TCR-mediated involvement of CD4+ transgenic T cells in spontaneous inflammatory bowel disease in lymphopenic mice.

Spontaneous colitis resembling ulcerative colitis developed in 3 of 10 independent TCR transgenic (Tg) mouse lines maintained under specific pathogen-free conditions. All three susceptible lines were CD4 lymphopenic, whereas resistant lines had normal numbers of CD4+ T cells. Thus, cytochrome c-specific 5C.C7 TCR Tg mice developed colitis only when crossed onto a SCID- or Rag-1-deficient background. A second line of lymphopenic cytochrome c-specific Tg mice bearing the AND TCR also developed colitis. In both cases, CD4+ T cells expressing the Tg-encoded TCR were preferentially activated in inflamed colons compared with lymph nodes or spleens. In contrast, Tg+CD4+ T cells remained quiescent in both inflamed and unaffected colons in another line of susceptible Tg mice carrying a TCR specific for myelin basic protein, suggesting a fortuitous cross-reactivity of the IEk-restricted cytochrome c-reactive AND and 5C.C7 TCRs with an Ag present in the gut. The percentage of CD4+ T cells expressing only endogenous TCR alpha-chains was increased consistently in inflamed colons in AND as well as 5C.C7 Rag-1-/- TCR Tg mice, suggesting that polyclonal CD4+ T cells were also involved in the pathogenesis of spontaneous colitis. Moreover, our data indicate that some alpha-chain rearrangement was still occurring in TCR Tg mice on a Rag-1-/- background, since activated CD4+ T cells expressing endogenously rearranged alpha-chains paired with the Tg-encoded beta-chain were detected consistently in the colons of such mice.     

Inflammation and ischemia-induced lung angiogenesis

A role for inflammation in modulating the extent of angiogenesis has been shown for a number of organs. The present study was undertaken to evaluate the importance of leukocyte subpopulations for systemic angiogenesis of the lung after left pulmonary artery ligation (LPAL) in a mouse model of chronic pulmonary thromboembolism. Since we (24) previously showed that depletion of neutrophils did not alter the angiogenic outcome, we focused on the effects of dexamethasone pretreatment (general anti-inflammatory) and gadolinium chloride treatment (macrophage inactivator) and studied Rag-1(-/-) mice (T/B lymphocyte deficient). We measured inflammatory cells in bronchoalveolar lavage fluid and lung homogenate macrophage inflammatory protein-2 (MIP-2) and IL-6 protein levels within 24 h after LPAL and systemic blood flow to the lung 14 days after LPAL with labeled microspheres as a measure of angiogenesis. Blood flow to the left lung was significantly reduced after dexamethasone treatment compared with untreated control LPAL mice (66% decrease; P < 0.05) and significantly increased in T/B lymphocyte-deficient mice (88% increase; P < 0.05). Adoptive transfer of splenocytes (T/B lymphocytes) significantly reversed the degree of angiogenesis observed in the Rag-1(-/-) mice back to the level of control LPAL. Average number of lavaged macrophages for each group significantly correlated with average blood flow in the study groups (r(2) = 0.9181; P = 0.01 different from 0). Despite differences in angiogenesis, left lung homogenate MIP-2 and IL-6 did not differ among study groups. We conclude that inflammatory cells modulate the degree of angiogenesis in this lung model where lymphocytes appear to limit the degree of neovascularization, whereas monocytes/macrophages likely promote angiogenesis.     

Therapeutic effect of anti-macrophage inflammatory protein 2 antibody on influenza virus-induced pneumonia in mice

