Ly6G deficiency alters the dynamics of neutrophil recruitment and pathogen capture during Leishmania major skin infection.

Neutrophils represent one of the first immune cell types recruited to sites of infection, where they can control pathogens by phagocytosis and cytotoxic mechanisms. Intracellular pathogens such as Leishmania major can hijack neutrophils to establish an efficient infection. However the dynamic interactions of neutrophils with the pathogen and other cells at the site of the infection are incompletely understood. Here, we have investigated the role of Ly6G, a homolog of the human CD177 protein, which has been shown to interact with cell adhesion molecules, and serves as a bona fide marker for neutrophils in mice. We show that Ly6G deficiency decreases the initial infection rate of neutrophils recruited to the site of infection. Although the uptake of L. major by subsequently recruited monocytes was tightly linked with the concomitant uptake of neutrophil material, this process was not altered by Ly6G deficiency of the neutrophils. Instead, we observed by intravital 2-photon microscopy that Ly6G-deficient neutrophils entered the site of infection with delayed initial recruitment kinetics. Thus, we conclude that by promoting neutrophils' ability to efficiently enter the site of infection, Ly6G contributes to the early engagement of intracellular pathogens by the immune system.

Cyclophosphamide treatment for hypertension and renal injury in an experimental model of systemic lupus erythematosus.

Cardiovascular disease is the major cause of mortality among patients with the autoimmune disorder systemic lupus erythematosus (SLE). Our laboratory previously reported that immunosuppression with mycophenolate mofetil, a common therapy in patients with SLE, attenuates the development of hypertension in an experimental model of SLE. Cyclophosphamide (CYC) is another common therapy for patients with SLE that has contributed to improved disease management; however, its impact on the development of hypertension associated with SLE is not clear. We tested whether treatment with CYC (25 mg/kg, once/week, IP injection) for 4 weeks would attenuate hypertension in an established female mouse model of SLE with hypertension (30-week-old NZBWF1 females). Plasma anti-dsDNA IgG levels, pathogenic for the disease, were lower in CYC-treated SLE mice compared to vehicle-treated SLE mice, suggesting efficacy of the therapy to suppress aberrant immune system function. Mean arterial pressure (MAP) was assessed by carotid artery catheters in conscious mice. Treatment did not attenuate the development of hypertension when compared to vehicle-treated SLE mice; however, urinary albumin excretion was lower in CYC-treated animals. Corresponding with the reduction in autoantibodies, data suggest that CYC treatment lowered circulating CD45R+ B cells. Paradoxically, circulating CD11b+ Ly6G+ neutrophils were increased in CYC-treated SLE mice compared to vehicle treated. Estrus cycling data also suggest that CYC treatment had an impact on ovarian function that may be consistent with reduced circulating estrogen levels. Taken together, these data suggest that CYC treatment attenuates autoantibody production and renal disease during SLE, but that the potential to affect MAP may be blunted by the increase in circulating neutrophils and CYC's impact on ovarian function.

Clinical significance of myositis-specific autoantibody profiles in Japanese patients with polymyositis/dermatomyositis.

