157:H7, on doxorubicin transport across the blood-brain barrier (BBB) and P-glycoprotein function, was investigated in ddY mice. Doxorubicin (30 mg kg(-1)) was administered intravenously or fluorescein isothiocyanate labeled dextran (FD-4) was infused (20 microg min(-1)) to the mice, who had received an intravenous injection of SLT-II (0.2 microg/animal) 6 or 24 h earlier. Blood and brain were removed 4 h after injection of doxorubicin or 60 min after infusion of FD-4. SLT-II significantly elevated the brain concentration and brain-to-plasma concentration ratio (K(p)) of doxorubicin and FD-4 24 h after injection, but did not alter 6 h after. Cyclosporin A (200 mg kg(-1)) significantly increased the K(p) value of doxorubicin in the control mice, but did not alter it in mice treated 24 h earlier with SLT-II. Pentoxifylline (100 mg kg(-1)) a TNF-alpha production inhibitor, ameliorated SLT-II-induced increases in the brain concentrations of both drugs and the K(p) value of FD-4, suggesting that TNF-alpha, at least in part, causes damage to the brain capillaries. Western blot analysis revealed that SLT-II increased the protein level of P-glycoprotein in the brain of mice 6 h after injection and the increased level remained unchanged for 24 h. SLT-II did not change ATP content in the brain of mice. These results suggest that the increased P-glycoprotein level cannot explain SLT-II-induced increase in the doxorubicin accumulation in brain. The present findings indicate that SLT-II impairs the BBB function and doxorubicin transport across the BBB, while it overexpresses P-glycoprotein.

Shiga-like toxin II derived from Escherichia coli O157:H7 modifies renal handling of levofloxacin in rats

The effect of Shiga-like toxin II (SLT-II) (2 microg/animal), which was derived from Escherichia coli O157:H7, on renal handling of levofloxacin (LVX), a model drug for quinolone antimicrobial agents, was investigated in rats 24 h after intravenous injection. In histopathological examination, acute tubular injury was observed in SLT-II-treated rats, but the glomeruli were not injured. SLT-II significantly increased the steady-state concentration of LVX in plasma to 1.5-fold that of control rats. SLT-II induced significant decreases in the glomerular filtration rate (GFR) and renal clearance (CL(R)) of LVX. SLT-II slightly, but significantly, increased the unbound fraction and decreased renal plasma flow with no change in the extraction ratio of p-aminohippurate. SLT-II significantly increased concentrations of tumor necrosis factor alpha (TNF-alpha) and nitrite and nitrate (NOx) in plasma. The TNF-alpha inhibitor pentoxifylline partly, but significantly, inhibited SLT-II-induced decreases in the GFR and CL(R) of LVX; in contrast, S-methylisothiourea, a selective inhibitor of inducible nitric oxide synthase, did not. Western blotting analysis revealed that SLT-II did not alter the levels of multidrug resistance-associated protein 2 (Mrp2) and P-glycoprotein in kidneys 24 h after injection, assuming the lack of involvement of Mrp2 and P-glycoprotein in SLT-II-induced acute renal tubular injury and renal handling of LVX observed 24 h after SLT-II injection. The present study suggests that SLT-II impairs the renal handling of LVX by decreasing GFR and causing decreased renal plasma flow.

Effects of pentoxifylline on pulmonary function and results of cytologic examination of bronchoalveolar lavage fluid in horses with recurrent airway obstruction

OBJECTIVES

To determine the effects of pentoxifylline (PTX) administration on lung function and results of cytologic examination of bronchoalveolar lavage fluid in horses affected by recurrent airway obstruction (RAO).

ANIMALS

10 RAO-affected horses.

PROCEDURES

6 horses were orally administered PTX (16 g) mixed with corn syrup, and 4 horses were administered corn syrup alone, twice daily for 14 days. Pulmonary function was evaluated before administration (day 0) and on days 8 and 15. Bronchoalveolar lavage (BAL) was performed on days 0 and 15. Reversibility of airway obstruction was assessed by measuring pulmonary function before and after administration of atropine (0.02 mg/kg, IV). Serum concentration of PTX was measured in 4 horses 30 minutes and 2 and 4 hours after administration of PTX on days 1, 2, 3, 7 and 14.

