Programmed cell death of keratinocytes in infliximab-treated plaque-type psoriasis.

BACKGROUND: Tumour necrosis factor (TNF)-alpha blockade using infliximab, a chimeric anti-TNF-alpha antibody, is an effective treatment for plaque-type psoriasis, inducing remission in about 80% of patients. OBJECTIVES: To examine infliximab-induced programmed cell death (PCD) of keratinocytes in psoriatic plaques on serial skin biopsy samples. METHODS: Five patients with moderate to severe plaque-type psoriasis received infliximab infusions intravenously (5 mg kg(-1)) at weeks 0, 2 and 6. Biopsies of nonlesional and lesional skin (days 0, 5, 14 and 21) were obtained. Conventional microscopy was used to examine the morphology of the psoriatic keratinocytes. In situ detection of apoptosis was performed by electron microscopy and by immunohistochemical staining with anti-p53 and anti-caspase-3 antibodies. Results Infusion of infliximab induced a clinical response in all five patients with psoriasis, with a mean Psoriasis Area and Severity Index improvement of 24.8% already at day 5. This was accompanied by significant histopathological changes in the skin biopsy samples after infliximab treatment. Light and electron microscopic evaluation revealed apoptosis-like morphological changes in lesional keratinocytes, i.e. nuclear condensation, chromatin fragmentation and cytoplasmic vesiculation, visible already after the first infusion. These damaged keratinocytes stained positively for p53, but not for active caspase-3. CONCLUSIONS: The effects of infliximab in psoriasis extend beyond merely anti-inflammatory actions, and may include caspase-independent PCD of lesional keratinocytes. The PCD of keratinocytes may be an important mechanism that could explain at least in part the rapid and sustained therapeutic effect of infliximab in psoriasis.

An autosomal factor from Drosophila arizonae restores normal spermatogenesis in Drosophila mojavensis males carrying the D. arizonae Y chromosome.

Males of Drosophila mojavensis whose Y chromosome is replaced by the Y chromosome of the sibling species Drosophila arizonae are sterile. It is shown that genetic material from the fourth chromosome of D. arizonae is necessary and sufficient, in single dose, to restore fertility in these males. In introgression and mapping experiments this material segregates as a single Mendelian factor (sperm motility factor, SMF). Light and electron microscopy studies of spermatogenesis in D. mojavensis males whose Y chromosome is replaced by introgression with the Y chromosome of D. arizonae (these males are symbolized as mojYa) revealed postmeiotic abnormalities all of which are restored when the SMF of D. arizonae is co-introgressed (these males are symbolized as mojYaSMFa). The number of mature sperm per bundle in mojYaSMFa is slightly less than in pure D. mojavensis and is even smaller in males whose fertility is rescued by introgression of the entire fourth chromosome of D. arizonae. These observations establish an interspecific incompatibility between the Y chromosome and an autosomal factor (or more than one tightly linked factors) that can be useful for the study of the evolution of male hybrid sterility in Drosophila and the genetic control of spermatogenesis.

Fine structure of the chorion of Manduca sexta and Sesamía nonagrioides as revealed by scanning electron microscopy and freeze-fracturing.

The fine structure of Manduca sexta and Sesamia nonagrioides chorion was investigated by scanning electron microscopy and freeze-fracturing. In both species the mature chorion exhibits a complex ultrastructure on its outer surface, with a large number of aeropyles forming polygonal arrays. The micropyle is surrounded by a rosette of approximately 80 follicular cell imprints. Scanning electron microscopy of vertically ripped sections reveals that both chorions consist of two main layers: a trabecular layer closest to the oocyte and a lamellar layer. The technique of freeze-fracturing, utilizing single-sided and rotary shadowing, clearly shows that fibrils, approximately 3-4 nm in diameter, constitute chorionic lamellae in both species. The fibrils appear to have a 'beaded' structure, with a 2-3 nm axial periodicity. Freeze-fracturing also provides a direct visualization of the helicoidal arrangement of these fibrils for the formation of chorion supramolecular architecture.

Induction of class II MHC antigen expression on the murine placenta by 5-azacytidine correlates with fetal abortion.

