Combination effect of recombinant human interleukin-1 alpha with antimicrobial agents

Proinflammatory Cytokines in the Treatment of Bacterial and Fungal Infections

Mortality due to severe bacterial infections has not been markedly effected by the introduction of new antimicrobial drugs over the last 30-40 years. This has emphasized the need for development of new therapeutic strategies to combat sepsis. The outcome of an infection depends on two factors: the growth of the microorganisms (including the effect of antibacterial drugs), and the host's defensive response to the invading organism. It is known that injection of bacterial products into experimental animals leads to enhanced nonspecific resistance to a variety of microorganisms. The discovery of the specific mediators responsible for modulation of host defense has created new possibilities for the development of alternative treatment strategies. Molecules such as interleukins, interferons, tumor necrosis factors and hematopoietic growth factors have become available in recombinant form, and their therapeutic potential in various infectious diseases has been tested in various experimental models of infections. Initial data in various patient groups indicate that adjunctive therapy with recombinant proinflammatory cytokines may have beneficial effects in the treatment of bacterial and fungal infections.

Molecular cloning of interleukin 1beta from rainbow trout Oncorhynchus mykiss reveals no evidence of an ice cut site

The complete coding sequence of rainbow trout IL-1beta has been obtained. The gene contains a short 5' UTR (97 bp), a 780 bp open reading frame and a 466 bp 3' UTR, which includes a polyadenylation signal, 7 ATTTA motifs and an 18 bp poly A tail. The predicted amino acid sequence (260 amino acids) contains 3 potential glycosylation sites, with a predicted molecular weight of 29 kDa, and shows between 49 and 56% amino acid similarity to mammalian IL-1betas and 57% similarity to carp IL-1beta. Greatest homology was apparent within the secondary structure of the gene, with few of the amino acids known to bind to the IL-1 receptor being conserved. No ICE cut site was apparent but multiple alignment with mammalian sequences allowed a putative mature peptide of 166 amino acids to be identified, in which Ala(95)would be the amino terminus. Northern blot analysis showed that whilst no IL-1beta expression was detectable in head kidney leukocytes immediately after isolation, expression could be induced by stimulation with LPS for 4 h in culture. Similarly, with isolated head kidney macrophages expression was significantly increased following stimulation with LPS.

Some pharmacokinetic parameters and dosage regimens for a long-acting formulation of oxytetracycline in 6- to 8-month-old male calves

A two-way crossover study was conducted in crossbred male calves (6-8 months old) to determine the bioavailability, pharmacokinetics and dosage regimens for a long-acting formulation of oxytetracycline (OTC-LA). The half-lives of oxytetracycline after intravenous and intramuscular administration were 7.8 h and 24 h, respectively. The volume of distribution and total body clearance values of the drug were 0.86+/-0.07 L and 76.1+/-3.3 (ml/h)/kg, respectively. The maximum concentration of the drug in the serum (4.7-7.4 microg/ml) was achieved 8-10 h after intramuscular administration. The minimum therapeutic serum concentration of drug of > or = 0.5 microg/ml was maintained between 15 min and 84 h after intramuscular administration. The intramuscular bioavailability of the drug was 89.1+/-4.2%. The dosage regimens to maintain the minimum therapeutic serum concentrations of OTC following intramuscular administration of OTC-LA were computed.

Inflammatory cytokines in animal health and disease

Inflammatory cytokines, including tumor necrosis factor (TNF), interleukin-1 (IL-1), IL-6 and IL-8, are rapidly induced early in a disease or injury process. They mediate and modulate myriad healing processes but, if overexpressed, may exacerbate the severity of a disease condition. In order to test this concept and to establish a foundation for the role of inflammatory cytokines in the pathogenesis of gram-negative bacterial infections in the respiratory tract of animals, the patterns of inflammatory cytokine expression were determined in experimental porcine pleuropneumonia. We observed that IL-1 and IL-6, but not TNF, were rapidly and dramatically elevated in the lavage fluid of the lung within 24 h of infection. The increased levels of IL-1 might contribute to increased severity of disease, but elevated IL-6 levels were consistent with a protective acute phase response. Additional studies were performed to examine the hypothesis that IL-4 expression later in infection might be involved in turning off the inflammatory response and promoting an antigen-specific humoral immune response. Interleukin-4 efficiently suppressed inflammatory cytokine production in alveolar macrophages. Its expression was induced in peripheral blood mononuclear cells by TNF, IL-4, and by reexposure to a specific antigen. To obtain the maximum amount of information on the role of inflammatory cytokines in animals of veterinary significance it will be useful to perform studies in species such that evolutionary relatedness will allow widespread application of the findings. Furthermore, the variety of molecules involved in inflammatory cytokine regulation will require much more extensive investigations of the relevant enzymes, inhibitors and receptors in veterinary species. Finally, the complexity and redundancy of immune defenses in animals mean that attempts to modulate health status through manipulation of inflammatory cytokines must be performed with caution and that a multiplicity of processes will be affected.