RESULTS

Administration of PTX to BAO-affected horses resulted in a decrease in elastance value on day 8 and on elastance and resistance (RL) values on days 8 and 15. Results for cytologic examination of BAL fluid obtained on day 15 did not differ significantly, compared with values for day 0. Values of RL decreased in all horses following administration of atropine. When mixed in corn syrup and administered orally, PTX was poorly absorbed in horses, and there was noticeable variation in serum PTX concentrations over time and among horses.

CONCLUSIONS AND CLINICAL RELEVANCE

Based on these results, it can be concluded that administration of PTX at high doses improved respiratory function of RAO-affected horses maintained in an unfavorable environment.

Effect of endotoxin on P-glycoprotein-mediated biliary and renal excretion of rhodamine-123 in rats

The effects of Klebsiella pneumoniae endotoxin on the biliary excretion and renal handling of rhodamine-123 were investigated in rats at different times after intraperitoneal injection (1 mg/kg of body weight). The typical substrates for P glycoprotein, i.e., cyclosporine, colchicine, and erythromycin, inhibited the biliary clearance of rhodamine-123, whereas a substrate for organic cation transporter, cimetidine, did not inhibit clearance, suggesting that rhodamine-123 is transported mainly by P glycoprotein. The biliary, renal, and tubular secretory clearances of rhodamine-123 and the glomerular filtration rate significantly decreased 6 h after injection of endotoxin but returned to control levels by 24 h. These results suggest that endotoxin-induced decreases in P-glycoprotein-mediated biliary excretion and renal handling of rhodamine-123 were probably due to impairment of P-glycoprotein-mediated transport ability. Pretreatment with pentoxifylline (50 mg/kg) significantly inhibited endotoxin-induced increases in tumor necrosis factor alpha (TNF-alpha) levels in plasma, which ameliorated the endotoxin-induced reduction of the biliary excretion of rhodamine-123. It is likely that endotoxin-induced impairment of the transport of rhodamine-123 is caused, in part, by overproduction of TNF-alpha. The effect of endotoxin on the expression of P-glycoprotein mRNA in liver and kidneys of rats was investigated by using a reverse transcriptase PCR. The expression of Mdr1a mRNA in both liver and kidney decreased 6 h after endotoxin injection and returned to control levels after 24 h, whereas the expression of Mdr1b mRNA in liver increased at both times and that in kidney decreased at 24 h. These findings suggest that K. pneumoniae endotoxin dramatically decreases P-glycoprotein-mediated biliary and renal excretion of rhodamine-123 probably by decreasing the expression of Mdr1a, which is likely due to increased plasma TNF-alpha levels.

Sodium fusidate (fusidin) ameliorates the course of monophasic experimental allergic encephalomyelitis in the Lewis rat

We have evaluated the effect of the immunosuppressant sodium fusidate (fusidin) on the course of acute monophasic experimental encephalomyelitis (EAE) in male Lewis rats. Prophylactic treatment with fusidin, 80 or 120 mg/kg bd wt., markedly ameliorated the course of the disease in rats immunized with myelin basic proteins in complete Freund's adjuvant, entailing delayed onset of symptoms, lower clinical scores and more rapid recovery than PBS-treated control rats. The fusidin-treated, immunized rats exhibited milder mononuclear cell infiltration of brains and spinal cords than control animals. These data provide further evidence for the anti-inflammatory effect of fusidin and suggest that this drug may be valuable for the treatment of human multiple sclerosis.

Role of vagus nerve signaling in CNI-1493-mediated suppression of acute inflammation

