Protein tyrosine phosphatase PTPN14 is a regulator of lymphatic function and choanal development in humans.

The lymphatic vasculature is essential for the recirculation of extracellular fluid, fat absorption, and immune function and as a route of tumor metastasis. The dissection of molecular mechanisms underlying lymphangiogenesis has been accelerated by the identification of tissue-specific lymphatic endothelial markers and the study of congenital lymphedema syndromes. We report the results of genetic analyses of a kindred inheriting a unique autosomal-recessive lymphedema-choanal atresia syndrome. These studies establish linkage of the trait to chromosome 1q32-q41 and identify a loss-of-function mutation in PTPN14, which encodes a nonreceptor tyrosine phosphatase. The causal role of PTPN14 deficiency was confirmed by the generation of a murine Ptpn14 gene trap model that manifested lymphatic hyperplasia with lymphedema. Biochemical studies revealed a potential interaction between PTPN14 and the vascular endothelial growth factor receptor 3 (VEGFR3), a receptor tyrosine kinase essential for lymphangiogenesis. These results suggest a unique and conserved role for PTPN14 in the regulation of lymphatic development in mammals and a nonconserved role in choanal development in humans.

Role of COX-2 in lymphangiogenesis and restoration of lymphatic flow in secondary lymphedema.

The pathophysiology of secondary lymphedema remains poorly understood. To clarify the roles of cyclooxygenase (COX)-2 in enhancement of lymphangiogenesis during secondary lymphedema, we tested a mouse tail model and evaluated the recurrence of lymph flow. To induce lymphedema, a circumferential incision was made in the tail of anesthetized mice to sever the dermal lymphatic vessels. The maximum diameters of the tails were measured weekly. We found that the diameters of the tails around the wounds were markedly increased after surgery, and reached maximum size 2 weeks after wounding in mice without a COX-2 inhibitor, celecoxib (Celecoxib-). Expression of COX-2 in wound granulation tissues was markedly increased 1 week after surgery compared with unwounded naive control mice. In Celecoxib-, recurrence of lymphatic flow in the wound granulation tissues was detected 3 weeks after surgical treatment. In contrast, lymphatic flow was markedly suppressed in mice treated with celecoxib (Celecoxib+). Newly formed lymphatic structures were identified in the granulation tissues formed at wounded lesions in Celecoxib-, whereas those were markedly suppressed in Celecoxib+. Interstitial tissue pressures in the distal areas of the tail wounds were markedly increased in Celecoxib+ with reduced expression of vascular endothelial cell growth factor (VEGF)-C. F4/80-positive cells were accumulated to the wound granulation tissues in Celecoxib-, and the accumulation of these cells was suppressed in Celecoxib+. Prostaglandin E(2) (PGE(2)) upregulated the expressions of VEGF-A and VEGF-C in cultured macrophages, but not human lymphatic microvascular endothelial cells. The present study therefore suggests that lymphangiogenesis, together with recurrence of lymph flow after surgical induction of lymphedema, is upregulated by COX-2 possibly via generation of PGs.

Sequential pneumatic compression for lymphedema. A controlled trial.

We examined prospectively the effect of a new compression device for lymphedema, which utilizes a short duration and high-pressure cycle, that provides a sequential milking pattern to the limb through multiple compartments. Twenty-five patients (seven patients for upper-extremity and 18 for lower-extremity problems) underwent 24 hours of treatment. All extremities showed a decrease in circumferential measurements with the maximal reduction occurring at the wrist (45%) for the upper extremities and at the mid-calf (47%) for the lower extremities. Lower-extremity leg volume was reduced by 45%. Despite the high pressures no elevation in serum muscle enzyme levels was noted. This device reduced lymphedematous limbs rapidly and safely.

[Mechanism of diagnostic significance of histidase release into the blood in lymphedema]. / Mekhanizm i diagnosticheskaia zhachimost' vykhoda gistidazy v krov' pri limfedeme.

The organ-specific enzyme histidase was measured as an indicator of skin involvement in the blood of 52 patients with primary and secondary lymphedema of the upper and lower limbs. A stable type of the disease (degree I) was characterized by washing histidase off the derma into the blood. Mild and moderate histidase washing associated with skin dystrophy occurred with progression of the disease (stage II and III, respectively). In advanced lymphedema (degree 4) histidase does not enter blood from the skin. This fact is explained by total impairment of skin cell elements and their replacement for fibrous tissue. Both in primary and secondary lymphedema complicated by erysipelas histidase is washed off the dermocytes. The findings justify use of blood histidase indices for assessment of lymphedema patients' condition, formulation of indications for operation and concluding on the latter efficacy.

