In vivo anti inflammatory effects of the M20 IL-1 inhibitor: I. Effects on acute inflammatory parameters

Prevalence of hypophosphatemia in sepsis and infection: the role of cytokines

BACKGROUND

Sepsis occurs following the presence of bacteria in the circulation and is associated with fever, hyperthermia, and hypotension. Hypophosphatemia develops in the early stages of sepsis. High levels of inflammatory cytokines also characterize early sepsis.

AIM

The aim of the present study was to correlate hypophosphatemia with cytokines and cytokine receptor levels during early sepsis. We aimed to reestablish the results obtained from patients in an in vivo experimental model, in order to understand the mechanism of hypophosphatemia induction in early sepsis.

METHODS

Ninety-nine patients were enrolled in this study and their clinical condition was classified as the presence of infection, sepsis, and bacterial growth in blood cultures. Phosphate levels and cytokine levels were recorded. In order to determine whether hypophosphatemia is correlated to the increased inflammatory cytokines, we injected normal mice with recombinant cytokines and studied their effect on phosphate levels.

RESULTS

Our results revealed that 80% of the septic patients had hypophosphatemia associated with very high levels of tumor necrosis factor (TNF)alpha and interleukin (IL)-6 and of soluble IL receptor (sIL)-2R and IL-6R, especially in those patients with positive blood cultures. Injection of IL-6, TNFalpha and IL-1beta in mice markedly decreased the phosphate serum levels.

CONCLUSIONS

Significant associations were demonstrated between high levels of inflammatory cytokines and their receptors and between serum phosphate levels, especially in patients with positive blood culture. Our results point to a correlation between the high inflammatory cytokines levels and hypophosphatemia during early sepsis. Cytokine levels and hypophosphatemia may be included in sepsis evaluation and prognosis. Anticytokine strategies might, therefore, reverse hypophosphatemia and other parameters of sepsis.

Tetracycline inhibits Porphyromonas gingivalis lipopolysaccharide-induced lesions in vivo and TNF alpha processing in vitro

Lipopolysaccharides (LPS) are considered one of the more important virulence factors related to the pathogenesis of periodontal diseases. Based on tetracycline (TTC) ability to bind divalent metal ions, the present study was designed to examine the effect of TTC on P. gingivalis LPS-induced lesions in vivo and on LPS-induced TNF alpha production in vitro. Subcutaneous injection of 50-100 micrograms of P. gingivalis LPS into BALB/C mice induced a visible lesion within 24 h with evident tissue necrosis. Daily systemic administration of TTC for the first 4 d following LPS challenge reduced the size of the lesion, and total inhibition of lesion formation was observed in 75-100% of the treated mice. A non-related broad spectrum antibiotic, ampicillin, or the IL-1 inhibitor ML-20, had no effect on the lesion size. In order to explore some aspects of the mechanism involved, we tested the effect of TTC on LPS-induced TNF alpha secretion by human monocytes in vitro. TTC (1 mM) was found to block LPS-stimulated TNF alpha secretion. Western blotting of monocyte cytoplasmic membranes for membrane-bound TNF alpha show that TTC causes the retention of membrane-associated TNF alpha on monocyte membranes, thereby preventing the release of TNF alpha into the culture media. The results suggest the TTC is an effective in vivo therapy for preventing P. gingivalis LPS-induced subcutaneous lesion formation in the murine model. The mechanism of TTC treatment probably involves blocking the activity of metalloproteinases, including TNF alpha processing enzyme, thereby preventing LPS-induced tissue destruction.

Cytokine inhibitors in autoimmune disease

The cytokine network participates in the modulation of the immune system. Furthermore, the formation of the cytokine-receptor complex, as well as the transcription, translation, secretion, or degradation of cytokines interfere with the functions of cytokines. Cytokine inhibitors include antagonists, soluble receptors, cytokine-binding proteins, and cytokines that block other cytokines. In autoimmune diseases, an abnormal production of proinflammatory cytokines, or a reduced inhibition of their actions, may lead to an imbalance. The main cytokine inhibitors include interleukin-1 receptor antagonist (IL-1ra), soluble IL-1 receptor (sIL-1R), soluble TNF-alpha receptors (soluble TNF-Rs), and certain cytokines, such as IL-4, TGF beta, and IL-10. The combination of cytokine inhibitors is a potential therapeutic approach in the treatment of immunoinflammatory diseases. The nonspecific effects of immunosuppressive drugs are improved by using inhibitors with more specific actions on the functions of proinflammatory cytokines.

The effect of human myelomonocytic leukemic cell line (M20) derived IL-1 inhibitor on human erythroid cell development

The effect of an inhibitor of IL-1, purified from a human myelomonocytic cell line (M20) on the development of human erythroid cell development was studied. The inhibitor, is a protein of 52 kD molecular weight that is distinct immunologically and functionally from other reported IL-1 inhibitors. The experiments were performed in a two-phase culture system that allows separation of the erythroid cell development into an erythropoietin (EPO)-independent phase, where early erythroid-committed BFUe proliferate and differentiate into the more mature progenitors, CFUe, and EPO-dependent phase, where CFUe further proliferate and mature into hemoglobin-containing orthochromatic normoblasts. The results indicated that in both developmental stages the M20-derived inhibitor reversibly blocked cell proliferation without interfering with cell differentiation.