IL-7 enhances the responsiveness of human T cells that develop in the bone marrow of athymic mice

The beige/nude/xid/human (bnx/hu) model of human hematopoiesis provides a unique opportunity to study extrathymic human T lymphocyte development in an in vivo system. Purified human hematopoietic stem cells develop into mature T lymphocytes and immature progenitors in the bone marrow of athymic bnx mice. The human T cells are all TCR alpha beta(+) and display a restricted TCRV beta repertoire. In the current studies, we examined the effects of systemic human IL-7 (huIL-7) administration on the phenotype and the activation status of the bnx/hu T cells. In the majority of the mice that did not have huIL-7 administration, a higher frequency of human CD3(+)/CD8(+) than CD3(+)/CD4(+) T cells developed in the bone marrow. This phenomenon is also frequently observed in human bone marrow transplant recipients. Extremely low levels of IL-2 were expressed by human CD3(+) cells isolated from these mice, in response to PMA plus ionomycin and to CD3 and CD28 cross-linking. IL-4 was not expressed by cells exposed to either stimulus, demonstrating a profound inability of the bnx/hu T cells to produce this cytokine. Systemic production of huIL-7 from engineered stromal cells transplanted into the mice increased the human CD4 to CD8 ratios, and increased the ratio of memory to naive CD4(+) and CD8(+) T cells. The human CD3(+) cells recovered from mice that had systemic huIL-7 and equivalent numbers of CD3(+)/CD4(+) and CD3(+)/CD8(+) cells in the marrow were still unable to produce IL-4 in response to any condition tested, but were capable of normal levels of IL-2 production following stimulation.     

Sustained engraftment of mice transplanted with IL-1-primed blood-derived stem cells.

IL-1 is considered the primary mediator of the acute phase response. One of the characteristic manifestations of this response is early neutrophilia that is probably caused by release of mature neutrophils from the bone marrow into the peripheral blood. In the present study, we assessed whether IL-1 had a similar releasing effect on the number of circulating progenitor cells and stem cells. Female BALB/c mice were injected i.p. with increasing (0.1-1.0 micrograms/mouse) concentrations of rhu-IL-1 alpha. IL-1 injection resulted in a marked dose-dependent increase in the number of polymorphonuclear neutrophils, granulocyte-macrophage colony-forming units (CFU-GM), and cells forming spleen colonies (CFU-S day 8 and day 12). The maximal increase was found at 4 to 8 h after injection of 1 micrograms IL-1 per mouse, yielding a mean fivefold elevation in neutrophil count, and a mean 30-fold and 10-fold increase in the number of circulating CFU-GM and CFU-S, respectively. In a subsequent series of experiments, lethally irradiated (8.5 Gy) female recipient animals were transplanted with 5 x 10(5) blood mononuclear cells derived from male IL-1-treated animals. Long-term survival was obtained in 68% of mice transplanted with peripheral blood cells derived from donor animals at 6 h after a single injection of 1 micrograms IL-1. The mean number of circulating CFU-GM in these donor animals was 557/ml blood. At 6 mo after transplantation, greater than 95% of the bone marrow cells were of male origin, as determined using in situ hybridization with a Y-chromosome specific probe. In contrast, long-term survival was reached in less than 10% of mice transplanted with an equal number of blood cells derived from saline-treated controls or donor animals treated with a dose of 0.1 micrograms IL-1. These results indicate that a single injection of IL-1 induces a shift of hematopoietic progenitor cells and marrow repopulating cells into peripheral blood and that these cells can be used to rescue and permanently repopulate the bone marrow of lethally irradiated recipients.     

