Morphological and quantitative analysis of spermatogonia in mouse testes using whole mounted seminiferous tubules. II. The irradiated testes

In adult male mice exposed to 300 R X-irradiation, the sper-matogonial population was selectively killed except for the radioresistant type A_s stem cells. Type A spermatogonia were minimal two days after irradiation, when only 20% of the control population was present in stages 5-6; these were predominately single and paired undifferentiated cells. When multiple injections of ³HTdR were given between 2 and 3.5 days post-irradiation, 90–95% of these survivors in stages 4-6 became labeled. Enhanced proliferation of these stem cells, and at times when they were normally quiescent, led to restoration of all classes of spermatogonia by 11 days after irradiation. Several autoradiographic studies were undertaken to better characterize the radioresistant cells. In mice given single or multiple injections of ³HTdR prior to irradiation, there was appreciable retention of label by those type A_s sper-matogonia that had originally incorporated ³HTdR in stages 2-4. This labeling pattern was identical to that of the long-cycling A_s stem cells in nonirradiated testes. Since the long-cycling A_s stem cells are thought to be characterized by a prolonged G₁ or “A-phase” which is known to be a highly radioresistant portion of the cell cycle, it was clear why these cells could preferentially survive irradiation doses that killed other spermatogonial types. It was proposed that following germ cell depletion, as after irradiation injury, the long-cycling A_s survivors could be prematurely triggered from A-phase into DNA synthesis, thereby, initiating restoration of the germ cell population.     

Aging Impairs Long-Term Hematopoietic Regeneration after Autologous Stem Cell Transplantation

Most of our knowledge of the effects of aging on the hematopoietic system comes from studies in animal models. In this study, to explore potential effects of aging on human hematopoietic stem and progenitor cells (HSPCs), we evaluated CD34⁺ cells derived from young (<35 years) and old (>60 years) adult bone marrow with respect to phenotype and in vitro function. We observed an increased frequency of phenotypically defined stem and progenitor cells with age, but no distinct differences with respect to in vitro functional capacity. Given that regeneration of peripheral blood counts can serve as a functional readout of HSPCs, we compared various peripheral blood parameters between younger patients (≤50 years; n = 64) and older patients (≥60 years; n = 55) after autologous stem cell transplantation. Patient age did not affect the number of apheresis cycles or the amount of CD34⁺ cells harvested. Parameters for short-term regeneration did not differ significantly between the younger and older patients; however, complete recovery of all 3 blood lineages at 1 year after transplantation was strongly affected by advanced age, occurring in only 29% of the older patients, compared with 56% of the younger patients (P = .009). Collectively, these data suggest that aging has only limited effects on CD34⁺ HSPCs under steady-state conditions, but can be important under consitions of chemotoxic and replicative stress.     

Human amniotic fluid stem cells support undifferentiated propagation and pluripotency of human embryonic stem cell without b-FGF in a density dependent manner

Human embryonic stem cells (hESCs) are pluripotent cells which can give rise to almost all adult cell lineages. Culture system of hESCs is complex, requiring exogenous b-FGF and feeder cell layer. Human mesenchymal stem cells (MSCs) not only synthesize soluble cytokines or factors such as b-FGF, but also provide other mechanism which might play positive role on sustaining hESCs propagation and pluripotency. Human amniotic fluid stem (AFS) cells, which share characteristics of both embryonic and adult stem cells, have been regarded as promising cells for regenerative medicine. Taking advantage by AFS cells, we studied the ability of AFS cells in supporting undifferentiated propagation and pluripotency of Chinese population derived X-01 hESCs. Human AF-type amniotic fluid stem cells (hAF-AFSCs) transcribed genes including Activin A, TGF-β1, Noggin and b-FGF, which involved in maintaining pluripotency and self-renewal of hESCs. Compared to mouse embryonic fibroblasts (MEFs), hAF-AFSCs secreted higher concentration of b-FGF which was important in hESCs culture (P < 0.05). The hESCs were propagated more than 30 passages on hAF-AFSCs layer with exogenous b-FGF supplementation, keeping undifferentiated status. While exogenous b-FGF was obviated, propagation of hESCs with undifferentiated status was dependent on density of hAF-AFSC feeder layer. Lower density of hAF-AFSCs resulted in rapid decline in undifferentiated clone number, while higher ones hindered the growth of colonies. The most appropriate hAF-AFSCs feeder density to maintain the X-01 hESC line without exogenous b-FGF was 15-20×10⁴/well. To the best of our knowledge, this is the first study demonstrating that hAF-AFSCs could support undifferentiated propagation and pluripotency of Chinese population derived hESCs without exogenous b-FGF supplementation.     

