Biomedical subjects

Iqbal S Grewal

Publications and source records attributed to Iqbal S Grewal.

14 recordsLinked to original sources

PubMed2006

Engineered anti-CD70 antibody with multiple effector functions exhibits in vitro and in vivo antitumor activities.

Antigens expressed on malignant cells in the absence of significant expression on normal tissues are highly desirable targets for therapeutic antibodies. CD70 is a TNF superfamily member whose normal expression is highly restricted but is aberrantly expressed in hematologic malignancies including non-Hodgkin lymphoma (NHL), Hodgkin disease, and multiple myeloma. In addition, solid tumors such as renal cell carcinoma, nasopharyngeal carcinoma, thymic carcinoma, meduloblastoma, and glioblastoma express high levels of this antigen. To functionally target CD70-expressing cancers, a murine anti-CD70 monoclonal antibody was engineered to contain human IgG1 constant domains. The engineered antibody retained the binding specificity of the murine parent monoclonal antibody and was shown to induce Fc-mediated effector functions including antibody-dependent cellular cytotoxicity, complement-dependent cytotoxicity, and antibody-dependent cellular phagocytosis in vitro. Further, administration of this antibody significantly prolonged survival of severe combined immunodeficient (SCID) mice bearing CD70+ disseminated human NHL xenografts. Survival of these mice was dependent upon the activity of resident effector cells including neutrophils, macrophages, and natural killer (NK) cells. These data suggest that an anti-CD70 antibody, when engineered to contain human IgG1 constant domains, possesses effector cell-mediated antitumor activity and has potential utility for anticancer therapy.

Animals↗

PubMed2006

Preclinical pharmacokinetics, pharmacodynamics, and activity of a humanized anti-CD40 antibody (SGN-40) in rodents and non-human primates.

1. Cell-surface expression of CD40 in B-cell malignancies and multiple solid tumors has raised interest in its potential use as a target for antibody-based cancer therapy. SGN-40, a humanized monoclonal anti-CD40 antibody, mediates antibody-dependent cytotoxicity and inhibits B-cell tumor growth in vitro, properties of interest for the treatment of cancers, and is currently in Phase I clinical trials for B-cell malignancies. In this study, we determined in vivo activity and pharmacokinetics properties of SGN-40. 2. Effect of SGN-40 in xenograft model of CD40-expressing B-cell lymphoma in severe-combined immune deficiency mice and its in vivo pharmacokinetics properties in normal mice, rats and cynomolgus monkeys were studied. 3. Treatment with SGN-40 significantly increased the survival of mice xenografted with human B-cell lymphoma cell line. SGN-40 exhibited nearly 100% bioavailability in mice and it cleared faster when given at a low dose. In monkeys, clearance of SGN-40 was also much faster at low dose, suggesting nonlinear pharmacokinetics in these species. In rats, however, SGN-40 clearance at all tested doses was similar, suggesting that pharmacokinetics were linear in this dose range in rats. Administration of SGN-40 to monkeys also produced marked, dose-dependent, and persistent depletion of peripheral CD20(+) B lymphocytes. 4. Data presented in this report suggest that SGN-40 is active in in vivo, and based upon interspecies scaling, SGN-40 clearance in humans is predicted to be similar to observed SGN-40 clearance in monkeys. These data suggest that SGN-40 has appropriate pharmacokinetic properties that support its clinical use.

Animals↗

PubMed2005

Immunomodulatory drug lenalidomide (CC-5013, IMiD3) augments anti-CD40 SGN-40-induced cytotoxicity in human multiple myeloma: clinical implications.

