Effects of recombinant human tumor necrosis factor alpha, lymphotoxin, and Escherichia coli lipopolysaccharide on hemodynamics, lung microvascular permeability, and eicosanoid synthesis in anesthetized sheep

Impaired Glucocorticoid Receptor Dimerization Aggravates LPS-Induced Circulatory and Pulmonary Dysfunction

Background: Sepsis, that can be modeled by LPS injections, as an acute systemic inflammation syndrome is the most common cause for acute lung injury (ALI). ALI induces acute respiratory failure leading to hypoxemia, which is often associated with multiple organ failure (MOF). During systemic inflammation, the hypothalamus-pituitary-adrenal axis (HPA) is activated and anti-inflammatory acting glucocorticoids (GCs) are released to overcome the inflammation. GCs activate the GC receptor (GR), which mediates its effects via a GR monomer or GR dimer. The detailed molecular mechanism of the GR in different inflammatory models and target genes that might be crucial for resolving inflammation is not completely identified. We previously observed that mice with attenuated GR dimerization (GR^dim/dim) had a higher mortality in a non-resuscitated lipopolysaccharide (LPS)- and cecal ligation and puncture (CLP)-induced inflammation model and are refractory to exogenous GCs to ameliorate ALI during inflammation. Therefore, we hypothesized that impaired murine GR dimerization (GR^dim/dim) would further impair organ function in LPS-induced systemic inflammation under human like intensive care management and investigated genes that are crucial for lung function in this setup.

Methods: Anesthetized GR^dim/dim and wildtype (GR^+/+) mice were challenged with LPS (10 mg·kg⁻¹, intraperitoneal) and underwent intensive care management (“lung-protective” mechanical ventilation, crystalloids, and norepinephrine) for 6 h. Lung mechanics and gas exchange were assessed together with systemic hemodynamics, acid-base status, and mitochondrial oxygen consumption (JO₂). Western blots, immunohistochemistry, and real time quantitative polymerase chain reaction were performed to analyze lung tissue and inflammatory mediators were analyzed in plasma and lung tissue.

Results: When animals were challenged with LPS and subsequently resuscitated under intensive care treatment, GR^dim/dim mice had a higher mortality compared to GR^+/+ mice, induced by an increased need of norepinephrine to achieve hemodynamic targets. After challenge with LPS, GR^dim/dim mice also displayed an aggravated ALI shown by a more pronounced impairment of gas exchange, lung mechanics and increased osteopontin (Opn) expression in lung tissue.

Conclusion: Impairment of GR dimerization aggravates systemic hypotension and impairs lung function during LPS-induced endotoxic shock in mice. We demonstrate that the GR dimer is an important mediator of hemodynamic stability and lung function, possibly through regulation of Opn, during LPS-induced systemic inflammation.

The Effects of Immediate Enteral Feeding with a Formula Containing High Levels of ω-3 Fatty Acids in Patients After Surgery for Esophageal Cancer

BACKGROUND

We investigated whether supplementation of enteral nutrition (EN) with omega-3 polyunsaturated acids (PUFAs) affected platelet aggregation, coagulation activity, and inflammatory response in the early stages after esophageal cancer surgery.

METHODS

Twenty-eight patients with esophageal cancer who underwent the same surgical procedure were selected for this study. All patients received EN, which was started immediately after the operation and was increased to a maximum volume of 1500 ml/day by the third postoperative day (POD). Eleven patients received a conventional EN formula (Ensure Liquid), while the remaining 17 patients received a different formula rich in omega-3 PUFAs (Racol [RAC]). Several markers of coagulation and fibrinolysis were determined in POD 2, while the concentrations of interleukin (IL)-6, IL-8, 6-keto-PGF1alpha and thromboxane B2 were determined on PODs 1, 3, and 5.