A model of inflammatory arthritis highlights a role for oncostatin M in pro-inflammatory cytokine-induced bone destruction via RANK/RANKL

Oncostatin M is a pro-inflammatory cytokine previously shown to promote marked cartilage destruction both in vitro and in vivo when in combination with IL-1 or tumour necrosis factor alpha. However, the in vivo effects of these potent cytokine combinations on bone catabolism are unknown. Using adenoviral gene transfer, we have overexpressed oncostatin M in combination with either IL-1 or tumour necrosis factor alpha intra-articularly in the knees of C57BL/6 mice. Both of these combinations induced marked bone damage and markedly increased tartrate-resistant acid phosphatase-positive multinucleate cell staining in the synovium and at the front of bone erosions. Furthermore, there was increased expression of RANK and its ligand RANKL in the inflammatory cells, in inflamed synovium and in articular cartilage of knee joints treated with the cytokine combinations compared with expression in joints treated with the cytokines alone or the control. This model of inflammatory arthritis demonstrates that, in vivo, oncostatin M in combination with either IL-1 or tumour necrosis factor alpha represents cytokine combinations that promote bone destruction. The model also provides further evidence that increased osteoclast-like, tartrate-resistant acid phosphatase-positive staining multinucleate cells and upregulation of RANK/RANKL in joint tissues are key factors in pathological bone destruction.     

Dendritic Cells Transduced to Express Interleukin 4 Reduce Diabetes Onset in Both Normoglycemic and Prediabetic Nonobese Diabetic Mice

Background

We and others have previously demonstrated that treatment with bone marrow derived DC genetically modified to express IL-4 reduce disease pathology in mouse models of collagen-induced arthritis and delayed-type hypersensitivity. Moreover, treatment of normoglycemic NOD mice with bone marrow derived DC, genetically modified to express interleukin 4 (IL-4), reduces the onset of hyperglycemia in a significant number of animals. However, the mechanism(s) through which DC expressing IL-4 function to prevent autoimmune diabetes and whether this treatment can reverse disease in pre-diabetic NOD mice are unknown.

Methodology/Principal Findings

DC were generated from the bone marrow of NOD mice and transduced with adenoviral vectors encoding soluble murine IL-4 (DC/sIL-4), a membrane-bound IL-4 construct, or empty vector control. Female NOD mice were segregated into normoglycemic (<150mg/dL) and prediabetic groups (between 150 and 250 mg/dL) on the basis of blood glucose measurements, and randomized for adoptive transfer of 10⁶ DC via a single i.v. injection. A single injection of DC/sIL-4, when administered to normoglycemic 12-week old NOD mice, significantly reduced the number of mice that developed diabetes. Furthermore, DC/sIL-4, but not control DC, decreased the number of mice progressing to diabetes when given to prediabetic NOD mice 12–16 weeks of age. DC/sIL-4 treatment also significantly reduced islet mononuclear infiltration and increased the expression of FoxP3 in the pancreatic lymph nodes of a subset of treated animals. Furthermore, DC/sIL-4 treatment altered the antigen-specific Th2:Th1 cytokine profiles as determined by ELISPOT of splenocytes in treated animals.

Conclusions

Adoptive transfer of DC transduced to express IL-4 into both normoglycemic and prediabetic NOD mice is an effective treatment for T1D.     

Safety and efficacy of adeno-associated viral vector-mediated insulin gene transfer via portal vein to the livers of streptozotocin-induced diabetic Sprague-Dawley rats

BACKGROUND: Previous studies demonstrating the efficacy of insulin gene therapy have mostly involved use of adenoviral vectors or naked DNA to deliver the insulin gene. However, this procedure may not guarantee long-term insulin production. To improve the performance, we prepared recombinant adeno-associated viral vectors (rAAV) harboring the gene encoding a furin-modified human insulin under the cytomegalovirus (CMV) promoter [rAAV-hPPI(F12)]. METHODS: Streptozotocin (STZ)-induced diabetic Sprague-Dawley rats were used as a diabetic animal model. The levels of blood glucose, insulin, and HbA1c were measured to test the effect. An intraperitoneal glucose tolerance test was performed to test the capability of blood glucose disposal. Immunohistochemical staining and Northern blot analyses were performed to survey the expression pattern of the therapeutic insulin gene. RESULTS: STZ-induced diabetic Sprague-Dawley rats infused via the portal vein with rAAV-hPPI(F12) produced human insulin and after a 6-h fast were normoglycemic for over 90 days post-treatment, whereas diabetic rats treated with recombinant adenoviral vector harboring the hPPI(F12) gene [rAV-hPPI(F12)] were normoglycemic only for days 3 to 13 post-treatment. Insulin mRNA was detected mainly in the liver of the rAAV-hPPI(F12)-treated diabetic rats. The glucose tolerance capability of the rAAV-hPPI(F12)-treated diabetic rats was comparable to that of non-diabetic rats, even without injection of recombinant insulin. Furthermore, blood HbA1c concentrations in rAAV-hPPI(F12)-treated diabetic rats were reduced to almost the normal level. Importantly, studies of rAV or rAAV vector-dependent side effects on the targeted liver strongly suggested that only rAAV treatment caused no side effects. CONCLUSIONS: These results demonstrate that our rAAV-mediated in vivo insulin gene therapy provides safer maintenance of the insulin gene expression required for long-term and thus more effective blood glycemic control.     