Myositis-specific autoantibodies, such as anti-melanoma differentiation associated gene 5 (MDA5) and anti-anti-amino acyl-tRNA synthetases (ARS) antibodies, are associated with interstitial lung diseases (ILD), which determine the prognosis of polymyositis/dermatomyositis (PM/DM) patients. However, there is a paucity of data on the clinical correlation between anti-Sjögren syndrome-related antigen A (anti-SSA)/Ro52 antibodies in PM/DM. We investigated the prevalence of myositis-specific autoantibodies including anti-SSA/Ro52 antibody and assessed the clinical significance of these antibodies in patients with PM/DM.We retrospectively reviewed demographic data and clinical outcomes in patients with PM/DM. The study population comprised 24 patients with PM and 60 patients with DM. The presence of anti-myositis-specific antibodies (MDA5, ARS, Jo-1, SSA/Ro52) was determined by immunosorbent assay (ELISA).Anti-MDA5 antibody was detected in 18 patients with DM (n = 60). Anti-ARS/anti-SSA/Ro52 antibodies were detected in 31 and 39 patients with PM/DM (n = 84). Rapidly progressive ILD patients were mainly found in the anti-MDA5 antibody-positive DM group. During the follow-up period, 9 patients died. Kaplan-Meier analysis demonstrated that survival rates seem to be lower in DM patients with anti-MDA5 antibodies compared with those without anti-MDA5 antibodies. Furthermore, dual positivity for anti-SSA/Ro52 and anti-MDA5 antibodies was significantly higher in nonsurviving DM patients compared with survivors.Although the presence of anti-ARS or anti-MDA5 antibodies is a prognostic marker in patients with PM/DM, combined presence of anti-SSA/Ro52 and anti-MDA5 antibodies represent another marker for clinical outcome in DM patients. Our results suggest that anti-SSA/Ro52 antibody positivity in DM patients with anti-MDA5 antibody reveals a subgroup of DM patients with poor prognosis.

Adipose tissue macrophages do not affect atherosclerosis development in mice.

BACKGROUND AND AIMS: Obese individuals have a higher risk of developing atherosclerosis, possibly driven by adipose tissue (AT) inflammation. We recently showed that AT macrophages (ATMs), which accumulate in the expanding obese AT, produce mediators causing immune cell recruitment from the bone marrow. In the current study, we evaluated whether ATMs are directly involved in atherosclerotic plaque development. METHODS: Lean ldlr-/- acceptor mice received visceral AT (vAT) from lean, obese, or ATM-depleted obese ldlr-/- mice. Acceptor mice were fed high cholesterol diet (HCD) for 4 weeks before and 8 weeks after AT transplantation to induce atherosclerosis. Atherosclerotic plaque development was studied 8 weeks after transplantation. RESULTS: Transplanting donor vAT from obese mice increased circulating triglycerides and B-cells, but decreased Ly6c- monocytes. Plasma cholesterol, Ly6c+ monocytes, T-cells, NK-cells and eosinophils were unaffected. Depleting ATMs from obese AT using clodronate liposomes prior to vAT transplantation prevented the increase in triglycerides and B-cells and decrease in Ly6c- monocytes, but did increase eosinophils. Circulating Cxcl1 was reduced by obese AT transplantation and Ifn-γ tended to be increased while Tnf and Il-1ß were unaffected. ATM-depleted obese AT transplantation also reduced Cxcl1, but increased circulating Tnf levels. However, obese AT transplantation with or without depletion of ATMs did not influence atherosclerotic plaque size, phenotype, or stability. CONCLUSIONS: ATMs from obese vAT do not affect atherosclerotic plaque development or phenotype.

Differential attenuation of ß2 integrin-dependent and -independent neutrophil migration by Ly6G ligation.

Antibody ligation of the murine neutrophil surface protein Ly6G disrupts neutrophil migration in some contexts but not others. We tested whether this variability reflected divergent dependence of neutrophil migration on ß2 integrins, adhesion molecules that interact with Ly6G at the neutrophil surface. In integrin-dependent murine arthritis, Ly6G ligation attenuated joint inflammation, even though mice lacking Ly6G altogether developed arthritis normally. By contrast, Ly6G ligation had no impact on integrin-independent neutrophil migration into inflamed lung. In peritoneum, the role of ß2 integrins varied with stimulus, proving dispensable for neutrophil entry in Escherichia coli peritonitis but contributory in interleukin 1 (IL-1)-mediated sterile peritonitis. Correspondingly, Ly6G ligation attenuated only IL-1 peritonitis, disrupting the molecular association between integrins and Ly6G and inducing cell-intrinsic blockade restricted to integrin-dependent migration. Consistent with this observation, Ly6G ligation impaired integrin-mediated postadhesion strengthening for neutrophils arresting on activated cremaster endothelium in vivo. Together, these findings identify selective inhibition of integrin-mediated neutrophil emigration through Ly6G ligation, highlighting the marked site and stimulus specificity of ß2 integrin dependence in neutrophil migration.