RESULTS

A total of 27 patients completed the study, 11 in the Ensure Liquid group and 16 in the RAC group. Administration of RAC significantly inhibited the postoperative decrease in platelet count. The level of D-dimer was attenuated significantly in the RAC group. Plasma IL-8 levels were decreased significantly in the RAC group on PODs 1 and 3. The anti-inflammatory effects of omega-3 PUFAs were confirmed by the clinical findings of lower body temperature. The plasma concentration of 6-keto-PFG1alpha also tended to decrease in the RAC group with a significant difference on POD 5.

CONCLUSIONS

Early EN with a large amount of omega-3 PUFAs in reduced platelet aggregation, coagulation activity, and cytokine production. All these effects would be expected to be beneficial in patients following esophageal cancer surgery. The clinical significance of the changes in eicosanoid production remains to be established.

Pulmonary Retention of Adipose Stromal Cells Following Intravenous Delivery Is Markedly Altered in the Presence of ARDS

Transplantation of mesenchymal stromal cells (MSCs) has been shown to effectively prevent lung injury in several preclinical models of acute respiratory distress syndrome (ARDS). Since MSC therapy is tested in clinical trials for ARDS, there is an increased need to define the dynamics of cell trafficking and organ-specific accumulation. We examined how the presence of ARDS changes retention and organ-specific distribution of intravenously delivered MSCs isolated from subcutaneous adipose tissue [adipose-derived stem cells (ADSCs)]. This type of cell therapy was previously shown to ameliorate ARDS pathology. ARDS was triggered by lipopolysaccharide (LPS) aspiration, 4 h after which 300,000 murine CRE⁺ ADSCs were delivered intravenously. The distribution of ADSCs in the lungs and other organs was assessed by real-time polymerase chain reaction (PCR) of genomic DNA. As anticipated, the majority of delivered ADSCs accumulated in the lungs of both control and LPS-challenged mice, with minor amounts distributed to the liver, kidney, spleen, heart, and brain. Interestingly, within 2 h following ADSC administration, LPS-challenged lungs retained significantly lower levels of ADSCs compared to control lungs (∼7% vs. 15% of the original dose, respectively), whereas the liver, kidney, spleen, and brain of ARDS-affected animals retained significantly higher numbers of ADSCs compared to control animals. In contrast, 48 h later, only LPS-challenged lungs continued to retain ADSCs (∼3% of the original dose), whereas the lungs of control animals and nonpulmonary organs in either control or ARDS mice had no detectable levels of ADSCs. Our data suggest that the pulmonary microenvironment during ARDS may lessen the pulmonary capillary occlusion by MSCs immediately following cell delivery while facilitating pulmonary retention of the cells.

The temporal evolution of acute respiratory distress syndrome following shock

BACKGROUND AND OBJECTIVE

The objective of this review is to provide an comprehensive overview of the evolution of acute respiratory distress syndrome (ARDS) in cellular, animal and human models with specific reference to sepsis and haemorrhage. Within this work we have attempted to describe the temporal evolution of the disease process.ARDS is a complication of pulmonary and systemic disease and it can follow sepsis or haemorrhage. The definition of this condition states an acute onset and this review seeks to clarify the time course of that onset following sepsis and haemorrhage. The underlying pathophysiological mechanisms include activation of the immune response, neutrophil activation and sequestration of these into the alveolus with subsequent tissue damage and hypoxia.

RESULTS

The biological evolution of these processes from sepsis or haemorrhage has been well described and the earliest measurable changes in the process occur within 15 min with the clinical manifestations of the syndrome occurring within 12 h. The rapid development of this condition should be considered during the treatment of haemorrhagic or septic shock.