We investigated the effect of anti-macrophage inflammatory protein 2 immunoglobulin G (aMIP-2 IgG) on the progression of influenza virus-induced pneumonia in mice. When mice were infected with a mouse lung-adapted strain of influenza A/PR/8/34 virus by intranasal inoculation, neutrophil counts in the bronchoalveolar lavage fluid (BALF) increased in parallel with the kinetics of MIP-2 production, which peaked 2 days after infection. After intracutaneous injection of a dose of 10 or 100 microg of aMIP-2 IgG once a day on days 0 and 1, neutrophil counts in BALF on day 2 were reduced to 49 or 37%, respectively, of the value in the control infected mice administered anti-protein A IgG. The antibody administration also improved lung pathology without affecting virus replication. Furthermore, by prolonged administration with a higher or lower dose for up to 5 days, body weight loss became slower and finally 40% of mice in both treatment groups survived potentially lethal pneumonia. These findings suggest that MIP-2-mediated neutrophil infiltration during the early phase of infection might play an important role in lung pathology. Thus, MIP-2 was considered to be a novel target for intervention therapy in potentially lethal influenza virus pneumonia in mice.     

A lethal myeloproliferative syndrome in mice transplanted with bone marrow cells infected with a retrovirus expressing granulocyte-macrophage colony stimulating factor.

Murine bone marrow cells infected with a novel recombinant retrovirus, MPZen(GM-CSF), were engrafted into lethally irradiated recipients. The transplanted animals developed extremely high circulating levels of GM-CSF (up to 3 x 10(5) units/ml), and greatly elevated peripheral nucleated cell counts (up to 110 x 10(6) per ml). Their haemopoietic tissues contained GM-CSF proviral DNA and produced substantial levels of GM-CSF. The mice died within 4 weeks of transplantation with extensive neutrophil and macrophage infiltration of the spleen, lung, liver and peritoneal cavity and significant infiltration of both heart and skeletal muscle by neutrophils, macrophages and eosinophils. The thymus and lymph nodes were deficient in lymphoid cells. No disease occurred when infected cells from haemopoietic tissues of the primary transplanted animals were injected into normal or sub-lethally irradiated mice. Dysregulated GM-CSF expression by haemopoietic cells thus produces a fatal albeit non-neoplastic myeloproliferative syndrome.     

Enhanced neointima formation following arterial injury in immune deficient Rag-1-/- mice is attenuated by adoptive transfer of CD8 T cells

T cells modulate neointima formation after arterial injury but the specific T cell population that is activated in response to arterial injury remains unknown. The objective of the study was to identify the T cell populations that are activated and modulate neointimal thickening after arterial injury in mice. Arterial injury in wild type C57Bl6 mice resulted in T cell activation characterized by increased CD4(+)CD44(hi) and CD8(+)CD44(hi) T cells in the lymph nodes and spleens. Splenic CD8(+)CD25(+) T cells and CD8(+)CD28(+) T cells, but not CD4(+)CD25(+) and CD4(+)CD28(+) T cells, were also significantly increased. Adoptive cell transfer of CD4(+) or CD8(+) T cells from donor CD8-/- or CD4-/- mice, respectively, to immune-deficient Rag-1-/- mice was performed to determine the T cell subtype that inhibits neointima formation after arterial injury. Rag-1-/- mice that received CD8(+) T cells had significantly reduced neointima formation compared with Rag-1-/- mice without cell transfer. CD4(+) T cell transfer did not reduce neointima formation. CD8(+) T cells from CD4-/- mice had cytotoxic activity against syngeneic smooth muscle cells in vitro. The study shows that although both CD8(+) T cells and CD4(+) T cells are activated in response to arterial injury, adoptive cell transfer identifies CD8(+) T cells as the specific and selective cell type involved in inhibiting neointima formation.     

Lymphocyte development and function in the absence of retinoic acid-related orphan receptor alpha