MicroRNA-21 Deficiency Alters the Survival of Ly-6Clo Monocytes in ApoE-/- Mice and Reduces Early-Stage Atherosclerosis-Brief Report.

Objective- To determine the role of microRNA-21 (miR-21) on the homeostasis of monocyte subsets and on atherosclerosis development in ApoE-/- (apolipoprotein E) mice. Approach and Results- In ApoE-/- mice, miR-21 expression was increased in circulating Ly-6Clo nonclassical monocytes in comparison to Ly-6Chi monocytes. The absence of miR-21 significantly altered the survival and number of circulating Ly-6Clo nonclassical monocytes in ApoE-/- mice. In the early stages of atherosclerosis, the absence of miR-21 limited lesion development both in the aortic sinus (by almost 30%) and in the aorta (by almost 50%). This was associated with less monocyte availability in circulation and increased apoptosis of local macrophages in plaques. At later stages of atherosclerosis, lesion size in the aortic root was similar in ApoE-/- and ApoE-/- miR-21-/- mice, but plaques showed a less stable phenotype (larger necrotic cores) in the latter. The loss of protection in advanced stages was most likely because of excessive inflammatory apoptosis related to an impairment of local efficient efferocytosis. Conclusions- Gene deletion of miR-21 in ApoE-/- mice alters Ly-6Clo nonclassical monocytes homeostasis and contribute to limit early-stage atherosclerosis.

NK1.1+ cells promote sustained tissue injury and inflammation after trauma with hemorrhagic shock.

Various cell populations expressing NK1.1 contribute to innate host defense and systemic inflammatory responses, but their role in hemorrhagic shock and trauma remains uncertain. NK1.1+ cells were depleted by i.p. administration of anti-NK1.1 (or isotype control) on two consecutive days, followed by hemorrhagic shock with resuscitation and peripheral tissue trauma (HS/T). The plasma levels of IL-6, MCP-1, alanine transaminase (ALT), and aspartate aminotransferase (AST) were measured at 6 and 24 h. Histology in liver and gut were examined at 6 and 24 h. The number of NK cells, NKT cells, neutrophils, and macrophages in liver, as well as intracellular staining for TNF-α, IFN-γ, and MCP-1 in liver cell populations were determined by flow cytometry. Control mice subjected to HS/T exhibited end organ damage manifested by marked increases in circulating ALT, AST, and MCP-1 levels, as well as histologic evidence of hepatic necrosis and gut injury. Although NK1.1+ cell-depleted mice exhibited a similar degree of organ damage as nondepleted animals at 6 h, NK1.1+ cell depletion resulted in marked suppression of both liver and gut injury by 24 h after HS/T. These findings indicate that NK1.1+ cells contribute to the persistence of inflammation leading to end organ damage in the liver and gut.

Expression of CD11c Is Associated with Unconventional Activated T Cell Subsets with High Migratory Potential.

CD11c is an α integrin classically employed to define myeloid dendritic cells. Although there is little information about CD11c expression on human T cells, mouse models have shown an association of CD11c expression with functionally relevant T cell subsets. In the context of genital tract infection, we have previously observed increased expression of CD11c in circulating T cells from mice and women. Microarray analyses of activated effector T cells expressing CD11c derived from naïve mice demonstrated enrichment for natural killer (NK) associated genes. Here we find that murine CD11c+ T cells analyzed by flow cytometry display markers associated with non-conventional T cell subsets, including γδ T cells and invariant natural killer T (iNKT) cells. However, in women, only γδ T cells and CD8+ T cells were enriched within the CD11c fraction of blood and cervical tissue. These CD11c+ cells were highly activated and had greater interferon (IFN)-γ secretory capacity than CD11c- T cells. Furthermore, circulating CD11c+ T cells were associated with the expression of multiple adhesion molecules in women, suggesting that these cells have high tissue homing potential. These data suggest that CD11c expression distinguishes a population of circulating T cells during bacterial infection with innate capacity and mucosal homing potential.