Evaluation of the anti-endotoxin effects of polymyxin B in a feline model of endotoxemia

Directed, effective therapies for feline sepsis are needed to reduce the high morbidity and mortality associated with this disease. We investigated the anti-endotoxin effects of polymyxin B (PMB) in a blinded, placebo controlled fashion, both ex vivo in a feline whole blood culture system and in vivo, using a low-dose endotoxin infusion in cats. Serial measures of systemic inflammation, and hemodynamic stability, were compared between groups. Ex vivo, PMB significantly decreased lipopolysaccharide-induced tumor necrosis factor (TNF) production from whole blood. PMB (1mg/kg over 30min) demonstrated anti-endotoxin effects in vivo, including decreased peak plasma TNF activity (P<0.001) and increased white blood cell count (P=0.019), with no adverse effects. Given the apparent safety and anti-endotoxin effects of PMB in this endotoxemia model, a carefully designed, randomized, blinded, placebo controlled clinical trial evaluating the use of PMB in naturally occurring Gram-negative feline sepsis should be considered.

Effects of sustained post-traumatic shock and initial fluid resuscitation on extravascular lung water content and pulmonary vascular pressures in a porcine model of shock

BACKGROUND

The temporal evolution of lung injury following post-traumatic shock is poorly understood. In the present study we have tested the hypothesis that manifestations of pulmonary vascular dysfunction may be demonstrable within the first hour after the onset of shock.

METHODS

Twenty-nine anaesthetized pigs (mean weight 27.4 kg; (SD) 3.2) were randomly allocated to three groups: control (C, n=9), shock resuscitated with either NaCl 0.9% (S, n=10), or 4% gelatine (G, n=10). Shock was maintained for 1 h followed by fluid resuscitation with either normal saline or 4% gelatine solution. Cardiac output (CO), mean arterial pressure (MAP), mixed venous saturation (Sv(O(2))), blood lactate concentration, mean pulmonary artery pressure (MPAP), MPAP/MAP, pulmonary vascular resistance (PVR), extravascular lung water index (EVLWi), Pa(O(2))/FI(O(2)), venous admixture (Q(.)(S)/Q(.)(T)), and dynamic lung compliance (C(dyn)) were measured at baseline, beginning of shock phase, end of shock phase, and post-resuscitation.

RESULTS

At the end of volume resuscitation CO was restored to control values in both shock groups. MAP remained significantly below control values (95% CI: C=70-95, S=28-52, G=45-69 mm Hg) in both shock groups. MPAP/MAP was significantly greater in both shock groups at the end of the shock phase (95% CI; C=0.15-0.24, S=0.28-0.38, G=0.32-0.42) and at the post-resuscitation phase (95% CI: C=0.12-0.30, S=0.43-0.61, G=0.32-0.49) indicating the presence of relative pulmonary hypertension. This was associated with a significant increase in PVR in Group S (F=3.9; P<0.05). There were no significant changes in Pa(O(2))/FI(O(2)), Q(.)(S)/Q(.)(T), EVLWi, or C(dyn). In a small cohort of animals a measurable increase in EVLWi (>30%) and reduction in C(dyn) (>10%) were observed.

CONCLUSIONS

Pulmonary vascular injury manifesting as relative pulmonary hypertension and increased PVR may occur within the first hour after the onset of shock. These changes may not be accompanied by overt changes in oxygenation, compliance, or EVLWi. Br J Anaesth 2003; 91: 224-32

Minimal lung and systemic responses to TNF-alpha in preterm sheep

TNF-alpha has been associated with chorioamnionitis and the subsequent development of bronchopulmonary dysplasia in preterm infants. We asked whether bioactive recombinant ovine TNF-alpha could induce chorioamnionitis, lung inflammation, lung maturation, and systemic effects in fetal sheep. We compared the responses to IL-1alpha, a cytokine known to induce these responses in preterm sheep. Intra-amniotic TNF-alpha caused no chorioamnionitis, no lung maturation, and a very small increase in inflammatory cells in the fetal lung after 5 h, 2 days (d), and 7 d. In contrast, IL-1alpha induced inflammation and lung maturation. TNF-alpha given into the airways at birth increased granulocytes in the bronchoalveolar lavage fluid of ventilated preterm lungs and decreased the mRNA for surfactant protein C but did not adversely effect postnatal lung function. An intravascular injection of IL-1alpha caused a systemic inflammatory response in fetal sheep, whereas there was no fetal response to intravascular TNF-alpha. Fetal and newborn preterm sheep are minimally responsive to TNF-alpha. Therefore, the presence of a mediator such as TNF-alpha in a developing animal does not necessarily mean that it is causing the responses anticipated from previous results in adult animals.

