Of mice and humans: how good are HLA transgenic mice as a model of human immune responses?

Background

Previous studies have defined vaccinia virus (VACV)-derived T cell epitopes in VACV-infected human leukocyte antigen-A*0201 (HLA-A2.1) transgenic (Tg) mice and A2.1-positive human Dryvax vaccinees. A total of 14 epitopes were detected in humans and 16 epitopes in A2.1 Tg mice; however, only two epitopes were independently reported in both systems. This limited overlap raised questions about the suitability of using HLA Tg mice as a model system to map human T cell responses to a complex viral pathogen. The present study was designed to investigate this issue in more detail.

Results

Re-screening the panel of 28 A2.1-restricted epitopes in additional human vaccinees and in A2.1 Tg mice revealed that out of the 28 identified epitopes, 13 were detectable in both systems, corresponding to a 46% concordance rate. Interestingly, the magnitude of responses in Tg mice against epitopes originally identified in humans is lower than for epitopes originally detected in mice. Likewise, responses in humans against epitopes originally detected in Tg mice are of lower magnitude.

Conclusion

These data suggest that differences in immunodominance patterns might explain the incomplete response overlap, and that with limitations; HLA Tg mice represent a relevant and suitable model system to study immune responses against complex pathogens.     

Lasting effects of an impairment of Th1-like immune response in γ-irradiated mice: A resemblance between irradiated mice and aged mice

Although one of the several chronic effects of ionizing radiation is aging, there are no experimental data on radiation-induced immunological aging. The most interesting change in aging was a helper T (Th) 1/Th2 imbalance. We investigated chronic effect on immune responses after ionizing radiation and its effects in irradiated mice were compared with those of aged mice. The 2-month-old mice received a whole-body irradiation of 5 Gy. At 6 months after irradiation, we compared the immune functions of the irradiated mice with those of normal mice of the same age and with those of older. Interferon (IFN)-γ and antigen-specific immunoglobulin (Ig)G2a level were lower in the irradiated mice than in normal mice of same age, showing similar levels to those of old normal mice. In contrast, interleukin (IL)-4 and IL-5 and antigen-specific IgG1 level were increased in irradiated mice when compared with the same aged-normal mice. Next, we investigated the low expression of IL-12p70, IL-12 receptors and IL-18 receptors in irradiated and old mice. Also, the decrease of natural killer cell activity was intensified in the irradiated mice, showing lower than values to those of old mice. Interestingly, in irradiated mice, the absolute numbers and the percentages of natural killer (NK) cells was extremely decreased. But the absolute numbers of Th cells and cytotoxic T (Tc) cells in old mice were significantly decreased. In conclusion, an immunological imbalance by the whole-body irradiation of 5 Gy induces to persist in the long term, resulting in the similar results with aging. Our results suggest that the downregulation of the Th1-like immune response shown in old mice rapidly occurred through exposure of ionizing radiation.     

Serine-204 in the linker region of Smad3 mediates the collagen-I response to TGF-β in a cell phenotype-specific manner

Regulation of TGF-β1/Smad3 signaling in fibrogenesis is complex. Previous work by our lab suggests that ERK MAP kinase phosphorylates the linker region (LR) of Smad3 to enhance TGF-β-induced collagen-I accumulation. However the roles of the individual Smad3LR phosphorylation sites (T179, S204, S208 and S213) in the collagen-I response to TGF-β are not clear. To address this issue, we tested the ability of Smad3 constructs expressing wild-type Smad3 or Smad3 with mutated LR phosphorylation sites to reconstitute TGF-β-stimulated COL1A2 promoter activity in Smad3-null or -knockdown cells. Blocking ERK in fibroblasts and renal mesangial cells inhibited both S204 phosphorylation and Smad3-mediated COL1A2 promoter activity. Mutations replacing serine at S204 or S208 in the linker region decreased Smad3-mediated COL1A2 promoter activity, whereas mutating T179 enhanced basal COL1A2 promoter activity and did not prevent TGF-β stimulation. Interestingly, mutation of all four Smad3LR sites (T179, S204, S208 and S213) was not inhibitory, suggesting primacy of the two inhibitory sites. These results suggest that in these mesenchymal cells, phosphorylation of the T179 and possibly S213 sites may act as a brake on the signal, whereas S204 phosphorylation by ERK in some manner releases that brake.     