Bone marrow-specific caspase-1/11 deficiency inhibits atherosclerosis development in Ldlr(-/-) mice.

Recent investigations have suggested that inflammasome activation plays an important role during atherosclerosis. Upon activation, the inflammasome induces processing and release of pro-inflammatory cytokines interleukin 1ß (IL-1ß) and interleukin 18 (IL-18) via activation of caspase-1/11. Previously, it was shown that complete caspase-1 deficiency is protective against atherosclerosis development. However, while macrophages are the main inflammatory cells involved in atherosclerosis, the exact role of macrophage-specific caspase-1/11 activation during development of cardiovascular disease has never been investigated. We hypothesized that hematopoietic caspase-1/11 deficiency leads to reduced atherosclerosis development. To investigate the specific contribution of hematopoietic caspase-1/11 activation to atherosclerosis development, Ldlr(-/-) mice received a transplant (tp) of wild-type (WT) or caspase-1/11(-/-) bone marrow, to create WT-tp mice and caspase-1/11(-/-) -tp mice, and fed a high-fat, high-cholesterol diet for 12 weeks. Our results showed an increase in anti-inflammatory blood leukocytes in caspase-1/11(-/-) -tp mice compared with WT-tp mice, as indicated by a decreased level of Ly6C(high) monocytes and an increased level of Ly6C(low) monocytes. In line with our hypothesis, hematopoietic deletion of caspase-1/11 resulted in a strong reduction in atherosclerotic plaque size. Furthermore, necrotic core content was dramatically decreased in caspase-1/11(-/-) -tp mice. Our data indicate that hematopoietic caspase-1/11 activation is involved in vascular inflammation and atherosclerosis, and plays an important role in cardiovascular disease progression.

Ly6C(high) monocytes become alternatively activated macrophages in schistosome granulomas with help from CD4+ cells.

Alternatively activated macrophages (AAM) that accumulate during chronic T helper 2 inflammatory conditions may arise through proliferation of resident macrophages or recruitment of monocyte-derived cells. Liver granulomas that form around eggs of the helminth parasite Schistosoma mansoni require AAM to limit tissue damage. Here, we characterized monocyte and macrophage dynamics in the livers of infected CX3CR1(GFP/+) mice. CX3CR1-GFP⁺ monocytes and macrophages accumulated around eggs and in granulomas during infection and upregulated PD-L2 expression, indicating differentiation into AAM. Intravital imaging of CX3CR1-GFP⁺ Ly6C(low) monocytes revealed alterations in patrolling behavior including arrest around eggs that were not encased in granulomas. Differential labeling of CX3CR1-GFP⁺ cells in the blood and the tissue showed CD4⁺ T cell dependent accumulation of PD-L2⁺ CX3CR1-GFP⁺ AAM in the tissues as granulomas form. By adoptive transfer of Ly6C(high) and Ly6C(low) monocytes into infected mice, we found that AAM originate primarily from transferred Ly6C(high) monocytes, but that these cells may transition through a Ly6C(low) state and adopt patrolling behavior in the vasculature. Thus, during chronic helminth infection AAM can arise from recruited Ly6C(high) monocytes via help from CD4⁺ T cells.

Ly-6Chigh monocytes depend on Nr4a1 to balance both inflammatory and reparative phases in the infarcted myocardium.