SGN-40, a humanized immoglobulin G1 (IgG1) anti-CD40 monoclonal antibody, mediates cytotoxicity against human multiple myeloma (MM) cells via suppression of interleukin (IL)-6-induced proliferative and antiapoptotic effects as well as antibody-dependent cell-mediated cytotoxicity (ADCC). Here, we studied the clinical significance of an immunomodulatory drug lenalidomide on SGN-40-induced cytotoxicity against CD138(+)CD40(+) MM lines and patient MM cells. Pretreatment with lenalidomide sensitized MM cells to SGN-40-induced cell death. Combined lenalidomide and SGN-40 significantly induced MM apoptosis, evidenced by enhanced cleavage of caspase-3/8/poly(ADP-ribose)polymerase and increased sub-G(0) cells, compared with either single agent at the same doses. Pretreatment of effector cells with lenalidomide augmented SGN-40-induced MM cell lysis, associated with an increased number of CD56(+)CD3(-) natural killer (NK) cells expressing CD16 and LFA-1. Importantly, pretreatment with lenalidomide or lenalidomide and SGN-40 markedly enhanced NK-cell-mediated lysis of autologous patient MM cells triggered by SGN-40. Lenalidomide also up-regulated CD40L on CD56(+)CD3(-) NK cells, facilitating IL-2-mediated activation of NK cells. In addition, lenalidomide induced the CD56(dim) NK subset, which are more potent mediators of ADCC against target MM cells than the CD56(bright) NK subset. Finally, pretreatment of both effector and target MM cells with lenalidomide markedly enhanced SGN-40-mediated ADCC against CD40-expressing MM cells. These studies, therefore, show that the addition of lenalidomide to SGN-40 enhances cytotoxicity against MM cells, providing the framework for combined lenalidomide and SGN-40 in a new treatment paradigm to both target MM cells directly and induce immune effectors against MM.

Antibodies, Monoclonal↗

PubMed2005

Preclinical antilymphoma activity of a humanized anti-CD40 monoclonal antibody, SGN-40.

SGN-40 is a humanized IgG1 antihuman CD40 that is currently in a phase I clinical trial for the treatment of multiple myeloma. As surface CD40 expression on B-lineage cells is maintained from pro-B cells to plasma cells, SGN-40 may be applicable to treatment of other B-cell neoplasias, including non-Hodgkin's lymphoma. In this study, we examined potential in vitro and in vivo anti-B-lineage lymphoma activity of SGN-40. Recombinant SGN-40 was expressed and purified from Chinese hamster ovary cells and characterized based on binding affinity, specificity, and normal B-cell stimulation. The ability of SGN-40 to target neoplastic B cells was examined in vitro by proliferation inhibition, cytotoxicity, and antibody-dependent cell cytotoxicity assays and in vivo by human lymphoma xenograft models. Recombinant SGN-40 showed high affinity, Kd of approximately 1 nmol/L, and specific binding to CD40. Whereas SGN-40 was a weak agonist in stimulating normal B-cell proliferation in the absence of IL-4 and CD40L, it delivered potent proliferation inhibitory and apoptotic signals to, and mediated antibody-dependent cytotoxicity against, a panel of high-grade B-lymphoma lines. These in vitro antilymphoma effects were extended to disseminated and s.c. xenograft CD40 tumor models. In these xenograft models, the antitumor activity of SGN-40 was comparable with that of rituximab. The preclinical in vitro and in vivo antilymphoma activity of SGN-40 observed in this study provides a rationale for the clinical testing of SGN-40 in the treatment of CD40+ B-lineage lymphomas.

Animals↗

PubMed2005

TNF-related apoptosis-inducing ligand (TRAIL)/Apo2L suppresses experimental autoimmune encephalomyelitis in mice.

Studies have suggested that endogenous TNF-related apoptosis-inducing ligand (TRAIL)/Apo2L may suppress the induction of some autoimmune diseases in mice. Here, we show that TRAIL/Apo2L suppresses autoimmune damage in relapsing-remitting, and non-remitting models of experimental autoimmune encephalomyelitis (EAE). TRAIL/Apo2L-deficient mice and wild-type mice treated with neutralizing anti-TRAIL/Apo2L antibody displayed enhanced clinical score, increased T-cell proliferative responses to myelin oligodendrocyte glycoprotein (MOG), and increased numbers of inflammatory lesions in the spinal cord and central nervous system. TRAIL neutralization immediately before disease onset was most effective at exacerbating disease score. More importantly, therapeutic intervention with recombinant soluble TRAIL/Apo2L delayed the onset and reduced the severity of MOG-induced EAE. These data are the first to illustrate the potential therapeutic value of recombinant TRAIL/Apo2L in suppressing T-cell-mediated autoimmune diseases.

