Dendritic cell CD83 homotypic interactions regulate inflammation and promote mucosal homeostasis.

Dendritic cells (DCs) form an extensive network in the intestinal lamina propria, which orchestrates the mucosal immune response. Alterations in DC function can predispose to inflammatory bowel disease, although by unknown mechanisms. We show that CD83, a highly regulated DC cell surface protein, modulates the immune response to prevent colitis. Mice with a conditional knockout of CD83 in DCs develop exacerbated colitis following dextran sodium sulfate challenge, whereas mucosal overexpression of CD83 inhibits DC inflammatory response and protects against colitis. These CD83 perturbations can be modeled in vitro where we show that CD83 homotypic interaction occurs via cell-cell contact and inhibits pro-inflammatory responses. CD83 knockdown or cytoplasmic truncation abrogates the effects of homotypic binding. We demonstrate that CD83 homotypic interaction regulates DC activation via the mitogen-activated protein kinase pathway by inhibiting p38α phosphorylation. Our findings indicate that CD83 homotypic interactions regulate DC activation and promote mucosal homeostasis.

The type 2 iodothyronine deiodinase is expressed in the rat uterus and induced during pregnancy.

Thyroid hormones are of considerable importance for vertebrate reproductive function and during development. To further assess the role of these compounds in this capacity, we examined the expression pattern of the type 2 iodothyronine deiodinase (D2), which converts T(4) to the more active hormone T(3), in the rat uterus in both the nonpregnant and the pregnant state. D2 activity was identified as the predominant, if not only, 5'-deiodinase in the nonpregnant rat uterus. The expression of D2 messenger RNA was located by in situ hybridization to the endometrial stromal cells, where the signal was particularly enriched in the region adjacent to the epithelial cells of the uterine lumen. During pregnancy, D2 activity increased, peaking on day 17 of gestation (embryonic day 17). At that time, uterine D2 activity exceeded that in the placenta, as well as that in the fetal tissues. In the earlier stages of pregnancy before placental formation (e.g. embryonic days 10-11), D2 messenger RNA in the rat uterus was located outside the decidual tissue, which was observed, as in previous studies, to highly express the inactivating type 3 deiodinase. In summary, the rat uterus, particularly during pregnancy, seems to be a site of active thyroid hormone metabolism, presumably designed to maintain the optimal thyroid hormone environment for both the fetus and the maternal uterine tissue.

Effects of selenium deficiency on tissue selenium content, deiodinase activity, and thyroid hormone economy in the rat during development.

The iodothyronine deiodinases, D1, D2, and D3, all contain selenium (Se) in the form of selenocysteine at their active sites, and they play crucial roles in determining the circulating and intracellular levels of the active thyroid hormone (TH), T3. However, not only are serum T3 levels normal in Se-deficient rats but phenotypic and reproductive abnormalities are minimal, and it has been suggested that regulatory mechanisms exist to conserve Se in critical tissues. The present study was designed to determine, in rats: 1) whether the effects of Se-deficiency are greater in the fetus and neonate than in the adult; 2) whether there are tissues other than brain and thyroid in which deiodinase activities are maintained; 3) whether the maintenance of deiodinase activity in a specific tissue is associated with a concomitant preservation of Se level in that tissue; and 4) whether TH economy and general health is maintained over several generations. The tissues studied included liver, cerebrum, thyroid, pituitary, skin, brown adipose tissue, uterus, ovary, testis, placenta, and the implantation site (uterus plus contents) at E9. The results have revealed that, with the exception of liver, skin, and nonpregnant uterus, all of the tissues studied maintained substantial deiodinase activity (>50%) during prolonged Se-deficiency. Second, although the ability of a tissue to maintain deiodinase activity in the face of dietary Se deprivation was associated in some tissues with a concomitant local preservation of Se concentration, this was not the case for all tissues. Only when Se levels were decreased by more than 80% was deiodinase activity markedly decreased. Third, the effects of Se-deficiency were no greater in the fetus than in the adult; and fourth, at the level of Se-deficiency employed in this study, TH economy and general health were successfully maintained over six generations of Se-deficient rats. How Se levels are maintained in specific tissues, whether Se is sequestered in specific cells of a tissue or organ during dietary Se deprivation, and the precise mechanisms by which plasma T3 levels are maintained in Se-deficient animals remain unanswered. Further insights may be gained by using diets that are even lower in Se than those that were used herein and/or by conducting studies using radioactive forms of Se and thyroid hormones.

Pregnant rat uterus expresses high levels of the type 3 iodothyronine deiodinase.