RATIONALE: Healing after myocardial infarction involves the biphasic accumulation of inflammatory lymphocyte antigen 6C (Ly-6C)(high) and reparative Ly-6C(low) monocytes/macrophages (Mo/MΦ). According to 1 model, Mo/MΦ heterogeneity in the heart originates in the blood and involves the sequential recruitment of distinct monocyte subsets that differentiate to distinct macrophages. Alternatively, heterogeneity may arise in tissue from 1 circulating subset via local macrophage differentiation and polarization. The orphan nuclear hormone receptor, nuclear receptor subfamily 4, group a, member 1 (Nr4a1), is essential to Ly-6C(low) monocyte production but dispensable to Ly-6C(low) macrophage differentiation; dependence on Nr4a1 can thus discriminate between systemic and local origins of macrophage heterogeneity. OBJECTIVE: This study tested the role of Nr4a1 in myocardial infarction in the context of the 2 Mo/MΦ accumulation scenarios. METHODS AND RESULTS: We show that Ly-6C(high) monocytes infiltrate the infarcted myocardium and, unlike Ly-6C(low) monocytes, differentiate to cardiac macrophages. In the early, inflammatory phase of acute myocardial ischemic injury, Ly-6C(high) monocytes accrue in response to a brief C-C chemokine ligand 2 burst. In the second, reparative phase, accumulated Ly-6C(high) monocytes give rise to reparative Ly-6C(low) F4/80(high) macrophages that proliferate locally. In the absence of Nr4a1, Ly-6C(high) monocytes express heightened levels of C-C chemokine receptor 2 on their surface, avidly infiltrate the myocardium, and differentiate to abnormally inflammatory macrophages, which results in defective healing and compromised heart function. CONCLUSIONS: Ly-6C(high) monocytes orchestrate both inflammatory and reparative phases during myocardial infarction and depend on Nr4a1 to limit their influx and inflammatory cytokine expression.

Deletion of FHL2 gene impaired ischemia-induced blood flow recovery by modulating circulating proangiogenic cells.

OBJECTIVE: The four and a half Lin11, Isl-1 and Mec-3 (LIM) domain protein 2 (FHL2) is a member of the four and a half LIM domain-only (FHL) gene family, and has been shown to play an important role in inhibiting inflammatory angiogenesis. Here, we tested the hypothesis that impaired ischemia-induced neovascularization in mice lacking FHL2 is related to a defect in proangiogenic cell mobilization and functions in vasculogenesis. APPROACH AND RESULTS: Unilateral hindlimb ischemia surgery was conducted in FHL2(-/-) mice and wild-type (FHL2(+/+)) mice. After hindlimb ischemia surgery, expression of FHL2 protein was noted in ischemic tissues of wild-type mice. All FHL2-null mice (100%) suffered from spontaneous foot amputation, but only 20% of wild-type mice had ischemia-induced foot amputation after ischemic surgery. Blood flow recovery was significantly impaired in FHL2(-/-) mice when compared with that in wild-type mice as determined by laser Doppler imaging. Histological analysis revealed that the capillary density in the ischemic limb was increased in wild-type mice, whereas no such increase was noted in FHL2(-/-) mice. Flow cytometry demonstrated that the number of CD34(+) or CD34(+)/Sca-1(+)/Flk-1(+) in peripheral blood after ischemic surgery significantly decreased in FHL2-null mice than those in wild-type mice after hindlimb ischemia surgery. FHL2 deficiency impaired ex vivo angiogenesis in mouse aortic-ring culture assay, which revealed that the mean density of the microvessels was significantly higher in the wild-type aorta than in the FHL2(-/-) aorta. Western blot analysis showed that vascular endothelial growth factor (VEGF), interleukin-6, matrix metalloproteinase-2, matrix metalloproteinase-9, vascular cell adhesion molecule-1, and intercellular adhesion molecule-1 levels were significantly downregulated in ischemic muscles in FHL2-null mice compared with wild-type mice. Deletion of FHL2 protein by FHL2 small interfering RNA impaired VEGF production under hypoxia conditions, and also suppressed endothelial progenitor cell angiogenic functions, but these effects could be recovered by administration of VEGF. CONCLUSIONS: Deficiency of FHL2 impairs ischemia-induced neovascularization, and these suppressive effects may occur through a reduction in proangiogenic cell mobilization, migration, and vasculogenesis functions.

Omega-3 fatty acids ameliorate atherosclerosis by favorably altering monocyte subsets and limiting monocyte recruitment to aortic lesions.

