An aged immune system drives senescence and ageing of solid organs.

Ageing of the immune system, or immunosenescence, contributes to the morbidity and mortality of the elderly1,2. To define the contribution of immune system ageing to organism ageing, here we selectively deleted Ercc1, which encodes a crucial DNA repair protein3,4, in mouse haematopoietic cells to increase the burden of endogenous DNA damage and thereby senescence5-7 in the immune system only. We show that Vav-iCre+/-;Ercc1-/fl mice were healthy into adulthood, then displayed premature onset of immunosenescence characterized by attrition and senescence of specific immune cell populations and impaired immune function, similar to changes that occur during ageing in wild-type mice8-10. Notably, non-lymphoid organs also showed increased senescence and damage, which suggests that senescent, aged immune cells can promote systemic ageing. The transplantation of splenocytes from Vav-iCre+/-;Ercc1-/fl or aged wild-type mice into young mice induced senescence in trans, whereas the transplantation of young immune cells attenuated senescence. The treatment of Vav-iCre+/-;Ercc1-/fl mice with rapamycin reduced markers of senescence in immune cells and improved immune function11,12. These data demonstrate that an aged, senescent immune system has a causal role in driving systemic ageing and therefore represents a key therapeutic target to extend healthy ageing.

Spleen regeneration after subcutaneous heterotopic autotransplantation in a mouse model.

BACKGROUND: Splenectomy may lead to severe postoperative complications, including sepsis and cancers. A possible solution to this problem is heterotopic autotransplantation of the spleen. Splenic autografts rapidly restore the regular splenic microanatomy in model animals. However, the functional competence of such regenerated autografts in terms of lympho- and hematopoietic capacity remains uncertain. Therefore, this study aimed to monitor the dynamics of B and T lymphocyte populations, the monocyte-macrophage system, and megakaryocytopoiesis in murine splenic autografts. METHODS: The model of subcutaneous splenic engraftment was implemented in C57Bl male mice. Cell sources of functional recovery were studied using heterotopic transplantations from B10-GFP donors to C57Bl recipients. The cellular composition dynamics were studied by immunohistochemistry and flow cytometry. Expression of regulatory genes at mRNA and protein levels was assessed by real-time PCR and Western blot, respectively. RESULTS: Characteristic splenic architecture is restored within 30 days post-transplantation, consistent with other studies. The monocyte-macrophage system, megakaryocytes, and B lymphocytes show the highest rates, whereas the functional recovery of T cells takes longer. Cross-strain splenic engraftments using B10-GFP donors indicate the recipient-derived cell sources of the recovery. Transplantations of scaffolds populated with splenic stromal cells or without them afforded no restoration of the characteristic splenic architecture. CONCLUSIONS: Allogeneic subcutaneous transplantation of splenic fragments in a mouse model leads to their structural recovery within 30 days, with full reconstitution of the monocyte-macrophage, megakaryocyte and B lymphocyte populations. The circulating hematopoietic cells provide the likely source for the cell composition recovery.

Splenocyte transfer from hypertensive donors eliminates premenopausal female protection from ANG II-induced hypertension.