Amino Acid Sequence↗

PubMed2004

A novel in vivo role for osteoprotegerin ligand in activation of monocyte effector function and inflammatory response.

Osteoprotegerin Ligand (OPGL) is a member of the tumor necrosis factor ligand superfamily and has been shown to be involved in interactions between T cells and dendritic cells. Its role in monocyte effector function, however, has not been defined. In the present study a role for OPGL in activating monocytes/macrophages has been characterized. OPGL was found to up-regulate receptor activator of NF-kappaB (RANK) receptor expression on monocytes, regulate their effector function by inducing cytokine and chemokine secretion, activate antigen presentation through up-regulation of co-stimulatory molecule expression, and promote survival. This activation is mediated through the MAPK pathway as evidenced by activation of p38 and p42/44 MAPK and up-regulation of BCL-XL protein levels. A physiological role for OPGL in monocyte activation and effector function was tested in a model of lipopolysaccharide-induced endotoxic shock. Administration of receptor activator of NF-kappaB (RANK)-Fc to block OPGL activity in vivo was able to protect mice from death induced by sepsis, indicating a hitherto undescribed role for OPGL in monocyte function and in mediating inflammatory response. This was further tested in an animal model of inflammation-mediated arthritis. Treatment with RANK-Fc significantly ameliorated disease development and attenuated bone destruction. Thus, our study strongly suggests that administration of receptor fusion proteins to specifically block OPGL activity in vivo may result in blocking development of monocyte/macrophage-mediated diseases.

Animals↗

PubMed2004

NTB-A, a new activating receptor in T cells that regulates autoimmune disease.

The CD28 co-stimulatory pathway is well established for T cell activation; however, results from CD28 -/- mice suggest the existence of additional co-stimulatory pathways. Here we report the further characterization of a new member of the CD2 superfamily, NTB-A, important in T cell co-stimulation. NTB-A is expressed on T cells, and its expression is up-regulated on activated cells. Triggering of NTB-A with monoclonal antibodies in the absence of CD28 signals leads to T cell proliferation and interferon-gamma secretion but not interleukin-4. Cross-linking of NTB-A also induces phosphorylation of NTB-A and the association of SAP (SLAM-associated protein), the protein absent in X-linked lymphoproliferative disease. T helper cells differentiated by cross-linking NTB-A and CD3 developed predominantly into Th1 cells not Th2 cells. In vivo blocking of NTB-A interactions with its ligands by using soluble NTB-A-Fc fusion protein inhibits B cell isotype switching to IgG2a and IgG3, commonly induced by Th1-type cytokines. Most important, treatment of mice with NTB-A-Fc delays the onset of antigen-induced experimental allergic encephalomyelitis in myelin basic protein-T cell receptor transgenic mice, suggesting a role in T cell-mediated autoimmune disease. Regulation of interferon-gamma secretion, and not interleukin-4 in vitro, as well as inhibition of Th1 cell-induced isotype switching and attenuation of experimental allergic encephalomyelitis indicate that NTB-A is important for Th1 responses. The observation that cross-linking of NTB-A induces T cell activation, expansion, and Th1-type cytokine production suggests NTB-A is a novel co-stimulatory receptor. The identification of NTB-A as a regulator of T cell response paves the way to provide novel therapeutic approaches for modulation of the immune response.

Animals↗

PubMed2004

Role of L-selectin in the development of autoimmune diabetes in non-obese diabetic mice.

