Reversal of in situ T-cell exhaustion during effective human antileukemia responses to donor lymphocyte infusion.

Increasing evidence across malignancies suggests that infiltrating T cells at the site of disease are crucial to tumor control. We hypothesized that marrow-infiltrating immune populations play a critical role in response to donor lymphocyte infusion (DLI), an established and potentially curative immune therapy whose precise mechanism remains unknown. We therefore analyzed marrow-infiltrating immune populations in 29 patients (22 responders, 7 nonresponders) with relapsed chronic myelogenous leukemia who received CD4(+) DLI in the pre-tyrosine kinase inhibitor era. Immunohistochemical analysis of pretreatment marrow revealed that the presence of >4% marrow-infiltrating CD8(+) (but not CD4(+)) T cells predicted DLI response, even in the setting of high leukemia burden. Furthermore, mRNA expression profiling of marrow-infiltrating T cells of a subset of responders compared with nonresponders revealed enrichment of T-cell exhaustion-specific genes in pretreatment T cells of DLI responders and significant downregulation of gene components in the same pathway in responders in conjunction with clinical response. Our data demonstrate that response to DLI is associated with quantity of preexisting marrow CD8(+) T cells and local reversal of T-cell exhaustion. Our studies implicate T-cell exhaustion as a therapeutic target of DLI and support the potential use of novel anti-PD1/PDL1 agents in lieu of DLI.

The effects of an ActRIIb receptor Fc fusion protein ligand trap in juvenile simian immunodeficiency virus-infected rhesus macaques.

There are no approved therapies for muscle wasting in children infected with human immunodeficiency virus (HIV), which portends poor disease outcomes. To determine whether a soluble ActRIIb receptor Fc fusion protein (ActRIIB.Fc), a ligand trap for TGF-ß/activin family members including myostatin, can prevent or restore loss of lean body mass and body weight in simian immunodeficiency virus (SIV)-infected juvenile rhesus macaques (Macaca mulatta). Fourteen pair-housed, juvenile male rhesus macaques were inoculated with SIVmac239 and, 4 wk postinoculation (WPI) treated with intramuscular injections of 10 mg ⋅ kg(-1) ⋅ wk(-1) ActRIIB.Fc or saline placebo. Body weight, lean body mass, SIV titers, and somatometric measurements were assessed monthly for 16 wk. Age-matched SIV-infected rhesus macaques were injected with saline. Intervention groups did not differ at baseline. Gains in lean mass were significantly greater in the ActRIIB.Fc group than in the placebo group (P < 0.001). Administration of ActRIIB.Fc was associated with greater gains in body weight (P = 0.01) and upper arm circumference than placebo. Serum CD4(+) T-lymphocyte counts and SIV copy numbers did not differ between groups. Administration of ActRIIB.Fc was associated with higher muscle expression of myostatin than placebo. ActRIIB.Fc effectively blocked and reversed loss of body weight, lean mass, and fat mass in juvenile SIV-infected rhesus macaques.

Increased ferroportin-1 expression and rapid splenic iron loss occur with anemia caused by Salmonella enterica Serovar Typhimurium infection in mice.

The Gram-negative intracellular bacterium Salmonella enterica serovar Typhimurium causes persistent systemic inflammatory disease in immunocompetent mice. Following oral inoculation with S. Typhimurium, mice develop a hematopathological syndrome akin to typhoid fever with splenomegaly, microcytic anemia, extramedullary erythropoiesis, and increased hemophagocytic macrophages in the bone marrow, liver, and spleen. Additionally, there is marked loss of iron from the spleen, an unanticipated result, given the iron sequestration reported in anemia of inflammatory disease. To establish why tissue iron does not accumulate, we evaluated multiple measures of pathology for 4 weeks following oral infection in mice. We demonstrate a quantitative decrease in splenic iron following infection despite increased numbers of splenic phagocytes. Infected mice have increased duodenal expression of the iron exporter ferroportin-1, consistent with increased uptake of dietary iron. Liver and splenic macrophages also express high levels of ferroportin-1. These observations indicate that splenic and hepatic macrophages export iron during S. Typhimurium infection, in contrast to macrophage iron sequestration observed in anemia of inflammatory disease. Tissue macrophage export of iron occurs concurrent with high serum concentrations of interferon gamma (IFN-γ) and interleukin 12 (IL-12). In individual mice, high concentrations of both proinflammatory (tumor necrosis factor alpha [TNF-α]) and anti-inflammatory (IL-10) cytokines in serum correlate with increased tissue bacterial loads throughout 4 weeks of infection. These in vivo observations are consistent with previous cell culture studies and suggest that the relocation of iron from tissue macrophages during infection may contribute to anemia and also to host survival of acute S. Typhimurium infection.

Effects of an ActRIIB.Fc Ligand Trap on Cardiac Function in Simian Immunodeficiency Virus-Infected Male Rhesus Macaques.

