[show abstract][hide abstract] ABSTRACT: Transplantation of T-cell-depleted BM (TDBM) under mild conditioning, associated with minimal toxicity and reduced risk of GVHD, offers an attractive therapeutic option for patients with non-malignant hematologic-disorders and can mediate immune tolerance to subsequent organ transplantation. However, overcoming TDBM rejection following reduced-conditioning remains a challenge. Here, we address this barrier using donor-derived central-memory CD8+T-cells (Tcm), directed against 3rd-party antigens. Our results show that fully allogeneic or (hostXdonor)F1-Tcm, support donor chimerism (>6 months) in sublethaly irradiated(5.5Gy) mice, without GVHD symptoms. Chimerism under yet lower irradiation(4.5Gy) was achieved by combining Tcm with short-term administration of low-dose Rapamycin. Importantly, this chimerism resulted in successful donor skin acceptance, while third-party skin was rejected. Tracking of host-anti-donor T-cells (HADTC), that mediate TDBMT rejection, in a novel bioluminescence-imaging model revealed that Tcm both induce accumulation and eradicate HADTC in the LNs, concomitant with their elimination from other organs, including the BM. Further analysis with 2-photon microcopy revealed that Tcm form conjugates with HADTC, resulting in decelerated and confined movement of HADTC within the LNs in an antigen-specific manner. Thus, anti-3rd-party Tcm support TDBMT engraftment under reduced-conditioning through lymph-node sequestration and deletion of HADTC, offering a novel and potentially safe approach for attaining stable hematopoietic chimerism.
[show abstract][hide abstract] ABSTRACT: Aberrant inflammation appears to be a pathogenic factor in autoimmune diseases and other noxious inflammatory
conditions in which the inflammatory process is misapplied, exaggerated, recurrent or chronic. The protein molecules
involved in pathogenic inflammation—disease-associated proteins (DAP )—which include chemokines, cytokines, and
growth factors and their receptors, appear normal; their networks of interaction are at fault. Here we demonstrate a new
approach to network regulation of inflammation based on peptide sequence motifs shared by the second extra-cellular
loop (EC L2) of different chemokine receptors; previously known chemokine receptor binding sites have not involved
the EC L2 loop. These motifs of 9 amino acids, which we detected by sequence alignment, manifest very low E-values
compared with slightly modified sequence variations, indicating that they were not likely to have evolved by chance. To
test whether this shared sequence network (SSN) might serve a regulatory function, we synthesized 9-amino acid SSN
peptides from the EC L2 loops of three different chemokine receptors. We administered these peptides to rats during the
induction of a model of autoimmune arthritis. Two of the peptides significantly downregulated the arthritis; one of the
peptides synergized with non-specific anti-inflammatory treatment with dexamethasone. These findings suggest that
the SSN peptide motif reported here is likely to have adaptive value in controlling inflammation. Moreover, detection of
SSN motif peptides could provide a network-based approach to immune modulation.
[show abstract][hide abstract] ABSTRACT: Mice are exceedingly sensitive to intra-peritoneal (IP) challenge with some virulent pneumococci (LD50 = 1 bacterium). To investigate how peripheral contact with bacterial capsular polysaccharide (PS) antigen can induce resistance, we pulsed bone marrow dendritic cells (BMDC) of C57BL/6 mice with type 4 or type 3 PS, injected the BMDC intra-foot pad (IFP) and challenged the mice IP with supra-lethal doses of pneumococci. We examined the responses of T cells and B cells in the draining popliteal lymph node and measured the effects on the bacteria in the peritoneum and blood. We now report that: 1) The PS co-localized with MHC molecules on the BMDC surface; 2) PS-specific T and B cell proliferation and IFNγ secretion was detected in the draining popliteal lymph nodes on day 4; 3) Type-specific resistance to lethal IP challenge was manifested only after day 5; 4) Type-specific IgM and IgG antibodies were detected in the sera of only some of the mice, but B cells were essential for resistance; 5) Control mice vaccinated with a single injection of soluble PS did not develop a response in the draining popliteal lymph node and were not protected; 6) Mice injected with unpulsed BMDC also did not resist challenge: In unprotected mice, pneumococci entered the blood shortly after IP inoculation and multiplied exponentially in both blood and peritoneum killing the mice within 20 hours. Mice vaccinated with PS-pulsed BMDC trapped the bacteria in the peritoneum. The trapped bacteria proliferated exponentially IP, but died suddenly at 18-20 hours. Thus, a single injection of PS antigen associated with intact BMDC is a more effective vaccine than the soluble PS alone. This model system provides a platform for studying novel aspects of PS-targeted vaccination.
