Gloria C. Koo

11β-HSD1 inhibition ameliorates metabolic syndrome and prevents progression of atherosclerosis in mice

The enzyme 11β–hydroxysteroid dehydrogenase (HSD) type 1 converts inactive cortisone into active cortisol in cells, thereby raising the effective glucocorticoid (GC) tone above serum levels. We report that pharmacologic inhibition of 11β-HSD1 has a therapeutic effect in mouse models of metabolic syndrome. Administration of a selective, potent 11β-HSD1 inhibitor lowered body weight, insulin, fasting glucose, triglycerides, and cholesterol in diet-induced obese mice and lowered fasting glucose, insulin, glucagon, triglycerides, and free fatty acids, as well as improved glucose tolerance, in a mouse model of type 2 diabetes. Most importantly, inhibition of 11β-HSD1 slowed plaque progression in a murine model of atherosclerosis, the key clinical sequela of metabolic syndrome. Mice with a targeted deletion of apolipoprotein E exhibited 84% less accumulation of aortic total cholesterol, as well as lower serum cholesterol and triglycerides, when treated with an 11β-HSD1 inhibitor. These data provide the first evidence that pharmacologic inhibition of intracellular GC activation can effectively treat atherosclerosis, the key clinical consequence of metabolic syndrome, in addition to its salutary effect on multiple aspects of the metabolic syndrome itself.

Serologic Detection of a Y-Linked Gene in XX Males and XX True Hermaphrodites

To test the hypothesis that H-Y antigen (present on both somatic and germ cells in normal males but not normal females) is essential for testicular differentiation, we studied four XX males and three XX true hermaphrodites. Blood cells from six subjects and cultured gonadal fibroblasts from a seventh expressed H-Y antigen. Since expression of this antigen requires the presence of a gene normally carried by the Y chromosome, this gene, and perhaps additional Y chromosomal material, should have been present in the genome of these subjects. In one patient this presence is accounted for by a Y-to-X translocation, detectable by chromosome banding. In another a normal Y chromosome was present in a minor population of cells. In the remaining five, no karyotypic abnormality was detectable. Immunologic detection of H-Y antigen is a sensitive test for the presence of the Y chromosome or of its male-determining segment.

Hormone-like role of H–Y antigen in bovine freemartin gonad

IN cattle, chorionic vascular anastomosis with a male twin modifies sexual development of a female twin foetus1,2. In this condition, testosterone-dependent masculinisation of the genital tract is only moderate: the ovary is virilised to resemble a small testis in the extreme case (for reviews see refs 3 and 4). Since testosterone derived from the male twin cannot modify the ovary5, the cellular theory of freemartinism has been proposed6,7. This theory is based on the finding that freemartins are XY/XX chimaeras with regard to not only their haemopoietic organs8,9 but also their gonads9. Indeed, the XY/XX mosaic or chimaeric gonad of mammals seems to show the definite tendency to develop as a testis. For example, so-called XX human males may actually be cryptic XY/XX mosaics10, and in certain strain combinations, a great preponderance of males is seen among the experimentally produced XY/XX mosaic mice11. It has been proposed that H–Y antigen disseminated by XY gonadal cells entices neighbouring XX cells to engage in testicular organisation12. Here we report the confirmation of this proposal on the strongly virilised foetal freemartin gonad.

Recessive sex-determining genes in human XX male syndrome.

Maleness is normally inherited as a dominant trait (a single copy of the Y chromosome induces testicular differentiation of the embryonic gonad), but our genealogic study of three XX males in one pedigree indicated an autosomal recessive mode of male inheritance. Subsequent study revealed the presence of H-Y antigens in the three XX males and in their mothers, and suggested that excess H-Y may be found in the fathers. Inasmuch as H-Y loci have been mapped to the human Y chromosome, these data favor the view that H-Y structural loci comprise a family of testis-determining genes, and that Y autosome (or Y-X) translocation can generate either dominant or recessive modes of XX sex reversal, depending upon the particular portion of H-Y genes transferred.

Recessive male-determining genes

The autosomal dominant gene polled (P) causes hornlessness in goats. Chromosomal females (XX) that are P/P homozygotes develop testes or ovotestes. Thus with respect to its testis-determining properties, P or a closely linked gene acts as an autosomal recessive. Polled intersex goats are H-Y+. This finding is consistent with the view that there may be a cluster of testis-determining H-Y genes on the Y chromosome, and that translocation of a subcritical portion of these genes may generate a recessive mode of sex determination.

Reacting mouse sperm with monoclonal H-Y antibodies does not influence sex ratio of eggs fertilized in vitro.