An important safety consideration in the use of antagonists of myostatin and activins is whether these drugs induce myocardial hypertrophy and impair cardiac function. The current study evaluated the effects of a soluble ActRIIB receptor Fc fusion protein (ActRIIB.Fc), a ligand trap for TGF-ß/activin family members including myostatin, on myocardial mass and function in simian immunodeficiency virus (SIV)-infected juvenile rhesus macaques (Macaca mulatta). Fourteen pair-housed, juvenile male rhesus macaques were inoculated with SIVmac239; 4 weeks postinoculation, they were treated with weekly injections of 10 mg/kg ActRIIB.Fc or saline for 12 weeks. Myocardial mass and function were evaluated using two-dimensional echocardiography at baseline and after 12 weeks. The administration of ActRIIB.Fc was associated with a significantly greater increase in thickness of left ventricular posterior wall and interventricular septum both in diastole and systole. Cardiac output and cardiac index increased with time, more in animals treated with ActRIIB.Fc than in those treated with saline, but the difference was not statistically significant. The changes in ejection fraction, fractional shortening, and stroke volume did not differ significantly between groups. The changes in end-diastolic and end-systolic volumes did not differ between groups. In addition to a large reduction in IGF1 mRNA expression in the ActRIIB.Fc-treated animals, complex changes were detected in the myocardial expression of proteins related to calcium transport and storage. In conclusion, ActRIIB.Fc administration for 12 weeks was associated with increased myocardial mass but did not adversely affect myocardial function in juvenile SIV-infected rhesus macaques. Further studies are necessary to establish long-term cardiac safety.

Administration of an activin receptor IIB ligand trap protects male juvenile rhesus macaques from simian immunodeficiency virus-associated bone loss.

HIV-infected individuals are at an increased risk of osteoporosis despite effective viral suppression. Observations that myostatin null mice have increased bone mass led us to hypothesize that simian immunodeficiency virus (SIV)-associated bone loss may be attenuated by blocking myostatin/TGFß signaling. In this proof-of-concept study, pair-housed juvenile male rhesus macaques were inoculated with SIVmac239. Four weeks later, animals were treated with vehicle or Fc-conjugated soluble activin receptor IIB (ActR2B·Fc, iv. 10mg∗kg-1∗week-1) - an antagonist of myostatin and related members of TGFß superfamily. Limb and trunk bone mineral content (BMC) and density (BMD) using dual-energy X-Ray absorptiometry, circulating markers of bone growth and turnover, and serum testosterone levels were measured at baseline and during the 12-week intervention period. The increase in BMC was significantly greater in the ActRIIB.Fc-treated group (+8g) than in the placebo group (-4g) (p<0.05). BMD also increased significantly more in the ActRIIB.Fc-treated macaques (+0.03g/cm2) than in the placebo-treated animals (+0g/cm2) (p<0.005). Serum osteocalcin was about two-fold higher in the ActRIIB.Fc-treated group than in the placebo group (p<0.05), but serum C-terminal telopeptide and testosterone levels did not differ significantly between groups. The expression levels of TNFalpha (p<0.05), GADD45 (p<0.005), and sclerostin (p<0.038) in the bone-marrow were significantly lower in the ActRIIB.Fc-treated group than in the placebo group. CONCLUSION: The administration of ActRIIB.FC in SIV-infected juvenile macaques significantly increases BMC and BMD in association with reduced expression levels of markers of bone marrow inflammation.

Removal of a high-fat diet, but not voluntary exercise, reverses obesity and diabetic-like symptoms in male C57BL/6J mice.

OBJECTIVE: Both the consumption of high-fat diets and exercise are known to produce alterations in metabolism and behavior. This study focuses on the effects of a change to a low-fat diet from a high-fat diet and voluntary exercise on obesity, type-2 diabetic-like symptoms, and locomotor behavior in male C57BL/6J mice. DESIGN: Mice were initially given either a high-fat diet or regular chow, along with a cage with a running-wheel to mimic exercise, or one without, to determine to what extend exercise affects these symptoms. Then half of the mice given a high-fat diet were switched to regular chow to ascertain if the switch in diet would improve type-2 diabetic-like and obesity symptoms. RESULTS: Wheel-running alone produced an improvement in insulin in mice continuously fed a high-fat diet (p=0.006), but running-wheels did not produce any further improvements in mice with regular chow replacement (p=0.999) or in controls (p=0.996). Replacement of a high-fat diet with regular chow led to physiological improvements in insulin (p=0.012) and leptin (p <0.001), glucose tolerance (p <0.001), and obesity (p <0.001), more so than exercise alone. Mice consuming a high-fat diet without a wheel exhibited reduced home-cage activity compared to controls after the diet switch (p=0.030), while no reduction was found in running-wheel activity between high-fat diet and regular chow consuming mice after switching diets (p=0.516). CONCLUSIONS: These results suggest that exercise is only partially beneficial to improving health outcomes in mice consuming a high-fat diet, whereas incorporating a better diet, even without exercise, improves quality of health and can suppress T2DM symptoms and related conditions more so than exercise alone.

Practical murine hematopathology: a comparative review and implications for research.

Hematologic parameters are important markers of disease in human and veterinary medicine. Biomedical research has benefited from mouse models that recapitulate such disease, thus expanding knowledge of pathogenetic mechanisms and investigative therapies that translate across species. Mice in health have many notable hematologic differences from humans and other veterinary species, including smaller erythrocytes, higher percentage of circulating reticulocytes or polychromasia, lower peripheral blood neutrophil and higher peripheral blood and bone marrow lymphocyte percentages, variable leukocyte morphologies, physiologic splenic hematopoiesis and iron storage, and more numerous and shorter-lived erythrocytes and platelets. For accurate and complete hematologic analyses of disease and response to investigative therapeutic interventions, these differences and the unique features of murine hematopathology must be understood. Here we review murine hematology and hematopathology for practical application to translational investigation.