TNF-alpha induced bronchial vasoconstriction

The pro-inflammatory characteristics of tumor necrosis factor-alpha (TNF-alpha) have been extensively characterized in in vitro systems. Furthermore, this cytokine has been shown to play a pivotal role in airways inflammation in asthma. Since the airway vasculature also performs an essential function in inflammatory cell transit to the airways, experiments were performed to determine the effects of TNF-alpha on bronchial vascular resistance (BVR). In anesthetized, ventilated sheep, the bronchial artery (BA) was cannulated and perfused with autologous blood. BVR was defined as inflow pressure/flow and averaged 6.3 +/- 0.2 mmHg. ml(-1). min(-1) (+/-SE) for the 25 sheep studied. Recombinant human TNF-alpha (10 microg for 20 or 40 min) infused directly into the BA resulted in a significant decrease in BVR to 87% of baseline (P < 0.05). This vasodilation was followed by a reversal of tone by 120 min and a sustained increase in BVR to 126% of baseline (P < 0.05). Since others have shown TNF-alpha caused coronary vasoconstriction through endothelial release of endothelin-1 (ET-1), an ET-1 antagonist was used to block bronchial vasoconstriction. BQ-123, a selective ET(A) receptor antagonist, was delivered to the bronchial vasculature prior to TNF-alpha challenge. Attenuation of bronchial vasoconstriction was observed at 120 min (P < 0.03). Thus TNF-alpha causes bronchial vasoconstriction by the secondary release of ET-1. Although TNF-alpha exerts pro-inflammatory actions on most cells of the airways, vasoactive properties of this cytokine likely further contribute to the inflammatory status of the airways.

TNF-alpha causes reversible in vivo systemic vascular barrier dysfunction via NO-dependent and -independent mechanisms

Tumor necrosis factor (TNF-alpha) and nitric oxide (NO) are important vasoactive mediators of septic shock. This study used a well-characterized quantitative permeation method to examine the effect of TNF-alpha and NO on systemic vascular barrier function in vivo, without confounding endotoxemia, hypotension, or organ damage. Our results showed 1) TNF-alpha reversibly increased albumin permeation in the systemic vasculature (e.g., lung, liver, brain, etc.); 2) TNF-alpha did not affect hemodynamics or blood flow or cause significant tissue injury; 3) pulmonary vascular barrier dysfunction was associated with increased lung water content and impaired oxygenation; 4) TNF-alpha caused inducible nitric oxide synthase (iNOS) mRNA expression in the lung and increased in vivo NO production; 5) selective inhibition of iNOS with aminoguanidine prevented TNF-alpha-induced lung and liver vascular barrier dysfunction; 6) aminoguanidine prevented increased tissue water content in TNF-alpha-treated lungs and improved oxygenation; and 7) nonselective inhibition of NOS with NG-monomethly-L-arginine increased vascular permeation in control lungs and caused severe lung injury in TNF-alpha-treated animals. We conclude that 1) TNF-alpha reversibly impairs vascular barrier integrity through NO-dependent and -independent mechanisms; 2) nonselective NOS inhibition increased vascular barrier dysfunction and caused severe lung injury, whereas selective inhibition of iNOS prevented impaired endothelial barrier integrity and pulmonary dysfunction; and 3) selective inhibition of iNOS may be beneficial in treating increased vascular permeability that complicates endotoxemia and cytokine immunotherapy.