A model of inflammatory arthritis highlights a role for oncostatin M in pro-inflammatory cytokine-induced bone destruction via RANK/RANKL

Oncostatin M is a pro-inflammatory cytokine previously shown to promote marked cartilage destruction both in vitro and in vivo when in combination with IL-1 or tumour necrosis factor alpha. However, the in vivo effects of these potent cytokine combinations on bone catabolism are unknown. Using adenoviral gene transfer, we have overexpressed oncostatin M in combination with either IL-1 or tumour necrosis factor alpha intra-articularly in the knees of C57BL/6 mice. Both of these combinations induced marked bone damage and markedly increased tartrate-resistant acid phosphatase-positive multinucleate cell staining in the synovium and at the front of bone erosions. Furthermore, there was increased expression of RANK and its ligand RANKL in the inflammatory cells, in inflamed synovium and in articular cartilage of knee joints treated with the cytokine combinations compared with expression in joints treated with the cytokines alone or the control. This model of inflammatory arthritis demonstrates that, in vivo, oncostatin M in combination with either IL-1 or tumour necrosis factor alpha represents cytokine combinations that promote bone destruction. The model also provides further evidence that increased osteoclast-like, tartrate-resistant acid phosphatase-positive staining multinucleate cells and upregulation of RANK/RANKL in joint tissues are key factors in pathological bone destruction.     

Juxtacrine effects of IL-1 alpha precursor promote iNOS expression in vascular smooth muscle cells

After injury to the blood vessel wall, vascular smooth muscle cells (SMC) synthesize interleukin (IL)-1 and inducible nitric oxide (NO) synthase (iNOS). The present study tested whether endogenous production of IL-1 alpha stimulates iNOS expression in vascular SMC, and assessed whether IL-1 alpha exerts autocrine effects on the cells producing IL-1 alpha or juxtacrine effects on cells that contact the IL-1 alpha producing cells. Rat aortic SMC were transiently transfected with expression plasmids encoding either IL-1 alpha precursor, which localizes to the plasma membrane, or mature IL-1 alpha, which remains cytosolic. iNOS mRNA levels, determined by RT-PCR, and production of nitrite, a stable oxidation product of NO, were markedly elevated in SMC overexpressing IL-1 alpha precursor, and modestly elevated in SMC overexpressing mature IL-1 alpha, relative to SMC transfected with vector alone. Exposure to exogenous IL-1 beta or TNF-alpha further stimulated iNOS gene expression in SMC producing IL-1 alpha; low levels of IL-1 beta (20 pg/ml) were effective in SMC transfected with IL-1 alpha precursor plasmid, whereas SMC transfected with mature IL-1 alpha plasmid or vector alone required higher concentrations of IL-1 beta (200 and 2,000 pg/ml, respectively). The increases in iNOS mRNA levels and NO production in SMC overexpressing IL-1 alpha precursor were prevented by exogenous IL-1 receptor antagonist, suggesting that these effects were mediated by the type I IL-1 receptor. Immunostaining studies indicated that IL-1 alpha precursor stimulates iNOS gene expression via cell-cell contact. Expression of iNOS was enhanced in cells that were in contact with a cell overexpressing IL-1 alpha precursor (identified by coexpression of green fluorescent protein), and in cells that were overexpressing IL-1 alpha themselves, but only when the cell contacted another cell. Together these results indicate that IL-1 alpha precursor acts by cell-cell contact as an autocrine and juxtacrine enhancer of iNOS gene expression, inducing moderate iNOS expression on its own, and markedly augmenting the responsiveness of rat aortic SMC to exogenous cytokines.     