OBJECTIVE: Fish oil, containing omega-3 fatty acids, attenuates atherosclerosis. We hypothesized that omega-3 fatty acid-enriched oils are atheroprotective through alteration of monocyte subsets and their trafficking into atherosclerotic lesions. METHODS AND RESULTS: Low-density lipoprotein receptor knockout and apolipoprotein E(-/-) mice were fed diets containing 10% (calories) palm oil and 0.2% cholesterol, supplemented with an additional 10% palm oil, echium oil (containing 18:4 n-3), or fish oil. Compared with palm oil-fed low-density lipoprotein receptor knockout mice, echium oil and fish oil significantly reduced plasma cholesterol, splenic Ly6C(hi) monocytosis by ≈50%, atherosclerosis by 40% to 70%, monocyte trafficking into the aortic root by ≈50%, and atherosclerotic lesion macrophage content by 30% to 44%. In contrast, atherosclerosis and monocyte trafficking into the artery wall was not altered by omega-3 fatty acids in apolipoprotein E(-/-) mice; however, Ly6C(hi) splenic monocytes positively correlated with aortic root intimal area across all diet groups. In apolipoprotein E(-/-) mice, fish oil reduced the percentage of blood Ly6C(hi) monocytes, despite an average 2-fold higher plasma cholesterol relative to palm oil. CONCLUSIONS: The presence of splenic Ly6C(hi) monocytes parallels the appearance of atherosclerotic disease in both low-density lipoprotein receptor knockout and apolipoprotein E(-/-) mice. Furthermore, omega-3 fatty acids favorably alter monocyte subsets independently from effects on plasma cholesterol and reduce monocyte recruitment into atherosclerotic lesions.

Enrichment of functionally distinct mouse hematopoietic progenitor cell populations using CD62L.

The details of the bifurcation of the lymphoid and myeloid lineages following commitment by multipotent progenitor cells (MPP) remain a topic of controversy. We report that the surface glycoprotein CD62L can be characterized as a novel marker of this and other stages of early hematopoietic differentiation. Cell isolation and transplant studies demonstrated CD62L(neg/low) long-term hematopoietic stem cells and CD62L(high) MPP within the traditionally defined c-kit(pos)Lin(neg/low)Sca-1(pos) stem/progenitor cell population. Within the MPP population, previously defined as c-kit(pos)Lin(neg/low)Sca-1(pos)-Thy-1.1(neg)Flt3(pos), Sca-1 and CD62L resolved four populations and segregated Sca-1(high)CD62L(neg/low) MPP from Sca-1(high)CD62L(high) leukocyte-biased progenitors. Using a novel transplantation method that allows tracking of erythroid and platelet engraftment as an alternative to the classical method of in vitro colony formation, we characterized Sca-1(high)CD62L(neg/low) cells as MPP, based on transient engraftment of these lineages. These data establish CD62L as a useful tool in the study of early hematopoiesis and emphasize the power of trilineage-engraftment studies in establishing the lineage potential of MPP subsets.

Genetic deletion of chemokine receptor Ccr6 decreases atherogenesis in ApoE-deficient mice.

RATIONALE: The chemokine receptor Ccr6 is a G-protein-coupled receptor expressed on various types of leukocytes identified in mouse atherosclerotic lesions. Recent evidence suggests that both CCR6 and its ligand CCL20 are also present in human atheroma; however, their functional roles in atherogenesis remain undefined. OBJECTIVE: Our objective was to delineate the role of Ccr6 in atherogenesis in the apolipoprotein E-deficient (ApoE(-/-)) mouse model of atherosclerosis. METHODS AND RESULTS: Both Ccr6 and Ccl20 are expressed in atherosclerotic aorta from ApoE(-/-) mice. Aortic lesion area in Ccr6(-/-)ApoE(-/-) mice was ∼40% and ∼30% smaller than in Ccr6(+/+)ApoE(-/-) mice at 16 and 24 weeks of age, respectively. Transplantation of bone marrow from Ccr6(-/-) mice into ApoE(-/-) mice resulted in ∼40% less atherosclerotic lesion area than for bone marrow from Ccr6(+/+) mice; lesions in Ccr6(-/-)ApoE(-/-) mice had 44% less macrophage content than lesions in Ccr6(+/+)ApoE(-/-) mice. Ccr6 was expressed on a subset of primary mouse monocytes. Accordingly, Ccl20 induced chemotaxis of primary monocytes from wild-type but not Ccr6(-/-) mice; moreover, Ccl20 induced monocytosis in ApoE(-/-) mice in vivo. Consistent with this, we observed 30% fewer monocytes in circulating blood of Ccr6(-/-)ApoE(-/-) mice, mainly because of fewer CD11b(+)Ly6C(high) inflammatory monocytes. CONCLUSIONS: Ccr6 promotes atherosclerosis in ApoE-deficient mice, which may be due in part to Ccr6 support of normal monocyte levels in blood, as well as direct Ccr6-dependent monocyte migration.