Premenopausal females are protected from angiotensin II (ANG II)-induced hypertension following the adoptive transfer of T cells from normotensive donors. For the present study, we hypothesized that the transfer of hypertensive T cells (HT) or splenocytes (HS) from hypertensive donors would eliminate premenopausal protection from hypertension. Premenopausal recombination-activating gene-1 (Rag-1)-/- females received either normotensive (NT) or hypertensive cells 3 wk before ANG II infusion (14 days, 490 ng/kg/min). Contrary to our hypothesis, no increase in ANG II-induced blood pressure was observed in the NT/ANG or HT/ANG groups. Flow cytometry demonstrated that renal FoxP3+ T regulatory cells were significantly decreased, and immunohistochemistry showed an increase in renal F4/80+ macrophages in the HT/ANG group, suggesting a shift in the renal inflammatory environment despite no change in blood pressure. Renal mRNA expression of macrophage chemoattractant protein-1 (MCP-1), endothelin-1 (ET-1), and G protein-coupled estrogen receptor-1 (GPER-1) was significantly decreased in the HT/ANG group. The adoptive transfer of hypertensive splenocytes before ANG II infusion (HS/ANG) eliminated premenopausal protection from hypertension and significantly decreased splenic FoxP3+ T regulatory cells compared with females that received normotensive splenocytes (NS/ANG). Expression of macrophage inflammatory protein 1α/chemokine (C-C motif) ligand 3 (MCP-1/CCL3), a potent macrophage chemokine, was elevated in the HS/ANG group; however, no increase in renal macrophage infiltration occurred. Together, these data show that in premenopausal females, T cells from hypertensive donors are not sufficient to induce robust ANG II-mediated hypertension; in contrast, transfer of hypertensive splenocytes (consisting of T/B lymphocytes, dendritic cells, and macrophages) is sufficient. Further work is needed to understand how innate and adaptive immune cells and estrogen signaling coordinate to cause differential hypertensive outcomes in premenopausal females.NEW & NOTEWORTHY Our study is the first to explore the role of hypertensive T cells versus hypertensive splenocytes in premenopausal protection from ANG II-induced hypertension. We show that the hypertensive status of T cell donors does not impact blood pressure in the recipient female. However, splenocytes, when transferred from hypertensive donors, significantly increased premenopausal recipient blood pressure following ANG II infusion, highlighting the importance of further investigation into estrogen signaling and immune cell activation in females.

Splenocyte transfer exacerbates salt-sensitive hypertension in rats.

NEW FINDINGS: What is the central question of this study? Recruitment of immune cells to the kidney potentiates hypertensive pathology, but more refined methods are needed to assess these cells functionally. Adoptive transfer studies of immune cells have been limited in rat models and especially in the study of salt-sensitive hypertension. We tested the hypothesis that splenocyte transfer into T-cell-deficient rats is sufficient to exacerbate salt-sensitive hypertension. What is the main finding and its importance? We demonstrate that transfer of splenocytes into T-cell-deficient animals exacerbates salt-sensitive hypertension, and an enrichment in the CD4+ compartment specifically induces this phenomenon. ABSTRACT: Increasing evidence of immune system activation during the progression of hypertension and renal injury has led to a need for new methods to study individual cell types. Transfer of immune cells serves as a powerful tool to isolate effects of specific subsets. Transfer studies in Rag1-/- mice have demonstrated an important role of T-cell activation in hypertension, but this approach has yielded limited success in rat models. Using the T-cell-deficient Dahl salt-sensitive (SS) rat, SSCD247-/- , we hypothesized that splenocyte transfer from SS wild-type animals into SSCD247-/- animals would populate the T-cell compartment. The Dahl SS background provides a model for studying salt-sensitive hypertension; therefore, we also tested whether the dietary salt content of the donor would confer differential salt sensitivity in the recipient. To test this, donors were maintained on either a low-salt or a high-salt diet, and at postnatal day 5 the recipients received splenocyte transfer from one of these groups before a high-salt diet challenge. We showed that splenocyte transfer elevated blood pressures while rats were fed low salt and exacerbated the salt-sensitive increase in pressure when they were fed fed high salt. Furthermore, transfer of splenocytes conferred exacerbated renal damage. Lastly, we confirmed the presence of T cells in the circulation and in the spleen, and that infiltration of immune cells, including T cells, macrophages and B cells, into the kidney was elevated in those receiving the transfer. Interestingly, the source of the splenocytes, from donors fed either a low-salt or a high-salt diet, did not significantly affect these salt-sensitive phenotypes.

Hepatic stellate cells regulate hepatic progenitor cells differentiation via the TGF-ß1/Jagged1 signaling axis.