Transfer of proalpha2(I) cDNA into cells of a murine model of human Osteogenesis Imperfecta restores synthesis of type I collagen comprised of alpha1(I) and alpha2(I) heterotrimers in vitro and in vivo

The oim mouse is a model of human Osteogenesis Imperfecta (OI) that has deficient synthesis of proalpha2(I) chains. Cells isolated from oim mice synthesize alpha1(I) collagen homotrimers that accumulate in tissues. To explore the feasibility of gene therapy for OI, a murine proalpha2(I) cDNA was inserted into an adenovirus vector and transferred into bone marrow stromal cells isolated from oim mice femurs. The murine cDNA under the control of the cytomegalovirus early promoter was expressed by the transduced cells. Analysis of the collagens synthesized by the transduced cells demonstrated that the cells synthesized stable type I collagen comprised of alpha1(I) and alpha2(I) heterotrimers in the correct ratio of 2:1. The collagen was efficiently secreted and also the cells retained the osteogenic potential as indicated by the expression of alkaline phosphatase activity when the transduced cells were treated with recombinant human bone morphogenetic protein 2. Injection of the virus carrying the murine proalpha2(I) cDNA into oim skin demonstrated synthesis of type I collagen comprised of alpha1 and alpha2 chains at the injection site. These preliminary data demonstrate that collagen genes can be transferred into bone marrow stromal cells as well as fibroblasts in vivo and that the genes are efficiently expressed. These data encourage further studies in gene replacement for some forms of OI and use of bone marrow stromal cells as vehicles to deliver therapeutic genes to bone.     

Blockade of prostaglandin biosynthesis in intact mice dramatically augments the expansion of committed myeloid progenitor cells (colony-forming units-granulocyte, macrophage) after acute administration of recombinant human IL-1 alpha

Injection of human rIL-1 alpha in intact normal mice has positive and negative effects on myelopoiesis. Within 6 h postinjection, peripheral neutrophilia can be demonstrated. However, bone marrow and spleen cells capable of inhibiting CFU-granulocyte macrophage proliferation are detected between 6 and 48 h postinjection. These myelopoietic suppressor cells belong to the monocytic lineage and are identical to inhibitory cells induced by PGE2. Treatment of mice with indomethacin, a PG synthesis inhibitor, completely blocked the generation of IL-1-alpha-induced myelopoietic suppressor cells, and significantly enhanced femoral and splenic CFU-GM proliferation after a single injection of 0.4 microgram/mouse IL-1. The peripheral blood neutrophilia observed within 6 h after IL-1 injection was delayed to 18 to 24 h postinjection in indomethacin-pretreated mice. In mice treated with four consecutive daily injections of 0.4 microgram IL-1, a sustained peripheral neutrophilia was observed. IL-1 had little effect on femoral CFU-GM in these animals, however, splenic CFU-GM was increased 7- to 10-fold by 4 to 7 days postinjection. In IL-1 plus indomethacin-treated mice, sustained peripheral neutrophilia was observed although to a lesser degree than with IL-1 alone. Marrow CFU-GM were relatively unaffected, however, splenic CFU-GM were increased by 27-fold. These results indicate that the in vivo administration of IL-1 results in neutrophilia and generation of myelopoietic suppressive effects, mediated by cyclo-oxygenase pathway products. Blockade of PG synthesis by using the cyclo-oxygenase inhibitor indomethacin abrogates the myelopoietic suppressive effects associated with IL-1 administration and optimizes its myelopoietic stimulatory capacity. The inclusion of a cyclo-oxygenase inhibitor may have significant relevance to the clinical use of IL-1.     