Synthesis and evaluation of bivalent, peptidomimetic antagonists of the αvβ3 integrins

Targeting the integrin α(v)β(3) by directly interfering with its function is considered to be an effective and non-cytotoxic strategy for the treatment of tumor. In this study, a series of bivalent analogs of peptidomimetic integrin antagonists IA 1 and IAC 2 were designed, synthesized, and evaluated for their ability to inhibit the integrin α(v)β(3). All the bivalent ligands exhibited increased potency compared to that of their monomeric counterparts for the integrin α(v)β(3) with low nanomolar range binding affinity. The best bivalent ligand 6 tested in the series has an IC(50)=0.09 nM evaluated by ELISA assay. We conclude that multivalency is providing a useful template for the development novel integrin α(v)β(3) antagonists as potential therapeutics.     

Stress proteins and the immune response to mycobacteria — Antigens as virulence factors?

Summary The immune response to mycobacterial infection includes pathogenic as well as protective activities. It is possible that different types of immune responses are associated with recognition of different antigenic determinants. Amongst the antigens which are prominent in antibody and T cell recognition of mycobacteria, we have identified members of highly conserved stress protein families. Mapping of antigenic determinants on stress proteins shows that both species-specific and conserved regions of these proteins can take part in immune recognition. Induction of an immune response to conserved, self-like, determinants on stress proteins could play a role in the immunopathology associated with chronic mycobacterial infections.     

Melanocyte-specific immune response in melanoma and vitiligo: two faces of the same coin?

The appearance of depigmentation during the course of malignant melanoma has been considered a good prognostic sign. Is it only a side-effect, informative of the immune system's response to the treatment, or does it act as a necessary amplifier of these clinically important anti-tumor responses? The current review will attempt to tackle this question by reviewing the current literature, as well as by posing some novel hypotheses. Understanding the nature of humoral and cellular immune responses directed against normal melanocytes and their malignant counterparts may lead to the design of improved therapeutic strategies relevant to both vitiligo and melanoma.     

Sewage pollution and extinction risk: an endangered limpet as a bioindicator?

The mollusc Patella ferruginea, endemic to the Mediterranean, is the most endangered marine species on the list of the European Council Directive 92/43/EEC and it is under serious risk of extinction. In spite of the low abundances and restricted distribution of this limpet, important populations have been found in the harbour of Ceuta, north Africa. The main objective of the present study was to characterise, for the first time, the effects of sewage pollution on P. ferruginea and related limpet species, and to evaluate the potential value of these limpet assemblages as bioindicators, using univariate and multivariate analyses. Physicochemical parameters and limpets were sampled in nine stations located at 0, 1, 2, 4, 8, 16, 32, 64 and 128 m away from the discharge point of a sewage effluent in Ceuta harbour. The stations closer to the outfall (0, 1, 2, 4 and 8) were characterised by higher values of turbidity, phosphate and ammonia in the water column, and organic matter, faecal coliforms and faecal Streptococci in sediments. A total of six limpet species were found and studied (Patella ferruginea, P. caerulea, P. nigra, P. rustica, P. ulyssiponensis and Siphonaria pectinata); the number of limpet species increased with increasing distance from the outfall, while diversity and evenness reached the highest values at intermediate sites. Siphonaria pectinata and P. caerulea were the most resistant and abundant species, while P. ferruginea was the most sensitive species to sewage pollution, only found at stations from 32 to 128 m. The distribution of this endangered limpet seems mainly affected by the pollution gradient, and not by the competition with the remaining limpets. The results of this study should be taken into account in future programmes of management and conservation of P. ferruginea.     

Effects of a β3-adrenergic agonist on the immune response in diet-induced (cafeteria) obese animals

Molecules with affinity for beta3-adrenoceptors are not only effective anti-obesity agents in rodent models, but may play a role in the regulation of the immune response. The aim of the current investigation was to analyse the effects of trecadrine on the immune response in diet-induced (cafeteria) obese rats. Male Wistar rats were divided into 2 groups, the control group (C, n=9) was fed with the standard pelleted chow laboratory diet, while the other group was fed with a high-fat (cafeteria) diet. Cafeteria-fed rats were divided into two new subgroups (n=9 each), which received either i.p. saline (obese, O) or trecadrine (1mg/kg/day) (obese+trecadrine, O+T) daily for 5 weeks. Lymphocyte subpopulations and the proliferative response were determined by validated procedures. The administration of trecadrine was able to prevent the onset of obesity in cafeteria-fed rats. Trecadrine-treatment to obese animals appeared to improve the number of lymphocyte subpopulations (CD4+ and CD8+) as compared to those animals only receiving the high-fat diet, being the values of the trecadrine-treated animals on the high-fat diet similar to the control rats. However, the lymphoproliferative response when stimulated with several mitogens was markedly reduced by the cafeteria intake and was further decreased by the beta3-adrenergic administration. The spleen mRNA expression level of UCP2, PPARgamma and Ob-Rb were not affected by the trecadrine treatment. Summing up, at the immune system level, trecadrine administration increased the proportion of CD4+ spleen lymphocytes, although it was not able to restore the lymphocyte proliferative response which was depressed.     

