How to Train Your T Cells: Overcoming Immune Dysfunction in Multiple Myeloma

The progression of multiple myeloma, a hematologic malignancy characterized by unregulated plasma cell growth, is associated with increasing innate and adaptive immune system dysfunction, notably in the T-cell repertoire. Although treatment advances in multiple myeloma have led to deeper and more durable clinical responses, the disease remains incurable for most patients. Therapeutic strategies aimed at overcoming the immunosuppressive tumor microenvironment and activating the host immune system have recently shown promise in multiple myeloma, particularly in the relapsed and/or refractory disease setting. As the efficacy of T-cell-dependent immuno-oncology therapy is likely affected by the health of the endogenous T-cell repertoire, these therapies may also provide benefit in alternate treatment settings (e.g., precursor disease; after stem cell transplantation). This review describes T-cell-associated changes during the evolution of multiple myeloma and provides an overview of T-cell-dependent immuno-oncology approaches under investigation. Vaccine and checkpoint inhibitor interventions are being explored across the multiple myeloma disease continuum; treatment modalities that redirect patient T cells to elicit an anti-multiple myeloma response, namely, chimeric antigen receptor (CAR) T cells and bispecific antibodies [including BiTE (bispecific T-cell engager) molecules], have been primarily evaluated to date in the relapsed and/or refractory disease setting. CAR T cells and bispecific antibodies/antibody constructs directed against B-cell maturation antigen have generated excitement, with clinical data demonstrating deep responses. An increased understanding of the complex interplay between the immune system and multiple myeloma throughout the disease course will aid in maximizing the potential for T-cell-dependent immuno-oncology strategies in multiple myeloma.

LKB1 inhibition of NF-κB in B cells prevents T follicular helper cell differentiation and germinal center formation

T-cell-dependent antigenic stimulation drives the differentiation of B cells into antibody-secreting plasma cells and memory B cells, but how B cells regulate this process is unclear. We show that LKB1 expression in B cells maintains B-cell quiescence and prevents the premature formation of germinal centers (GCs). Lkb1-deficient B cells (BKO) undergo spontaneous B-cell activation and secretion of multiple inflammatory cytokines, which leads to splenomegaly caused by an unexpected expansion of T cells. Within this cytokine response, increased IL-6 production results from heightened activation of NF-κB, which is suppressed by active LKB1. Secreted IL-6 drives T-cell activation and IL-21 production, promoting T follicular helper (TFH ) cell differentiation and expansion to support a ~100-fold increase in steady-state GC B cells. Blockade of IL-6 secretion by BKO B cells inhibits IL-21 expression, a known inducer of TFH -cell differentiation and expansion. Together, these data reveal cell intrinsic and surprising cell extrinsic roles for LKB1 in B cells that control TFH -cell differentiation and GC formation, and place LKB1 as a central regulator of T-cell-dependent humoral immunity.

Bone marrow stromal cells create a permissive microenvironment for myeloma development: a new stromal role for Wnt inhibitor Dkk1

The rapid progression of multiple myeloma is dependent upon cellular interactions within the bone marrow microenvironment. In vitro studies suggest that bone marrow stromal cells (BMSC) can promote myeloma growth and survival and osteolytic bone disease. However, it is not possible to recreate all cellular aspects of the bone marrow microenvironment in an in vitro system, and the contributions of BMSCs to myeloma pathogenesis in an intact, immune competent, in vivo system are unknown. To investigate this, we used a murine myeloma model that replicates many features of the human disease. Coinoculation of myeloma cells and a BMSC line, isolated from myeloma-permissive mice, into otherwise nonpermissive mice resulted in myeloma development, associated with tumor growth within bone marrow and osteolytic bone disease. In contrast, inoculation of myeloma cells alone did not result in myeloma. BMSCs inoculated alone induced osteoblast suppression, associated with an increase in serum concentrations of the Wnt signaling inhibitor, Dkk1. Dkk1 was highly expressed in BMSCs and in myeloma-permissive bone marrow. Knockdown of Dkk1 expression in BMSCs decreased their ability to promote myeloma and the associated bone disease in mice. Collectively, our results show novel roles of BMSCs and BMSC-derived Dkk1 in the pathogenesis of multiple myeloma in vivo.

Tumor-host cell interactions in the bone disease of myeloma

Multiple myeloma is a hematological malignancy that is associated with the development of a destructive osteolytic bone disease, which is a major cause of morbidity for patients with myeloma. Interactions between myeloma cells and cells of the bone marrow microenvironment promote both tumor growth and survival and bone destruction, and the osteolytic bone disease is now recognized as a contributing component to tumor progression. Since myeloma bone disease is associated with both an increase in osteoclastic bone resorption and a suppression of osteoblastic bone formation, research to date has largely focused upon the role of the osteoclast and osteoblast. However, it is now clear that other cell types within the bone marrow, including cells of the immune system, mesenchymal stem cells and bone marrow stromal cells, can contribute to the development of myeloma bone disease. This review discusses the cellular mechanisms and potential therapeutic targets that have been implicated in myeloma bone disease.