Retention of stemness and vasculogenic potential of human umbilical cord blood stem cells after repeated expansions on PES-nanofiber matrices

Despite recent advances in cardiovascular medicine, ischemic diseases remain a major cause of morbidity and mortality. Although stem cell-based therapies for the treatment of ischemic diseases show great promise, limited availability of biologically functional stem cells mired the application of stem cell-based therapies. Previously, we reported a PES-nanofiber based ex vivo stem cell expansion technology, which supports expansion of human umbilical cord blood (UCB)-derived CD133⁺/CD34⁺ progenitor cells ∼225 fold. Herein, we show that using similar technology and subsequent re-expansion methods, we can achieve ∼5 million-fold yields within 24 days of the initial seeding. Interestingly, stem cell phenotype was preserved during the course of the multiple expansions. The high level of the stem cell homing receptor, CXCR4 was expressed in the primary expansion cells, and was maintained throughout the course of re-expansions. In addition, re-expanded cells preserved their multi-potential differential capabilities in vitro, such as, endothelial and smooth muscle lineages. Moreover, biological functionality of the re-expanded cells was preserved and was confirmed by a murine hind limb ischemia model for revascularization. These cells could also be genetically modified for enhanced vasculogenesis. Immunohistochemical evidences support enhanced expression of angiogenic factors responsible for this enhanced neovascularization. These data further confirms that nanofiber-based ex-vivo expansion technology can generate sufficient numbers of biologically functional stem cells for potential clinical applications.     

CD4+ CD25+ Treg regulate the contribution of CD8+ T-cell subsets in repopulation of the lymphopenic environment

Peripheral T‐cell expansion is of major relevance for immune function after lymphopenia. In order to promote regeneration, the process should result in a peripheral T‐cell pool with a similar subpopulation structure as before lymphopenia. We investigated the repopulation of the CD8⁺ central‐memory T cells (T_CM) and effector‐memory T cells (T_EM) pools after adoptive transfer of sorted CD8⁺ T cells from naïve, T_CM and T_EM subsets into T‐cell‐deficient hosts. We show that the initial kinetics of expansion are distinct for each subset and that the contribution to the repopulation of the CD8⁺ T‐cell pool by the progeny of each subset is not a mere function of its initial expansion. We demonstrate that CD4⁺CD25⁺ Treg play a major role in the repopulation of the CD8⁺ T‐cell pool and that CD8⁺ T‐cell subsets impact on each other. In the absence of CD4⁺CD25⁺ Treg, a small fraction of naïve CD8⁺ T cells strongly proliferates, correlating with further expansion and differentiation of co‐expanding CD8⁺ T cells. CD4⁺CD25⁺ Treg suppress these responses and lead to controlled repopulation, contributing decisively to the maintenance of recovered T_CM and T_EM fractions, and leading to repopulation of each pool with progeny of its own kind.     