Protein-energy malnutrition decreases the expression of TLR-4/MD-2 and CD14 receptors in peritoneal macrophages and reduces the synthesis of TNF-alpha in response to lipopolysaccharide (LPS) in mice

Protein-energy malnutrition (PEM) modifies resistance to infection, impairing a number of physiological processes, including hematopoiesis. In this study, we examined a few aspects of the inflammatory response to LPS in a model of PEM. We evaluated the cellularity of the blood, bone marrow and spleen, as well as phagocytic, fungicidal and spreading activity, the production in vivo and in vitro of TNF-alpha, IL-1alpha and IL-6, and the expression of CD14 and TLR-4/MD-2 receptors in macrophages. Two-month-old male Swiss mice were submitted to PEM with a low-protein diet containing 4% protein as compared to 20% protein in the control diet. When the experimental group had attained about 20% loss of their original body weight, they were used in the experiments. Malnourished animals presented anemia, leucopenia and severe reduction in bone marrow, spleen and peritoneal cavity cellularity. The production of TNF-alpha, IL-1alpha and IL-6 stimulated in vivo with LPS and the production of IL-6 in bone marrow cells cultured with LPS and the production of TNF-alpha in bone marrow, spleen and peritoneal cells cultured with LPS were significantly lower in malnourished animals. The expression of CD14 and TLR-4/MD-2 receptors was found to be significantly lower in macrophages of malnourished animals. These findings suggest that malnourished animals present a deficient response to LPS. The lower expression of the CD14 and TLR-4/MD-2 receptors may be partly responsible for the immunodeficiency observed in the malnourished mice. These data lead us to infer that the nutritional state interferes with the activation of macrophages and with the capacity to mount an immune response.     

Establishment of a novel factor-dependent myeloid cell line from primary cultures of mouse bone marrow

We describe here a novel myelomonocytic cell line (OTT1) obtained from primary cultures of mouse bone marrow cells infected with a retroviral vector carrying the mouse interleukin (IL)-1 alpha gene. OTT1 cells are dependent for their survival and proliferation on IL-3, granulocyte-macrophage colony-stimulating factor (GM-CSF) or, unexpectedly, IL-5. Despite their IL-5 dependency, OTT1 cells form colonies showing predominantly monocyte maturation when plated in methylcellulose. It is suggested that constitutive expression of the exogenous IL-1 alpha gene may predispose to a monocytic phenotype. OTT1 cells should be a useful experimental model to investigate the molecular mechanisms of IL-5 signal transduction and the possible interrelationships between this signal pathway and those utilized by IL-3 and GM-CSF.     

The prevention and treatment of murine colitis using gene therapy with adenoviral vectors encoding IL-10

IL-10-deficient (IL-10(-/-)) mice develop colitis with many similarities to Crohn's disease. Daily IL-10 injections have a short systemic half-life and are unable to induce complete remission in IL-10(-/-) mice with established disease. In this paper, we investigate the duration, potency, and immunogenicity of gene therapy using an adenoviral vector encoding murine IL-10 (AdvmuIL-10). A single systemic injection of AdvmuIL-10 was sufficient not only to prevent the onset of colitis for at least 10 wk but also to induce clinical and histological remission in mice with established disease. In addition, AdvmuIL-10 diminished the systemic manifestations of disease, including elevated acute-phase proteins, as well as the local consequences of inflammation such as raised stool IL-1beta concentrations. Both IL-10 protein and the effects of secreted IL-10 were detectable for 10 wk after AdvmuIL-10 injection. Furthermore, the immunoregulatory effect of a single AdvmuIL-10 injection was manifest both by a reduction in TNF-alpha, IFN-gamma, and RANTES release from stimulated splenocyte cultures, and also by a change in the proportion of CD45RB(high/low) lymphocytes in the spleen compared with control mice. The delivery of AdvmuIL-10 resulted in a significantly diminished host antiadenoviral response compared with control adenoviral vectors. Thus, gene therapy strategies using adenoviral vectors encoding immunoregulatory and antiinflammatory cytokines may prove to be a potent approach for the treatment of chronic inflammatory disease. Antiinflammatory cytokine expression protects against immune responses directed at gene vectors.     