Although thyroid hormones are critically important for the coordination of morphogenic processes in the fetus and neonate, premature exposure of the embryo to levels of the hormones present in the adult is detrimental and can result in growth retardation, malformations, and even death. We report here that the pregnant rat uterus expresses extremely high levels of the type 3 iodothyronine deiodinase (D3), which inactivates thyroxine and 3,3', 5-triiodothyronine by 5-deiodination. Both D3 mRNA and activity were present at the implantation site as early as gestational day 9 (E9), when expression was localized using in situ hybridization to uterine mesometrial and antimesometrial decidual tissue. At later stages of gestation, uterine D3 activity remained very high, and the levels exceeded those observed in the placenta and in fetal tissues. After days E12 and E13, as decidual tissues regressed, D3 expression became localized to the epithelial cells lining the recanalized uterine lumen that surrounds the fetal cavity. These findings strongly suggest that the pregnant uterus, in addition to the placenta, plays a critical role in determining the level of exposure of the fetus to maternal thyroid hormones.

Expression profiles of the three iodothyronine deiodinases, D1, D2, and D3, in the developing rat.

Thyroid hormone (TH) is essential for normal development in vertebrate species. Although the mechanisms by which TH regulates developmental processes are not fully understood, intracellular T3 levels are likely to be a critical aspect of the process. Furthermore, as different tissues and organs have specific temporal patterns of development, their T3 requirements may vary widely. Differential regulation of intracellular T3 levels in peripheral tissues as a result of differences in the activities of the three iodothyronine deiodinases (D1, D2, and D3) could offer an important means of achieving coordination of T3-dependent developmental processes among tissues. To obtain evidence for this concept we have documented the levels of expression of all three types of deiodinase in 11 tissues of the fetus, the neonate, and the adult rat. In most fetal tissues, D3 was the predominant deiodinase, but it declined after birth as the activities of D1 and D2 increased. Exceptions to this pattern were skin and brown adipose tissue (BAT), in which D2 activity was highest in the fetus, and testis and thyroid in which D2 activity was higher in the neonate than in the adult. D1 was the only 5'D enzyme expressed in liver, kidney and intestine at all stages studied, and D3 was not expressed in these tissues after birth. Thyroid, pituitary, and BAT expressed either D2 or D2 plus D1, but did not express D3 at any stage studied. Cerebrum, cerebellum, ovary, testis, skin, and placenta expressed all three deiodinases. Two other points were evident. First, the maximum 5'D activity attained, and thus presumably the amount of T3 generated, in liver, kidney, intestine, thyroid, pituitary, and BAT was very much higher than that in cerebrum, cerebellum, ovary, testis, skin, and placenta. Second, in the tissues where 5'D activity was relatively low, coexpression of D3 with D1 and D2 was the general rule, suggesting the need for very tight control of intracellular T3 levels. The findings are consistent with the view that the deiodinases play a major role in achieving the intracellular T3 levels that are optimal for the development of each tissue. Additional studies are in progress to demonstrate the functional consequences of these deiodinase expression patterns.

Assessing efficiency in general practice: an application of data envelopment analysis.

As with any health care process, the efficiency with which outputs are produced in general practice is of considerable importance. Using data from Lincolnshire, this study utilizes data envelopment analysis to examine the relationships between practice costs and outputs, measured not only as the number of patients treated, but also on the basis of performance indicators. The technique permits the construction of an efficiency ranking, facilitating the accurate targeting of monitoring resources.

Uromodulin (Tamm-Horsfall protein) is a leukocyte adhesion molecule.

Uromodulin (Tamm-Horsfall protein), the most abundant constituent of human urine, is synthesized exclusively in the kidney tubular epithelium and its amino acid sequence suggests a capacity for cell adhesion. We investigated adhesion between human uromodulin and neutrophils by allowing uromodulin, immobilized on microtiter plates, to interact with neutrophils. It was found that neutrophils attached to uromodulin in a saturable manner. The binding was inhibited by uromodulin in solution. It required metabolically active cells, was calcium sensitive and could be inhibited by arginine-glycine- aspartate-containing peptides in solution. These data suggest that uromodoulin can act as a specific ligand for neutrophils. This interaction is potentially important in leukocyte trafficking in the kidney and in the pathogenesis of interstitial nephritis.

Avian hematozoa from west-central Bolivia.

A total of 641 birds representing 135 species of 25 families from Noel Kempff Mercado National Park in west-central Bolivia was examined for hematozoa; only 33 (5.1%) harbored blood parasites. Microfilariae were the most commonly encountered hematozoans, followed, in numerical sequence, by species of Haemoproteus and Plasmodium; Trypanosoma, Atoxoplasma, and Hepatozoon were seen infrequently. The survey included 13 new host-parasite records, and 58 species of birds were examined for blood parasites for the first time; 43 were parasite-free. The low prevalence of parasitism recorded in this survey is compared to other areas in the Neotropical region and to prevalence of blood parasites in the avifauna of other major land masses.

Pregnancy-specific beta 1 glycoprotein in rat: tissue distribution of the mRNA and identification of testicular cDNA clones.

