Coagulation Activation and Tissue Necrosis in Meningococcal Septic Shock: Severely Reduced Protein C Levels Predict a High Mortality

Fulminant meningococcal septic shock in a boy with combined inherited properdin and protein C deficiency

A 7-year-old patient with fulminant septic shock due to Neisseria meningitidis of the uncommon serogroup Y developed extensive gangrene of the limbs. Multiple amputations were necessary and a pulmonary embolism occurred within 2 days post-operatively. Complement and haemostatic system studies, done after recovery, showed a complete absence of properdin antigen and a low protein C antigen and activity level in plasma. Defective haemolytic activity in gel by the alternative pathway of complement activation could be restored with purified properdin, indicating a properdin deficiency type 1. Protein C antigen level as well as activity were in agreement with a protein C deficiency type I. The polymerase chain reaction (PCR) product of exon five of the protein C gene showed a substitution of 72Gly by Arg. Both deficiencies were traced among relatives of the patient. Serum of the father of the patient's mother was also properdin-deficient. Microsatellite haplotyping of the X-chromosome of the patient and his relatives showed that a distinct haplotype cosegregated with the properdin deficiency (Lodscore 2.25; four informative meioses). The protein C type I deficiency was present in the patient's mother and her mother and cosegregated with the mutation found. So far as is known, this is the first patient described with combined inherited properdin deficiency and protein C deficiency.

Two mutations in the promoter region of the human protein C gene both cause type I protein C deficiency by disruption of two HNF-3 binding sites

Protein C is a vitamin K-dependent zymogen of a serine protease that inhibits blood coagulation by the proteolytic inactivation of factors Va and VIIIa. Individuals affected with protein C deficiency are at risk for thrombosis. Genetic analyses of affected individuals, to determine the cause of the protein C deficiency, revealed a large variety of mutations in the protein C gene, including several in the promoter region of this gene. Comparison of the region around two of these mutations, A-32-->G and T-27-->A, with transcription factor consensus sequences suggested the presence of two overlapping and inversely oriented HNF-3 binding sites. Direct evidence for the presence of the two HNF-3 binding sites in the protein C promoter was obtained using electrophoretic mobility shift assays and UV cross-linking experiments. These experiments revealed that HNF-3 can bind specifically to both putative HNF-3 sites in the wild-type protein C promoter. Due to the T-27-->A mutation, one binding site is completely lost, while the other site still binds HNF-3, but with strongly reduced affinity. As a consequence of the A-32-->G mutation, the protein C promoter loses all its HNF-3 binding capacity. Transient transfection experiments demonstrated that the binding of HNF-3 to the protein C promoter is of physiological significance. This followed from experiments in which the introduction of the A-32-->G or T-27-->A mutation resulted in a 4-5-fold reduced promoter activity in HepG2 cells. Furthermore, transactivation of the wild-type protein C promoter construct with HNF-3 showed a 4-5-fold increased promoter activity in HepG2 cells. In HeLa cells, significant wild-type promoter activity was only observed after transactivation with HNF-3. When a promoter construct containing the T-->A mutation at position -27 was used, the transactivation potential of HNF-3 was 2-fold reduced in HepG2 cells, whereas in HeLa cells no transactivation was observed. With the promoter construct containing the A-32-->G mutation, no transactivation by HNF-3 was found either in HepG2 or in HeLa cells.

Inherited complement deficiency in children surviving fulminant meningococcal septic shock

We evaluated the complement system in 29 children (mean age: 4.5 years) who survived fulminant meningococcal septic shock. No terminal complement deficiencies were found. One patient, who experienced the most dramatic disease course, had a decreased haemolytic activity in the haemolysis-in-gel test for the alternative pathway. The properdin concentration in serum of this patient was < 0.1 microgram/ml (n = 17.1-27.7 micrograms/ml). Coagulation studies revealed a heterozygeous type I protein C deficiency as well. He was the only patient with a Neisseria meningitidis group Y infection.

CONCLUSION

Fulminant meningococcal disease due to uncommon serogroups should lead to screening of the alternative pathway of complement activation.