Hepatic stellate cells (HSCs) play an important microenvironmental role in hepatic progenitor cells (HPCs) differentiation fate. To reveal the specific mechanism of HSCs induced by transforming growth factor ß1 (TGF-ß1) signaling in HPCs differentiation process, we used Knockin and knockdown technologies induced by lentivirus to upregulate or downregulate TGF-ß1 level in mouse HSCs (mHSCs) (mHSCs-TGF-ß1 or mHSCs-TGF-ßR1sih3). Primary mouse HPCs (mHPCs) were isolated and were cocultured with mHSCs-TGF-ß1 and mHSCs-TGF-ßR1sih3 for 7 days. Differentiation of mHPCs was detected by quantitative reverse transcriptase polymerase chain reaction analysis and immunofluorence in vitro. mHPCs-E14.5 cell lines and differently treated mHSCs were cotransplanted into mice spleens immediately after establishment of acute liver injury model for animal studies. Engraftment and differentiation of transplanted cells as well as liver function recovery were measured at the seventh day via different methods. mHSCs-TGF-ß1 were transformed into myofibroblasts and highly expressed Jagged1, but that expression was reduced after blockage of TGF-ß1 signaling. mHPCs highly expressed downstream markers of Jagged1/Notch signaling and cholangiocyte markers (CK19, SOX9, and Hes1) after coculture with mHSCs-TGF-ß1 in vitro. In contrast, mature hepatocyte marker (ALB) was upregulated in mHPCs in coculture conditions with mHSCs-TGF-ßR1sih3. At the seventh day of cell transplantation assay, mHPCs-E 14.5 engrafted and differentiated into cholangiocytes after cotransplanting with TGF-ß1-knockin mHSCs, but the cells had a tendency to differentiate into hepatocytes when transplanted with TGF-ßR1-knockdown mHSCs, which corresponded to in vitro studies. HSCs play an important role in regulating HPCs differentiation into cholangiocytes via the TGF-ß1/Jagged1 signaling axis. However, HPCs have a tendency to differentiate into hepatocytes after blockage of TGF-ß1 signaling in HSCs.

Resolution of bleomycin-induced murine pulmonary fibrosis via a splenic lymphocyte subpopulation.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a progressive disease with high mortality, and the pathogenesis of the disease is still incompletely understood. Although lymphocytes, especially CD4+CD25+FoxP3+ regulatory T cells (Tregs), have been implicated in the development of IPF, contradictory results have been reported regarding the contribution of Tregs to fibrosis both in animals and humans. The aim of this study was to investigate whether a specific T cell subset has therapeutic potential in inhibiting bleomycin (BLM)-induced murine pulmonary fibrosis. METHODS: C57BL/6 mice received BLM (100 mg/kg body weight) with osmotic pumps (day 0), and pulmonary fibrosis was induced. Then, splenocytes or Tregs were adoptively transferred via the tail vein. The lungs were removed and subjected to histological and biochemical examinations to study the effects of these cells on pulmonary fibrosis, and blood samples were collected by cardiac punctures to measure relevant cytokines by enzyme-linked immunosorbent assay. Tregs isolated from an interleukin (IL)-10 knock-out mice were used to assess the effect of this mediator. To determine the roles of the spleen in this model, spleen vessels were carefully cauterized and the spleen was removed either on day 0 or 14 after BLM challenge. RESULTS: Splenocytes significantly ameliorated BLM-induced pulmonary fibrosis when they were administered on day 14. This effect was abrogated by depleting Tregs with an anti-CD25 monoclonal antibody. Adoptive transfer of Tregs on day 14 after a BLM challenge significantly attenuated pulmonary fibrosis, and this was accompanied by decreased production of fibroblast growth factor (FGF) 9-positive cells bearing the morphology of alveolar epithelial cells. In addition, BLM-induced plasma IL-10 expression reverted to basal levels after adoptive transfer of Tregs. Moreover, BLM-induced fibrocyte chemoattractant chemokine (CC motif) ligand-2 production was significantly ameliorated by Treg adoptive transfer in lung homogenates, accompanied by reduced accumulation of bone-marrow derived fibrocytes. Genetic ablation of IL-10 abrogated the ameliorating effect of Tregs on pulmonary fibrosis. Finally, splenectomy on day 0 after a BLM challenge significantly ameliorated lung fibrosis, whereas splenectomy on day 14 had no effect. CONCLUSIONS: These findings warrant further investigations to develop a cell-based therapy using Tregs for treating IPF.

