Clinical effects of inhibiting leukocyte adhesion with monoclonal antibody to intercellular adhesion molecule-1 (enlimomab) in the treatment of partial-thickness burn injury

BACKGROUND

A randomized, prospective, multicenter, double-blind, placebo-controlled, phase II clinical trial was performed to determine whether inhibition of leukocyte adherence by administration of monoclonal antibody directed against intercellular adhesion molecule-1 would improve burn wound healing.

METHODS

One hundred ten patients with burn injury ranging from 10% to 30% total body surface area were enrolled. Fifty-six patients received placebo (saline) and 54 patients received murine monoclonal antibody to the human intercellular adhesion molecule-1 (enlimomab). Treatment was initiated within 6 hours of injury. Patients had three distinct partial-thickness wound sites assessed. Laser Doppler flowmetry was used to stratify wounds on the day of injury. Wounds were assessed for healing status on day 21 postburn and categorized as healed, nonhealed, or grafted.

RESULTS

Patients treated with enlimomab had a significantly increased percentage of wounds that healed spontaneously in less than 21 days overall and when stratified by burn wound laser Doppler blood flow readings for those wounds at greatest risk for nonhealing.

CONCLUSION

These results support the concept that leukocyte adherence is involved in the pathogenesis of burn wound necrosis and suggest a therapeutic mechanism for modulating the inflammatory response after the burn injury that may improve wound healing.

Doxycycline treatment reduces ischemic brain damage in transient middle cerebral artery occlusion in the rat

Agents that inhibit leukocyte adhesion including intercellular adhesion molecule-1 antibodies (anti-ICAM-1) have shown beneficial effects in experimental central nervous system (CNS) ischemia. Doxycycline inhibits leukocyte function in vitro by binding divalent cations and reduces spinal cord reperfusion injury. The authors used a clinically relevant model of focal CNS reperfusion injury to test whether treatment with doxycycline would reduce cerebral ischemic damage and improve functional outcome. Reversible middle cerebral artery occlusion was produced in adult Sprague-Dawley rats by advancing a filament into the internal carotid artery for 2 h. Animals received either i.p. doxycycline (10 mg/kg) (N = 13) or saline (N = 11) 30 min before ischemia, followed by 10 mg/kg every 8 h x 6. Both functional assessment (5 point neurologic scale) and infarct volume was evaluated at 48 h. Functional efficacy: doxycycline 0.5 +/- 0.2 (mean +/- SE) vs control 1.3 +/- 0.3 (p = 0.03). Infarct volume: doxycycline 56 +/- 18 mm3 vs control 158 +/- 44 mm3 (p = 0.03); This protective effect supports the role of doxycycline in reducing CNS reperfusion injury.

Inhibition of neutrophil adhesion does not prevent ischemic spinal cord injury

Paraplegia may occur after transient aortic occlusion as a consequence of primary ischemia to the spinal cord or injury during the reperfusion period. In animal models of ischemia/reperfusion there is evidence that reperfusion injury may be modulated partially by neutrophils. The efficacy of the neutrophil adherence blocking murine monoclonal antibody (MAb 60.3) was assessed in spinal cord ischemia/reperfusion in rabbits. Spinal cord ischemia was accomplished by balloon catheter occlusion of the infrarenal aorta. Neurologic assessment was graded as normal, partial neurologic deficit, or complete paralysis. Electrophysiologic monitoring with somatosensory evoked potentials was used to determine the optimal length of time of occlusion. Animals were treated randomly with 2 mg/kg of intravenous Mab 60.3 (n = 8) or saline solution (n = 9) with the investigator unaware of treatment. Mean occlusion times were no different between groups (control, 32.7 +/- 3.6 minutes versus MAb, 32.4 +/- 6.0 minutes). Five (55%) saline-treated and four (50%) MAb 60.3-treated animals became paraplegic. Animals with initial paraparesis all progressed to flaccid paraplegia within 24 hours. We conclude that spinal cord injury after transient aortic occlusion is independent of the CD11/CD18 glycoprotein complex of the neutrophil. Injury in this setting may occur during ischemia and thus may not be dependent on neutrophils or reperfusion.

Effect of inhibiting leukocyte integrin (CD18) and selectin (L-selectin) on susceptibility to infection with Pseudomonas aeruginosa

Leukocyte (WBC) adherence to endothelial cells has been implicated in the pathogenesis of microvascular injury. The process of leukocyte adherence is mediated by both the integrin and selectin families of molecules, and their interaction with specific endothelial ligands. Antibodies directed against the leukocyte integrin CD18 and L-selectin have been developed and functionally inhibit leukocyte adherence in models of inflammatory injury. We asked the question: Does inhibition of leukocyte adherence by administration of monoclonal antibody directed against either CD18, integrins (R15.7, R7.1) or against L-selectin (DREG 200) increase susceptibility to infection? New Zealand white rabbits were shaved and injected subcutaneously on their dorsum with Pseudomonas aeruginosa (ATCC#27853) at two sites each of 10(8) and 10(7) colony forming units. Animals were monitored with daily determination of weight, temperature, WBC counts, hematocrit, and killed at 1 week for determination of abscess formation. There were four blinded experimental groups: (1) Saline (2 mL/kg); (2) DREG 200 (2 mg/kg); (3) R7.1 (2 mg/kg); or (4) R15.7 (2 mg/kg). At the 10(7) and 10(8) injection sites the R15.7 group had an increased rate and size of abscess formation compared with controls. The R7.1 group had an increased rate at the 10(8) injection site. There was no significant difference in the percentage of the abscess formation or mean area between the controls and DREG 200-treated groups. We conclude that giving antibody to CD18 increased susceptibility to infection while giving antibody to L-selectin does not.

Interleukin 4 induces cellular adhesion among B lymphocytes

We here report that interleukin 4 (IL-4) alone is able to induce cellular adhesion among mouse lymphocytes, and together with lipopolysaccharide (LPS), it increases the adhesion induced by LPS. The adhesion was inhibited by antibodies against IL-4. IL-4 appears to be acting mainly on B lymphocytes, since the response caused by IL-4 alone was much less sensitive to depletion of adherent cells than the LPS response. Depletion of T cells had no effect on IL-4- or LPS-induced adhesion. IL-4 could together with Con A, but not alone, induce adhesion among T cells. Cell clusters, which were formed after 2-3 days of LPS plus IL-4 stimulation, could be completely dissociated, and when the cells were recultured in medium, they readily started to reaggregate. The adhesion molecule lymphocyte function-associated antigen 1 (LFA-1) is, at least in part, involved in LPS plus IL-4-induced adhesion. Antibodies against LFA-1 inhibited the adhesion, but antibodies against other cell surface molecules were without inhibitory effect. Adhesion induced by IL-4 alone may involve other adhesion molecules than LFA-1.