Reactivity of glycoconjugate in membrane system II: Can a neutral glycolipid function as lectin receptor in the presence of gangliosides in plasma membrane?

To examine how surface Potential controls the reactivity of glycoconjugates at cell surface, the interaction of galactose-sPecific lectinse.g. peanut agglutinin,Ricinus cummunis agglutinin with liPosomes bearing asialo GM₁ were studied in the Presence of varying amount of ganglioside mixture, GM_n. The Presence of 5% GM_n causes comPlete slowing down of PreciPitin reaction and thereby make carbohydrate moiety of asialo GM₁ comPletely inaccessiblei.e. ‘cryPtic’. In contrast the Presence of 1–2% GM_n enhances the aPParent rate and amPlitude of the PreciPitin reaction as surface Potential becomes more negative. The relevance of the findings has been discussed in relation to the exPression and involvement of the cell-surface sialic acid residues during develoPment and differentiation.     

Characterization of a heat resistant ß-glucosidase as a new reporter in cells and mice

Background   

Reporter genes are widely used in biology and only a limited number are available. We present a new reporter gene for the localization of mammalian cells and transgenic tissues based on detection of the bglA (SYNbglA) gene of Caldocellum saccharolyticum that encodes a thermophilic β-glucosidase.     

L-carnitine: a partner between immune response and lipid metabolism ?

The authors demonstrated that in vivo administered L-carnitine strongly ameliorated the immune response in both healthy individuals receiving Intralipid and ageing subjects with cardiovascular diseases, as shown by the enhancement of mixed lymphocyte reaction. Notably, in the latter group L-carnitine treatment also resulted in a significant reduction of serum levels of both cholesterol and triglycerides. Therefore, the hypothesis is that L-carnitine supplementation could ameliorate both the dysregulated immune response and the abnormal lipid metabolism in several conditions.     

FoxO1 as a double-edged sword in the pancreas: analysis of pancreas- and β-cell-specific FoxO1 knockout mice

Diabetes is characterized by an absolute or relative deficiency of pancreatic β-cells. New strategies to accelerate β-cell neogenesis or maintain existing β-cells are desired for future therapies against diabetes. We previously reported that forkhead box O1 (FoxO1) inhibits β-cell growth through a Pdx1-mediated mechanism. However, we also reported that FoxO1 protects against β-cell failure via the induction of NeuroD and MafA. Here, we investigate the physiological roles of FoxO1 in the pancreas by generating the mice with deletion of FoxO1 in the domains of the Pdx1 promoter (P-FoxO1-KO) or the insulin 2 promoter (β-FoxO1-KO) and analyzing the metabolic parameters and pancreatic morphology under two different conditions of increased metabolic demand: high-fat high-sucrose diet (HFHSD) and db/db background. P-FoxO1-KO, but not β-FoxO1-KO, showed improved glucose tolerance with HFHSD. Immunohistochemical analysis revealed that P-FoxO1-KO had increased β-cell mass due to increased islet number rather than islet size, indicating accelerated β-cell neogenesis. Furthermore, insulin-positive pancreatic duct cells were increased in P-FoxO1-KO but not β-FoxO1-KO. In contrast, db/db mice crossed with P-FoxO1-KO or β-FoxO1-KO showed more severe glucose intolerance than control db/db mice due to decreased glucose-responsive insulin secretion. Electron microscope analysis revealed fewer insulin granules in FoxO1 knockout db/db mice. We conclude that FoxO1 functions as a double-edged sword in the pancreas; FoxO1 essentially inhibits β-cell neogenesis from pancreatic duct cells but is required for the maintenance of insulin secretion under metabolic stress.     

Biomass as a source of monomers: I — Synthesis of 2-vinylfuran

The condensation reaction between furfural and methyltriphenyl-phosphonium bromide was carried out using a solid-liquid transfer process in the presence of an excess of potassium carbonate. 2-vinylfuran was obtained selectively and quantitatively. Nitrobenzene was used as a solvent and 2-vinylfuran could thus be extracted readily; no polymerisation side reactions were involved.     

Can persistent Epstein-Barr virus infection induce chronic fatigue syndrome as a Pavlov reflex of the immune response?