The orphan nuclear receptor, retinoid acid-related orphan receptor (ROR)alpha, is essential for the development of cerebellar Purkinje cells and bone tissue. RORalpha may also play a critical role in lymphocyte development and function because staggerer mice, a natural mutant strain with a disrupted expression of RORalpha, have reduced thymic and splenic cellularity. In this report, we analyzed the role of RORalpha in lymphocyte development by examining lymphoid compartments in RORalpha(-/-) mice and Rag-2(-/-) mice reconstituted with RORalpha(-/-) bone marrow. We found that T and B cell development was severely defective in RORalpha(-/-) mice, but not in Rag-2(-/-)/RORalpha(-/-) chimeric mice. We also analyzed cellular and humoral immune responses in Rag-2(-/-)/RORalpha(-/-) chimeric mice. Our results show that serum IgG levels were elevated in Rag-2(-/-)/RORalpha(-/-) chimeric mice after immunization with a T-dependent Ag compared with control chimeras. IFN-gamma production by RORalpha(-/-) CD8(+) T cells after TCR stimulation was also increased. Furthermore, RORalpha(-/-) mast cells and macrophages produced an increased amount of TNF-alpha and IL-6 upon activation. These results indicate that RORalpha indirectly regulates lymphocyte development by providing an appropriate microenvironment and controls immune responses by negatively regulating cytokine production in innate immune cells and lymphocytes.     

Chronic inflammatory disease alters adhesion molecule requirements for acute neutrophil emigration in mouse skin

Mutant mice triply deficient in ICAM-1, E-selectin, and P-selectin did not develop the neutrophilic skin lesions that spontaneously arise in mutants doubly deficient in E-selectin and P-selectin. Thus, ICAM-1 is essential to skin disease resulting from endothelial selectin deficiency. During experimental dermatitis, acute neutrophil emigration was completely prevented in young mice deficient in both selectins (E/P and E/P/I mutants). However, older E/P mutants with spontaneous skin lesions displayed an endothelial selectin-independent pathway for acute neutrophil emigration. In contrast, emigration remained compromised in E/P/I mutants and CD18 mutants regardless of age or lesions. Experimentally induced chronic lesions elicited this pathway for acute emigration in young E/P mutants. Thus, an endothelial selectin-independent pathway for acute neutrophil emigration is induced in E/P mice by chronic inflammation at distant sites, and this pathway may contribute to skin disease resulting from endothelial selectin deficiency.     

CD73-generated adenosine restricts lymphocyte migration into draining lymph nodes

After an inflammatory stimulus, lymphocyte migration into draining lymph nodes increases dramatically to facilitate the encounter of naive T cells with Ag-loaded dendritic cells. In this study, we show that CD73 (ecto-5'-nucleotidase) plays an important role in regulating this process. CD73 produces adenosine from AMP and is expressed on high endothelial venules (HEV) and subsets of lymphocytes. Cd73(-/-) mice have normal sized lymphoid organs in the steady state, but approximately 1.5-fold larger draining lymph nodes and 2.5-fold increased rates of L-selectin-dependent lymphocyte migration from the blood through HEV compared with wild-type mice 24 h after LPS administration. Migration rates of cd73(+/+) and cd73(-/-) lymphocytes into lymph nodes of wild-type mice are equal, suggesting that it is CD73 on HEV that regulates lymphocyte migration into draining lymph nodes. The A(2B) receptor is a likely target of CD73-generated adenosine, because it is the only adenosine receptor expressed on the HEV-like cell line KOP2.16 and it is up-regulated by TNF-alpha. Furthermore, increased lymphocyte migration into draining lymph nodes of cd73(-/-) mice is largely normalized by pretreatment with the selective A(2B) receptor agonist BAY 60-6583. Adenosine receptor signaling to restrict lymphocyte migration across HEV may be an important mechanism to control the magnitude of an inflammatory response.     

Overlapping and selective roles of endothelial intercellular adhesion molecule-1 (ICAM-1) and ICAM-2 in lymphocyte trafficking

The integrin LFA-1 interacts with a variety of ligands termed ICAMs. ICAM-1 and ICAM-2 are both expressed on endothelium and serve as counterreceptors during lymphocyte trafficking. In this study, we analyzed their relative contribution to lymphocyte recirculation through lymph nodes and to recruitment into lung and inflamed skin by blocking mAbs against ICAM-1 and ICAM-2 and mice deficient for ICAM-1. The entry of lymphocytes into peripheral and mesenteric lymph nodes was found to be unaffected by the functional deletion of either ICAM-1 or ICAM-2. However, when both pathways were blocked, recirculation through lymph nodes was strongly reduced. Trapping of lymphocytes in the lung after i.v. injection is partly mediated by LFA-1/ICAM interactions; the data presented in this study show an exclusive role of ICAM-1 in LFA-1-dependent lung trapping. Similarly, ICAM-1, but not ICAM-2, was required for the migration of T effector cells into the inflamed skin. These results indicate that ICAM-1 and ICAM-2 have redundant functions in lymphocyte recirculation through lymph nodes, but ICAM-1 is unique in supporting migration into inflamed sites and trapping within the lung.     