Human lymphotoxin mutein lacks hypotensive activity but has higher in vivo antitumor activity than lymphotoxin or tumor necrosis factor

A serious drawback of tumor necrosis factor alpha (TNF) as a clinical antitumor agent is that it also has hypotensive activity. To overcome this problem, derivatives of its sister cytokine lymphotoxin (TNF-beta or LT) were prepared. One of them, mutein 2 (Mut2) has a deletion of amino acids 1-7 but contains substituted amino acids, Met-Phe-Pro at positions 8-10 of the mature human LT. This mutein has no hypotensive activity at the maximum dose (10 mg/kg) tested on rats. In contrast, a much lower dose (1 mg/kg) of TNF and LT caused a significant blood pressure drop. In vivo studies revealed that Mut2 was more effective than TNF or LT against MethA (a mouse tumor line) as judged by the therapeutic ratio [calculated as LD50 (dose that kills 50% of the animals)/ED50 (dose that reduces the tumor size by 50%)]. With five other different mouse tumors and two different human tumors, Mut2 was also effective and the effectiveness was comparable or superior to that of TNF or LT. These results suggest the possibility that this derivative may be usable as a clinical antitumor agent without the serious side effects associated with TNF.

Effects of ozone on the epithelial and inflammatory responses in the airways: role of tumor necrosis factor

We have investigated the possibility that tumor necrosis factor alpha (TNF) plays a role in the increased airway permeability and an inflammatory response following an acute ozone (O3) exposure. Male Sprague-Dawley rats were injected, intraperitoneally, with either rabbit anti-mouse antibody to TNF (anti-TNF) or preimmune rabbit serum, 2 h before a 3-h exposure to O3 or purified air. Permeability, as determined by [99mTc] diethylenetriamine pentaacetate (DTPA) transport, total protein and albumin concentrations in the bronchoalveolar lavage (BAL), and the inflammatory cell response in the BAL were assessed 10 h after the exposure was completed. The O3-exposed group that was injected with anti-TNF showed a significant decrease in permeability to DTPA in comparison to the O3- exposed group injected with preimmune rabbit serum. There was no difference between the anti-TNF group and the purified air group. In contrast, the total protein and albumin levels in the BAL were significantly greater in both of the O3-exposed groups than in the purified air group. The concentrations of protein and albumin in the anti-TNF group did, however, show an attenuating trend when compared to the preimmune O3-exposed group. The polymorphonuclear leukocytes (PMNs) in BAL of the anti-TNF group also showed an attenuating trend when compared to the preimmune O3-exposed group, but both of these O3-exposed groups were significantly greater than the purified air group. Lung sections stained with naphthol AS-D chloroacetate esterase showed an increase in the number of stained PMNs in the anti-TNF group in comparison to the preimmune O3- and air-exposed groups. These data suggest that TNF plays a role in the increase in tracheal permeability as determined by DTPA transport, while the contributing role that TNF plays in bronchoalveolar permeability and the inflammatory response seen following an acute exposure to 0.8 ppm O3 is less evident.

Acute metabolic effects of human recombinant tumor necrosis factor beta in the rat

BACKGROUND

Cancer cachexia is associated with several alterations in host metabolism, including hypoaminoacidemia and an increase in gluconeogenesis (GLC) and lipolysis. Tumor necrosis factor beta (TNF beta), a lymphokine released by mitogen-activated T lymphocytes and several cancer cell lines, causes an increase in lipolysis in 3T3L1 adipocytes. Since little is known about the metabolic effects of TNF beta in vivo, we examined its acute effects in the rat.

METHODS

Twenty-eight male Fischer rats were injected intraperitoneally with TNF beta (250 micrograms/kg) or saline (CTL), and after 4 h, isolated hepatocytes were obtained (by in situ collagenase liver perfusion [n = 12]) or aortic blood was collected (n = 16). Hepatocytes were incubated with 10 mM alanine (ALA) or 10 mM lactate (LAC), and glucose production was measured. Rates of GLC (nmol glucose/10(6) cells/min) were determined by linear regression. Plasma lactate, glucose, insulin, and amino acids (AA) (nmol/ml) were measured, and values were expressed as means +/- SEM. Comparisons between groups were made by unpaired t test or Mann-Whitney U test, and significance was defined as p < 0.05.