CNI-1493 is a potent anti-inflammatory agent, which deactivates macrophages and inhibits the synthesis of proinflammatory mediators. The objective of the present study was to identify the role of the central nervous system (CNS) and efferent vagus nerve signaling in CNI-1493-mediated modulation of acute inflammation in the periphery. CNI-1493 was administered either intracerebroventricularly (i.c.v., 0.1-1,000 ng/kg) or intravenously (i.v., 5 mg/kg) in anesthetized rats subjected to a standard model of acute inflammation (subcutaneous (s.c.) injection of carrageenan). I.c.v. CNI-1493 significantly suppressed carrageenan-induced paw edema, even in doses at least 6-logs lower than those required for a systemic effect. Bilateral cervical vagotomy or atropine blockade (1 mg/kg/h) abrogated the anti-inflammatory effects of CNI-1493 (1 microg/kg, i.c.v. or 5 mg/kg, i.v.), indicating that the intact vagus nerve is required for CNI-1493 activity. Recording of the efferent vagus nerve activity revealed an increase in discharge rate starting at 3-4 min after CNI-1493 administration (5 mg/kg, i.v.) and lasting for 10-14 min (control activity=87+/-5.4 impulses/s versus CNI-1493-induced activity= 229+/-6.7 impulses/s). Modulation of efferent vagus nerve activity by electrical stimulation (5 V, 2 ms, 1 Hz) of the transected peripheral vagus nerve for 20 min (10 min before carrageenan administration and 10 min after) also prevented the development of acute inflammation. Local administration of the vagus nerve neurotransmitter, acetylcholine (4 microg/kg, s.c.), or cholinergic agonists into the site of carrageenan-injection also inhibited acute inflammation. These results now identify a previously unrecognized role of efferent vagus nerve activity in mediating the central action of an anti-inflammatory agent.

Sodium fusidate ameliorates the course of diabetes induced in mice by multiple low doses of streptozotocin

We studied the effects of the immunosuppressant sodium fusidate (fusidin) on murine immunoinflammatory diabetes mellitus (DM) induced by multiple low doses of streptozotocin (SZ). Fusidin was given by gavage to three strains of mice (C57KsJ, C57BL/6, CD1) at doses 10 or 100 mg/kg body weight every other day. The drug was administered as an early or late prophylactic regime starting either 1 day prior to the first or after the fifth and last injection of SZ. In both situations the largest dose of fusidin successfully reduced the clinical, chemical and histological signs of DM, the treated mice having significantly lower glycaemic values and milder (often absent) insulitis compared with sham-treated animals or controls given SZ alone. The antidiabetogenic effect was long-lasting as it was maintained up to 1 month after cessation of therapy. In contrast, fusidin prophylaxis failed to prevent development of hyperglycaemia acutely induced by one single and high (160 mg/kg) dose of SZ, which is a model of DM primarily due to the toxic action of SZ on the beta cells and does not involve immunopathogenetic mechanisms. On day 14 after SZ, fusidin markedly altered the circulating cytokine profile induced in vivo by ConA, reducing the levels of IFN-gamma, IL-2 and TNF-alpha and augmenting the level of IL-6. However, only the inhibitory effect of the drug on the synthesis/release of IFN-gamma seemed to be causally related to its capacity to counteract the SZ-induced DM. In fact, the disease was prevented by a neutralizing monoclonal antibody (mAb) against IFN-gamma, but not by anti-IL-2 receptor mAb, a soluble form of TNF-receptor type 1 or recombinant human IL-6. The prevention of disease by fusidin was also partly reversed by exogenously administered recombinant mouse IFN-gamma. The data provide further in-vivo evidence for the anti-diabetogenic and immunomodulatory properties of fusidin and indicate that this drug could have a role in prevention and treatment of human type 1 DM.

Lipopolysaccharide-induced lung injury in mice. I. Concomitant evaluation of inflammatory cells and haemorrhagic lung damage

Intratracheal instillation of lipopolysaccharide (LPS) induces an inflammatory response characterized by infiltration of polymorphonuclear neutrophils (PMNs) into the extracellular matrix and by the release of mediators that play a fundamental role in lung damage. In the present study, we developed a mouse model which allows correlation of the inflammatory response and haemorrhagic tissue injury in the same animal. In particular, the different steps of the inflammatory response and tissue damage were evaluated by the analysis of three parameters: myeloperoxidase (MPO) activity in the parenchyma, reflecting PMNs accumulation into the lung, inflammatory cells count in the bronchoalveolar lavage fluid (BALF), reflecting their extravasation, and total haemoglobin estimation in BALF, a marker of haemorrhagic tissue damage consequent to PMNs degranulation. In our experimental conditions, intra-tracheal administration of 10 microg/mouse of LPS evoked an increase of MPO activity in the lung at 4 h (131%) and 6 h (147%) from endotoxin challenge. A significant increase of PMNs in the BALF was noticed at these times with a plateau between the 12nd and 24th h. PMN accumulation produced a time-dependent haemorrhagic lung damage until 24 h after LPS injection (4 h: +38%; 6 h: +23%; 12 h: +44%; 24 h: +129% increase of haemoglobin concentration in the BALF vs. control). Lung injury was also assessed histopathologically. Twenty-four hours after the challenge, diffuse alveolar haemorrhage, as well as PMN recruitment in the interstitium and alveolus were observed in the LPS group. This model was pharmacologically characterized by pretreatment of LPS-treated mice with antiinflammatory drugs acting on different steps of the <<inflammatory cascade>>. We demonstrated that: a) betamethasone (1, 3, 10, 30 mg/kg p.o.) reduced in a dose-dependent manner the MPO activity, the number of inflammatory cells and, at the same time, lung injury; b) pentoxifylline, a TNFalpha production inhibitor (200 mg/kg i.p.), inhibited PMN extravasation and lung haemorrhage but it was not able to reduce MPO activity in the lung; c) L-680,833, an anti-elastase compound (30 mg/kg po), decreased significantly only the haemorrhagic lung damage; d) indomethacin, a non steroidal antiinflammatory drug (5 mg/kg p.o.), did not show any effect on any of the parameters considered. In conclusion, our in vivo mouse model is a practical alternative to animal models of ARDS (Adult Respiratory Distress Syndrome) recently described and it permits to dissect and to characterize the different steps of PMNs infiltration and, at the same time, the damage caused by their activation.