Lung injury during LPS-induced inflammation occurs independently of the receptor P2Y<Subscript>1</Subscript>

Disruption of the lung endothelial and epithelial barriers during acute inflammation leads to excessive neutrophil migration. It is likely that activated platelets promote pulmonary recruitment of neutrophils during inflammation, and previous studies have found that anti-platelet therapy and depletion of circulating platelets have lung-protective effects in different models of inflammation. Because ADP signaling is important for platelet activation, I investigated the role of the ADP-receptor P2Y₁, a G protein-coupled receptor expressed on the surface of circulating platelets, during lipopolysaccharide (LPS)-induced inflammation and lung injury in P2Y₁-null and wild-type mice. Systemic inflammation was induced by a single intraperitoneal dose of LPS (3 mg/kg), and the mice were analyzed 24 h posttreatment. The data show that the LPS-induced inflammation levels were comparable in the P2Y₁-null and wild-type mice. Specifically, splenomegaly, counts of circulating platelets and white blood cells (lymphocytes and neutrophils), and assessments of lung injury (tissue architecture and cell infiltration) were similar in the P2Y₁-null and wild-type mice. Based on my results, I conclude that lung injury during LPS-induced inflammation in mice is independent of P2Y₁ signaling. I propose that if a blockade of purinergic signaling in platelets is a potential lung-protective strategy in the treatment of acute inflammation, then it is more likely to be a result of the disruption of the signaling pathway mediated by P2Y₁₂, another G protein-coupled receptor that mediates platelet responses to ADP.     

Urokinase-type plasminogen activator is required for the generation of a type 1 immune response to pulmonary Cryptococcus neoformans infection.

Urokinase-type plasminogen activator (uPA)(-/-) mice cannot mount protective host defenses during infection with the opportunistic yeast Cryptococcus neoformans (52D). Because effective host defense against C. neoformans requires specific immune responses and the generation of type 1 (T1) cytokines, we determined how the absence of uPA impacts these processes. Wild-type (WT) and uPA(-/-) mice were inoculated with C. neoformans. Macrophage antifungal activity was assessed histologically, T lymphocyte responses in vivo and proliferation in vitro were quantified, and cytokine concentrations were determined by ELISA. uPA(-/-) macrophages have impaired antimicrobial activity. Regional lymph nodes of infected uPA(-/-) mice contained fewer cells than WT, suggesting impaired T cell proliferation in response to the pathogen in vivo. In vitro, uPA(-/-) T lymphocytes had impaired proliferative responses to C. neoformans rechallenge compared with WT. Infected WT mice generated T1 cytokines in the lung, characterized by high levels of IFN-gamma and IL-12. uPA(-/-) mice had decreased levels of IFN-gamma and IL-12, and increased IL-5, a type 2 cytokine. In the absence of uPA, the cytokine profile of regional lymph nodes shifted from a T1 pattern characterized by IFN-gamma and IL-2 to a weak, nonpolarized response. We conclude that in the absence of uPA, lymphocyte proliferative responses are diminished, and mice fail to generate protective T1 cytokines, resulting in impaired antimicrobial activity. This study provides novel evidence that uPA is a critical modulator of immune responses and of immune cell effector functions in vivo.     