RESULTS

TNF beta caused a 130% increase in gluconeogenesis from alanine (2.7 +/- 0.5 vs 1.2 +/- 0.2 nmol glucose/10(6) cells/min, TNF vs CTL), and a 60% increase from lactate (7.5 +/- 1.0 vs 4.6 +/- 0.5 nmol glucose/10(6) cells/min, TNF vs CTL). Plasma insulin levels in TNF treated rats were 1.2 +/- 0.2 ng/ml compared to 1.1 +/- 0.2 ng/ml in CTL. Total amino acid levels in TNF treated rats were 3,175 +/- 111 nmol/ml compared to 3,190 +/- 103 nmol/ml in CTL.

CONCLUSION

In vivo TNF beta causes an increase in hepatic gluconeogenesis from alanine and lactate with no change in plasma insulin or amino acids.

HA-1A in septic patients with ARDS: results from the pivotal trial

OBJECTIVE

To evaluate the effects of HA-1A, a human monoclonal antiendotoxin antibody, in septic patients with ARDS.

DESIGN

Substudy of a multicenter, double-blinded, placebo-controlled trial of HA-1A in septic patients.

PATIENTS

63 septic patients with ARDS at the time of study entry.

INTERVENTION

A single intravenous injection of HA-1A (100 mg) or placebo.

RESULTS

A quantitative radiographic score, the PaO2/FIO2 ratio and an index of the severity of ARDS did not show a significant difference between the treatment and placebo groups at 3, 5 and 7 days after treatment. The duration of endotracheal intubation did not differ between the two groups. 15 of 30 HA-1A treated patients (50%) and 23 of 33 placebo-treated patients (69.7%) died within 28 days. The daily mortality was always lower in the HA-1A group, but this difference was not statistically significant at 28 days. The 28-day survival curves for the two treatment groups adjusted by covariate analysis were not significantly different (p = 0.07). Using logistic regression, a significant independent effect of HA-1A treatment was detected upon the early survival rate at 7 days (p = 0.03) but not at 14 and 28 days.

CONCLUSION

A single injection of HA-1A in septic patients with ARDS did not reverse acute respiratory failure or improve long-term survival.

Tumor necrosis factor inhibits stimulated but not basal release of nitric oxide

Tumor necrosis factor alpha (TNF alpha) increases nitric oxide (NO) synthase in vascular endothelium, but it inhibits endothelium-dependent relaxation (EDR) of vascular smooth muscle. We tested whether TNF alpha inhibits the response to, or release of, NO in bovine pulmonary artery (BPA) using the technique of perfusion-superfusion bioassay and ozone chemiluminescence. Effluent from the perfused BPA with endothelium (donor)-relaxed endothelium-rubbed bovine coronary artery (BCA) (detector). Moreover, effluent from the donor stimulated with acetylcholine (ACh) or bradykinin (BK) (0.001 to 100 nmol) relaxed the detector. Direct application of these agonists to the detector failed to produce relaxation. Basal and agonist-stimulated effluent from the donor treated with L-NG-monomethylarginine (LNMMA) (100 microM) suppressed effluent-mediated relaxation of the detector. ACh and BK released LNMMA-inhibitable nitrite and nitrate from the BPA. Thus, the effluent contained NO. Exposure of the donor to TNF alpha (1.25 micrograms/ml) for 60 min did not affect basal release of NO, but it attenuated bioassayable and chemiluminescence-detectable NO release by ACh and BK. The inhibition of NO release was directly related to the magnitude of inhibition of EDR by ACh and BK. Thus, TNF alpha selectively inhibits receptor-mediated release of NO without affecting basal release of NO. This effect differs from that of L-arginine-based inhibitors of NO and represents a unique physiologic mechanism of regulation of NO in the endothelium.