Lipopolysaccharide-induced lung injury in mice. II. Evaluation of functional damage in isolated parenchyma strips

Pulmonary inflammatory diseases are characterized by changes in airway responsiveness. This phenomenon is commonly related to the action of inflammatory mediators produced by infiltrated leukocytes. The aim of this study was to investigate in an ex vivo experimental model the effect of acute instillation of lipopolysaccharide (bacterial endotoxin; LPS) on lung parenchyma contractility. We firstly characterized the responsiveness of isolated murine lung to airway stimuli. Murine parenchymal strips were found to be mainly sensitive to 5-hydroxytryptamine (5-HT) while the cholinergic agonist, methacholine (MCh), evoked a smaller contractile response. 5-HT responsiveness was inhibited by methysergide. No significant parenchymal contraction was evoked by histamine, substance P and bradykinin. Lung responsiveness to 5-HT was significantly reduced by in vivo LPS treatment and this effect was only partially paralleled by leukocyte infiltration. In addition, LPS-induced hyporesponsiveness was significantly inhibited by betamethasone (BMS) or pentoxifylline (PTX) pretreatment suggesting that 5-HT lung hyporesponsiveness could be mediated by LPS-induced inflammatory mediators such as inflammatory cytokines.

The effect of pentoxifiline on post-injury hyperalgesia in rats and postoperative pain in patients

Recent studies demonstrate that activation of proinflammatory cytokines following injury intensifies the process of nociception. The present investigation assessed the influence of pre-injury pentoxifiline (PTFL, a non-specific cytokine inhibitor) on the development of post-injury nociception in animals and patients. It was established that intrathecal or intraperitoneal PTFL, elevated the nociceptive threshold for mechanical stimuli in the formalin test in rats. Pre-injury PTFL also inhibited pain-related behaviour. These findings correlate with a lower TNFalpha level in the serum of animals receiving pre-injury PTFL. In clinical investigations PTFL was administered intravenously before elective cholecystectomy. Patients who received preoperative PTFL had lower opioid requirements in the early postoperative period than control. At the same time, serum levels of TNFalpha and IL6 were lower in the PTFL group. Our results confirm the hypothesis as to the possibility of modulating of nociception through preemptive administration of a cytokine inhibitor.

Cytochromes and cytokines: changes in drug disposition in animals during an acute phase response: a mini-review

Diseases are a major cause of variation in drug response. Although many different diseases are known that have an effect on the pharmacokinetics or sometimes the pharmacodynamics of a drug, disorders associated with a so-called acute phase response (APR) are the most important in this respect. During APR, for example caused by tissue damage or invasion of a pathogen, a group of symptoms can be observed that often include fever, lassitude, inhibition of gastric function and synthesis of acute phase proteins. All phases that together determine the pharmacokinetic profile of a drug, absorption, distribution, metabolism and excretion, can be affected during APR. From a clinical point of view however, the effects on absorption and metabolism are the most relevant. For drugs that are given orally, a slower absorption rate is often observed during APR due to a delayed gastric emptying. Even more important from a clinical point of view is the depression of biotransformation capacity in the liver during APR, especially affecting the enzymes of the cytochrome P450 (CYP450) complex. Although much has become known about the mechanism of this effect, a number of questions remain. Cytokines, nitric oxide and possibly the enzyme heme oxygenase are playing a role in a complex process that depends on a mutual interaction between Kupffer cells (macrophages) and hepatocytes in the liver. The clinician should be aware of unexpected changes in drug effects or residue levels due to cumulation of the compound during disease or after vaccination. In these situations, drugs that are excreted unchanged may be better alternatives.