The Fifth Domain of Beta 2 Glycoprotein I Protects from Natural IgM Mediated Cardiac Ischaemia Reperfusion Injury

Reperfusion after a period of ischemia results in reperfusion injury (IRI) which involves activation of the inflammatory cascade. In cardiac IRI, IgM natural antibodies (NAb) play a prominent role through binding to altered neoepitopes expressed on damaged cells. Beta 2 Glycoprotein I (β2GPI) is a plasma protein that binds to neoepitopes on damaged cells including anionic phospholipids through its highly conserved Domain V. Domain I of β2GPI binds circulating IgM NAbs and may provide a link between the innate immune system, IgM NAb binding and cardiac IRI. This study was undertaken to investigate the role of Β2GPI and its Domain V in cardiac IRI using wild-type (WT), Rag-1 ^-/- and β2GPI deficient mice. Compared with control, treatment with Domain V prior to cardiac IRI prevented binding of endogenous β2GPI to post-ischemic myocardium and resulted in smaller myocardial infarction size in both WT and β2GPI deficient mice. Domain V treatment in WT mice also resulted in less neutrophil infiltration, less apoptosis and improved ejection fraction at 24 h. Rag-1 -/- antibody deficient mice reconstituted with IgM NAbs confirmed that Domain V prevented IgM NAb induced cardiac IRI. Domain V remained equally effective when delivered at the time of reperfusion which has therapeutic clinical relevance.Based upon this study Domain V may function as a universal inhibitor of IgM NAb binding in the setting of cardiac IRI, which offers promise as a new therapeutic strategy in the treatment of cardiac IRI.     

Pulmonary immune cells and inflammatory cytokine dysregulation are associated with mortality of IL-1R1-/-mice infected with influenza virus (H1 N1)

Respirovirus infection can cause viral pneumonia and acute lung injury (ALI).The interleukin-1 (IL-1) family consists of proinflammatory cytokines that play essential roles in regulating immune and inflammatory responses in vivo.IL-1 signaling is associated with protection against respiratory influenza virus infection by mediation of the pulmonary anti-viral immune response and inflammation.We analyzed the infiltration lung immune leukocytes and cytokines that contribute to inflammatory lung pathology and mortality of fatal H1N1 virus-infected IL-1 receptor 1 (IL-1R1) deficient mice.Results showed that early innate immune cells and cytokine/chemokine dysregulation were observed with significantly decreased neutrophil infiltration and IL-6,TNF-α,G-CSF,KC,and MIP-2 cytokine levels in the bronchoalveolar lavage fluid of infected IL-1R1-/-mice in comparison with that of wild type infected mice.The adaptive immune response against the H1N1 virus in IL-1R1-/-mice was impaired with downregulated anti-viral Th1 cell,CD8+ cell,and antibody functions,which contributes to attenuated viral clearance.Histological analysis revealed reduced lung inflammation during early infection but severe lung pathology in late infection in IL-1R1-/-mice compared with that in WT infected mice.Moreover,the infected IL-1R1-/-mice showed markedly reduced neutrophil generation in bone marrow and neutrophil recruitment to the inflamed lung.Together,these results suggest that IL-1 signaling is associated with pulmonary anti-influenza immune response and inflammatory lung injury,particularly via the influence on neutrophil mobilization and inflammatory cytokine/chemokine production.     

Role of circulating granulocytes in sheep lung injury produced by phorbol myristate acetate

Phorbol myristate acetate (PMA) and endotoxin cause pulmonary granulocyte sequestration and alteration in lung fluid and solute exchange in awake sheep that are felt to be analogous to the adult respiratory distress syndrome in humans. The basic hypothesis that PMA causes lung injury by activating circulating granulocytes has never been tested. The effects of infused PMA on lung mechanics and the cellular constituents of lung lymph have also not been reported. We therefore characterized the effects of intravenous PMA, 5 micrograms/kg, on lung mechanics, pulmonary hemodynamics, lung fluid and solute exchange, pulmonary gas exchange, blood and lymph leukocyte counts, and plasma and lymph cyclooxygenase products of arachidonate metabolism in 10 awake sheep with normal granulocyte counts and after granulocyte depletion with hydroxyurea. PMA significantly altered lung mechanics from base line in both nongranulocyte depleted and granulocyte-depleted sheep. Dynamic compliance decreased by over 50% and resistance to airflow across the lungs increased over threefold acutely following PMA infusion in both sets of experiments. Changes in lung mechanics, pulmonary hemodynamics, lung fluid and solute exchange, pulmonary gas exchange, and plasma and lymph arachidonate metabolites were not significantly affected by greater than 99% depletion of circulating granulocytes. We conclude that the lung injury caused by PMA in chronically instrumented awake sheep probably is not a result of activation of circulating granulocytes.     