PLoS ONE 01/2012; 7(6):e39193. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: Histologic overexpression of the estrogen receptor α (ER) is a well-established prognostic marker in breast cancer. Noninvasive imaging techniques that could detect ER overexpression would be useful in a variety of settings where patients' biopsies are problematic to obtain. This study focused on developing, by in vivo MRI, strategies to measure the level of ER expression in an orthotopic mouse model of human breast cancer. Specifically, novel ER-targeted contrast agents based on pyridine-tetra-acetate-Gd(III) chelate (PTA-Gd) conjugated to 17β-estradiol (EPTA-Gd) or to tamoxifen (TPTA-Gd) were examined in ER-positive or ER-negative tumors. Detection of specific interactions of EPTA-Gd with ER were documented that could differentiate ER-positive and ER-negative tumors. In vivo competition experiments confirmed that the enhanced detection capability of EPTA-Gd was based specifically on ER targeting. In contrast, PTA-Gd acted as an extracellular probe that enhanced ER detection similarly in either tumor type, confirming a similar vascular perfusion efficiency in ER-positive and ER-negative tumors in the model. Finally, TPTA-Gd accumulated selectively in muscle and could not preferentially identify ER-positive tumors. Together, these results define a novel MRI probe that can permit selective noninvasive imaging of ER-positive tumors in vivo.
Cancer Research 12/2011; 71(24):7387-97. · 8.65 Impact Factor
[show abstract][hide abstract] ABSTRACT: Steady-state egress of hematopoietic progenitor cells can be rapidly amplified by mobilizing agents such as AMD3100, the mechanism, however, is poorly understood. We report that AMD3100 increased the homeostatic release of the chemokine stromal cell derived factor-1 (SDF-1) to the circulation in mice and non-human primates. Neutralizing antibodies against CXCR4 or SDF-1 inhibited both steady state and AMD3100-induced SDF-1 release and reduced egress of murine progenitor cells over mature leukocytes. Intra-bone injection of biotinylated SDF-1 also enhanced release of this chemokine and murine progenitor cell mobilization. AMD3100 directly induced SDF-1 release from CXCR4(+) human bone marrow osteoblasts and endothelial cells and activated uPA in a CXCR4/JNK-dependent manner. Additionally, ROS inhibition reduced AMD3100-induced SDF-1 release, activation of circulating uPA and mobilization of progenitor cells. Norepinephrine treatment, mimicking acute stress, rapidly increased SDF-1 release and progenitor cell mobilization, whereas β2-adrenergic antagonist inhibited both steady state and AMD3100-induced SDF-1 release and progenitor cell mobilization in mice. In conclusion, this study reveals that SDF-1 release from bone marrow stromal cells to the circulation emerges as a pivotal mechanism essential for steady-state egress and rapid mobilization of hematopoietic progenitor cells, but not mature leukocytes.