Enhancement of bone repair with a helper-dependent adenoviral transfer of bone morphogenetic protein-2

Regional gene therapy, which involves the delivery of growth factors to a specific anatomic site, has the potential to enhance bone formation in clinical application. Helper-dependent adenoviral vectors, which have deleted all of the viral coding regions, have been shown to be safe and highly efficient with long-lasting transgene expression. In this study, we constructed a helper-dependent adenoviral vector producing bone morphogenetic protein-2 (AdHDBMP-2). The AdHDBMP-2 increased the alkaline phosphatase activity of W-20-17 cells in vitro. In addition, when AdHDBMP-2 infected rat bone marrow cells were implanted into the hindlimbs of SCID mice, orthotopic bone formation was shown at 2 weeks. To our knowledge, this is the first study to demonstrate bone formation with the helper-dependent adenoviral vector with the BMP-2 expression cassette. This type of gene therapy vector could prove to be highly useful for bone augmentation in patients with bone loss associated with trauma, revision total joint arthroplasty, or cancer.     

In vivo effects of interleukin-17 on haematopoietic cells and cytokine release in normal mice

In order to gain more insight into mechanisms operating on the haematopoietic activity of the T-cell-derived cytokine, interleukin-17 (IL-17) and target cells that first respond to its action in vivo, the influence of a single intravenous injection of recombinant mouse IL-17 on bone marrow progenitors, further morphologically recognizable cells and peripheral blood cells was assessed in normal mice up to 72 h after treatment. Simultaneously, the release of IL-6, IL-10, IGF-I, IFN-gamma and NO by bone marrow cells was determined. Results showed that, in bone marrow, IL-17 did not affect granulocyte-macrophage (CFU-GM) progenitors, but induced a persistant increase in the number of morphologically recognizable proliferative granulocytes (PG) up to 48 h after treatment. The number of immature erythroid (BFU-E) progenitors was increased at 48 h, while the number of mature erythroid (CFU-E) progenitors was decreased up to 48 h. In peripheral blood, white blood cells were increased 6 h after treatment, mainly because of the increase in the number of lymphocytes. IL-17 also increased IL-6 release and NO production 6 h after administration. Additional in vitro assessment on bone marrow highly enriched Lin- progenitor cells, demonstrated a slightly enhancing effect of IL-17 on CFU-GM and no influence on BFU-E, suggesting the importance of bone marrow accessory cells and secondary induced cytokines for IL-17 mediated effects on progenitor cells. Taken together, these results demonstrate that in vivo IL-17 affects both granulocytic and erythroid lineages, with more mature haematopoietic progenitors responding first to its action. The opposite effects exerted on PG and CFU-E found at the same time indicate that IL-17, as a component of a regulatory network, is able to intervene in mechanisms that shift haematopoiesis from the erythroid to the granulocytic lineage.     

Studies using leukemia inhibitory factor (LIF) knockout mice and a LIF adenoviral vector demonstrate a key anti-inflammatory role for this cytokine in cutaneous inflammation

Previous work has implicated the cytokine leukemia inhibitory factor (LIF) in cutaneous inflammation, although results have differed as to whether LIF is pro- or anti-inflammatory in this setting. We examined edema, inflammatory cell infiltration, and cytokine responses following CFA injection in the adult mouse footpad. Inflammatory cell infiltration and edema are significantly enhanced when CFA is injected in LIF knockout mice as compared with injection of wild-type littermates. Moreover, local injection of an adenoviral vector encoding LIF suppresses both measures of inflammation. In contrast, injection of an adenoviral vector encoding beta-galactosidase has no discernable effect on inflammation. In addition, comparison of the CFA responses in LIF knockout vs wild-type skin reveals that LIF is an important regulator of IL-1beta, IL-6, IL-7, IL-2Ralpha, and IFN-gamma in cutaneous inflammation. These and our previous data indicate that both endogenous and exogenous LIF are anti-inflammatory in the CFA model and that LIF is a key regulator of the cytokine cascade. The results also indicate that adenoviral gene delivery can be an effective therapeutic approach in this paradigm.     