Antibody production in early life supported by maternal lymphocyte factors

To examine the influence of maternal lymphocyte factors on the immune responses in offspring in early life, antibody production in neonates born to either normal or lymphocyte-deficient mothers was analyzed. Recombination activating gene (Rag)-2(+/-) mouse neonates born to Rag-2(+/+), Rag-2(+/-)or Rag-2(-/-)mothers were injected with goat anti-mouse IgD antiserum, and IgE and IgG(1) production was evaluated. The levels of IgE and IgG(1) were higher in the pups born to Rag-2(+/+)and Rag-2(+/-) dams than to lymphocyte-deficient Rag-2(-/-) dams. The enhanced antibody production in the former compared with the latter neonates was also found following immunization with ovalbumin or TNP-Ficoll. Thus, the presence of maternal lymphocyte factors was suggested in neonates that augmented antigen-specific antibody production in both T cell-dependent and -independent pathways. A reduction in antibody production was observed in normal neonates when they were foster-nursed by Rag-2(-/-) mothers. Thus, the maternal lymphocyte factors enhancing the immune responses in newborns were shown to be present in breast-milk.     

Subset-specific reductions in lung lymphocyte accumulation following intratracheal antigen challenge in endothelial selectin-deficient mice

We previously demonstrated induction and expression of CD62E and CD62P in the lungs of mice primed and then challenged with intratracheal (i.t.) SRBC. The current study examined accumulation of endogenous lymphocytes in the lungs of endothelial E- and P-selectin-deficient (E(-)P(-)) mice after i.t. SRBC challenge. Compared with syngeneic wild-type (wt) mice, E(-)P(-) mice showed an 85-95% decrease in CD8(+) T cells and B cells in the lungs at both early and late time points. In contrast, CD4(+) T cell accumulation was reduced by approximately 60% early, but equivalent to wt levels later. Surprisingly, many gammadelta T cells were found in lungs and blood of E(-)P(-) mice but were undetectable in the lungs and blood of wt mice. Absolute numbers of peripheral blood CD4, CD8, and B lymphocytes in E(-)P(-) mice equaled or exceeded the levels in wt mice, particularly after challenge. Trafficking studies using alphabeta T lymphoblasts confirmed that the recruitment of circulating cells after challenge was markedly reduced in E(-)P(-) mice. Furthermore, Ag priming occurred normally in both the selectin-deficient and wt mice, because primed lymphocytes from both groups transferred Ag sensitivity into naive wt mice. Lung production of mRNA for six CC and two CXC chemokines after challenge was equivalent by RT-PCR analysis in wt and E(-)P(-) mice. Therefore, reduced lung accumulation of alphabeta T cells and B cells in E(-)P(-) mice did not result from reduced delivery of circulating lymphocytes to the lungs, unsuccessful Ag priming, or defective pulmonary chemokine production. Selectin-dependent lymphocyte recruitment into the lungs following i.t.-SRBC challenge is subset specific and time dependent.     

Immunohistologic and functional characterization of a vascular addressin involved in lymphocyte homing into peripheral lymph nodes