Ethylenecarbodiimide-fixed splenocytes carrying whole islet antigens decrease the incidence of diabetes in NOD mice via down-regulation of effector memory T cells and autoantibodies.

Type 1 diabetes mellitus (T1DM) is a syndrome of loss of glucose homeostasis caused by the loss of ß cell chronic autoimmunity against islet cells. Islet-specific epitopes coupled antigen presenting cells by Ethylenecarbodiimide (ECDI) is a promising strategy to induce antigen-specific tolerance. However, single epitope induced tolerance is insufficient to prevent the onset of T1DM. The aim of this study is to evaluate the efficacy of whole islet antigens in preventing the onset and progression of T1DM and identify the underlying immune mechanism in NOD mice. In this study, the whole islet antigens, derived from islet lysate isolated from BALB/c mice, were coupled to splenocytes of BALB/c mice by ECDI fixation (SP-Islet lysate), and then intravenously administrated to NOD mice. The results showed that, compared with control group, SP-Islet lysate group significantly decreased T1DM incidence and improved the survival of NOD mice. SP-Islet lysate treated mice had reduced insulitis score and autoantibody levels, and improved glucose tolerance and insulin/glucagon production. Furthermore, the effector memory T cells (TEMs) were downregulated and regulatory T cells (Tregs) were upregulated by the SP-Islet lysate treatment, with reduced populations of Th1&Th17 cells. In conclusion, ECDI-fixed splenocytes carrying whole islet antigens effectively prevented the onset of T1DM in NOD mice, via suppressing the production of autoantibodies and inducing anergy of autoreactive T cells.

De novo hepatocellular carcinoma post-multivisceral transplantation in a child.

De novo hepatocellular carcinoma (HCC) post-transplantation in patients without viral hepatitis is extremely rare, with only three reported adult cases in the English literature. Here, we present a case of de novo HCC that developed in a 7-year-old female, who at 8 months of age received a liver, small bowel, spleen, and pancreas transplantation 6.5 years ago for gastroschisis and total parenteral nutrition (TPN)-related cirrhosis. The post-transplant course was complicated by Epstein-Barr virus (EBV) infection, post-transplant lymphoproliferative disease, and subsequent development of multifocal EBV-associated post-transplant smooth muscle tumors (EBV-PTSMT) in the small bowel 1 year and 10 months after transplantation, respectively. This was managed by reducing immunosuppression with rituximab and EBV-specific cytotoxic T-cell therapy. She was noted to have a new lesion in her transplanted liver graft 6.5 years post-transplantation that was diagnosed as HCC. The HCC was resected, and the patient remained clinically stable for 7 months. At that time, recurrence of the HCC was discovered on MRI. She passed away 6 months after. To the best of our knowledge, this is the first reported occurrence of de novo HCC post-transplantation in the pediatric population that is unrelated to viral hepatitis in either recipient or donor.

Quercitrin ameliorates the development of systemic lupus erythematosus-like disease in a chronic graft-versus-host murine model.