A partial cDNA of pregnancy-specific beta 1 glycoprotein isolated from human term placenta was used as probe for slot-blot analysis of total RNA extracted from placental and non-placental tissues in the rat. RNA hybridization with the probe was observed in rat placenta, indicating the presence of mRNA highly homologous to human SP1. The quantity of hybridizing RNA increased with increasing gestational age. In non-pregnant rats, SP1-hybridizing mRNAs were found in uterus, intestine and testis, while no hybridizing material was detected in liver or muscle. The amount of rat SP1 mRNA, based on percentage of total tissue RNA, was greatest in the testis followed by intestine, uterus and placenta. Using the same probe, six clones were obtained by screening a rat testis cDNA library. These clones carried cDNA inserts ranging in size from 1530 to 1983 bp. An internal EcoRI site was present in all cDNA clones. Southern blot analysis confirmed that the cDNA insert of all the clones was homologous to human placental SP1 cDNA. These results suggest a possible origin for the trace quantities of SP1 detected in non-pregnant individuals. It also confirms that the rat is an appropriate model for studying the physiological functions of SP1.

Absence of a 23 kd protein in testes of testicular feminization rat.

Cryptorchid testes of testicular feminization rats are very low in zinc in spite of normal zinc status of the animals. Analysis of the cytosol of the cryptorchid testes by gel permeation chromatography showed decreased zinc binding by proteins eluted at fractions corresponding to 30,000 dalton. Further analysis by sodium dodecylsulphate polyacrylamide gel electrophoresis indicated the absence of a protein with molecular weight of 23,000.

Abnormal zinc metabolism in unilateral maldescended testes of a mutant rat strain.

The status of zinc in a mutant rat strain with heritable maldescended testes was examined. In rats with unilateral maldescended testis, the ectopic testis consistently had decreased zinc content (121.0 +/- 23.0 micrograms zinc/g dry wt), while the eutopic testis had zinc content similar to that of normal rats (182.0 +/- 5.0 micrograms zinc/g dry wt). Uptake of zinc by the ectopic testis was comparable to normal. Sephadex gel chromatography showed greatly reduced zinc content of one of the endogenous zinc binding fractions with a mol wt of 30,000 of cytosol of the ectopic testis in spite of a near normal protein content. Incorporation of zinc-65 into this fraction was also shown to be greatly reduced in ectopic testis. Sodium dodecylsulphate-polyacrylamide gel electrophoresis demonstrated that a protein of 23,000 Da was greatly reduced in quantity. This 23-kDa protein in ectopic testis may play a role in reduced testicular function of the ectopic testis.

Intestinal transport of manganese from human milk, bovine milk and infant formula in rats.

The transport of manganese from extrinsically labeled human milk, bovine milk and infant formula was studied by the everted intestinal sac method. Tissue/mucosal flux data indicated that transport of manganese into the intestinal tissue was significantly greater with bovine milk and formula than from human milk. Similarly, the total flux of manganese from the mucosal to serosal surface was less when human milk was used. Smaller molecular weight manganese binding ligands isolated from the milk samples enhanced the mucosal to tissue movement of manganese as contrasted to the higher molecular weight manganese binding ligands. Most significantly the data suggest that the transport and uptake of manganese is less in the presence of human milk and its isolated manganese fractions than it is in bovine milk or infant formula.

Zinc metabolism in testicular feminization and surgical cryptorchid testes in rats.

Rats with testicular feminization (Tfm) had been reported to have a testis specific zinc deficiency. In this report it is demonstrated that this organ specific zinc deficiency was not corrected by intraperitoneal zinc administration. Normal littermates on the other hand showed a positive testicular response to zinc administration. The increased testicular zinc level in control animals returned to normal 1 week after the zinc treatment probably due to the fast turnover of this element in the testis. Not only surgically induced cryptorchidism but also surgical cryptorchidism and epididymodeferentectomy (to simulate Tfm conditions in normal adult rats) caused a drastic reduction in testicular zinc level. Unlike in Tfm rats, however, the decrease in zinc content in operated animals was not accompanied by a corresponding decrease in alkaline phosphatase activity. Zinc concentration and alkaline phosphatase activity in plasma or other organs were not affected by the surgical procedure. The testicular copper content in the operated animals was higher than that of the unoperated controls.

Comparative studies of manganese binding in human breast milk, bovine milk and infant formula.

The difference in ligand localization of manganese in human breast milk, cow's milk and infant formula was investigated. Extrinsic labeling technique was used and the different manganese-binding ligands were separated by gel permeation column chromatography. Manganese was found to bind to different ligands in human milk, cow's milk and infant formula. In human milk, manganese was bound by two high molecular weight proteins, the major one of 407,300 daltons and the minor one of 128,800 daltons. The 407,300-dalton protein was homogeneous with respect to molecular weight and charge and upon saturation with manganese had a metal to protein ratio of 1:1. Cow's milk had three manganese-binding species, with molecular weights of 234,000, 83,200 and less than 1000. The 234,000-dalton manganese-binding fraction was heterogeneous and contained several species with slightly different charge as revealed by DEAE-Sephacel ion-exchange chromatography. Infant formula on the other hand had no high molecular weight manganese-binding species. All the extrinsically added manganese was found in fractions with molecular weight of less than 1000.