The tissue localization or "homing" of circulating lymphocytes is directed in part by specialized vessels that define sites of lymphocyte exit from the blood. In peripheral lymph nodes, mucosal lymphoid tissues (Peyer's patches and appendix), and sites of chronic inflammation, for example, lymphocytes leave the blood by adhering to and migrating between those endothelial cells lining postcapillary high endothelial venules (HEV). Functional analyses of lymphocyte interactions with HEV have shown the lymphocytes can discriminate between HEV in different tissues, indicating that HEV express tissue-specific determinants or address signals for lymphocyte recognition. We recently described such a tissue-specific "vascular addressin" that is selectively expressed by endothelial cells supporting lymphocyte extravasation into mucosal tissues and that appears to be required for mucosa-specific lymphocyte homing (Streeter, P. R., E. L. Berg, B. N. Rouse, R. F. Bargatze, and E. C. Butcher. 1988. Nature (Lond.). 331:41-46). Here we document the existence and tissue-specific distribution of a distinct HEV differentiation antigen. Defined by monoclonal antibody MECA-79, this antigen is expressed at high levels on the lumenal surface and in the cytoplasm of HEV in peripheral lymph nodes. By contrast, although MECA-79 stains many HEV in the mucosal Peyer's patches, expression in most cases is restricted to the perivascular or ablumenal aspect of these venules. In the small intestine lamina propria, a mucosa-associated site that supports the extravasation of lymphocytes, venules do not stain with MECA-79. Finally, we demonstrate that MECA-79 blocks binding of both normal lymphocytes and a peripheral lymph node-specific lymphoma to peripheral lymph node HEV in vitro and that it also inhibits normal lymphocyte homing to peripheral lymph nodes in vivo without significantly influencing lymphocyte interactions with Peyer's patch HEV in vitro or in vivo. Thus, MECA-79 defines a novel vascular addressin involved in directing lymphocyte homing to peripheral lymph nodes.     

Chronopharmacologic Effects of Recombinant Human Granulocyte Colony-Stimulating Factor (rhG-CSF) on Hematopoiesis in Mice

Chronopharmacologic effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) on circulating white blood cell and differential counts as well as bone marrow granulocyte-macrophage colony-forming units (CFU-GM) counts were investigated in B6D2F1 mice. The animals were synchronized with an alternation of 12 h of light (L) and 12 h of darkness (D) (LD 12:12) for 3 weeks prior to study, then received a daily subcutaneous injection of rhG-CSF (400 µg/kg/day) for 4 consecutive days at 3, 9, 15 or 21 h ours a fter l ight o nset (HALO). Samples were obtained on the fifth day at the same circadian stage as that of rhG-CSF injection. rhG-CSF significantly increased the 24-h mean of leukocyte, neutrophil, lymphocyte and CFU-GM counts. Maximum increase in leukocyte and neutrophil counts was observed when rhG-CSF was administered in the middle of the dark span, while maximum stimulatory effect on circulating lymphocytes or on CFU-GM counts was obtained with rhG-CSF administration near the middle of the light span. The results indicate that choosing the dosing time of this cytokine may selectively orient its pharmacologic action. Appropriate chronomodulated delivery schemes of rhG-CSF may further reduce hematological toxicity following chemotherapy.     

Chronopharmacologic Effects of Recombinant Human Granulocyte Colony-Stimulating Factor (rhG-CSF) on Hematopoiesis in Mice

Chronopharmacologic effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) on circulating white blood cell and differential counts as well as bone marrow granulocyte-macrophage colony-forming units (CFU-GM) counts were investigated in B6D2F1 mice. The animals were synchronized with an alternation of 12 h of light (L) and 12 h of darkness (D) (LD 12:12) for 3 weeks prior to study, then received a daily subcutaneous injection of rhG-CSF (400 µg/kg/day) for 4 consecutive days at 3, 9, 15 or 21 h ours a fter l ight o nset (HALO). Samples were obtained on the fifth day at the same circadian stage as that of rhG-CSF injection. rhG-CSF significantly increased the 24-h mean of leukocyte, neutrophil, lymphocyte and CFU-GM counts. Maximum increase in leukocyte and neutrophil counts was observed when rhG-CSF was administered in the middle of the dark span, while maximum stimulatory effect on circulating lymphocytes or on CFU-GM counts was obtained with rhG-CSF administration near the middle of the light span. The results indicate that choosing the dosing time of this cytokine may selectively orient its pharmacologic action. Appropriate chronomodulated delivery schemes of rhG-CSF may further reduce hematological toxicity following chemotherapy.