The fertility of Y-bearing mouse sperm was examined after reacting cauda epididymal sperm with monoclonal H-Y antibodies and protein A sensitized sheep red blood cells. Treated sperm were used for the in vitro fertilization of mouse oocytes which subsequently produced live offspring. There was no significant shift in the sex ratio in favor of females, suggesting that X- and Y-bearing sperm may share the surface antigen. Additional studies were directed toward ascertaining whether haploid expression, as measured by the presence of H-Y antigen, occurs in epididymal sperm or during their capacitation in vitro. Ligation of the corpus epididymus, preventing subsequent transport of sperm to the cauda region, resulted in a linear decrease in H-Y positive cauda sperm. By 17 days after ligation, no positively reacting sperm were observed. Incubation of cauda epididymal sperm for 3 h in capacitating medium eliminated positive reaction by the capacitated sperm to the H-Y antiserum. Furthermore, the percentage of H-Y-positive sperm from different regions of the male reproductive tract appeared to decrease during their transport from the testis to the epididymus and vas deferens. We suggest that H-Y antigen appears on the sperm surface during association with testicular constituents and is removed during epididymal transport and capacitation. No evidence of haploid expression by epididymal mouse sperm was found.

A simplified technique for H-Y typing

Abstract Sperm and male lymphocytes of the mouse, when sensitized with H-Y antibody, form rosettes with sheep erythrocytes to which Staphylococcal Protein A has been coupled. This provides a useful method for typing cells for H-Y antigen by absorbing the H-Y antiserum with cells from the individuals to be typed for H-Y.

Application of monoclonal anti-HY antibody for human H-Y typing

SummaryWe have successfully produced monoclonal anti-H-Y antibody by fusing NS-1 myeloma cells with splenocytes from C57BL/6 females immunized with syngeneic male splenocytes. We have proved that the antibody is male specific and that it cross reacts with human H-Y. We have further tested 80 normal individuals for H-Y antigen and obtained significant differences between males and females. Therefore, the monoclonal anti-H-Y antibody is useful for clinical typing of human H-Y antigen.

H-Y antigen in X,i(Xq) gonadal dysgenesis: Evidence of X-linked genes in testicular differentiation

SummaryThree years ago, we detected H-Y antigen in the white blood cells of a phenotypic female with several of the stigmata of Turners syndrome, and the mosaic karyotype: 45,X/46,X,i(Xq). We surmised at the time that the isochromosome, i(Xq), may have contained occult Y-chromosome-derived material. We have now confirmed the presence of H-Y in this patient and we have obtained evidence for the presence of H-Y in four of five other similar patients, all of whom are notable for carrying at least a single cell line with the karyotype 46,X,i(Xq). Although we cannot categorically exclude the presence of Y-chromosomal genes in the cells of these patients, there is no cytogenetic evidence of structural rearrangement involving the Y in any of the cases. Expression of H-Y antigen in association with i(Xq) thus implies that H-Y structural genes are X-situated, or alternatively that they are autosomal and X-regulated. It would follow that the H-Y+ cellular phenotype per se is not a valid marker for the Y-chromosome, and that H-Y genes that have been mapped to the pericentric region of the Y may be regulatory.

Inherited XX sex reversal in the cocker spaniel dog

SummaryNine XX true hermaphrodites and two XX males were discovered in a family of American cocker spaniels. The true hermaphrodites were partially-masculinized females with ovotestes; the XX males had malformed male external genitalia and cryptorchid aspermatogenic testes. Wolffian and Mullerian duct derivatives were present in both true hermaphrodites and XX males. All four sires of sex-reversed dogs were normal XY males; five of the dams were anatomically normal females and one was an XX true hermaphrodite. A second true hermaphrodite reproduced as a female, producing anatomically normal offspring.All matings that produced sex-reversed offspring were consanguineous. Matings of the parents of sex-reversed cocker spaniels to normal beagles with no family history of intersexuality produced only normal offspring. Examination of G-banded karyotypes of the affected animals, their parents, and siblings, revealed no structural anomalies of the chromosomes that were consistently associated with sex-reversal.In assays for serologically-detectable H-Y antigen, the group of XX true hermaphrodites and the group of XX males had mean levels of the antigen not significantly different from that in normal male controls. Female parents of sex-reversed dogs and some of their female siblings were typed H-Y antigen positive, but the mean level of the antigen in this group was less than that of normal male controls.It is proposed that XX sex reversal in cocker spaniels is due to a mutant gene which when homozygous in females, results in a level of H-Y antigen similar to that found in normal males and the gonads develop as ovotestes or testes. When the gene is heterozygous in females, the level of serologically-detectable H-Y antigen is lowr than that found in normal males and the gonads develop as normal ovaries. The persistence of Mullerian structures in the presence of testicular tissue suggests that Mullerian inhibiting substance is deficient or ineffective in its action in this condition.