Cyclosporin but not everolimus inhibits chemokine receptor expression on CD4+ T cell subsets circulating in the peripheral blood of renal transplant recipients

The peripheral chemokine receptors chemokine receptor 3 (CXCR3) and CC chemokine receptor 5 (CCR5) have been reported to be associated with allograft rejection. The impact of the expression of immunosuppressive drugs on peripherally circulating CD4⁺ T cell subsets after renal transplantion is unknown. Expression of CXCR3 and CCR5 was investigated by flow cytometry in 20 renal allograft recipients participating in a prospective, randomized trial ({"type":"clinical-trial","attrs":{"text":"NCT00514514","term_id":"NCT00514514"}}NCT00514514). Initial immunosuppression consisted of basiliximab, cyclosporin A (CsA), mycophenolate sodium and corticosteroids. After 3 months, patients were treated either with CsA, mycophenolate sodium (MPA) plus corticosteroids (n = 6), CsA and everolimus plus corticosteroids (n = 8) or CsA-free (CsA_free) receiving everolimus, MPA and corticosteroids (n = 6). After initial reduction of CD4⁺forkhead box protein 3 (FoxP3)⁺ and CD4⁺CD25^hiFoxP3⁺ regulatory T cells (T_regs) (P < 0·05; P < 0·01), 3-month post-transplant percentages of T_regs were reconstituted in CsA_free and CsA_lo arms compared to CsA_reg 12 months post transplant. Expression of CCR5 and CXCR3 on CD4⁺FoxP3⁺ and CD4⁺FoxP3^- T cells 12 months post transplant was increased in CsA_freeversus CsA_reg. Increase in CCR5⁺CXCR3⁺ co-expressing CD4⁺FoxP3^- cells between 3 and 12 months correlated negatively with the glomerular filtration rate (GFR) slope/year [modification of diet in renal disease (MDRD); r = −0·59, P < 0·01]. CsA, but not everolimus, inhibits both T_reg development and expression of CXCR3 and CCR5 on CD4⁺ T cell subsets. Increase in CCR5⁺CXCR3⁺ co-expressing CD4⁺FoxP3^- T cells is associated with early loss in allograft function.     

Proliferation of spermatogonia and Sertoli cells in maturing mice

Summary Spermatogonial proliferation was studied in mice from day 13 p.p. when the seminiferous epithelium is incomplete, until week 12 p. p. when a steady state at adult levels has been attained. Counts of undifferentiated, A ₁ and intermediate spermatogonia and primary spermatocytes in stages IV and IX of the cycle of the seminiferous epithelium were made in whole mounted seminiferous tubules. Sertoli cell proliferation was studied in a separate series from 6 to 14 days p.p. employing the ³H-thymidine labeling index.It appeared that 1. Sertoli cell proliferation stops at day 12 whereafter the cells obtain their adult appearance; 2. The numbers of stem cell spermatogonia and the production of differentiating A ₁ spermatogonia increase almost twofold between day 13 and week 12; 3. The efficiency of the divisions of the differentiating A ₁-B spermatogonia is similar to that in the adult throughout this period; 4. At all ages studied, the cell counts revealed an almost constant numerical relationship between Sertoli cells and germ cells, which suggests a function of Sertoli cells in the regulation of spermatogonial proliferation.     

Combined Env- and Gag-specific T cell responses in relation to programmed death-1 receptor and CD4+ T cell loss rates in human immunodeficiency virus-1 infection

Additional progression markers for human immunodeficiency virus (HIV) infection are warranted. In this study we related antigen-specific responses in CD4⁺ and CD8⁺ T cells to CD38, reflecting chronic immune activation, and to CD4⁺ T cell loss rates. Clones transiently expressing CD107a (CD8⁺) or CD154 (CD4⁺) in response to Gag, Env and Nef overlapping peptide pools were identified, along with their expression of the inhibitory programmed death-1 receptor (PD-1) in fresh peripheral blood mononuclear cells (PBMC) from 31 patients off antiretroviral treatment (ART). HIV-specific CD8⁺ T cell responses dominated over CD4⁺ T cell responses, and among CD8⁺ responses, Gag and Nef responses were higher than Env-responses (P < 0·01). PD-1 on CD8⁺ HIV-specific subsets was higher than CMV-specific CD8⁺ cells (P < 0·01), whereas PD-1 on HIV-specific CD4⁺ cells was similar to PD-1 on CMV-specific CD4⁺ cells. Gag and Env CD8⁺ responses correlated oppositely to the CD4 loss rate. Env/Gag CD8⁺ response ratios, independently of PD-1 levels, correlated more strongly to CD4 change rates (r = −0·50 to −0·77, P < 0·01) than the total number of Gag-specific CD8⁺ cells (r = 0·44–0·85, P ≤ 0·02). The Env/Gag ratio performed better than CD38 and HIV-RNA in logistic regression analysis predicting CD4 change rate as a measure of progression. In conclusion, HIV-specific CD8⁺CD107a⁺ Env/Gag response ratio was a stronger predictor for progression than CD38 and HIV-RNA. The Env/Gag ratio may reflect the balance between possibly beneficial (Gag) and detrimental (Env) CD8⁺ T cell responses and should be explored further as a progression marker.     