Endothelial progenitor cells contribute to the vascularization of endometriotic lesions.

Endometriosis is a frequent gynecological disease that is characterized by the development of vascularized endometriotic lesions inside the peritoneal cavity. Herein, we analyzed whether circulating endothelial progenitor cells (EPCs) are recruited and incorporated into the microvasculature of these lesions. Intraperitoneal endometriotic lesions were surgically induced in irradiated FVB/N mice, which were reconstituted with bone marrow from FVB/N-TgN (Tie2/green fluorescent protein [GFP]) 287 Sato mice. Vascularization and recruitment of GFP-positive EPCs in the lesions was analyzed by intravital fluorescence microscopy and immunohistochemistry over 4 weeks. The numbers of stem cell antigen-1 (Sca-1)/vascular endothelial growth factor receptor-2-positive EPCs in blood and hematopoietic organs of additional endometriotic and control mice were assessed by flow cytometry. We found that approximately 15% of the microvascular endothelium in engrafting endometriotic lesions consisted of incorporated GFP-positive EPCs. Recruitment of EPCs into the lesions coincided with the establishment of own blood supply and the expression of stromal cell-derived factor-1. Accordingly, treatment with the stromal cell-derived factor-1/chemokine receptor type 4 axis antagonist AMD3100 significantly decreased the number of recruited EPCs and the vascularization of endometriotic lesions. However, endometriosis did not induce increased levels of EPCs in the blood, bone marrow, and spleen of C57BL/6 mice. To our knowledge, our findings indicate for the first time that vasculogenesis (ie, de novo generation of blood vessels from EPCs) may represent an integral mechanism in the pathogenesis of endometriosis.

Circulating Ly-6C+ myeloid precursors migrate to the CNS and play a pathogenic role during autoimmune demyelinating disease.

Mature myeloid cells (macrophages and CD11b(+) dendritic cells) form a prominent component of neuroinflammatory infiltrates in multiple sclerosis and experimental autoimmune encephalomyelitis (EAE). The mechanism by which these cells are replenished during relapsing and chronic neuroinflammation is poorly understood. Here we demonstrate that CD11b(+)CD62L(+)Ly6C(hi) monocytes with colony-forming potential are mobilized into the bloodstream by a granulocyte-macrophage colony-stimulating factor-dependent pathway immediately before EAE relapses. Circulating Ly6C(hi) monocytes traffic across the blood-brain barrier, up-regulate proinflammatory molecules, and differentiate into central nervous system dendritic cells and macrophages. Enrichment of Ly6C(hi) monocytes in the circulating pool is associated with an earlier onset and increased severity of clinical EAE. Our studies indicate that granulocyte-macrophage colony-stimulating factor-driven release of Ly6C(hi) precursors from the bone marrow prevents exhaustion of central nervous system myeloid populations during relapsing or chronic autoimmune demyelination, suggesting a novel pathway for therapeutic targeting.

Blood monocyte subsets differentially give rise to CD103+ and CD103- pulmonary dendritic cell populations.