Interleukin-1 and related pro-inflammatory cytokines in the treatment of bacterial infections in neutropenic and non-neutropenic animals

Bacterial infections in the immunocompromized host cause considerable mortality, and even the recently developed antimicrobial strategies often fail to cure these infections, especially in granulocytopenic patients. Cytokines and hematopoietic growth factors have been shown to stimulate host defense mechanisms in vitro and in vivo. We discuss the possible role of the pro-inflammatory cytokines interleukin-1, tumor necrosis factor-alpha, interleukin-6 and interleukin-8 as modulators of host resistance to bacterial infections. Interleukin-1 has been shown effective in various animal models of potentially lethal bacterial infection, even during severe granulocytopenia. The protective mechanism of interleukin-1 may be mediated via downregulation of cytokine receptors and cytokine production, and via induction of acute phase proteins. Moreover, in subacute and chronic infections interleukin-1 interferes with microbial outgrowth, via mechanisms that have only been partially elucidated.

Tumor necrosis factor and interleukin-6 in Candida albicans infection in normal and granulocytopenic mice

We administered a neutralizing monoclonal antibody to tumor necrosis factor (TNF) during infection with Candida albicans in normal and granulocytopenic mice. Mice were rendered granulocytopenic (less than 0.1 x 10(9) granulocytes per liter) with cyclophosphamide. Growth of C. albicans from the kidneys was significantly increased in normal mice treated with the antibody to TNF, compared with that in control mice, after 36 h (3.6 x 10(4) +/- 1.2 x 10(4) CFU per kidney versus 9.1 x 10(3) +/- 6.2 x 10(3) CFU per kidney; P less than 0.05) and after 72 h (3.7 x 10(6) +/- 2.7 x 10(6) CFU per kidney versus 2.3 x 10(4) +/- 1.3 x 10(4) CFU per kidney; P less than 0.01). In granulocytopenic mice, the antibody to TNF had no effect on the growth of C. albicans from the kidneys. Furthermore, our study showed that the cytokines TNF and interleukin-6 (IL-6) were produced in a dose-dependent manner during C. albicans infection. TNF was detectable between 6 and 60 h, with peak levels at 24 h. Both TNF and IL-6 levels were significantly higher in cyclophosphamide-treated mice than in normal mice. Heat-inactivated C. albicans induced a TNF response different from that induced by viable C. albicans, with an early peak occurring at 3 to 4 h and declining to non-detectable levels after 15 to 24 h. Peak levels of TNF obtained with heat-inactivated C. albicans were lower than those obtained with viable C. albicans. Our study demonstrates that TNF and IL-6 are produced systemically during C. albicans infection and suggests that TNF is essential for granulocyte antifungal activity in vivo.

Combined effect of fluconazole and recombinant human interleukin-1 on systemic candidiasis in neutropenic mice

The aim of the present study was to investigate the efficacy of treatment with a combination of fluconazole and human recombinant interleukin-1 alpha (IL-1 alpha) in normal or neutropenic mice with systemic Candida albicans infection. Six hours after intravenous injection of 5 x 10(4) CFU of C. albicans organisms, oral treatment twice daily with 2.5 or 10 mg of fluconazole per kg of body weight, a single intraperitoneal injection of 80 ng of IL-1, or a combination of the two was started. IL-1 had no influence on the antifungal activity of fluconazole in vitro or on the pharmacokinetics of fluconazole. For both normal and neutropenic mice, the number of C. albicans organisms cultured from the kidneys after 36 h of treatment was significantly lower in mice treated with IL-1 alone than in untreated animals. Treatment with fluconazole alone also significantly lowered the number of C. albicans organisms in the kidneys compared with that in untreated controls. In normal mice, the combination of fluconazole and IL-1 was not better than fluconazole alone. In neutropenic mice, combined treatment with IL-1 and 10 mg of fluconazole per kg led to significantly lower numbers of C. albicans organisms in the kidneys and the spleen than treatment with either agent alone. Although the precise mechanism by which IL-1 enhances resistance to infection is not clear, the additive effect of IL-1 and fluconazole in vivo indicates that combined therapy with immunomodulators and antifungal drugs is beneficial in immunocompromised mice with systemic fungal infections.