GM-CSF: a strong arteriogenic factor acting by amplification of monocyte function.

We investigated the role of the colony stimulating factor for monocytes (GM-CSF) to test the hypothesis whether prolongation of the monocyte's life cycle will support arteriogenesis (rapid growth of preexisting collateral arteries). This appeared logical in view of our discovery that circulating monocytes play an important part in the positive remodeling of small preexisting arterioles into arteries to compensate for arterial occlusions (arteriogenesis) and especially following our findings that MCP-1 markedly increases the speed of arteriogenesis. The continuous infusion of GM-CSF for 7 days into the proximal stump of the acutely occluded femoral artery of rabbits by osmotic minipump produced indeed a marked arteriogenic response as demonstrated by an increase (2-fold) in number and size of collateral arteries on postmortem angiograms and by the increase of maximal blood flow during vasodilation measured in vivo by blood pump perfusion of the hindquarter (5-fold). When GM-CSF and MCP-1 were simultaneously infused the effects on arteriogenesis were additive on angiograms as well as on conductance. GM-CSF was also able to widen the time window of MCP-1 activity: MCP-1 treatment alone was ineffective when given after the third week following occlusion. When administered together with GM-CSF about 80% of normal maximal conductance of the artery that was replaced by collaterals were achieved, a result that was not reached before by any other experimental treatment. Experiments with cells isolated from treated animals showed that monocyte apoptosis was markedly reduced. In addition we hypothesize that GM-CSF may aid in releasing pluripotent monocyte (stem-) cells from the bone marrow into the circulation. In contrast to MCP-1, GM-CSF showed no activity on monocyte transmigration through- and also no influence on monocyte adhesion to cultured endothelial cells. In conclusion we have discovered a new function of the hemopoietic stem cell factor GM-CSF, which is also a powerful arteriogenic peptide that acts via prolongation of the life cycle of monocytes/macrophages.

Ehlers-Danlos syndrome type VI: lysyl hydroxylase deficiency due to a novel point mutation (W612C).

Ehlers-Danlos syndrome type VI (EDS VI) is a rare autosomal recessively inherited disease of connective tissue. The characteristic symptoms are hyperflexibility of joints and hyperelasticity of skin together with marked scoliosis, ocular manifestations and involvement of the vascular system. The underlying biochemical defect in EDS VI is a deficiency in lysyl hydroxylase (PLOD) activity resulting from mutations in the PLOD gene causing a low hydroxylysine content in various tissues. We found that two out of three patients showed a recently described duplication of about 800 bp in their LH mRNA. In the third patient we identified a new point mutation (2036 G-->C) resulting in a substitution of tryptophan by cysteine in the highly conserved C-terminal region of the enzyme (W612C). In addition, this mutation destroys a restriction site of MwoI. Restriction analysis of the patient's cDNA with MwoI showed the sole occurrence of the mutated transcript, while one allele in his genomic DNA contained the MwoI restriction site. Restriction analysis of the genomic DNA of the unaffected parents displayed a heterozygous loss of the restriction site for MwoI in the mother while the DNA of the father appeared normal. Our study demonstrates that the new point mutation (W612C) in conjunction with a functionless allele, most probably a null allele, for the LH gene may explain the functional deficiencies seen in this patient.

The early pregnancy factor (EPF) in pregnancies of women with habitual abortions.

The EPF activity of 67 sera, obtained during the 6th to 9th week of pregnancy, was determined using the rosette inhibition test. The sera of uncomplicated pregnancies (n = 9) and of women with habitual abortions who came to delivery during the most recent pregnancy (n = 10) contained the highest EPF activity during the 6th week of gestation. When pregnancies ended in another abortion (n = 10) the EPF was never detected, or disappeared at least 1-2 weeks before abortion. In the absence of EPF activity the relative risk of abortion was 7.6 (first determination) or 20.0 (second determination 1 week later). In comparison, the risk was lower when the more commonly used pregnancy parameters (HCG 4.4 (5.7), estradiol 2.6 (4.9), or progesterone (2.7 (2.7)) were depressed. Our results suggest that the EPF determination has high prognostic value in patients with high risk pregnancies and in pregnancies which follow treatment for sterility.