One of the flagship actions of the Pharmaceutical Strategy for Europe is to address environmental challenges associated with pharmaceutical use. This includes strengthening the Environmental Risk Assessment (ERA) at marketing authorisation (MA) of pharmaceuticals, and revision of the pharmaceutical legislation where needed. The overall aim of an ERA should be to enable comprehensive and effective identification and management of environmental risks of pharmaceuticals without affecting the availability of pharmaceuticals to patients. As experts in the evaluation of ERAs of human medicinal products submitted by pharmaceutical industries (Applicants), we have summarized the current status of the ERA and suggest legislative changes to improve environmental protection without affecting availability. Six regulatory goals were defined and discussed, including possible ways forward: 1) mandatory ERAs in accordance to the EMA guideline at the time of the MA, 2) enforcement of risk mitigation measures including re-evaluation of the ERA, 3) facilitated exchange of environmental data between pharmaceutical and environmental legislations, 4) substance-based assessments, 5) transparency of data, and 6) a catching-up procedure for active pharmaceutical ingredients that lack an ERA. These legislative proposals can be considered as prerequisites for a harmonised assessment and effective management of environmental risks and hazards of human pharmaceuticals.
Summary The role of secretory IgM in protecting kidney tissue from immune complex glomerulonephritis induced by 4 mg horse spleen apoferritin and 0·05 mg lipopolysaccharide has been investigated in mutant mice in which B cells do not secrete IgM, but are capable of expressing surface IgM and IgD and secreting other Ig isotypes. Glomerular size, number of glomeruli per cross-section, glomerular cellularity and urine content of protein and creatinine was comparable in treated secreted IgM (sIgM)-deficient and wild-type mice. Assessment of urinary proteins by sodium dodecyl sulphate-polyacrylamide gel electrophoresis showed a 30 kDa low molecular weight protein in treated sIgM-deficient animals only, reflecting dysfunction of proximal tubules. A shift of bound C3 from glomeruli to the tubulo-interstitial compartment in sIgM-deficient mice also suggests tubulo-interstitial damage. In contrast, local C3 synthesis within the kidney tissue did not differ between the two treated groups. Apoptosis physiologically present to maintain kidney cell homeostasis was increased slightly in treated wild-type mice. These results indicate that secretory IgM can protect the tubulo-interstitial compartment from immune complex-induced damage without having an effect on the glomerulus.
Abstract The role secretory IgM has in protecting splenic tissue from LPS‐induced damage was assessed in mice incapable of secreting IgM but able to express surface IgM and IgD. Within seconds after LPS challenge, 99% of the 131 I‐labeled LPS was found in the liver and the spleen of both sIgM‐deficient and wild‐type mice. In the spleen FITC‐labeled LPS was found on the surface of 2F8 + scavenger receptor macrophages localized in the outer marginal zone, while none of the labeled LPS could be detected on marginal zone ER‐TR9 + and MOMA‐1 + macrophages. An additional population of macrophages, MOMA‐2 + , were capable of producing C3 locally in the T and B cell zone after LPS challenge. Local C3 production was regulated, as no C3 was found in splenic tissue of unchallenged mice. Interestingly, in the absence of circulating and locally produced secretory IgM, MOMA‐2 + macrophages of the T and B cell zone failed to establish an additional ring of C3‐producing macrophages in the outer B cell zone close to the marginal zone upon LPS challenge. The consequence was a massive destruction of the microarchitecture of the spleen where marginal zones disorganized, lymphoid follicles and T cell zones disrupted and follicular DC (FDC) networks disappeared.
Adequate numbers and functional maturity are needed for leukocytes to exhibit a protective role in host defense. During intrauterine life, the skin immune system has to acquire these prerequisites to protect the newborn from infection in the hostile external environment after birth. We investigated the quantitative, phenotypic, and functional development of skin leukocytes and analyzed the factors controlling their proliferation and trafficking during skin development. We show that CD45+ leukocytes are scattered in embryonic human skin and that their numbers continuously increase as the developing skin generates an environment that promotes proliferation of skin resident leukocytes as well as the influx of leukocytes from the circulation. We also found that CD45+HLA-DRhighCD1c+ dendritic cells (DCs) are already present in the epidermis and dermis at 9 wk estimated gestational age (EGA) and that transforming growth factor β1 production precedes Langerin and CD1a expression on CD45+CD1c+ Langerhans cell (LC) precursors. Functionally, embryonic antigen-presenting cells (APCs) are able to phagocytose antigen, to up-regulate costimulatory molecules upon culture, and to efficiently stimulate T cells in a mixed lymphocyte reaction. Collectively, our data provide insight into skin DC biology and the mechanisms through which skin DCs presumably populate the skin during development.