Autoimmune diabetes is characterized by an early mononuclear infiltration of pancreatic islets and later selective autoimmune destruction of insulin-producing beta cells. Lymphocyte homing receptors have been considered candidate targets to prevent autoimmune diabetes. L-selectin (CD62L) is an adhesion molecule highly expressed in naive T and B cells. It has been reported that blocking L-selectin in vivo with a specific antibody (Mel-14) partially impairs insulitis and diabetes in autoimmune diabetes-prone non-obese diabetic (NOD) mice. In the present study we aimed to elucidate whether genetic blockade of leukocyte homing into peripheral lymph nodes would prevent the development of diabetes. We backcrossed L-selectin-deficient mice onto the NOD genetic background. Surprisingly NOD/L-selectin-deficient mice exhibited unaltered islet mononuclear infiltration, timing of diabetes onset and cumulative incidence of spontaneous diabetes when compared to L-selectin-sufficient animals. CD4, CD8 T cells and B cells were present in islet infiltrates from 9-week-old L-selectin-sufficient and -deficient littermates. Moreover, total splenocytes from wild-type, heterozygous or NOD/L-selectin-deficient donor mice showed similar capability to adoptively transfer diabetes into NOD/SCID recipients. On the other hand, homing of activated, cloned insulin-specific autoaggressive CD8 T cells (TGNFC8 clone) is not affected in NOD/L-selectin-deficient recipients. We conclude that L-selectin plays a small role in the homing of autoreactive lymphocytes to regional (pancreatic) lymph nodes in NOD mice.

Adoptive Transfer↗

PubMed2004

APRIL-deficient mice have normal immune system development.

APRIL (a proliferation-inducing ligand) is a member of the tumor necrosis factor (TNF) superfamily. APRIL mRNA shows high levels of expression in tumors of different origin and a low level of expression in normal cells. APRIL shares two TNF receptor family members, TACI and BCMA, with another TNF homolog, BLyS/BAFF. BLyS is involved in regulation of B-cell activation and survival and also binds to a third receptor, BR3/BAFF-R, which is not shared with APRIL. Recombinant APRIL and BLyS induce accumulation of B cells in mice, while BLyS deficiency results in severe B-cell dysfunction. To investigate the physiological role of APRIL, we generated mice that are deficient in its encoding gene. APRIL(-/-) mice were viable and fertile and lacked any gross abnormality. Detailed histological analysis did not reveal any defects in major tissues and organs, including the primary and secondary immune organs. T- and B-cell development and in vitro function were normal as well, as were T-cell-dependent and -independent in vivo humoral responses to antigenic challenge. These data indicate that APRIL is dispensable in the mouse for proper development. Thus, BLyS may be capable of fulfilling APRIL's main functions.

Animals↗

PubMed2003

Loss of TACI causes fatal lymphoproliferation and autoimmunity, establishing TACI as an inhibitory BLyS receptor.

BLys , a key cytokine that sustains B cell maturation and tolerance, binds three receptors: BR3, BCMA, and TACI. Results from knockout mice implicate a major functional role for BR3 and a redundant one for BCMA in B cell function. TACI's role is controversial based on defects in TI antibody responses accompanied by B cell hyperplasia in knockout mice. We have presently characterized a precise role for TACI in vivo. TACI(-/-) mice develop fatal autoimmune glomerulonephritis, proteinurea, and elevated levels of circulating autoantibodies. Treatment of B cells with TACI agonistic antibodies inhibits proliferation in vitro and activation of a chimeric receptor containing the TACI intracellular domain induces apoptosis. These results demonstrate the critical requirement for TACI in regulating B cell homeostasis.

Animals↗

PubMed2003

Recombinant humanized anti-CD40 monoclonal antibody triggers autologous antibody-dependent cell-mediated cytotoxicity against multiple myeloma cells.

Multiple myeloma (MM) is currently incurable, and novel therapies are needed. In this study, we examined a novel recombinant humanized monoclonal antibody against CD40 (rhuCD40 mAb) and demonstrate for the first time that rhuCD40 mAb induces antibody-dependent cell-mediated cytotoxicity (ADCC) against CD40-positive MM cells. Importantly, we show that rhuCD40 mAb induces autologous ADCC against primary patient MM cells, without triggering ADCC against normal B cells. This study, therefore, both demonstrates that rhuCD40 mAb triggers autologous ADCC against patient MM cells and provides the framework for the clinical evaluation of rhuCD40 mAb immunotherapy to improve patient outcome in MM.