Evidence that mast cell degranulation, histamine and tumour necrosis factor alpha release occur in LPS-induced plasma leakage in rat skin

1. In the present study we investigated the role of mast cells during inflammation in rat skin. As the release of several pro-inflammatory mediators, such as histamine and tumour necrosis factor alpha (TNFalpha), occurs following mast cell activation we studied whether mast cell degranulation and the release of both histamine (H) and TNFalpha occurred in a model of lipopolysaccharide (LPS)-induced plasma leakage in rat skin. 2. Plasma leakage in the rat skin was measured over a period of 2 h as the local accumulation of intravenous injection of 125I-human serum albumin (125I-HSA) in response to intradermal injection of LPS. LPS (10 microg site-1) produced an increase of plasma leakage (50.1+/-2.3 microl site-1) as compared to saline (9.0+/-3.2 microl site-1). Histological analysis of rat tissue showed that LPS induced a remarkable mast cell degranulation (59.8+/-2.1%) as compared to saline (13.5+/-2.2%). 3. Ketotifen (10-9 - 10-7 mol site-1), a well-known mast cell-membrane stabilizer, produced a dose-related inhibition of LPS-induced plasma leakage by 36+/-3.5%, 47+/-4.0%, 60+/-3.3% respectively. In addition, ketotifen (10-7 mol site-1) inhibited mast cell degranulation by 59. 2+/-2.7%. 4. Chlorpheniramine maleate (CPM) (10-9 - 10-7 mol site-1), an H1 histamine receptor antagonist only partially inhibited LPS-induced plasma leakage in rat skin (38+/-1.1% at the highest dose). Furthermore, CPM (10-7 mol site-1) did not prevent mast cell degranulation. 5. A polyclonal antibody against TNFalpha (1:500, 1:100, 1:50 v v-1 dilution), locally injected, decreased LPS-induced plasma leakage in the skin by 15+/-2.0%, 24+/-2.1% and 50+/-3.0% respectively. 6. Taken together these results suggest that LPS-induced plasma leakage in rat skin is mediated, at least in part, by mast cell degranulation and by the release of histamine and TNFalpha from these cells.

Amelioration of experimental allergic neuritis by sodium fusidate (fusidin): suppression of IFN-gamma and TNF-alpha and enhancement of IL-10

The immunomodulating antibiotic drug fusidic acid and its sodium salt sodium fusidate (fusidin) ameliorate several organ-specific immunoinflammatory diseases. Because preliminary observations suggest that fusidin may also exert a beneficial effect in Guillain-Barré syndrome (GBS), here we have studied the effects of fusidin on actively induced experimental autoimmune neuritis (EAN) in rats, a known animal model for GBS. Both prophylactic and therapeutic treatment with fusidin (4 mg/rat day ip) markedly ameliorated the clinical course of the disease compared to vehicle-treated animals. The beneficial effects were associated with profound modifications of the capacity of these rats to produce and release pro- and anti-inflammatory cytokines such as IFN-gamma, TNF-alpha and IL-10, which are important in regulating the development of EAN.

Fusidic acid non-antibacterial activity

In 1978 the first report was published indicating that fusidic acid had an immunomodulatory effect. This study describing an in vitro effect on white cells was followed by an in vivo study showing improved survival in heart transplanted mice. In 1990 these immunomodulatory effects were shown to be related to suppression of cytokine production in animal models of septic shock and insulin dependent diabetes. Disease modulation has been investigated in a number of immunologically mediated diseases, HIV infection, Behcet's disease, Crohn's disease, uveitis and scleroderma. However whether fusidic acid has any useful function as an immunomodulating agent has yet to be fully explored.