Leukemia: official journal of the Leukemia Society of America, Leukemia Research Fund, U.K 04/2011; 25(8):1286-96. · 10.16 Impact Factor
[show abstract][hide abstract] ABSTRACT: Talin1 is a key integrin coactivator. We investigated the roles of this cytoskeletal adaptor and its target integrins in B-cell lymphogenesis, differentiation, migration, and function. Using CD19 Cre-mediated depletion of talin1 selectively in B cells, we found that talin1 was not required for B-cell generation in the bone marrow or for the entry of immature B cells to the white pulp of the spleen. Loss of talin1 also did not affect B-cell maturation into follicular B cells but compromised differentiation of marginal zone B cells. Nevertheless, serum IgM and IgG levels remained normal. Ex vivo analysis of talin1-deficient spleen B cells indicated a necessary role for talin1 in LFA-1 and VLA-4 activation stimulated by canonical agonists, but not in B-cell chemotaxis. Consequently, talin1 null B splenocytes could not enter lymph nodes nor return to the bone marrow. Talin1 deficiency in B cells was also impaired in the humoral response to a T cell-dependent antigen. Collectively, these results indicate that talin1 is not required for follicular B-cell maturation in the spleen or homeostatic humoral immunity but is critical for integrin-dependent B lymphocyte emigration to lymph nodes and optimal immunity against T-dependent antigens.
[show abstract][hide abstract] ABSTRACT: Diffusion MRI studies revealed specific morphological and physiological properties of MCF7 tumors implanted in the mammary gland of immunodeficient mice. These tumors mimic the histological and pathophysiological properties of human breast cancer in patients. The experiments were conducted by (1) applying varying diffusion gradient strengths, Gd, from 0 to 20 G/cm and a short diffusion time (td = 16 ms) in order to minimize the effect of restriction and exchange of water between the intra- and extracellular compartments, and (2) applying a strong constant gradient and diffusion times up to 96 ms, revealing water restriction and exchange. The normalized signal intensity was plotted against the diffusion weighting factor b, taking into account interaction with the imaging gradients. The curves were analyzed by applying a bi-exponential decay function assuming two exchanging water compartments, with fast and slow diffusion coefficients. The amplitudes and decay constants of the two exponents, a fast and a slow one, were related to the fraction and apparent diffusion coefficients of the extra- and intracellular water, respectively, considering contributions of restriction and exchange. During tumor progression the distribution of the diffusion parameters for the same experimental protocol varied and became less homogeneous. This was predominantly due to variations in the cellularity and increased necrosis. Upon treatment of the tumors with a new anti-estrogenic drug, tamoxifen methiodide, the changes in the diffusion parameters indicated increased cell swelling. Hence, this cytostatic response to treatment was detected before actual cell death was apparent. The potential capacity of diffusion MRI is of high clinical relevance and may help improve the noninvasive diagnosis and followup of treatment of this devastating disease.
Israel Journal of Chemistry. 03/2010; 43(1‐2):103 - 114.
[show abstract][hide abstract] ABSTRACT: Chemokines regulate the pathways that restrict homing of specific subsets of immune cells, and thereby fine tune the immune response at specific lymphoid and peripheral tissues. CCL2 is a chemokine that induces migration of monocytes, memory T cells, and dendritic cells. Previously, we demonstrated that pM levels of CCL2 dramatically inhibit migration of T cells. The aim was to test whether subphysiological doses of CCL2 can ameliorate murine colitis and inflammation-induced colorectal cancer.
TNBS (2,4,6 trinitrobenzene sulfonic acid) colitis and dextran sodium sulfate (DSS) colitis were induced in Balb/c and C57BL/6 mice, respectively. Mice were treated daily with intraperitoneal CCL2 injections. Disease activity was assessed clinically, histologically, and by measuring inflammatory cytokine levels. In addition, an inflammatory cancer model was induced by azoxymethane-DSS (AOM-DSS) in Balb/c mice. Mice were treated daily with CCL2 for 11 weeks and then assessed for number of tumors in the colons.
Daily administration of CCL2 (60-120 ng) significantly decreased the development of TNBS- and DSS-induced colitis. In a DSS-AOM model, CCL2-treated mice developed significantly fewer tumors (P < 0.005) at 11 weeks. Chronic inflammation in the CCL2-treated mice was significantly less pronounced as compared to phosphate-buffered saline-treated mice.
Administration of pM levels of CCL2 significantly inhibits migration of T cells in amelioration of TNBS and DSS colitis and inhibits development of colorectal cancer in an AOM-DSS colitis model in mice. Thus, pM levels of CCL2 may be clinically beneficial as an antiinflammatory agent in IBD.