Multipotent mesenchymal stromal cells (MSCs) are found in a variety of adult tissues including human dermis. These MSCs are morphologically similar to bone marrow–derived MSCs, but are of unclear phenotype. To shed light on the characteristics of human dermal MSCs, this study was designed to identify and isolate dermal MSCs by a specific marker expression profile, and subsequently rate their mesenchymal differentiation potential. Immunohistochemical staining showed that MSC markers CD73/CD90/CD105, as well as CD271 and SSEA-4, are expressed on dermal cells in situ. Flow cytometric analysis revealed a phenotype similar to bone marrow–derived MSCs. Human dermal cells isolated by plastic adherence had a lower differentiation capacity as compared with bone marrow–derived MSCs. To distinguish dermal MSCs from differentiated fibroblasts, we immunoselected CD271+ and SSEA-4+ cells from adherent dermal cells and investigated their mesenchymal differentiation capacity. This revealed that cells with increased adipogenic, osteogenic, and chondrogenic potential were enriched in the dermal CD271+ population. The differentiation potential of dermal SSEA-4+ cells, in contrast, appeared to be limited to adipogenesis. These results indicate that specific cell populations with variable mesenchymal differentiation potential can be isolated from human dermis. Moreover, we identified three different subsets of dermal mesenchymal progenitor cells. Multipotent mesenchymal stromal cells (MSCs) are found in a variety of adult tissues including human dermis. These MSCs are morphologically similar to bone marrow–derived MSCs, but are of unclear phenotype. To shed light on the characteristics of human dermal MSCs, this study was designed to identify and isolate dermal MSCs by a specific marker expression profile, and subsequently rate their mesenchymal differentiation potential. Immunohistochemical staining showed that MSC markers CD73/CD90/CD105, as well as CD271 and SSEA-4, are expressed on dermal cells in situ. Flow cytometric analysis revealed a phenotype similar to bone marrow–derived MSCs. Human dermal cells isolated by plastic adherence had a lower differentiation capacity as compared with bone marrow–derived MSCs. To distinguish dermal MSCs from differentiated fibroblasts, we immunoselected CD271+ and SSEA-4+ cells from adherent dermal cells and investigated their mesenchymal differentiation capacity. This revealed that cells with increased adipogenic, osteogenic, and chondrogenic potential were enriched in the dermal CD271+ population. The differentiation potential of dermal SSEA-4+ cells, in contrast, appeared to be limited to adipogenesis. These results indicate that specific cell populations with variable mesenchymal differentiation potential can be isolated from human dermis. Moreover, we identified three different subsets of dermal mesenchymal progenitor cells. alkaline phosphatase multipotent mesenchymal stromal cell
The adult human skin harbors a variety of leukocytes providing immune surveillance and host defense, but knowledge about their ontogeny is scarce. In this study we investigated the number and phenotype of leukocytes in prenatal human skin (dermal dendritic cells (DDCs), macrophages, T cells (including FoxP3(+) regulatory T cells), and mast cells) to unravel their derivation and to get a clue as to their putative function in utero. By flow cytometry and immunofluorescence, we found a distinction between CD206(+)CD1c(+)CD11c(+) DDCs and CD206(+)CD209(+)CD1c(-) skin macrophages by 9 weeks estimated gestational age (EGA). T cells appear at the end of the first trimester, expressing CD3 intracytoplasmatically. During midgestation, CD3(+)FoxP3(-) and CD3(+)FoxP3(+) cells can exclusively be found in the dermis. Similarly, other leukocytes such as CD117(+) (c-kit) mast cells were not identified before 12-14 weeks EGA and only slowly acquire a mature phenotype during gestation. Our data show at which time point during gestation antigen-presenting cells, T cells, and mast cells populate the human dermis and provide a step forward to a better understanding of the development of the human skin immune system.
Abstract As the phenotype of adult dermal stem cells is still elusive, and the hematopoietic stem cell is one of the best-characterized stem cells in the body, we tested dermal cell suspensions, sections, and wholemounts in newborn and adult mice for hematopoietic stem cell marker expression. Phenotypic analysis revealed that a small population of CD45+ cells and a large population of CD45– cells expressed CD34, CD117, and stem cell antigen-1 molecules. When cultivated in selected media supplemented with hematopoietic cytokines, total dermal cells, lineage–, and/or highly enriched phenotypically defined cell subsets produced hematopoietic and nonhematopoietic colonies. When injected into lethally irradiated recipient mice, a small percentage of newborn dermal cells was able to migrate into hematopoietic tissues and the skin and survived through the 11-month monitoring period. Our ability to isolate a candidate autologous stem cell pool will make these cells ideal vehicles for genetic manipulation and gene therapy.