Differentiation stages of eosinophils characterized by hyaluronic acid binding via CD44 and responsiveness to stimuli

To characterize interleukin (IL)-5-induced eosinophils, we examined the expression of CD44, very late antigen (VLA)-4, and the IL-5 receptor alpha chain, as well as the levels of eosinophil peroxidase and the generation of superoxide. Eosinophils were prepared from IL-5-transgenic mice, then characterized using electron microscopy to determine their responses to stimuli. Whereas CD44 densities remained almost constant, the level of VLA-4 increased in parallel with eosinophil maturation. Although a subset of IL-5-induced eosinophils with high side scatter recovered from bone marrow and rare ones found in blood recognized hyaluronic acid (HA), most did not have this property. Bone marrow eosinophils with high side scatter and lower density contained eosinophil peroxidase, not only in granules, but also in membranous structures for 30% of this population. This population developed HA-binding ability in response to IL-3, IL-4, IL-5, granulocyte-macrophage colony-stimulating factor, macrophage inflammatory protein (MIP)-2, monocyte chemotactic protein (MCP)-1, eotaxin, nerve growth factor (NGF), and opsonized zymosan (OZ). Peripheral blood eosinophils acquired HA-binding ability in response to the same stimuli, but their responses were less than those of bone marrow eosinophils with high levels of side scatter. However, splenic eosinophils did not respond to these stimuli. Although peripheral blood eosinophils did not proliferate when stimulated by IL-5, these were the only cells that released eosinophil peroxidase in response to IL-4, MIP-2, MCP-1, eotaxin, NGF, and OZ. With the exception of a subset of bone marrow eosinophils, the ability to acquire HA binding, but not the ability to generate superoxide, correlated with eosinophil peroxidase activity and major basic protein accumulation in the granules of maturing cells.     

The in vivo effects of interleukin 1. I. Bone marrow cells are induced to cycle after administration of interleukin 1

We have previously reported that interleukin 1 (IL-1) administration 20 hr before irradiation protects mice from lethal effects of radiation. The recovery of total nucleated bone marrow cells and of hematopoietic progenitor cells was enhanced in IL-1 treated, as compared to untreated, irradiated mice. This suggested that IL-1 administration may affect the cells in the bone marrow of normal mice. Intraperitoneal administration of recombinant IL-1 resulted in bone marrow cell enlargement and increased cycling of these enlarged cells. In addition, the capacity of bone marrow cells from IL-1 treated mice to proliferate in response to granulocyte macrophage-colony-stimulating factor (GM-CSF) in cell suspension cultures was enhanced. The above effects were not genetically restricted as C57BL/6, B6D2F1, C3H/HeN, and C3H/HeJ mice showed similar responses. A comparative study showed that 100 ng of IL-1 was much more effective in stimulating bone marrow cells by the above criteria than 5 micrograms GM-CSF. Since IL-1, unlike CSF, can not be demonstrated to have a direct in vitro stimulatory effect on bone marrow cells, the aforementioned in vivo effects of IL-1 are presumably mediated by other hematopoietic growth factors. We have previously shown that IL-1 induces the appearance of high titers of CSF in the serum. Consequently hematopoietic growth factors that are generated at local sites following IL-1 administration may mediate the observed cell cycling effect.     

IL-1alpha stimulation of osteoclast survival through the PI 3-kinase/Akt and ERK pathways.

Osteoclasts, cells that resorb bone, die once fully differentiated. Several factors including interleukin-1 (IL-1) have been shown to regulate the survival of mature osteoclasts. However, information on the mechanism underlying the regulation of osteoclast survival has been limited. In this study, we investigated the mechanism for the IL-1-stimulated survival of osteoclasts. Treatment of purified osteoclasts with IL-1alpha led to activation of the serine-threonine kinases Akt and ERK. Blocking the activation of Akt with LY294002, a specific inhibitor of the Akt up-stream molecule PI 3-kinase, or an with adenoviral vector for a dominant-negative form of Akt prevented the stimulation of osteoclast survival by IL-1alpha. PD98059, a specific inhibitor of the ERK-activating kinase MEK1, also abolished the effects of IL-1alpha on ERK activation and osteoclast survival. IL-1alpha reduced the apoptosis of osteoclasts by reducing caspase 3 activity. The IL-1alpha-mediated suppression of apoptosis was abolished by the PI 3-kinase/Akt or MEK1/ERK pathway inhibitor. These findings implicate the PI 3-kinase/Akt and ERK signaling pathways in the promotion of osteoclast survival by IL-1alpha.