There are two major myeloid pulmonary dendritic cell (DC) populations: CD103+ DCs and CD11bhigh DCs. In this study, we investigated in detail the origins of both myeloid DC pools using multiple experimental approaches. We show that, in resting lung, Ly-6ChighCCR2high monocytes repopulated CD103+ DCs using a CCR2-dependent mechanism, and these DCs preferentially retained residual CCR2 in the lung, whereas, conversely, Ly-6ClowCCR2low monocytes repopulated CD11bhigh DCs. CX3CR1 was required to generate normal numbers of pulmonary CD11bhigh DCs, possibly because Ly-6Clow monocytes in the circulation, which normally express high levels of CX3CR1, failed to express bcl-2 and may have diminished survival in the circulation in the absence of CX3CR1. Overall, these data demonstrate that the two circulating subsets of monocytes give rise to distinct tissue DC populations.

Development of murine plasmacytoid dendritic cells defined by increased expression of an inhibitory NK receptor, Ly49Q.

Plasmacytoid dendritic cells (PDCs) are defined in mice by a unique combination of markers: CD11c, B220, and Ly6C/G. We have reported previously that PDCs express Ly49Q, a lectin-type killer cell inhibitory receptor. We now find that different expression levels of Ly49Q define sequential developmental stages of PDCs in bone marrow. Although PDCs in spleen and lymph nodes express high levels of Ly49Q, a significant portion of CD11c(+)B220(+) PDCs in bone marrow lack Ly49Q, as well as the CD4 and MHC II. Purified Ly49Q(-) marrow PDCs spontaneously up-regulate Ly49Q after overnight culture without cell proliferation and acquire most features of typical PDCs in spleen. When exposed to TLR ligands, such as CpG-oligodeoxynucleotide and hemagglutinating virus of Japan (Sendai virus), Ly49Q(-) PDCs increase CD86 and MHC class II expression but produce less IFN-alphabeta, IL-6, and IL-12p70 than Ly49Q(+) PDCs, although they are able to produce comparable amounts of TNF-alpha. However, interestingly, Ly49Q(-) PDCs do not produce TNF-alpha in response to the TLR2 ligand, Pam3SCK(4), whereas Ly49Q(+) PDCs did. Therefore, Ly49Q is a new marker to identify a precursor form of PDCs that participates in innate immunity.

A murine model of antimetabolite-based, submyeloablative conditioning for bone marrow transplantation: biologic insights and potential applications.

OBJECTIVE: Nonmyeloablative conditioning regimens for marrow transplantation are desirable in many settings. Because repeated doses of the antimetabolite 5-fluorouracil (5-FU) decreases marrow long-term repopulating ability (LTRA) upon transplantation into lethally irradiated hosts, we hypothesized that mice given sequential doses of 5-FU (termed paired dose 5-FU) may permit substantial syngeneic marrow engraftment. METHODS: C57Bl/6 or X-linked chronic granulomatous disease (X-CGD) mice were administered 5-FU (150 mg/kg) on days -5 and -1. Assessment of host marrow phenotype and repopulating ability occurred on day 0. Transplantation of syngeneic donor marrow occurred on day 0 or day +15. RESULTS: We confirmed that the number of Sca-1+lin- cells and the LTRA of marrow from paired dose 5-FU-treated animals were diminished. C57Bl/6 hosts conditioned with paired doses of 5-FU followed by transplantation of 20 x 10(6) fresh B6.SJL marrow cells on day 0 displayed 44.9% +/- 7.1% donor chimerism 2 months posttransplant, and 34.4% +/- 8.6% donor chimerism 6 months posttransplant. In contrast, paired dose 5-FU-conditioned hosts transplanted with similar numbers of donor cells on day +15 exhibited only 3.4% +/- 1.2% donor chimerism at 2 months. Paired dose 5-FU-conditioned X-CGD hosts transplanted with MSCV-m91Neo-transduced X-CGD marrow averaged 6.6% +/- 2.3% (range, 4%-10%) NADPH oxidase-reconstituted neutrophils 12-16 months after transplant. CONCLUSION: These findings support the concept that impairment of host stem cell competitiveness may be an important mechanism for permitting engraftment of donor cells, and suggest that only a brief period of modest host stem cell impairment may be necessary to achieve substantial donor cell engraftment.