Tamm-Horsfall glycoprotein in human amniotic fluid

Human chorionic gonadotrophin pharmaceutical formulations of urinary origin display high levels of contaminant proteins-A label-free quantitation proteomics study

To determine whether there is a measurable protein background in different formulations of urinary and recombinant human chorionic gonadotropin (hCG). Primary outcome measures: identification of contaminant proteins in urinary-derived formulations of hCG; secondary outcome measures: quantitative values of contaminant proteins in different batches of urinary -derived hCG formulations. It was found that urinary-derived batches have high presence of contaminant proteins beside the active substance. The relative amount of contaminant proteins and hCG differs strongly between different batches.

Tamm-Horsfall Protein is a Potent Immunomodulatory Molecule and a Disease Biomarker in the Urinary System

Tamm–Horsfall protein (THP), or uromodulin (UMOD), is an 80–90-kDa phosphatidylinositol-anchored glycoprotein produced exclusively by the renal tubular cells in the thick ascending limb of the loop of Henle. Physiologically, THP is implicated in renal countercurrent gradient formation, sodium homeostasis, blood pressure regulation, and a defense molecule against infections in the urinary system. Investigations have also revealed that THP is an effective binding ligand for serum albumin, immunoglobulin G light chains, complement components C1 and C1q, interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor (TNF)-α, and interferon-γ through its carbohydrate side chains for maintaining circulatory and renal immune homeostasis. Thus, THP can be regarded as part of the innate immune system. UMOD mutations play crucial roles in congenital urolithiasis, hereditary hyperuricemia/gout, and medullary cystic kidney diseases. Recent investigations have focused on the immunomodulatory effects of THP on immune cells and on THP as a disease biomarker of acute and chronic kidney diseases. Our studies have suggested that normal urinary THP, through its epidermal growth factor (EGF)-like domains, binds to the surface-expressed EGF-like receptors, cathepsin G, or lactoferrin to enhance polymorphonuclear leukocyte phagocytosis, proinflammatory cytokine production by monocytes/macrophages, and lymphocyte proliferation by activating the Rho family and mitogen-activated protein kinase signaling pathways. Furthermore, our data support both an intact protein core structure and carbohydrate side chains are important for the different protein-binding capacities of THP. Prospectively, parts of the whole THP molecule may be used for anti-TNF-α therapy in inflammatory diseases, autoantibody-depleting therapy in autoimmune disorders, and immune intensification in immunocompromised hosts.

Tamm-Horsfall protein regulates circulating and renal cytokines by affecting glomerular filtration rate and acting as a urinary cytokine trap

Although few organ systems play a more important role than the kidneys in cytokine catabolism, the mechanism(s) regulating this pivotal physiological function and how its deficiency affects systemic cytokine homeostasis remain unclear. Here we show that elimination of Tamm-Horsfall protein (THP) expression from mouse kidneys caused a marked elevation of circulating IFN-γ, IL1α, TNF-α, IL6, CXCL1, and IL13. Accompanying this were enlarged spleens with prominent white-pulp macrophage infiltration. Lipopolysaccharide (LPS) exacerbated the increase of serum cytokines without a corresponding increase in their urinary excretion in THP knock-out (KO) mice. This, along with the rise of serum cystatin C and the reduced inulin and creatinine clearance from the circulation, suggested that diminished glomerular filtration may contribute to reduced cytokine clearance in THP KO mice both at the baseline and under stress. Unlike wild-type mice where renal and urinary cytokines formed specific in vivo complexes with THP, this "trapping" effect was absent in THP KO mice, thus explaining why cytokine signaling pathways were activated in renal epithelial cells in such mice. Our study provides new evidence implicating an important role of THP in influencing cytokine clearance and acting as a decoy receptor for urinary cytokines. Based on these and other data, we present a unifying model that underscores the role of THP as a major regulator of renal and systemic immunity.

Goat uromodulin promoter directs kidney-specific expression of GFP gene in transgenic mice

BACKGROUND

Uromodulin is the most abundant protein found in the urine of mammals. In an effort to utilize the uromodulin promoter in order to target recombinant proteins in the urine of transgenic animals we have cloned a goat uromodulin gene promoter fragment (GUM promoter) and used it to drive expression of GFP in the kidney of transgenic mice.

RESULTS

The GUM-GFP cassette was constructed and transgenic mice were generated in order to study the promoter's tissue specificity, the GFP kidney specific expression and its subcellular distribution. Tissues collected from three GUM-GFP transgenic mouse lines, and analyzed for the presence of GFP by Western blotting and fluorescence confirmed that the GUM promoter drove expression of GFP specifically in the kidney. More specifically, by using immuno-histochemistry analysis of kidney sections, we demonstrated that GFP expression was co-localized, with endogenous uromodulin protein, in the epithelial cells of the thick ascending limbs (TAL) of Henle's loop and the early distal convoluted tubule in the kidney.

CONCLUSION

The goat uromodulin promoter is capable of driving recombinant protein expression in the kidney of transgenic mice. The goat promoter fragment cloned may be a useful tool in targeting proteins or oncogenes in the kidney of mammals.

