How does cross-reactive stimulation affect the longevity of CD8+ T cell memory?

Immunological memory--the ability to "remember" previously encountered pathogens and respond faster upon re-exposure is a central feature of the immune response in vertebrates. The cross-reactive stimulation hypothesis for the maintenance of memory proposes that memory cells specific for a given pathogen are maintained by cross-reactive stimulation following infections with other (unrelated) pathogens. We use mathematical models to examine the cross-reactive stimulation hypothesis. We find that: (i) the direct boosting of cross-reactive lineages only provides a very small increase in the average longevity of immunological memory; (ii) the expansion of cross-reactive lineages can indirectly increase the longevity of memory by reducing the magnitude of expansion of new naive lineages which occupy space in the memory compartment and are responsible for the decline in memory; (iii) cross-reactive stimulation results in variation in the rates of decline of different lineages of memory cells and enrichment of memory cell population for cells that are cross-reactive for the pathogens to which the individual has been exposed.     

Class-based stratification matrix for physical leaf traits in phenetic relations of Withania somnifera (L.) Dunal accessions

Withania somnifera (L.) Dunal is a promising herb with many pharmaceutical and therapeutic uses ranging from immunomodulation to anticarcinogenicity. It is commonly known as Indian ginseng, as it is comparable to Panax ginseng, which is a widely studied and utilized herb. There are limited studies on the genetic diversity of W. somnifera from the northeastern region of the Indian Subcontinent. This paper describes the characterization of wild accessions collected from Tamil Nadu State. A total of 15 accessions collected from wild populations were studied for their physical leaf traits such as leaf fresh weight (g), dry weight (mg), leaf dry matter content (mg g^?1), specific leaf area (mm² mg^?1), leaf size (mm²), total carbon and nitrogen, and total withaferin-A content in leaves. An attempt was made to correlate physical leaf traits with withaferin-A content. The molecular traits, which were treated in a presence–absence matrix, failed to group the hyper-withaferin-A accessions. The quantified physical leaf traits were converted into a presence–absence matrix using a novel method of class-based stratification. The phenetic relations inferred from the Fitch–Margoliash algorithm applied to physical leaf trait data resulted in grouping of accessions with high withaferin-A content. These traits were used in the selection of promising accessions which can be further used for breeding programmes.     

Cutting edge: gut microenvironment promotes differentiation of a unique memory CD8 T cell population

Whether tissue microenvironment influences memory CD8 T cell differentiation is unclear. We demonstrate that virus-specific intraepithelial lymphocytes in gut resemble neither central nor effector memory CD8 T cells isolated from spleen or blood. This unique phenotype arises in situ within the gut, suggesting that anatomic location plays an inductive role in the memory differentiation program. In support of this hypothesis, memory CD8 T cells changed phenotype upon change in location. After transfer and in vivo restimulation, gut or spleen memory cells proliferated, disseminated into spleen and gut, and adopted the memory T cell phenotype characteristic of their new environment. Our data suggests that anatomic location directly impacts the memory T cell differentiation program.     

Ghrelin ovarian cell expression in patients with polycystic ovary syndrome: an immunohistochemical evaluation.

INTRODUCTION: The influence of ghrelin on different organs has been studied recently, e.g. in the regulation of pituitary hormone release, regulation of energy homeostasis, glucose metabolism and insulin secretion, cell proliferation, and reproductive function. However, the etiology of polycystic ovary syndrome has not been fully explained. The aim of our study was to estimate the presence of ghrelin in polycystic ovaries cells and evaluation of the relationship between ghrelin occurrence and cells proliferation. METHODS: In the present work we have compared ten polycystic ovaries with ovaries without pathology as the control group. We used immunohistochemical method to detect ghrelin. The cells proliferation was evaluated by Ki 67 proliferation index. RESULTS: Ghrelin immunostaining was demonstrated in cytoplasm of ovarian secondary interstitial cells and in atretic corpus luteum. The cell nuclei were ghrelin positive in granulosa, theca layers of follicular cyst in both groups as well as in luteal cells of young corpus luteum in healthy ovaries. Ki 67 immunostaining was observed in granulosa and theca layers of follicular cyst in polycystic and healthy ovaries. CONCLUSIONS: It is possible that local ghrelin expression plays an important role in the direct control of ovarian development and function and ghrelin may participate in patomechanism of PCOS.     