Effects of LPS on transport of indocyanine green and alanine uptake in perfused rat liver

Lipopolysaccharide (LPS) initiates cholestasis. Whether this process is mediated by tumor necrosis factor-alpha (TNF-alpha) and whether the cholestatic response to LPS is associated with intrahepatic accumulation of possibly toxic substances are under debate. To study these questions the hepatic uptake and biliary excretion of indocyanine green (ICG) was examined in the isolated perfused rat liver 18 h after intravenous treatment of rats with either saline, 1 mg/kg body wt LPS, or LPS and intraperitoneal pentoxifylline (POF) (n = 6 in each group). POF inhibits TNF-alpha release after LPS administration. LPS induced a typical acute-phase response with increased mRNA for acute-phase proteins, reduced albumin mRNA, and increased hepatic uptake of alanine. Intrinsic hepatic clearance of ICG in controls (1.01 +/- 0.05 ml. min(-1). g liver(-1)) was similarly decreased by LPS alone (0.62 +/- 0.04 ml. min(-1). g(-1); P = 0.002 vs. control) or combined with POF (0.66 +/- 0.06 ml. min(-1). g(-1)). A kinetic analysis indicated that LPS reduced both uptake and excretion processes in a balanced manner, so that intrahepatic ICG content was unaffected or even slightly reduced, as confirmed by measurement of ICG contents in the perfused livers. In livers from parallel-treated nonperfused rats, mRNA for the organic anion transporting protein-1 (Oatp1, which is likely to mediate ICG uptake) was unaffected by LPS, whereas the concentration of Oatp1 protein was reduced. Thus LPS induced an acute-phase response that included downregulation of ICG uptake by reduction of Oatp1 protein concentration, possibly at a posttranscriptional level. TNF-alpha appears not to be the mediator because POF did not modify these LPS effects.

Effects of octreotide treatment on early TNF-alpha production and localization in experimental chronic colitis

BACKGROUND

Colitis induced by trinitrobenzene sulphonic acid (TNB) is a model of Th1 disease, mainly explored from the third day of induction. It has recently been shown that octreotide and other somatostatin analogues can modify inflammatory/immune processes by acting on cytokines.

AIM

To examine TNFalpha production and the effect of preventive treatment with octreotide, during the early phase of TNB-colitis.

METHODS

Thirty milligrams TNB with 50% ethanol was instilled into the colon of male Wistar rats. Treated groups received octreotide (2x10 microg x day/rat) or dexamethasone (1x2 mg x day/kg), subcutaneously, with the first injection before TNB. Eight and 80 h later, the colon was excised and processed for histology, TNFalpha immunohistochemistry, quantification of cytokine release ex vivo and tissue-inducible NO synthase (iNOS) activity.

RESULTS

Maximal TNFalpha production was observed at the 8th hour, associated with intense immunostaining of the external muscle layer. Octreotide treatment decreased TNFalpha expression (staining and activity) and iNOS activity. At the 80th hour, submucosal macrophages were positive for TNFalpha and colonic production of IL1beta and interferon gamma was increased; all these effects were reduced by octreotide treatment.

CONCLUSIONS

TNFalpha was expressed early by resident muscle cells, before staining of infiltrated immune cells and increased production of interferon gamma. TNFalpha regulation by octreotide suggests that this drug might exert anti-inflammatory properties via smooth muscle cells.

Role of tumour necrosis factor-alpha and inducible nitric oxide synthase in the prevention of nitro-flurbiprofen small intestine toxicity

The present study compares the intestinal toxicity of nitro-flurbiprofen and flurbiprofen in order to determine their differential properties on tumour necrosis factor-alpha production and inducible nitric oxide synthase induction. Rats received one s.c. injection of flurbiprofen, nitro-flurbiprofen at equimolar dose of solvent. Twenty-four hours later, the rats were sacrificed and small intestine tissue was taken up for macroscopical quantification of ulceration, ex vivo production of tumour necrosis factor-alpha and nitrites, and determination of tissue inducible nitric oxide synthase and myeloperoxidase activities. Anti-inflammatory activity was examined in the carrageenan-induced paw edema model. We demonstrated that flurbiprofen induced dose-dependently small intestine production of tumour necrosis factor-alpha, nitrites, myeloperoxidase and inducible nitric oxide synthase activities. On the other hand, nitro-flurbiprofen did neither induce tumour necrosis factor-alpha nor nitrite production. Concurrently, no small intestine ulceration was observed with nitro-flurbiprofen whereas flurbiprofen induced dose-dependent ulceration. Nitro-flurbiprofen is devoid of intestinal toxicity despite inhibiting cyclooxygenase activity. This is associated with the absence of tumour necrosis factor-alpha and inducible nitric oxide synthase induction in normal rats. Nitro-flurbiprofen is an anti-inflammatory drug with a much more favorable gastro-intestinal toxicity profile than flurbiprofen.