Systemic lupus erythematosus (SLE) is a serious disorder of immune regulation characterized by overproduction of autoantibodies, lupus nephritis, CD4+ T cell aberrant activation, and immune complex-mediated inflammation. The chronic graft vs. host disease (cGVHD) mouse model is a well-established model of SLE. Quercitrin is a natural compound found in Tartary buckwheat with a potential anti-inflammatory effect that is used to treat heart and vascular conditions. In our previous study, we determined that quercitrin is an immunosuppressant with beneficial effects in mouse models of immune diseases. We hypothesized that quercitrin could prevent lupus nephritis in the cGVHD mouse model by decreasing the production of autoantibodies and inflammatory cytokines, and reducing immune cell activation. cGVHD was induced by injecting DBA/2 spleen cells into the tail vein of BDF1 mice. The cGVHD mice exhibited significant proteinuria, which is a marker of nephritis. Quercitrin decreased the number of serum antibodies, CD4+ T cell activation, as well as the expression levels of T-bet, GATA-3, and selected cytokines. Moreover, quercitrin treatment decreased the expression of inflammatory genes and cytokines in the kidney, as well as in peritoneal macrophages. In addition, quercitrin inhibited LPS-induced cytokines as well as the phosphorylation of ERK, p38 MAPK, and JNK in Raw264.7 cells. Overall, quercitrin ameliorated the symptoms of lupus nephritis in the cGVHD mouse model, which may be due to the inhibition of CD4 T cell activation and anti-inflammatory effects on macrophages.

Preemptive donor apoptotic cell infusions induce IFN-γ-producing myeloid-derived suppressor cells for cardiac allograft protection.

We have previously shown that preemptive infusion of apoptotic donor splenocytes treated with the chemical cross-linker ethylcarbodiimide (ECDI-SPs) induces long-term allograft survival in full MHC-mismatched models of allogeneic islet and cardiac transplantation. The role of myeloid-derived suppressor cells (MDSCs) in the graft protection provided by ECDI-SPs is unclear. In this study, we demonstrate that infusions of ECDI-SPs increase two populations of CD11b(+) cells in the spleen that phenotypically resemble monocytic-like (CD11b(+)Ly6C(high)) and granulocytic-like (CD11b(+)Gr1(high)) MDSCs. Both populations suppress T cell proliferation in vitro and traffic to the cardiac allografts in vivo to mediate their protection via inhibition of local CD8 T cell accumulation and potentially also via induction and homing of regulatory T cells. Importantly, repeated treatments with ECDI-SPs induce the CD11b(+)Gr1(high) cells to produce a high level of IFN-γ and to exhibit an enhanced responsiveness to IFN-γ by expressing higher levels of downstream effector molecules ido and nos2. Consequently, neutralization of IFN-γ completely abolishes the suppressive capacity of this population. We conclude that donor ECDI-SPs induce the expansion of two populations of MDSCs important for allograft protection mediated in part by intrinsic IFN-γ-dependent mechanisms. This form of preemptive donor apoptotic cell infusions has significant potential for the therapeutic manipulation of MDSCs for transplant tolerance induction.

Murine spleen tissue regeneration from neonatal spleen capsule requires lymphotoxin priming of stromal cells.

Spleen is a tissue with regenerative capacity, which allows autotransplantation of human spleen fragments to counteract the effects of splenectomy. We now reveal in a murine model that transplant of neonatal spleen capsule alone leads to the regeneration of full spleen tissue. This finding indicates that graft-derived spleen stromal cells, but not lymphocytes, are essential components of tissue neogenesis, a finding verified by transplant and regeneration of Rag1KO spleen capsules. We further demonstrate that lymphotoxin and lymphoid tissue inducer cells participate in two key elements of spleen neogenesis, bulk tissue regeneration and white pulp organization, identifying a lymphotoxin-dependent pathway for neonatal spleen regeneration that contrasts with previously defined lymphotoxin-independent embryonic spleen organogenesis.

Changes in Differentiation of Thymic T Cells in the Progeny of Female Mice Subjected to Immune System Stimulation during Early Pregnancy.

Differentiation of T cells was studied in the progeny of female C57Bl/6 mice subjected to immunostimulation by administration of concanavalin A or adoptive transfer of concanavalin A-activated splenocytes. Acceleration of T cell maturation during the prepubertal period and decelerated differentiation during the pubertal and post-pubertal periods were revealed.