Spermatogonial stem cells in the albino rat

The existence of two classes of spermatogonial stem cells in the rat testis, i.e., reserve type A₀ spermatogonia and renewing, types A₁-A₄ spermatogonia, postulated by Clermont and Bustos-Obregon (′68), was reexamined in a quantitative analysis of type A spermatogonia in both whole mounts of tubules and in radioautographed sections of testes from animals killed at various times, up to 26 days, after one or multiple injections of ³H-thymidine. The cell counts obtained from whole mounts of tubules revealed that the number of isolated type A₀ cells per unit area of limiting membrane remained constant throughout the cycle of the seminiferous epithelium. Paired type A₀ spermatogonia also remained unchanged in number per unit area of basement membrane from stage I to stage VIII of the cycle. The low mitotic index of type A₀ spermatogonia (0.1%) indicated that these cells were not actively involved in the production of spermatogonia or spermatocytes during each cycle of the seminiferous epithelium and thus were considered as reserve stem cells. The type A₁ spermatogonia, which are formed during stage I of the cycle, remained resting until stage IX, when they undertook a series of four successive divisions resulting in the production of new type A₁ and Intermediate-type spermatogonia. An analysis of the labeling indices of type A spermatogonia obtained from cell counts in radioautographed testicular sections after a single or multiple ³H-thymidine injections indicated that the percentages of labeled type A cells corresponded to the percentages of type A₁-A₄ at each stage, whereas the percentages of unlabeled type A cells corresponded to the percentages of type A₀ spermatogonia obtained from counts of cells in whole mounts. This confirmed that type A₀ cells were generally non-proliferative throughout the cycle of the seminiferous epithelium while the type A₁-A₄ spermatogonia underwent complete renewal during each cycle. The present results thus support the concept of the existence of two classes of spermatogonial stem cells in rats.     

Increase in tumour‐infiltrating lymphocytes with regulatory T cell immunophenotypes and reduced ζ‐chain expression in nasopharyngeal carcinoma patients

The pathological significance of the mechanisms of tumour immune-evasion and/or immunosuppression, such as loss of T cell signalling and increase in regulatory T cells (T_regs), has not been well established in the nasopharyngeal carcinoma (NPC) microenvironment. To evaluate the T_reg immunophenotypes in tumour-infiltrating lymphocytes (TILs), we performed a double-enzymatic immunostaining for detection of forkhead box P3 (FoxP3) and other markers including CD4, CD8, and CD25 on 64 NPC and 36 non-malignant nasopharyngeal (NP) paraffin-embedded tissues. Expression of CD3ζ and CD3ε was also determined. The prevalence of CD4⁺FoxP3⁺ cells in CD4⁺ T cells and the ratio of FoxP3⁺/CD8⁺ were increased significantly in NPC compared with those in NP tissues (P < 0·001 and P = 0·025 respectively). Moreover, the ratio of FoxP3⁺/CD25⁺FoxP3⁻ in NPC was significantly lower than that in NP tissues (P = 0·005), suggesting an imbalance favouring activated phenotype of T cells in NPC. A significant negative correlation between the abundance of FoxP3⁺ and CD25⁺FoxP3⁻ cells (P < 0·001) was also identified. When histological types of NPC were considered, a lower ratio of FoxP3⁺/CD25⁺FoxP3⁻ was found in non-keratinizing and undifferentiated carcinomas. Increased CD4⁺FoxP3⁺/CD4⁺ proportion and FoxP3⁺/CD8⁺ ratio were associated with keratinizing squamous cell carcinoma. A reduced expression of CD3ζ in TILs was found in 20·6% of the NPC tissues but none of the NP tissues. These data provide evidence for the imbalances of T_reg and effector T cell phenotypes and down-regulation of signal-transducing molecules in TILs, supporting their role in suppression of immune response and immune evasion of NPC.     