Tamm-Horsfall glycoprotein: biology and clinical relevance

Tamm-Horsfall glycoprotein (THP) is the most abundant urinary protein in mammals. Urinary excretion occurs by proteolytic cleavage of the large ectodomain of the glycosyl phosphatidylinositol-anchored counterpart exposed at the luminal cell surface of the thick ascending limb of Henle's loop. We describe the physical-chemical structure of human THP and its biosynthesis and interaction with other proteins and leukocytes. The clinical relevance of THP reported here includes: (1) involvement in the pathogenesis of cast nephropathy, urolithiasis, and tubulointerstitial nephritis; (2) abnormalities in urinary excretion in renal diseases; and (3) the recent finding that familial juvenile hyperuricemic nephropathy and autosomal dominant medullary cystic kidney disease 2 arise from mutations of the THP gene. We critically examine the literature on the physiological role and mechanism(s) that promote urinary excretion of THP. Some lines of research deal with the in vitro immunoregulatory activity of THP, termed uromodulin when isolated from urine of pregnant women. However, an immunoregulatory function in vivo has not yet been established. In the most recent literature, there is renewed interest in the capacity of urinary THP to compete efficiently with urothelial cell receptors, such as uroplakins, in adhering to type 1 fimbriated Escherichia coli. This property supports the notion that abundant THP excretion in urine is promoted in the host by selective pressure to obtain an efficient defense against urinary tract infections caused by uropathogenic bacteria.

Tamm-Horsfall glycoprotein (THG) purified from normal human pregnancy urine increases phagocytosis, complement receptor expressions and arachidonic acid metabolism of polymorphonuclear neutrophils

Tamm-Horsfall glycoprotein (THG) purified from normal human pregnancy urine was found to increase polymorphonuclear neutrophil (PMN) phagocytosis (46.57 +/- 3.54% in the medium versus 75.85 +/- 5.37% in the presence of 25 micrograms/ml THG) after 30 min preincubation. The phagocytosis-enhancing activity of THG was dose-dependent (5-50 micrograms/ml) and was possibly mediated by the increased expressions of complement receptor type 1 (CR1) and type 3 (CR3) on the neutrophils. The release of [3H]arachidonic acid and prostaglandin E2 (PGE2), but not thromboxane B2 (TXB2), from neutrophils were also significantly enhanced by THG. Using 3,3'-dihexyloxacarbocyanine iodide as indicator, THG (25 micrograms/ml) depolarized the membrane potential of PMN after 30 min preincubation. In addition, THG exhibited a specific membranotropic effect with PMN. It is conceivable that THG binds to the cell surface and depolarizes the membrane potential of PMN which subsequently enhances the release of arachidonic acid metabolites and the translocation of the complement receptors to the membrane. These biochemical events lead to the increment of PMN phagocytosis and suggests that THG may play an important role in the defense mechanisms of the urinary tract in that a large amount of THG is usually present.

Amniotic fluid laminin and type IV collagen in normal and pathological pregnancies

Specific radioimmunoassays for the fragment P1 of human laminin and the 7-S collagen domain of human type IV collagen were used to quantify these basement membrane proteins in second trimester amniotic fluid samples from 21 normal and 41 pathological pregnancies, the latter group being defined by elevated amniotic fluid alpha-foetoprotein (AFP) or abnormal foetal karyotype, or both. The mean laminin P1 concentration in the normal 15 to 18-wk pregnancies was 36 micrograms/l (range 10-77) and that of the 7-S collagen was 46 micrograms/l (range 7-152). The molecular size of the antigens in amniotic fluid from both normal and pathological pregnancies, when assessed by gel filtration was very large, probably representing intact laminin and type IV collagen. Pathological pregnancies, e.g. cases of Turner syndrome, Meckel syndrome and anencephaly often had elevated amniotic fluid laminin and type IV collagen concentrations. A weak, but nevertheless significant, correlation was found between the amniotic fluid laminin and type IV collagen concentrations and also between type IV collagen and AFP, but none between laminin and AFP. In eight pregnancies with foetuses suffering from the congenital nephrotic syndrome of the Finnish type, a genetic disease assumed primarily to involve some component of the glomerular basement membrane, the amniotic fluid concentrations of both laminin and type IV collagen were within normal limits in spite of an elevated amniotic fluid AFP.

gamma-Glutamyl transpeptidase in human amniotic fluid and in fetal tissues

The activity of gamma-glutamyl transpeptidase (GGT) was measured in 360 amniotic fluid samples from second and third trimester pregnancies with fetal and maternal disorders. The enzyme level was within the normal range in all but one of the 18 second trimester pregnancies with congenital malformations. On cellulose acetate electrophoresis, GGT fractionated as an alpha 1-band in all mid-trimester samples tested. Highly elevated GGT values were found in five samples from the third trimester gestations with fetal gastroschisis, hydrops fetalis and Meckel's syndrome. The enzyme in these samples showed alpha 1-mobility while most of the third trimester amniotic fluids contained GGT with beta-mobility. Considerable GGT activity was observed in several fetal tissues that are in contact with the amniotic fluid. Highest levels were found in meconium and bile from a second trimester fetus. The total activity and electrophoretic mobility of GGT in late amniotic fluid and in urine from newborns was similar.