Imaging Tolerance Induction in the Classic Medawar Neonatal Mouse Model: Active Roles of Multiple F1-Donor Cell Types.

The immature immune system is uniquely susceptible to tolerance induction and thus an attractive target for immunomodulation strategies for organ transplantation. Newborn mice injected with adult semi-allogeneic lymphohematopoietic cells accept transplants without immunosuppressive drugs. Early in vivo/in situ events leading to neonatal tolerance remain poorly understood. Here, we show by whole body/organ imaging that injected cells home to lymphoid organs and liver where various F1-donor cell types selectively alter neonatal immunity. In host thymus, F1-donor dendritic cells (DC) interact with developing thymocytes and regulatory T cells suggesting a role in negative selection. In spleen and lymph nodes, F1-donor regulatory T/B cells associate with host alloreactive cells and by themselves prolong cardiac allograft survival. In liver, F1-donor cells give rise to albumin-containing hepatocyte-like cells. The neonatal immune system is lymphopenic, Th-2 immunodeviated and contains immature DC, suggesting susceptibility to regulation by adult F1-donor cells. CD8a T cell inactivation greatly enhances chimerism, suggesting that variable emerging neonatal alloreactivity becomes a barrier to tolerance induction. This comprehensive qualitative imaging study systematically shows contribution of multiple in vivo processes leading simultaneously to robust tolerance. These insights into robust tolerance induction have important implications for development of strategies for clinical application.

Transplantation of human spleen into immunodeficient NOD/SCID IL2Rγ(null) mice generates humanized mice that improve functional B cell development.

We previously generated humanized TB34N mice that received human fetal thymus (T), bone tissue (B) and fetal liver-derived (FL)-CD34(+) cells (34) in immunodeficient, NOD/SCID IL2Rγ(null) (N) mice. Although humanized TB34N mice had excellent hematopoiesis, here, we sought to further improve this model by additional transplantation of human spleen tissue (S) as a secondary hematopoietic tissue (TBS34N). The human spleen grafts were enlarged and differentiated into a similar morphology of adult humans, including follicular lymphoid structures with T- and B-cells. The TBS34N mice mimicked mature human immune system (HIS): mature T- and B-cells and follicular dendritic cells; activated germinal center B-cells expressing CD71, BR3(+) cells, memory B-cells and activation-induced cytidine deaminase(+) B-cells; CD138(+) plasma cells were enriched in the mouse spleen. HBsAg-specific hIgG antibodies were secreted into the sera of all TBS34N mice upon immunization with HBsAg. Taken together, the humanized TBS34N mice improved mature HIS and achieved adaptive antibody responses.

Spleen function after preservation in a physiological solution.

BACKGROUND: The purpose of this study was to evaluate the morphology and function of implanted autogenous spleen tissue after 24 h of preservation in a physiological solution. MATERIAL AND METHODS: Thirty-five male rats were divided into seven groups (n = 5): group 1, without surgical procedure; group 2, total splenectomy; group 3, total splenectomy and immediate implant of autogenous spleen tissue; group 4, total splenectomy and preservation of the entire spleen in lactated Ringer solution at room temperature for 24 h, followed by spleen sectioning and implantation; group 5, total splenectomy, followed by spleen sectioning and preservation in lactated Ringer solution at room temperature for 24 h and subsequent implantation of the slices; group 6, total splenectomy and preservation of the entire spleen in lactated Ringer solution at 4°C for 24 h, followed by spleen sectioning and implantation; and group 7, total splenectomy, the spleen was sliced and preserved in lactate Ringer solution at 4°C for 24 h, followed by implantation of the slices. After 90 d, scintigraphic studies using sulfur colloid labeled with 99mTc of the liver, lungs, spleen, implants, and a blood clot were performed. Hematological (erythrogram, leukogram, and platelets) and histologic studies were carried out. RESULTS: The autogenous splenic implants regenerated in all animals that received those implants preserved at 4°C and immediately after excision. The scintigraphic study showed a better phagocytic function in groups 1, 3, 6, and 7. No difference was observed in the hematological study. CONCLUSIONS: Spleen tissue preserved in lactated Ringer solution at 4°C for 24 h maintains its vitality and capacity to recover hematological and phagocytic functions.