Lung transplantation affects expression of the chemokine receptor type 4 on specific T cell subsets

Alloreactive T cells that infiltrate the graft after lung transplantation (LTx) play a role in chronic rejection. Chemokines such as thymus and activation-regulated chemokine (TARC), macrophage-derived chemokine (MDC) and monocyte chemotactic protein-1 (MCP-1) are produced locally in the lung and attract T cells via chemokine receptor 4 (CCR4). In a TARC gradient, cells expressing CCR4⁺⁺ migrate more efficiently than CCR4⁺-expressing cells. In this study, we compared the CCR4 expression of T cells in blood from 20 lung transplant recipients to healthy controls. We then examined whether CCR4 expression is associated with the occurrence of chronic rejection. The CCR4⁺⁺ expression was decreased on CD4 T cells from LTx patients (P < 0·0001) when compared to healthy controls. The analysis of CD4 T cell subsets showed that this decrease was present on central memory, effector memory and terminally differentiated T cells (P = 0·0007, P < 0·0001 and P = 0·05, respectively), while a trend was found for naive CD4 T cells (P = 0·06). Also, the expression of CCR4⁺ on regulatory T cells (T_regs) was decreased in LTx patients when compared to healthy controls (P = 0·02). Interestingly, the CCR4⁺⁺ expression on CD4 effector memory T cells was decreased in patients developing chronic rejection sometimes more than a year before the clinical diagnosis when compared to patients who did not (P = 0·04). The analysis of CD8 T cell subsets only showed the CCR4⁺ expression to be increased significantly on effector memory and terminally differentiated CD8 T cells (P = 0·02, P = 0·03, respectively) in LTx patients, but no relation was found in chronic rejection. In conclusion, the expression of CCR4 on T cell subsets was altered after LTx and appears to be related to chronic rejection.     

Isolation and characterization of CD105+/CD90+ subpopulation in breast cancer MDA-MB-231 cell line

Background: The epithelial-mesenchymal transition (EMT) generates cells with properties of stem cells, if that happened, the stem cell should be with mesenchymal property. This study aimed to identify a group of cells with mesenchymal stem cell (MSC)-like characteristics in breast cancer bone metastatic cell line MDA-MB-231, moreover, the relevance between breast cancer stem cells and the EMT was observed. CD105 and CD90, identified as the standards of MSCs, were used for the identification. Methods: The CD105⁺/CD90⁺ and CD105^-/CD90^- subpopulation of MDA-MB-231 cells were detected and sorted by flow cytometry. MSC-like characteristics in cell proliferation, migration and cell cycle were investigated here by MTT asaay, transwell migration assay, and PI staining respectively. The expression profiles of some stem cell-associated genes were also observed by quantitative real time PCR. Results: Around 0.99% and 90.77% of parental cells were identified as CD105⁺/CD90⁺ and CD105^-/CD90^- cell subpopulations respectively. The CD105⁺/CD90⁺ cells exhibited stronger migratory capacity as compared to parental and CD105^-/CD90^- cells, while less CD105⁺/CD90⁺ cells were arrested in the S phase. Besides, pluripotent stem cell factors, like Oct-4, Nanog, Klf4 and Sox-2, were all upregulated in CD105⁺/CD90⁺ cells, with also proliferation increase, as compared with other two populations. Conclusion: The CD105⁺/CD90⁺ subpopulation from breast cancer MDA-MB-231 cells was proven to possess “mesenchymal stem cell-like” characteristics, and its high migratory ability might be associated with EMT. Moreover, using the surface markers of CD105 and CD90 for the identification of MSCs might provide new theoretical basis for the recurrence and metastasis of breast cancer.     