Increase in tumor necrosis factor-alpha production linked to the toxicity of indomethacin for the rat small intestine

1. The toxic effects of nonsteroidal anti-inflammatory drugs for the lower gastrointestinal tract share certain features with inflammatory processes, suggesting that the release of inflammation cytokines such as TNF-alpha may damage the intestine. 2. Rats received a s.c. injection of indomethacin. Then, jejunum-ileum was taken up for the quantification of ulcerations, production of TNF-alpha, nitrites and PGE2 ex vivo and activity of calcium-independent NO synthase and myeloperoxydase. Activation of NO metabolism and myeloperoxydase were measured as potential effectors of TNF-alpha. 3. Jejunum-ileum from rats having received indomethacin (10 mg kg(-1)) produced TNF-alpha ex vivo. Cytokine production was associated with the onset of macroscopic ulcerations of the small intestine, and preceded nitrite production and tissue activity of myeloperoxidase. 4. Similar intestinal ulcerations and upregulation of TNF-alpha were obtained with flurbiprofen (30 mg kg(-1)), chemically unrelated to indomethacin. 5. TNF-alpha production was proportional to the indomethacin dose (from 3-20 mg kg(-1)) and correlated with the surface area of ulcerations and nitrite production, 24 h after indomethacin administration. 6. Pretreatment of rats with RO 20-1724, a type-IV phosphodiesterase inhibitor which inhibits TNF-alpha synthesis, substantially reduced jejunum-ileum ulcerations, TNF-alpha and nitrite production and tissue enzyme activities. 7. These findings provide evidence that TNF-alpha is increased in indomethacin-induced intestinal ulcerations and support suggestions that TNF-alpha is involved at an early stage of nonsteroidal anti-inflammatory drug toxicity for the small intestine.

Transient suppression of macrophage functions by liposome-encapsulated drugs

Macrophages play an important role in host defense reactions, for example, by phagocytosis of particulate materials. This process also results in the rapid removal of targeting devices such as liposomes and adenovirus vectors and of non-autologous grafted cells and materials. Another aspect of macrophage function is their production and secretion of proinflammatory cytokines. Transient and organ-specific suppression of macrophage function by liposome-mediated manipulation has been shown to improve the efficacy of drug and gene targeting and to reduce the symptoms of inflammatory reactions.

The role of tumor necrosis factor-alpha in the pathogenesis of anorexia and bulimia nervosa, cancer cachexia and obesity

In this paper a new immunological model of anorexia and bulimia nervosa will be presented in which the inflammatory cytokines are conceived as the fundamental regulators of body metabolism. This conception differs from the conventional view in which the inflammatory cytokines are perceived primarily as peptide molecules utilized by the immune system to control infection, inflammation and tissue or neuronal damage. Given that the inflammatory cytokines are also fundamental regulators of body metabolism, when they become dysregulated they create physiological chaos which results in the development of a number of autoimmune, metabolic and psychiatric disorders. In this proposed immunological model of anorexia and bulimia nervosa, elevated tumor necrosis factor-alpha features as the primary cause of these conditions. Pathophysiological parallels are drawn between anorexia nervosa and cancer cachexia in terms of the causal role the cytokines, neuropeptides and neurotransmitters play in the manifestation of shared symptoms. These shared symptoms include elevated tumour necrosis factor-alpha, down-regulated interleukin-2 and interleukin-4 and depletion of lean body mass. Furthermore, the following neuropeptides are dysregulated in both anorexia nervosa and cancer cachexia: vasoactive intestinal peptide, cholecystokinin, corticotropin-releasing factor, neuropeptide Y, peptide YY and beta-endorphin. In addition, in anorexia and bulimia nervosa, secretion of the neurotransmitter serotonin is inhibited while norepinephrine is enhanced. It will be argued that the causal interplay between the cytokines, neuropeptides and neurotransmitters initiates a cascade of biochemical events which may result in either anorexia or bulimia nervosa, or cancer cachexia. The extent to which these inflammatory cytokines, neuropeptides and neurotransmitters are causally efficacious in the pathogenesis of other autoimmune disorders, such as diabetes mellitus and rheumatoid arthritis, will also be addressed.