A murine model of myeloma that allows genetic manipulation of the host microenvironment

Multiple myeloma, and the associated osteolytic bone disease, is highly dependent upon cellular interactions within the bone marrow microenvironment. A major limitation of existing myeloma models is the requirement for a specific host strain of mouse, preventing molecular examination of the bone marrow microenvironment. The aim of the current study was to develop a model of myeloma in which the host microenvironment could be modified genetically. The Radl 5T murine model of myeloma is well characterized and closely mimics human myeloma. In the current study, we demonstrate 5T myeloma establishment in recombination activating gene 2 (RAG-2)-deficient mice, which have improper B- and T-cell development. Importantly, these mice can be easily bred with genetically modified mice to generate double knockout mice, allowing manipulation of the host microenvironment at a molecular level. Inoculation of 5TGM1 myeloma cells into RAG-2(-/-) mice resulted in myeloma development, which was associated with tumor growth within bone and an osteolytic bone disease, as assessed by microcomputed tomography (microCT), histology and histomorphometry. Myeloma-bearing RAG-2(-/-) mice displayed many features that were similar to both human myeloma and the original Radl 5T model. To demonstrate the use of this model, we have examined the effect of host-derived matrix metalloproteinase 9 (MMP-9) in the development of myeloma in vivo. Inoculation of 5TGM1 myeloma cells into mice that are deficient in RAG-2 and MMP-9 resulted in a reduction in both tumor burden and osteolytic bone disease when compared with RAG-2-deficient wild-type myeloma-bearing mice. The establishment of myeloma in RAG-2(-/-) mice permits molecular examination of the host contribution to myeloma pathogenesis in vivo.

Myeloma cells exhibit an increase in proteasome activity and an enhanced response to proteasome inhibition in the bone marrow microenvironment in vivo

The proteasome inhibitor bortezomib has a striking clinical benefit in patients with multiple myeloma. It is unknown whether the bone marrow microenvironment directly contributes to the dramatic response of myeloma cells to proteasome inhibition in vivo. We have used the well-characterized 5TGM1 murine model of myeloma to investigate myeloma growth within bone and response to the proteasome inhibitor bortezomib in vivo. Myeloma cells freshly isolated from the bone marrow of myeloma-bearing mice were found to have an increase in proteasome activity and an enhanced response to in vitro proteasome inhibition, as compared with pre-inoculation myeloma cells. Treatment of myeloma-bearing mice with bortezomib resulted in a greater reduction in tumor burden when the myeloma cells were located within the bone marrow when compared with extra-osseous sites. Our results demonstrate that myeloma cells exhibit an increase in proteasome activity and an enhanced response to bortezomib treatment when located within the bone marrow microenvironment in vivo.

Pharmacologic and genetic manipulation of MMP-2 and -9 affects retinal neovascularization in rodent models of OIR

PURPOSE

The efficacy of three matrix metalloproteinase (MMP) inhibitors with various selectivities (Ro-31-9790, AG3340, and DPC-A37668) was investigated in a rat model of retinopathy of prematurity, to examine the roles of MMP-2 and -9 in retinal neovascularization. The susceptibilities of MMP-2(-/-) and -9(-/-) mice to preretinal neovascularization were investigated in a mouse model of oxygen-induced retinopathy.

METHODS

Sprague-Dawley newborn rats were exposed to alternating episodes of 50% and 10% oxygen (variable oxygen exposure) to induce retinal neovascularization. Three MMP inhibitors with various selectivity profiles were administered to variable oxygen-exposed rats via local or systemic routes. Antineovascular efficacy was determined in drug-treated versus vehicle-treated rat pups by computerized imaging of adenosine diphosphatase (ADPase)-stained retinal flatmounts. Wild-type C57BL/6J and isogenic MMP-2(-/-) and -9(-/-) mice were exposed to 75% oxygen followed by normoxia. The mice were killed immediately before or after the normoxic exposure, and eyes were either harvested for retinal dissection and flatmounting or were paraffin embedded and sectioned. Retinal vascular area and retinal neovascularization were assessed by adenosine diphosphatase staining of retinal flatmounts and by counting preretinal nuclei of hematoxylin and eosin-stained retinal sections, respectively.