Origin of Hematopoietic Progenitors during Embryogenesis

It has been widely accepted that hematopoietic and endothelial cell lineages diverge from a common progenitor referred to as the hemangioblast. Recently, analyses of the potential of progenitor cells purified from mouse embryos as well as embryonic stem cells differentiating in vitro resolved intermediate stages between mesodermal cells and committed precursors for hematopoietic and endothelial cell lineages. There are two distinct hematopoietic cell lineages which have different origins, i.e., primitive hematopoietic lineage derived from mesoderm or hemangioblasts and definitive hematopoietic lineage derived from endothelial cells. The endothelium is suggested to provide a milieu in which the definitive hematopoietic lineage acquires multiple potentials.     

Cooperative action of CD8 T lymphocytes and natural killer cells controls tumour growth under conditions of restricted T‐cell receptor diversity

In mice expressing a transgenic T-cell receptor (TCR; TCRP1A) of DBA/2 origin with reactivity towards a cancer-germline antigen P1A, the number of TCRP1A CD8⁺ T cells in lymphoid organs is lower in DBA/2 than in B10.D2 or B10.D2(× DBA/2)F₁ mice. This reduction results from haemopoietic cell autonomous differences in the differentiation of the major histocompatibility complex class I-restricted TCRP1A thymocytes controlled by DBA/2 versus B10.D2-encoded genes. We report here that the lower number of TCRP1A CD8⁺ T cells in DBA/2 mice correlated with their poor resistance to P1A-expressing mastocytoma solid tumours. Functional potency of CD8⁺ cytolytic T lymphocytes (CTL) from the above strains was not compromised, but their number after expansion appeared to be influenced by their genetic background. Intriguingly, non-transgenic DBA/2 mice resisted P1A⁺ tumours more efficiently despite poor representation of P1A-specific CTL. This was partly the result of their more heterogeneous TCR repertoire, including reactivity to non-P1A tumour antigens because mice that had rejected a P1A⁺ tumour became resistant to a P1A⁻ variant of the tumour. Such ‘cross-resistance’ did not develop in the TCRP1A transgenic mice. Nonetheless, reconstitution of RAGº^/º mice with TCRP1A CD8⁺ T cells, with or without CD4⁺ T cells, or exclusive representation of TCRP1A CD8⁺ T cells in RAGº^/º TCRP1A transgenic mice efficiently resisted the growth of P1A-expressing tumours. Natural killer cells present at a higher number in RAGº^/º mice also contributed to tumour resistance, in part through an NKG2D-dependent mechanism. Hence, in the absence of a polyclonal T-cell repertoire, precursor frequencies of natural killer cells and tumour-specific CTL affect tumour resistance.     

Quantity and Quality Reconstitution of NKG2A+ Natural Killer Cells Are Associated with Graft-versus-Host Disease after Allogeneic Hematopoietic Cell Transplantation

The immune mechanism underlying graft-versus-host disease (GVHD) after allogeneic stem cell transplantation (HSCT) remains unclear. Natural killer (NK) cells play a crucial role in mediating pathogen-specific immunity and are the first donor-derived lymphocytes reconstituted post-HSCT. However, NK cells vary at different stages after HSCT. Here, we found that the absolute NKG2A⁺ subset cell counts and the percentages of NKG2A⁺ among NK cells were significantly reduced in GVHD patients after HSCT compared with those from non-GVHD patients. Moreover, the reduction in NKG2A⁺ NK cells in post-HSCT GVHD patients was ascribed to increased apoptosis and a decreased proliferation capacity while retaining a strong graft-versus-leukemia effect. In vitro assays showed that co-culture of T cells with NKG2A⁺ NK cells significantly reduced IFN-γ secretion by T cells and increased IL-4 secretion. Moreover, the CD25 expression level was decreased, whereas the number of cells with the CD4⁺CD25⁺FOXP3⁺ phenotype was increased. In addition, the NKG2A⁺ NK cells induced T cell apoptosis and decreased T cell proliferation during the co-culture process. Importantly, NKG2A⁺ NK cells mainly regulated activated but not resting T cells. In vivo assays showed that the serologic IL-10 level was evidently lower in GVHD than in non-GVHD patients, whereas the IL-1β, IFN-γ, and tumor necrosis factor-α levels were higher in GVHD patients. Furthermore, the NKG2A⁺ NK cell ratio from GVHD patients was markedly increased by the presence of exogenous IL-10 but not by other cytokines. In contrast, the NKG2A⁺ cell ratio from non-GVHD patients was not increased by IL-10. Therefore, post-HSCT GVHD may be ascribed to the reduced induction of NKG2A⁺ NK cells by IL-10, which further overactivates T cells.     