Lymphoedema of the rabbit ear following partial and complete lymphatic blockade; its effects on fibrotic development, enzyme types and their activity levels.

The dorsal surface of the rabbit ear was found to be a suitable place for the production of long-lasting lymphoedema. Its major tissues (skin and sub cutaneous) are those to which secondary lymphoedema is confined in clinical situations. After 32 weeks of partial lymphatic blockade total tissue activity levels of neutral proteinase and beta-glucuronidase were depressed while alkaline phosphatase was elevated. Subsequent complete lymphatic blockade for a further 5 weeks resulted in severe fibrosis of the s.c. tissues. The total tissue activity levels of 3 characteristic lysosomal macrophage hydrolases--acid protease, beta-glucuronidase and acid phosphatase--were significantly increased. There were strong correlations between the activity levels of these enzymes and the extent of fibrosis, increased fibrosis being characterized by higher activity levels. This, together with other evidence, suggested--as fibrosis became more severe--the total number of macrophages increased, but a high proportion of these were non-stimulated. Since these cells (when stimulated) are normally responsible for the lysis of collagen and removal of fibrotic tissue the impairment of their function as occurs in chronic lymphoedema results in further fibrosis and the continuation of the vicious circle.

The influence of various benzo-pyrones on acid and neutral protease activity levels, the cells from which they may arise and their importance in the resolution of lymphoedema.

The availability of digestable material to a phagocyte determines not only the rapidity and completeness of digestion but the amount of lysosomal enzyme which reaches the extracellular compartment and the circulation. The measurement of enzyme activities in thermally injured limbs has shown the benzo-pyrones to enhance acid protease activity. There is much evidence to suggest this activity originates from macrophages which enter the thermally injured regions in great numbers. In this paper the administration of benzo-pyrones to animals with lymphoedema is reported to enhance neutral protease activity levels. This activity is not associated with mononuclear cells but with the neutrophils. Although additional histological work must be done to confirm the presence of neutrophils in lymphoedematous tissues there is evidence to suggest the increases in neutral protease levels arise from neutrophils and that in lymphoedema it is these cells which are acted upon by the benzo-pyrones. They then cause the removal of protein by enhancing its lysis either within the cells or in the extracellular compartment.

Iminopeptiduria, skin ulcerations, and edema in a boy with prolidase deficiency.

A 12-year-old boy with recurrent skin ulceration, chronic generalized lymphedema, and mild mental retardation was found to excrete massive amounts of dipeptides, most (but not all) of which had proline or hydroxyproline as the carboxyl terminal residue. Glycylproline predominated. Prolidase deficiency was demonstrated in red blood cells and in fibroblastic cells. Prolidase activity was present in continuous lymphoid cell cultures at the same low level observed in control cells.

Mild phenotypic expression of alpha-N-acetylgalactosaminidase deficiency in two adult siblings.

Two adult siblings with an alpha-N-acetylgalactosaminidase deficiency are described. The patients' major features are massive lymphoedema and angiokeratoma corporis diffusum. Neurological evaluation performed in one of the patients was considered within normal limits. Blood type is A positive in each case. Ultrastructural examination of skin revealed numerous vacuoles in endothelial cells and pericytes. Fibroblast activity of alpha-N-acetylgalactosaminidase was decreased to 0.6-2% of mean normal value. Chromatography of urinary oligosaccharides showed abnormal bands identical to those excreted by two infantile patients with Schindler disease. The bands were identified as sialyloligosaccharides, and gas chromatography revealed the presence of N-acetylgalactosamine-rich compounds accounting for 30% of the total monosaccharide content of the oligosaccharide fraction. These findings confirm the heterogeneity of alpha-N-acetylgalactosaminidase deficiency and emphasize the need to consider this lysosomal storage disease in the differential diagnosis of patients with angiokeratoma.

Fabry's disease with familial lymphedema of the lower limbs. Case report and family study.

The case of a 49-year-old man with Fabry's disease (FD), confirmed by histopathological findings of kidney and skin biopsies and enzymatic studies, is reported. Clinical symptoms mainly consisted in severe neurological involvement, and in conspicuous lymphedema of the lower limbs. Two decreased brothers of the patient were also affected with symptons strongly suggesting FD, as well as the lymphedema of the lower limbs. On the basis of these data, the association of FD with familial lymphedema of the lower limbs is discussed: a lipid accumulation in the lymphatic as well as the blood vessel wall is proposed as a possible explanation; the hypothesis of an inborn error in the development of the lymphatic system, controlled by a gene closedly associated with the FD gene on the same chromosome can also be advanced.