RESULTS

Ro-31-9790, AG3340, and DPC-A37668 had no effect on normal development of the rat retinal vasculature, regardless of dose or route of administration. Intravitreal injection of Ro-31-9790 (broad-spectrum) immediately after variable-oxygen exposure and 2 days after exposure resulted in 78% and 82% inhibition of retinal neovascularization, respectively. AG3340 (MMP-2- and -9-selective inhibitor) and DPC-A37668 (MMP-2-selective inhibitor) resulted in 65% and 52% inhibition, respectively, when administered by intravitreal injection immediately after variable-oxygen exposure. Intraperitoneal injection of 5, 15, and 50 mg/mL AG3340 or DPC-A37668 for 6 days after variable oxygen exposure resulted in 22% to 39% and 0% to 31% inhibition of neovascularization, respectively. AG3340 and DPC-A37668 administered by oral gavage at doses of 3, 10, or 30 mg/mL provided up to 42% and 86% inhibition of neovascularization, respectively. The average vascular areas of retinas from MMP-2(-/-) or -9(-/-) mice at postnatal day 12 were not significantly different from the wild-type control. There was a 75% (P < 0.001) and 44% (P < 0.01) reduction in preretinal neovascularization in oxygen-exposed MMP-2(-/-) and -9(-/-) mice at postnatal day 19, respectively, compared with wild-type control mice.

CONCLUSIONS

The results of this study suggest that MMP-2 plays a predominant role in retinal angiogenesis in both the mouse and rat models of oxygen-induced retinopathy. Furthermore, MMP-2 inhibition may be a viable therapeutic approach for ocular diseases characterized by retinal neovascularization.

Absence of interleukin-3 does not affect the severity of local and systemic anaphylaxis but does enhance eosinophil infiltration in a mouse model of allergic peritonitis

Interleukin-3 (IL-3), which is derived from T cells and other sources, can promote the differentiation, proliferation, and migration of mast cells, basophils, and eosinophils. However, little is known about the ability of IL-3 to regulate the function of these cells in IgE-dependent and -independent allergic responses in vivo. Therefore, we sought to investigate the extent to which endogenously produced IL-3 can influence mast cell secretory function, the expression of local and systemic anaphylactic responses, and ragweed-induced eosinophilic peritonitis. We found that peritoneal mast cells from IL-3 deficient (IL-3 -/-) mice released less serotonin following challenge with low doses of anti-IgE antibody or antigen ex vivo than do cells isolated from corresponding wild-type (IL-3 +/+) mice. Both IL-3 -/- and +/+ mice expressed equivalent IgE-dependent passive cutaneous anaphylaxis responses following challenge with specific antigen and exhibited equivalent active systemic anaphylaxis responses to ovalbumin as assessed by changes in body temperature, death rates, total IgE production, and histamine release. In contrast, ragweed allergen immunization and peritoneal allergen challenge resulted in eosinophil recruitment that was greater in IL-3 -/- mice than in IL-3 +/+ mice. Our data demonstrates that IL-3 does not appear to be essential for local or systemic anaphylaxis. However, IL-3 production in vivo was found to enhance the mediator release from freshly isolated peritoneal mast cells stimulated ex vivo, and, unexpectedly, to inhibit the accumulation of eosinophils associated with a ragweed-induced allergic peritonitis model.

The burden of environmental tobacco smoke exposure on the respiratory health of children 2 months through 5 years of age in the United States: Third National Health and Nutrition Examination Survey, 1988 to 1994

OBJECTIVE

To measure the effect of environmental tobacco smoke (ETS) on respiratory health in a national sample of young children.

METHODS

The study evaluated children 2 months through 5 years of age participating in the Third National Health and Nutrition Examination Survey, 1988 to 1994. The group was a representative sample of the US population (N = 7680). A parental report of household smoking or maternal smoking during pregnancy ascertained ETS exposure. Respiratory outcomes were based on parental report of wheezing, cough, upper respiratory infection, or pneumonia in the last 12 months and chronic bronchitis or physician-diagnosed asthma at any time. Logistic regression was used to adjust for age, sex, race/ethnicity, birth weight, day care, family history of allergy, breastfeeding, education level of head of household, and household size.