Differential effect of pentoxifylline on lipopolysaccharide-induced downregulation of cytochrome P450

It is now established that inflammatory stimuli such as lipopolysaccharides (LPS) and polyinosinic acid:polycytidylic (polyIC) suppress hepatic expression of cytochrome P450 (P450) genes in rat liver. Previous studies have suggested that LPS- or polyIC-induced downregulation of P450 was due to endogenously released inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha), interleukin-1, interleukin-6, and interferons (IFNs). To improve our understanding of the role of inflammatory cytokines in mediating P450 depression, we investigated the possibility of preventing P450 downregulation with pentoxifylline. Pentoxifylline has been shown to inhibit LPS-induced TNF-alpha production by suppression of TNF-alpha gene expression. The present study shows that in uninduced male rats pentoxifylline selectively prevents the downregulation of microsomal P4501A2 and P4502B caused by LPS. No protective effect of pentoxifylline on the downregulation of P4502E1 and P4503A1/2 was observed. PolyIC-induced downregulation of P4501A2, P4502B, P4502E1, and P4503A1/2 was not affected by pentoxifylline. These results suggest that the LPS-induced downregulation of P4501A2 and P4502B is mediated to a large extent by TNF-alpha. Other cytokines might be involved in the suppression of P4502E1 and P4503A1/2. The fact that polyIC-induced downregulation is not protected by pentoxifylline is further evidence that this agent acts via a selective induction of IFNs.

Improved survival and antagonistic effect of sodium fusidate on tumor necrosis factor alpha in a neonatal mouse model of endotoxin shock

Unlike the antibiotics erythromycin and penicillin G, sodium fusidate (fusidin) pretreatment (80 mg/kg of body weight) increased the survival rate of neonatal BALB/c mice challenged with Salmonella enteritidis lipopolysaccharide. Fusidin also significantly reduced the plasma tumor necrosis factor alpha levels. Hence, fusidin may prove useful in the management of bacterial sepsis in humans.

Fusidic acid and insulin-dependent diabetes mellitus

Insulin-dependent diabetes mellitus (IDDM) is a major cause of morbidity and mortality from long-standing complications. The autoimmune nature of IDDM has encouraged use of immunosuppressive and antiinflammatory strategies to better preserve residual pancreatic beta-cell function at the time of diagnosis. Fusidic acid and its sodium salt, fusidin, is a relatively atoxic antibiotic used mainly in the treatment of staphylococcal infections. Recently, fusidin has been demonstrated to possess immunosuppressive functions in vitro and in vivo, and the drug has shown promise in preventing the disease in animal models of IDDM and in a preliminary trial in IDDM patients.

Tumor necrosis factor-alpha prevents interleukin-1 beta from augmenting capsaicin-induced vasodilatation in the rat skin

The effect of tumor necrosis factor-alpha (TNF alpha) and tumor necrosis factor-beta (TNF beta) on the capsaicin-induced increase in cutaneous blood flow was investigated in anaesthetized rats. Skin blood flow was measured by laser-Doppler flowmetry. Intraplantar subcutaneous injections of 5-500 pg TNF alpha and 50-5000 pg TNF beta had no effect on local blood flow, whereas 5000 pg TNF alpha induced a transient hyperaemia. However, neither the pretreatment with TNF alpha (5-5000 pg) nor that with TNF beta (50-5000 pg) enhanced the vasodilatator response to intraplantar capsaicin (0.03 micrograms; 0.1 microgram), whereas 50 pg interleukin-1 beta augmented the capsaicin-induced hyperaemia (P < 0.05). This enhancement of the cutaneous hyperaemic response to capsaicin was absent when interleukin-1 beta (50 pg) was co-injected with TNF alpha (500 pg or 5000 pg). The vasodilatation caused by calcitonin gene-related peptide or bradykinin was not altered by 500 pg or 5000 pg TNF alpha. These data indicate that TNFs, in contrast to interleukin-1 beta, do not amplify the hyperaemic response to afferent nerve stimulation with capsaicin but reverse the augmentation mediated by interleukin-1 beta.