[show abstract][hide abstract] ABSTRACT: Although mesenchymal stromal cells (MSCs) exhibit marked immunoregulatory activity through multiple mechanisms, their potential to completely evade rejection upon transplantation into allogeneic recipients is controversial. To directly address this controversy, the survival of luciferase-labeled MSCs (Luc(+) MSCs) was evaluated by imaging in allogeneic recipients. This analysis showed that although MSCs exhibited longer survival compared to fibroblasts (Fib), their survival was significantly shorter compared to that exhibited in syngeneic or in immune-deficient Balb-Nude or non-obese diabetic severe combined immunodeficiency (NOD-SCID) recipients. Graft rejection in re-challenge experiments infusing Luc(+) Fib into mice, which had previously rejected Luc(+) MSCs, indicated potential induction of immune memory by the MSCs. This was further analyzed in T-cell antigen receptor (TCR) transgeneic mice in which either CD4 TEA mice or CD8 T cells (2C mice) bear a TCR transgene against a specific MHC I or MHC II, respectively. Thus, following a re-challenge with MSCs expressing the cognate MHC haplotype, an enhanced percentage of 2C CD8(+) or TEA CD4(+) T cells exhibited a memory phenotype (CD122(+), CD44(+), and CD62L(low)). Collectively, these results demonstrate that MSCs are not intrinsically immune-privileged, and under allogeneic settings, these cells induce rejection, which is followed by an immune memory. Considering that the use of allogeneic or even a third party ("off the shelf") MSCs is commonly advocated for a variety of clinical applications, our results strongly suggest that long-term survival of allogeneic MSCs likely represents a major challenge.
[show abstract][hide abstract] ABSTRACT: We recently reported that heat shock protein 60 (HSP60) via TLR4 signaling activates B cells and induces them to proliferate and secrete IL-10. We now report that HSP60 inhibits mouse B cell apoptosis, spontaneous or induced by dexamethasone or anti-IgM activation. Unlike HSP60 enhancement of B cell proliferation and IL-10 secretion, TLR4 signaling was not required for the inhibition of apoptosis by HSP60; nevertheless, MyD88 was essential. Inhibition of apoptosis by HSP60 was associated with up-regulation of the antiapoptotic molecules Bcl-2, Bcl-x(L), and survivin, maintenance of the mitochondrial transmembrane potential, and inhibition of caspase-3 activation. Moreover, B cells incubated with HSP60 manifested prolonged survival following transfer into recipient mice. These results extend the varied role of HSP60 in the innate regulation of the adaptive immune response.
The Journal of Immunology 07/2009; 183(2):890-6. · 5.52 Impact Factor
[show abstract][hide abstract] ABSTRACT: The role of c-Myc in estrogen regulation of vascular endothelial growth factor (VEGF) and of the vasculature function has been investigated in breast cancer cells and tumors. The studies were performed on MCF7 wild-type cells and MCF7-35im clone, stably transfected with an inducible c-Myc gene. In vitro and ex vivo methods for investigating molecular events were integrated with in vivo magnetic resonance imaging of the vascular function. The results showed that the c-Myc upregulation by estrogen is necessary for the transient induction of VEGF transcription; however, overexpression of c-Myc alone is not sufficient for this induction. Furthermore, both c-Myc and the activated estrogen receptor alpha (ERalpha) were shown to co-bind the VEGF promoter in close proximity, indicating a novel mechanism for estrogen regulation of VEGF. Studies of long-term estrogen treatment and overexpression of c-Myc alone demonstrated regulation of stable VEGF expression levels in vitro and in vivo, maintaining steady vascular permeability in tumors. However, withdrawal of estrogen from the tumors resulted in increased VEGF and elevated vascular permeability, presumably due to hypoxic conditions that were found to dominate VEGF overexpression in cultured cells. This work revealed a cooperative role for ERalpha and c-Myc in estrogen regulation of VEGF and the ability of c-Myc to partially mimic estrogen regulation of angiogenesis. It also illuminated the differences in estrogen regulation of VEGF during transient and long-term sustained treatments and under different microenvironmental conditions, providing a complementary picture of the in vitro and in vivo results.