RESULTS

Approximately 38% of children were presently exposed to ETS in the home, whereas 23.8% were exposed by maternal smoking during pregnancy. ETS exposure increased chronic bronchitis and three or more episodes of wheezing among children 2 months to 2 years old and asthma among children 2 months to 5 years old. For household exposure, a consistent effect was seen only at >/=20 cigarettes smoked per day. Adjusted odds ratios for increased risk (95% confidence interval) for household exposures (>/=20 cigarettes smoked per day vs none smoked) and maternal prenatal exposure (prenatal smoking vs no smoking), respectively, for children 2 months to 2 years old were chronic bronchitis, 2.5 (1.6, 4.1); 2.2, (1.6, 3); three or more episodes of wheezing, 2.7 (1.7, 4.2), 2.1 (1. 5, 2.9); and for children 2 months to 5 years old were asthma, 2.1 (1.4, 3.2); 1.8 (1.3, 2.6). Reported use within the past month of prescription medications for asthma (beta-agonists or inhaled steroids) was not different between those with asthma reporting ETS exposure and those reporting no exposure; percent of patients with asthma reporting use of medication by household exposure was 0, 25. 7%; 1 to 19 cigarettes smoked per day, 32.9%; and >/=20 cigarettes smoked per day, 23.1%; percent of patients with asthma reporting use of medication by maternal smoking during pregnancy was no, 28.9%; yes, 22.7%. Among children 2 months to 2 years of age exposed to ETS, 40% to 60% of the cases of asthma, chronic bronchitis, and three or more episodes of wheezing were attributable to ETS exposure. For diagnosed asthma among children 2 months through 5 years old, there were 133 800 to 161 600 excess cases. Among exposed children 2 months through 2 years of age, there were 61 000 to 79 200 excess cases of chronic bronchitis and 126 700 to 172 000 excess cases of three or more episodes of wheezing.

CONCLUSIONS

ETS exposure is common among children in the United States. The reported prevalence of asthma, wheezing, and chronic bronchitis was increased with ETS exposures. No statistically significant increase in the prevalence of upper respiratory infection, pneumonia, or cough was associated with ETS exposure. ETS exposure has little effect on the respiratory health of children between 3 and 5 years of age, with the exception of asthma. ETS appears to increase the prevalence of asthma rather than the severity as measured by medication use. These findings reinforce the need to reduce the exposure of young children to ETS.

The acute oral toxicity and primary ocular and dermal irritation of selected N-alkyl-2-pyrrolidones

N-alkyl-2-pyrrolidones are a class of materials that are increasingly used in food, drug, cosmetic and industrial applications; however, toxicological data is only available for a few members of the class. The acute oral toxicity, primary dermal irritation and primary ocular irritation of N-methyl-, N-ethyl-, N-hydroxyethyl-, N-isopropyl-, N-cyclohexyl-, N-octyl-, N-dodecyl-, N-coco- and N-tallow-2-pyrrolidone are reported. Additionally, N-octyl-, N-decyl-, N-dodecyl-, N-tetradecyl-, N-hexadecyl- and N-octadecyl-2-pyrrolidone had the primary ocular and dermal irritation indices measured as a 2% aqueous suspension. These data show a wide range of toxicities dependent upon the alkyl substituent.

Laboratory procedures for the maintenance of a removable partial overdenture

Laboratory procedures in support of maintenance therapy for a typical patient with a removable partial overdenture were described. These procedures consisted of the fabrication of a gold metal coping and the reline of the prosthesis with autopolymerizing acrylic resin. In designing the coping contours, the technician must consider the path of insertion of the prosthesis and the space requirement for the overlying resin tooth. Reproduction of the dowel preparation is facilitated by using a plastic dowel as part of the coping wax pattern. The removable partial overdenture was relined with autopolymerizing acrylic resin in a reline jig. Tooth-colored acrylic resin was used in the concavity formed by the overdenture abutment to enhance esthetics. The requirement of a coordinated effort between the dentist and the dental laboratory technician is critical to the successful treatment of the removable partial overdenture patient.

A Study of GP Hospital Admissions in B.C

This study shows a comprehensive picture of the cases admitted by a group of general practitioners to two community hospitals in Victoria, B.C. An attempt is made to find out if any difference in the pattern of practice is due to the doctor's age, country of training or hospital status.Some differences were noted, especially in consultation rates, but we feel that this sample is inadequate to demonstrate fully some trends which we believe exist.

A rat liver system that catalyses a pyridoxal phosphate-independent alpha beta-eliminto

1. Attempts were made to demonstrate the presence of pyridoxal phosphate in the rat liver system catalysing the alphabeta-elimination of l-serine O-sulphate. 2. Methods designed to resolve protein-bound cofactor, spectroscopic examination of a purified enzyme system and attempted reactivation of apo-(alanine aminotransferase) failed to demonstrate the presence of pyridoxal phosphate. 3. The activity of the alphabeta-eliminating system remained constant in vitamin B(6)-deficient animals even though the activities of other pyridoxal phosphate-dependent systems fell markedly. 4. The metabolism of l-serine O[(35)S]-sulphate in vivo appears to be normal in vitamin B(6)-deficient animals. 5. No incorporation of tritium into the alphabeta-eliminating system occurred after administration of tritiated pyridoxine to experimental animals.