Chronic fatigue syndrome is a protracted illness condition (lasting even years) appearing with strong flu symptoms and systemic defiances by the immune system. Here, by means of statistical mechanics techniques, we study the most widely accepted picture for its genesis, namely a persistent acute mononucleosis infection, and we show how such infection may drive the immune system towards an out-of-equilibrium metastable state displaying chronic activation of both humoral and cellular responses (a state of full inflammation without a direct 'causes-effect' reason). By exploiting a bridge with a neural scenario, we mirror killer lymphocytes T(K) and B cells to neurons and helper lymphocytes [Formula: see text] and [Formula: see text] to synapses, hence showing that the immune system may experience the Pavlov conditional reflex phenomenon: if the exposition to a stimulus (Epstein-Barr virus antigens) lasts for too long, strong internal correlations among B,T(K) and T(H) may develop ultimately resulting in a persistent activation even though the stimulus itself is removed. These outcomes are corroborated by several experimental findings.     

Intestinal microflora and homeostasis of the mucosal immune response: implications for probiotic bacteria?

The intestinal microflora can be considered a postnatally acquired organ that is composed of a large diversity of bacteria that perform important functions for the host and can be modulated by environmental factors, such as nutrition. Specific components of the intestinal microflora, including lactobacilli and bifidobacteria, have been associated with beneficial effects on the host, such as promotion of gut maturation and integrity, antagonisms against pathogens and immune modulation. Beyond this, the microflora seems to play a significant role in the maintenance of intestinal immune homeostasis and prevention of inflammation. The contribution of the intestinal epithelial cell in the first line of defense against pathogenic bacteria and microbial antigens has been recognized. However, the interactions of intestinal epithelial cells with indigenous bacteria are less well understood. This review will summarize the increasing scientific attention to mechanisms of the innate immune response of the host towards different components of the microflora, and suggest a potential role for selected probiotic bacteria in the regulation of intestinal inflammation.     

Downregulation of immune response by the human cytokines Interleukin-32α and β in cell-mediated rejection

Xenotransplantation of porcine organs has the potential to help overcome the severe shortage of human tissues and organs available for human transplantation. However, numerous hurdles such as immune-mediated xenograft rejection remain before clinical xenotransplantation.In this study, we elucidated the role of human TNF-α-inducing factor, Interleukin-32 (IL-32), in porcine kidney cells (PK-15) during cell-mediated rejection by examining host cell responses. CD8⁺ and CD4⁺ T cells numbers were reduced in the lymph nodes of PK-15/IL-32β injected mice. CD3⁺ Tcells were in mice injected with control cells but PK-15/IL-32α- and PK-15/IL-32β-injected cell numbers were lower in lymphnodes than un transfected controls. In Mixed lymphocyte reaction cultures, the rates of cell proliferation were increased in both PK-15/IL-32α- and PK-15/IL-32β-injected groups compared to the untransfected control groups. The Stable porcine PK-15 cells expression IL-32α and IL-32β inhibited cytotoxic T lymphocyte (CTLs) after cellular xenograft. Our results suggest that human IL-32α and IL-32β regulates on xenograft rejection in cellular xenotransplantation.     

Is there a typical germinal center? A large-scale immunohistological study on the cellular composition of germinal centers during the hapten-carrier-driven primary immune response in mice

Germinal centers (GCs) are complex, multicell-type, transient structures that form in secondary lymphatic tissues in response to T cell-dependent stimulation. This process is crucial to the adaptive immune response because it is the source of affinity maturation and long-lived B cell memory. Our previous studies showed that the growth of murine splenic GCs is nonsynchronized, involving broad-volume distributions of individual GCs at any time. This raises the question whether such a thing as a typical GC exists. To address this matter, we acquired large-scale confocal data on GCs throughout the course of the 2-phenyl-5-oxazolone chicken serum albumin-driven primary immune response in BALB/c mice. Semiautomated image analysis of 3457 GC sections revealed that, although there is no typical GC in terms of size, GCs have a typical cellular composition in that the cell ratios of resident T cells, macrophages, proliferating cells, and apoptotic nuclei are maintained during the established phase of the response. Moreover, our data provide evidence that the dark zone (DZ) and light zone (LZ) compartments of GCs are about the same size and led us to estimate that the minimal cell loss rate in GCs is 3% per hour. Furthermore, we found that the population of GC macrophages is larger and more heterogeneous than previously thought, and that despite enrichment of T cells in the LZ, the DZ of murine splenic GCs is not poor in T cells. DZ and LZ differ in the T cell-to-macrophage ratio rather than in the density of T cells.