Endocrine Related Cancer 05/2009; 16(3):819-34. · 5.26 Impact Factor
[show abstract][hide abstract] ABSTRACT: Our studies focus on the pathways that restrict homing of specific subsets of immune cells, and thereby fine-tune the immune response at specific lymphoid and peripheral tissues. Here, we report that CCL2 (at picomolar [pM] levels) renders both murine and human T cells defective in their ability to develop CCR7-triggered activation of LFA-1- and LFA-1-mediated adhesion strengthening to endothelial ICAM-1 both in vitro and in vivo. CCL2 also attenuated lymphocyte chemotaxis toward lymph node chemokines. Consequently, low-dose CCL2 inhibited lymphocyte homing to peripheral lymph nodes but did not affect lymphocyte trafficking through the spleen. Impaired homing of lymphocytes to peripheral lymph nodes resulted in attenuated progression of both asthma and adjuvant arthritis. Thus, pM levels of circulating CCL2 can exert global suppressive effects on T-cell trafficking and differentiation within peripheral lymph nodes, and may be clinically beneficial as an anti-inflammatory agent.
[show abstract][hide abstract] ABSTRACT: Solid tumors often develop high interstitial fluid pressure (IFP) as a result of increased water leakage and impaired lymphatic drainage, as well as changes in the extracellular matrix composition and elasticity. This high fluid pressure forms a barrier to drug delivery and hence, resistance to therapy. We have developed techniques based on contrast enhanced magnetic resonance imaging for mapping in tumors the vascular and transport parameters determining the delivery efficiency of blood borne substances. Sequential images are recorded during continuous infusion of a Gd-based contrast agent and analyzed according to a new physiological model, yielding maps of microvascular transfer constants, as well as outward convective interstitial transfer constants and steady state interstitial contrast agent concentrations both reflecting IFP distribution. We further demonstrated in non small cell human lung cancer xenografts the capability of our techniques to monitor in vivo collagenase induced increase in contrast agent delivery as a result of decreased IFP. These techniques can be applied to test drugs that affect angiogenesis and modulate interstitial fluid pressure and has the potential to be extended to cancer patients for assessing resistance to drug delivery.
Microvascular Research 08/2008; 76(2):94-103. · 2.93 Impact Factor
[show abstract][hide abstract] ABSTRACT: Intravenous immunoglobulin (IVIG) administration has been beneficially used for the treatment of a variety of autoimmune diseases including myasthenia gravis (MG). We have demonstrated that IVIG administration in experimental autoimmune MG (EAMG) results in suppression of disease that is accompanied by decreased Th1 cell and B cell proliferation. Chromatography of pooled human immunoglobulins (IVIG) on immobilized IgG, isolated from rats with EAMG or from MG patients, results in a depletion of the suppressive activity of the IVIG. Moreover, reconstitution of the activity-depleted IVIG with the eluted minute IVIG fractions that had been adsorbed onto the EAMG- or MG-specific columns recovers the depleted immunosuppressive activity. This study supports the notion that the therapeutic effect of IVIG is mediated by an antigen-specific anti-immunoglobulin (anti-idiotypic) activity that is essential for its suppressive activity.
Annals of the New York Academy of Sciences 07/2008; 1132:244-8. · 4.38 Impact Factor
[show abstract][hide abstract] ABSTRACT: Intravenous immunoglobulin (IVIG) treatment is beneficially used in autoimmune disorders including myasthenia gravis (MG) although its mode of action and active components are still not fully identified. In an attempt to isolate from IVIG a disease-specific suppressive fraction, IVIG was passed on columns of IgG from rats with experimental autoimmune MG (EAMG) or from MG patients. These chromatographies resulted in depletion of the suppressive activity of IVIG on rat EAMG whereas the minute amounts of IgG fractions eluted from the EAMG- or MG-specific columns retained the immunosuppressive activity of IVIG. These results demonstrate that a minor disease-specific immunoglobulin fraction present in IVIG is essential for its suppressive activity.
Journal of Neuroimmunology 03/2008; 194(1-2):89-96. · 3.03 Impact Factor