Left ventricular systolic and diastolic dysfunction after infusion of tumor necrosis factor-alpha in conscious dogs

We used a load-insensitive index of systolic left ventricular (LV) function and an analysis of diastolic pressure-dimension relationships to test the hypothesis that recombinant human (rh) tumor necrosis factor-alpha (TNF alpha) impairs LV function in dogs. Animals were studied 7-10 d after aseptic implantation of instrumentation to monitor cardiac output, external anterior-posterior LV diameter, and LV and pleural pressures. Data were analyzed from seven dogs that received active rhTNF alpha (100 micrograms/kg over 60 min) and from five dogs that received heat-inactivated rhTNF alpha. At 24 h after infusion of active rhTNF alpha, the slope of the LV end-diastolic dimension-stroke work relationship decreased significantly, indicating a decrement in LV systolic contractility. Simultaneously, LV unstressed dimension increased significantly, suggesting diastolic myocardial creep. The end-diastolic relationship between LV transmural pressure and normalized LV dimension (strain) was markedly displaced to the left, suggesting increased diastolic elastic stiffness. Despite these changes in LV performance, cardiac index was maintained by tachycardia. The abnormalities in LV function were resolved by 72 h. We conclude that rhTNF alpha reversibly impairs LV systolic and diastolic function in unanesthetized dogs. Because dysfunction occurs greater than 6 h after the infusion of rhTNF alpha and persists for 24-48 h, the mechanism underlying this phenomenon may involve secondary mediators or a change in myocardial gene expression.

Multiple Organ Failure Syndrome—Part I: Epidemiology, Prognosis, and Pathophysiology

The multiple organ failure syndrome (MOFS) is the leading cause of death in intensive care units. Although sepsis is an important cause of MOFS, it is clear that MOFS can occur in the absence of infection. The pathophysiology of MOFS is complex and multifactorial and includes derangements in oxygen delivery and consumption, the release of inflammatory and vasoactive mediators capable of inflicting tissue damage, and alterations in the barrier function of the intestinal mucosa. Although advances have been made in our understanding of MOFS, treatment remains nonspecific and largely supportive. Early and aggressive restoration of tissue perfusion, adequate treatment of infection, timely nutritional support, and support of individual failed organs remain the mainstay of therapy. Therapeutic agents directed against the various mediators associated with the pathophysiology of MOFS may prove useful in the future.

Novel muteins of human tumor necrosis factor alpha

For chemical synthesis of a gene coding for human tumor necrosis factor alpha (TNF-alpha), DNA sequence predicted by the amino acid sequence of human TNF molecule was prepared. Codons were chosen according to the codon usage in Escherichia coli (E. coli). The 490 bp gene was assembled by enzymic ligation of 42 oligonucleotides and was cloned into a vector (pKK223-3) for high expression of active TNF-alpha in E. coli. With use of site-directed mutagenesis on this DNA, five different muteins of TNF-alpha were synthesized. TNF-M1 and TNF-M4 have deletions of His-73 and Gln-102, respectively. These deletions didn't cause loss of the cytotoxic activity against L929 cells. TNF-M5, which has a substitution of Asp-10 to Arg, had the similar cytotoxic activity to that of TNF-alpha. The cytotoxic spectra against several tumor cells were not changed by this substitution. TNF-M3 has an amino acid substitution of Glu-116 to His which occupies this position in human TNF-beta. This substitution didn't change the cytotoxicity. In addition, evidence was presented that the change of the carboxyl terminal residue doesn't always influence the cytotoxic activity of TNF-alpha. Many different muteins were also isolated by random mutagenesis with hydroxylamine-HCl. One of the muteins, which carries a mutation of His-15 to Tyr, lost the cytotoxic activity almost completely.