Protein energy malnutrition impairs homeostatic proliferation of memory CD8 T cells

Nutrition is a critical but poorly understood determinant of immunity. There is abundant epidemiological evidence linking protein malnutrition to impaired vaccine efficacy and increased susceptibility to infections; yet, the role of dietary protein in immune memory homeostasis remains poorly understood. In this study, we show that protein-energy malnutrition induced in mice by low-protein (LP) feeding has a detrimental impact on CD8 memory. Relative to adequate protein (AP)-fed controls, LP feeding in lymphocytic choriomeningitis virus (LCMV)-immune mice resulted in a 2-fold decrease in LCMV-specific CD8 memory T cells. Adoptive transfer of memory cells, labeled with a division tracking dye, from AP mice into naive LP or AP mice demonstrated that protein-energy malnutrition caused profound defects in homeostatic proliferation. Remarkably, this defect occurred despite the lymphopenic environment in LP hosts. Whereas Ag-specific memory cells in LP and AP hosts were phenotypically similar, memory cells in LP hosts were markedly less responsive to polyinosinic-polycytidylic acid-induced acute proliferative signals. Furthermore, upon recall, memory cells in LP hosts displayed reduced proliferation and protection from challenge with LCMV-clone 13, resulting in impaired viral clearance in the liver. The findings show a metabolic requirement of dietary protein in sustaining functional CD8 memory and suggest that interventions to optimize dietary protein intake may improve vaccine efficacy in malnourished individuals.     

ZBTB32 Is an Early Repressor of the CIITA and MHC Class II Gene Expression during B Cell Differentiation to Plasma Cells

CIITA and MHC class II expression is silenced during the differentiation of B cells to plasma cells. When B cell differentiation is carried out ex vivo, CIITA silencing occurs rapidly, but the factors contributing to this event are not known. ZBTB32, also known as repressor of GATA3, was identified as an early repressor of CIITA in an ex vivo plasma cell differentiation model. ZBTB32 activity occurred at a time when B lymphocyte-induced maturation protein-1 (Blimp-1), the regulator of plasma cell fate and suppressor of CIITA, was minimally induced. Ectopic expression of ZBTB32 suppressed CIITA and I-A gene expression in B cells. Short hairpin RNA depletion of ZBTB32 in a plasma cell line resulted in re-expression of CIITA and I-A. Compared with conditional Blimp-1 knockout and wild-type B cells, B cells from ZBTB32/ROG-knockout mice displayed delayed kinetics in silencing CIITA during ex vivo plasma cell differentiation. ZBTB32 was found to bind to the CIITA gene, suggesting that ZBTB32 directly regulates CIITA. Lastly, ZBTB32 and Blimp-1 coimmunoprecipitated, suggesting that the two repressors may ultimately function together to silence CIITA expression. These results introduce ZBTB32 as a novel regulator of MHC-II gene expression and a potential regulatory partner of Blimp-1 in repressing gene expression.     

RNA inhibition highlights cyclin d1 as a potential therapeutic target for mantle cell lymphoma

Mantle cell lymphoma is characterized by a genetic translocation results in aberrant overexpression of the CCND1 gene, which encodes cyclin D1. This protein functions as a regulator of the cell cycle progression, hence is considered to play an important role in the pathogenesis of the disease. In this study, we used RNA interference strategies to examine whether cyclin D1 might serve as a therapeutic target for mantle cell lymphoma. Knocking down cyclin D1 resulted in significant growth retardation, cell cycle arrest, and most importantly, induction of apoptosis. These results mark cyclin D1 as a target for mantle cell lymphoma and emphasize the therapeutic potential hidden in its silencing.     

A new technique in computer modeling of molecules with transparency effect, due to partially stripped surfaces

Conventional space filling molecular modeling in computers, using the scan method, takes considerable computer time and effort. In depicting the CPK-image on a computer screen, the hidden-point removal is the main task and on such an image, the front-line atoms hide the back-benchers and their whereabouts become completely unknown, in a given view of the picture. While in search of a simple and faster algorithm for producing surface graphics of molecules, we have developed a novel method, which is considerably faster than the conventional one and it has an interesting transparency-effect which would be useful in the various fields of molecular designs.