Effect on cellular and humoral immune responses of the AS03 adjuvant system in an A/H1N1/2009 influenza virus vaccine administered to adults during two randomized controlled trials

The influence of AS03_A, a tocopherol oil-in-water emulsion-based adjuvant system, on humoral and cell-mediated responses to A/California/7/2009 H1N1 pandemic vaccine was investigated. In two observer-blind studies, a total of 261 healthy adults aged 18 to 60 years were randomized to receive either AS03_A-adjuvanted H1N1 vaccine containing 3.75 μg hemagglutinin (HA) or nonadjuvanted H1N1 vaccine containing 15 or 3.75 μg HA on days 0 and 21. Hemagglutination inhibition (HI) antibody and T-cell responses were analyzed up to day 42. A first dose of AS03_A-adjuvanted vaccine (3.75 μg HA) or nonadjuvanted vaccine (15 μg HA) induced HI responses of similar magnitudes that exceeded licensure criteria (e.g., 94 to 100% with titers of ≥40). A lower response following 3.75 μg HA without adjuvant was observed (73% with titers of ≥40). Following a second dose, geometric mean HI titers at day 42 were higher for AS03_A-adjuvanted vaccine (636 and 637) relative to nonadjuvanted vaccine (341 for 15 μg HA and 150 for 3.75 μg HA). Over the 42-day period, the increase in frequency of A/H1N1/2009-specific CD4⁺ T cells was significantly higher in the adjuvanted group than in the nonadjuvanted group. There was no evidence of correlation between baseline CD4⁺ T-cell frequencies and day 21 HI antibody titers, while there was some correlation (R = 0.35) between day 21 CD4⁺ T-cell frequencies and day 42 HI titers. AS03_A adjuvant enhanced the humoral and CD4⁺ T-cell-mediated responses to A/H1N1/2009 vaccine. Baseline A/H1N1/2009-specific CD4⁺ T-cell frequencies did not predict post-dose 1 antibody responses, but there was some correlation between post-dose 1 CD4⁺ T-cell frequencies and post-dose 2 antibody responses.     

The role of HER2 in early breast cancer metastasis and the origins of resistance to HER2-targeted therapies

The HER2 gene encodes the receptor tyrosine kinase HER2 and is often over-expressed or amplified in breast cancer. Up-regulation of HER2 contributes to tumor progression. Many aspects of tumor growth are favorably affected through activation of HER2 signaling. Indeed, HER2 plays a role in increasing proliferation and survival of the primary tumor and distant lesions which upon completion of full transformation cause metastases. P185^HER2/neu receptors and signaling from them and associated molecules increase motility of both intravasating and extravasating cells, decrease apoptosis, enhance signaling interactions with the microenvironment, regulate adhesion, as well as a multitude of other functions.Recent experimental and clinical evidence supports the view that the spread of incompletely transformed cells occurs at a very early stage in tumor progression. This review concerns the identification and characterization of HER2, the evolution of the metastasis model, and the more recent cancer stem cell model. In particular, we review the evidence for an emerging mechanism of HER2⁺ breast cancer progression, whereby the untransformed HER2-expressing cell shows characteristics of stem/progenitor cell, metastasizes, and then completes its final transformation at the secondary site.