[The Experimental Model of Autoimmune Process: the Role of Epigenetic Variation in the Population of Mice Hybrids].

BACKGROUND: At the development of graft versus host disease in genetically homogeneous population of (C57BI/6 x DBA/2) Fl mice two clinical phenotypes of SLE-like disease were revealed: lupus+ (immune complex glomerulonephritis and hemnolytic anemia) and lupus - (hemolytic anemia). The GvHD phenotypic heterogeneity is determined by the Th2-polarization: Th2 lymphocyte predominant activity, leads to the lupus+development, or prevalence activity of Th1 cells, leads to the lupus- development. OBJECTIVE: Our aim was to evaluate the possibility of using an experimental model of autoimmnune disease for studying and testing of epigenetic modifications, shifting Th1/Th2 balance in vivo. METHODS: Chronic GVHD was induced in B6D2F1 mice by the transplantation of 130x10(6) parental DBA/2 splenocytes. Anti-ds-DNA, total IgG and IgGI, IgG2a Abs were measured by ELISA. RESULTS: Six- to 8-week-old female DBA/2 and B6D2F1 mice were obtained from Biological Research Laboratory (Novosibirsk). It was established that regular moderate physical activity (unladed swimming) shifted Th1/Th2 balance towards Th1. This leads to a decrease in a population of recipients the lupus+ mice from 57 to 26% (p <0,001) with significantly reduced hypergammaglobulinemia (IgG from 2,8 to 2,0 mg/ml; p <0,047) and DNA antibodies titer from 0,18 to 0,12 OD (p =0,05). Administration of epigenetic modificator bisphenol A at low doses, which mimicking estrogen effects, enhances the proportion of lupus+ mice in experimental groups from 33 to 64% (p <0,001) and impairs their clinical status by the increasing the urine protein level from 2.8 to 4,2 mg/ml (p <0,001) in animals. CONCLUSION: Th1/Th2 - balance presumably is determined by the immune system epigenetic modification in experimental mice, formed on the previous stages of ontogeny and defines the direction of immune processes development in individual animal.

Vaccines against human HER2 prevent mammary carcinoma in mice transgenic for human HER2.

INTRODUCTION: The availability of mice transgenic for the human HER2 gene (huHER2) and prone to the development of HER2-driven mammary carcinogenesis (referred to as FVB-huHER2 mice) prompted us to study active immunopreventive strategies targeting the human HER2 molecule in a tolerant host. METHODS: FVB-huHER2 mice were vaccinated with either IL-12-adjuvanted human HER2-positive cancer cells or DNA vaccine carrying chimeric human-rat HER2 sequences. Onset and number of mammary tumors were recorded to evaluate vaccine potency. Mice sera were collected and passively transferred to xenograft-bearing mice to assess their antitumor efficacy. RESULTS: Both cell and DNA vaccines significantly delayed tumor onset, leading to about 65% tumor-free mice at 70 weeks, whereas mock-vaccinated FVB-huHER2 controls developed mammary tumors at a median age of 45 weeks. In the DNA vaccinated group, 65% of mice were still tumor-free at about 90 weeks of age. The number of mammary tumors per mouse was also significantly reduced in vaccinated mice. Vaccines broke the immunological tolerance to the huHER2 transgene, inducing both humoral and cytokine responses. The DNA vaccine mainly induced a high and sustained level of anti-huHER2 antibodies, the cell vaccine also elicited interferon (IFN)-γ production. Sera of DNA-vaccinated mice transferred to xenograft-carrying mice significantly inhibited the growth of human HER2-positive cancer cells. CONCLUSIONS: Anti-huHER2 antibodies elicited in the tolerant host exert antitumor activity.

