Despite this delay in viral clearance, B6 mice did not develop any overt signs of HLH or worsening of tissue inflammation (Figure 6 and data not shown)

Despite this delay in viral clearance, B6 mice did not develop any overt signs of HLH or worsening of tissue inflammation (Figure 6 and data not shown). There are several properties of ruxolitinib that make it particularly appealing as a treatment of HLH. test was used. Significance is reported as *(< .05) and **(< .001). values < .05 were considered significant. Results Ruxolitinib ameliorates the hematologic manifestations of CpG-induced HLH Following the repeated engagement of Toll-like receptor 9 by the serial administration of CpG DNA, B6 mice experience activation of the innate immune system and develop many of the cardinal manifestations of HLH, including trilineage cytopenias, hypercytokinemias, and tissue inflammation.18 Because an HLH-like disease can be induced in wild-type (WT) mice, this model of CpG-induced inflammation has been used to simulate the secondary forms of disease, which are generally not associated with germ line mutations. To determine whether inhibition of JAK signaling would attenuate disease severity, B6 mice were administered PBS or CpG every other day for 9 days (Figure 1A). Beginning on day 4, mice were treated or not with ruxolitinib twice daily by oral gavage. On day 9, animals were euthanized, and organs harvested and examined. Open in a separate window Figure 1 Treatment with ruxolitinib lessens CpG-induced splenomegaly and cytopenias. (A) C57BL/6 (B6) mice were treated with PBS or CpG (50 RAD140 g) RAD140 every other day as indicated (open/white arrow). Beginning on day 4, mice did or did not receive ruxolitinib (Ruxo) twice daily by oral gavage. On day 9, mice were euthanized and analyses performed. (B) Whole-spleen images from treatment groups. (C) Splenomegaly was quantified by measuring the ratio of spleen to body weight 100. (D) Blood was analyzed for WBCs, RBCs, hemoglobin, platelets, neutrophils (NC), and lymphocytes (LC). Individual symbols each depict 1 mouse with horizontal lines representing the mean standard deviation (SD). Data are representative of 3 independent experiments. *< .05. Compared with control PBS-treated mice, CpG-treated animals developed marked splenomegaly as determined by gross visual inspection (Figure 1B) and measurement of the spleen-to-body weight ratio (Figure 1C). CpG-treated animals also developed pancytopenia, including reductions in the white blood cell (WBC) count, hemoglobin (Hgb), red blood cell (RBC) count, and platelet count (Plt; Figure 1D). The reduction in WBC was primarily due to a decrease in the absolute lymphocyte count. Remarkably, treatment of CpG-injected mice with ruxolitinib at a dose previously shown to lessen disease features and prolong survival in a murine model of JAK2-driven myeloproliferative disorder20 significantly lessened these clinical and laboratory parameters, restoring spleen size, WBC, RBC, Hgb, and Plt count to those observed in control PBS-injected mice (Figure 1D). Of note, the administration of ruxolitinib to control PBS-injected mice had no effect on baseline hematologic parameters (Figure 1D). Ruxolitinib lowers serum cytokine levels and reduces tissue inflammation in CpG-treated mice CpG-treated mice exhibit elevated levels of serum cytokines, including IFN, which is critical for disease initiation and progression.18 To examine whether JAK inhibition reduces CpG-induced hypercytokinemia, we measured serum cytokine levels in mice that had or had not received treatment with ruxolitinib. As previously reported, CpG-treated mice developed increased serum IFN, IL-6, and IL-12 (Figure 2A). In contrast, these proinflammatory cytokines RAD140 were significantly lower and reduced to baseline levels in ruxolitinib-treated animals (Figure 2A). Curiously, ruxolitinib treatment of CpG-injected mice did not show lowering of every cytokine, as can be seen by the modest but not statistically significant decrease in the serum level of IL-10 (Figure 2A). Open in a separate window Figure 2 Ruxolitinib treatment reduces CpG-induced hypercytokinemias and ameliorates liver inflammation. (A) Serum cytokine levels were assessed on day 9. (B) H&E-stained liver sections demonstrate inflammatory infiltrates (dark purple clusters), indicated by arrows. Representative sections are shown at a magnification of 20 (top panels) and following computer analysis of inflammatory area RAD140 (bottom panels). (C) The number of inflammatory foci (left) and percent area occupied by inflammatory foci with respect to the high-power field (HPF) of view (right) was determined by computer analysis of histologic samples. Symbols in panel A represent individual Mouse monoclonal to CD56.COC56 reacts with CD56, a 175-220 kDa Neural Cell Adhesion Molecule (NCAM), expressed on 10-25% of peripheral blood lymphocytes, including all CD16+ NK cells and approximately 5% of CD3+ lymphocytes, referred to as NKT cells. It also is present at brain and neuromuscular junctions, certain LGL leukemias, small cell lung carcinomas, neuronally derived tumors, myeloma and myeloid leukemias. CD56 (NCAM) is involved in neuronal homotypic cell adhesion which is implicated in neural development, and in cell differentiation during embryogenesis mice in each treatment group where in panel C they represent the number of, or area encompassed by, inflammatory foci (clusters containing >8 lymphocytes) per 20 field of view. Data shown are mean SD and are representative of 3 independent experiments. *< .05; **< .001. In HLH, activated immune cells infiltrate organs where they cause considerable.