Antibodies, Monoclonal↗

PubMed2003

A crucial role of CD4 T cells as a functional source of CD154 in the initiation of insulin-dependent diabetes mellitus in the non-obese diabetic mouse.

Although the critical requirement of CD4 T cells in type I (insulin-dependent) diabetes mellitus (T1DM) has been well documented, information on the exact role(s) of CD4 T cells in T1DM development is still limited. Here, utilizing non-obese diabetic (NOD) mice deficient for CD154 (CD154-KO/NOD), we have identified a mandatory role of CD4 T cells as the functional source of CD154 in the initiation of T1DM. Without CD154, CD4 T cells were not capable of mediating help in disease development in NOD mice. In fact, full expression of CD154 on the CD4 T cells seems to be essential in the normal spontaneous development of T1DM, since no diabetes was observed in CD154(+/-) mice in which around half of CD4 T cells do not express CD154 at all, at least by the time they were 40 weeks old. It was also shown that transgenic expression of CD80 on beta cells of pancreatic islets, which is believed to provide beta cells with the ability to prime cytotoxic T lymphocytes specific for islet antigens, did not restore insulitis in CD154-KO/NOD mice. Taken collectively, these results indicated that CD4 T cells play a crucial role in T1DM as a source of CD154, and that the role of CD154 on CD4 T cells in insulitis may not be just to facilitate priming and expanding of auto-reactive CD8 T cells by activating antigen-presenting cells bearing islet antigens.

Animals↗

PubMed2002

BAFF/BLyS receptor 3 binds the B cell survival factor BAFF ligand through a discrete surface loop and promotes processing of NF-kappaB2.

The TNF-like ligand BAFF/BLyS is a potent survival factor for B cells. It binds three receptors: TACI, BCMA, and BR3. We show that BR3 signaling promotes processing of the transcription factor NF-kappaB2/p100 to p52. NF-kappaB2/p100 cleavage was abrogated in B cells from A/WySnJ mice possessing a mutant BR3 gene, but not in TACI or BCMA null B cells. Furthermore, wild-type mice injected with BAFF-neutralizing BR3-Fc protein showed reduced basal NF-kappaB2 activation. BR3-Fc treatment of NZB/WF1 mice, which develop a fatal lupus-like syndrome, inhibited NF-kappaB2 processing and attenuated the disease process. Since inhibiting the BR3-BAFF interaction has therapeutic ramifications, the ligand binding interface of BR3 was investigated and found to reside within a 26 residue core domain. When stabilized within a structured beta-hairpin peptide, six of these residues were sufficient to confer binding to BAFF.

Amino Acid Sequence↗

PubMedDate not supplied

Expression of transgene encoded TGF-beta in islets prevents autoimmune diabetes in NOD mice by a local mechanism.

To analyse the effects of TGF-beta in insulin dependent diabetes mellitus (IDDM), we have developed non-obese diabetic (NOD) transgenic mice expressing TGF-beta under the control of the rat insulin II promoter. Pancreata of TGF-beta transgenic mice were roughly one twentieth of the size of pancreata of wild-type NOD mice and showed small clusters of micro-islets rather than normal adult islets. However, these islets produced sufficient levels of insulin to maintain normal glucose levels and mice were protected from the diabetes, which developed in their negative littermates. A massive fibrosis was seen in the transgenic pancreata that was accompanied with infiltration of mononuclear cells that decreased with age. Interestingly, these mice showed normal anti-islet immune response in their spleens and remained susceptible to adoptive transfer of IDDM by mature cloned CD8 effector cells. TUNEL assays revealed increased apoptosis of invading cells when compared to non-transgenic NOD mice. Taken together, these results suggest that TGF-beta protects islets by a local event.

Animals↗