Regulation of acute graft-versus-host disease by microRNA-155.

Acute graft-versus-host disease (aGVHD) remains a major complication of allogeneic hematopoietic stem cell transplant (alloHSCT), underscoring the need to further elucidate its mechanisms and develop novel treatments. Based on recent observations that microRNA-155 (miR-155) is up-regulated during T-cell activation, we hypothesized that miR-155 is involved in the modulation of aGVHD. Here we show that miR-155 expression was up-regulated in T cells from mice developing aGVHD after alloHSCT. Mice receiving miR-155-deficient donor lymphocytes had markedly reduced lethal aGVHD, whereas lethal aGVHD developed rapidly in mice recipients of miR-155 overexpressing T cells. Blocking miR-155 expression using a synthetic anti-miR-155 after alloHSCT decreased aGVHD severity and prolonged survival in mice. Finally, miR-155 up-regulation was shown in specimens from patients with pathologic evidence of intestinal aGVHD. Altogether, our data indicate a role for miR-155 in the regulation of GVHD and point to miR-155 as a novel target for therapeutic intervention in this disease.

Blood clearance of Howell-Jolly bodies in an experimental autogenic splenic implant model.

BACKGROUND: Autogenic splenic implant (ASI) is one of the few alternatives for preservation of splenic tissue when total splenectomy is inevitable. The aim of this study was to determine the morphological and functional regeneration of ASIs, as indicated by the clearance of Howell-Jolly (HJ) bodies, in an experimental model. METHODS: Ninety-nine male Wistar rats were divided into three groups: sham-operated (group 1), total splenectomy alone (group 2), and total splenectomy combined with ASI (group 3). Animals in group 3 were further allocated to nine subgroups of nine rats each, and analysed at different time points (1, 4, 8, 12, 16, 20, 24, 28 and 32 weeks after surgery). Blood smears were prepared at predetermined times for detection of HJ bodies. Morphological regeneration of tissue in the ASI was analysed by histology. RESULTS: At 1 week, the regenerated mass corresponded to about 7 per cent of the tissue implanted, reaching approximately 54 per cent at 24 weeks. The HJ body levels were increased in groups 2 and 3 until 8 weeks after surgery, following which levels in the ASI group became similar to those in the sham-operated group. HJ bodies were difficult to detect when a level of 22.5 per cent of regenerated ASI mass was reached. CONCLUSION: Functional regeneration of ASIs occurred from 8 weeks after surgery. When 22.5 per cent of regenerated ASI mass was reached almost no HJ bodies could be observed in the bloodstream, resembling a spleen in situ. SURGICAL RELEVANCE: Splenectomy has been practised routinely, both in the emergency setting and as a therapeutic elective procedure. There is a correlation between asplenia/hyposplenia and the occurrence of fulminant sepsis, underlining the importance of developing surgical methods for preserving splenic function. Both clinical and experimental studies have shown at least partial morphological and functional regeneration of autogenic splenic implants (ASIs). Experimental studies investigating the immunoprotective effect of ASIs, based mostly on exposure of animals to various bacteria, have demonstrated that ASIs can increase the rate of bacterial clearance and decrease mortality from sepsis. Clinical studies have shown their ability to remove colloidal substances and altered erythrocyte corpuscular inclusions, such as Howell-Jolly, Heinz and Pappenheimer bodies, from the bloodstream. In this experimental study the functional and morphological regeneration of ASIs was studied over time in rats.

Can the spleen be divided into two functional parts?

Solid evidence has revealed unsuspected functions of the spleen. Asplenic or hyposplenic patients bear an increased susceptibility to overwhelming postsplenectomy infection. We, for the first time, performed the split splenic transplantation to redress hemophilia A. We also resected the middle part of the spleen completely and anatomically for the first time. Our findings illustrate that the spleen can be divided into 2 functional parts, and may shed a new light on the understanding and practice in splenic surgery.