During the gestational cycle the placental tissue does not express class II MHC antigens and whether this phenomenon is important to fetal survival has not yet been evoked. It has been reported that class II antigen expression precedes renal and cardiac graft rejection, which may also be the case in fetal abortion. In a recent report we showed that placental cells can be induced to express class II antigens in vitro and that these cells undergo different regulatory mechanisms depending on their anatomical position in the placenta. Thus, spongiotrophoblast-derived cells express these antigens after interferon-gamma treatment, whereas labyrinthine trophoblast-derived cells are induced by 5-azacytidine. In the present study we examined the effect of 5-azacytidine on class II antigen expression in the placenta and fetal abortion in vivo. We report that 5-azacytidine, when given to pregnant females before the ectoplacental cone formation, dramatically increases fetal loss, which correlates with class II antigen expression in the labyrinthine trophoblast zone. No site effects of 5-azacytidine on placental cell proliferation, splenic T and B cell responses, or reproductive capability of treated females were observed. However, after treatment with 5-azacytidine placental cells can stimulate maternal spleen cells to proliferate in a mixed cell reaction, whereas untreated controls cannot. Furthermore, the abortive effect of 5-azacytidine can be rescued in allogeneic pregnancy by anti-paternal class II monoclonal antibody injection into the animals during the 5-azacytidine treatment. These results suggest that the maintenance of the class II antigen-negative expression on the placenta is indeed necessary to avoid maternal immune attack and ensure fetal survival.

A female sterile screen of the Drosophila melanogaster X chromosome using hybrid dysgenesis: identification and characterization of egg morphology mutants.

We have conducted a hybrid dysgenic screen of the X chromosome for mutations affecting female fertility, with particular attention to those causing abnormal egg and eggshell morphology. In a screen of 4017 dysgenic strains, 398 mutants derived from 168 different germ lines were isolated and assigned to eight classes according to their diverse phenotypes. One interesting class consists of mutants that block oogenesis at specific stages. Our analysis has focused on mutations affecting eggshell formation, including mutants that lay morphologically abnormal sterile eggs as well as those that lay no eggs but exhibit blocks in the late stages of oogenesis. A subset of 48 mutants was assorted into 30 allelic groups by inter se complementation and genetically localized by interval mapping. Two multiallele complementation groups, de1 (7 alleles) and ne1 (8 alleles), were identified as well as five two-allele complementation groups. A search for alleles among mutants generated in other female sterile screens was unsuccessful, pointing to the distinctive nature of the dysgenic mutant collection. The single case of allelism determined in this study was one with a lethal allele of the Broad-Complex, l(1)npr, suggesting a possible involvement of ecdysone in choriogenesis. A subset of 18 dysgenic strains was analyzed for P element hybridization and 16 of these were found to have hybridization signals in the appropriate cytogenetic interval. By examining these signals in two or more alleles of the same complementation group, we have been able to tentatively localize two mutations. Light and electron microscopy of the eggshell in 43 different strains has revealed a variety of effects. The respiratory appendages were defective in 27 of these mutants. Effects on the ultrastructure of the main body of the endochorion were not strongly correlated with the appendage defects, and could be classified as minor (14 mutants) or major (16 mutants). Although 13 mutants showed no ultrastructural chorion defects, six of these had defective respiratory appendages.

Genetic analysis of chorion formation in Drosophila melanogaster: I. The effects of one somatic-specific and seven germ-line-specific mutations.

Eight X-linked recessive female sterile mutations, derived from a hybrid dysgenic screen of Drosophila melanogaster and representing eight distinct loci, have been characterized by genetic and ultrastructural analysis. Four have abnormal respiratory appendages, three have essentially normal appendages but show moderate defects in the endochorion, and one mutant, fs(1)ne1a, exhibits major defects in both the endochorion and the respiratory appendages. Germ line clones of all eight mutants were generated using the dominant female sterile technique. Seven of the eight mutations are germ line specific, indicating that, although the eggshell is produced by the follicular cells, germ line functions play a significant role in its elaboration. The mutant that shows major defects, fs(1)ne1a, is somatic line specific, and exerts its effect in the ovary.

Trans-acting amplification mutants and other eggshell mutants of the third chromosome in Drosophila melanogaster.

We report on the characterization of five third chromosome mutations with strong effects on the formation of the eggshell or chorion. Three mutations, defining two loci, result in substantially reduced follicle cell-specific amplification of the major chorion structural genes and, hence, in underproduction of the corresponding mRNAs and proteins. The other two mutations, though displaying structural chorion abnormalities, appear to have no significant effect on amplification and to express normally the major chorion structural genes. The possible nature of these mutations is discussed.