Macrophages and their monocyte precursors mediate innate immune responses and can promote a spectrum of phenotypes from pro-inflammatory to pro-resolving. Currently, there are few markers that allow for robust dissection of macrophage phenotype. We recently identified CD38 as a marker of inflammatory macrophages in murine in vitro and in vivo models. However, it is unknown whether CD38 plays a similar marker and/or functional role in human macrophages and inflammatory diseases. Here, we establish that CD38 transcript and protein are robustly induced in human macrophages exposed to LPS (±IFN-γ) inflammatory stimuli, but not with the alternative stimulus, IL-4. Pharmacologic and/or genetic CD38 loss-of-function significantly reduced the secretion of inflammatory cytokines IL-6 and IL-12p40 and glycolytic activity in human primary macrophages. Finally, monocyte analyses in systemic lupus erythematosus patients revealed that, while all monocytes express CD38, high CD38 expression in the non-classical monocyte subpopulation is associated with disease. These data are consistent with an inflammatory marker role for CD38 in human macrophages and monocytes.

The interleukin-27 (IL-27)/T-cell cytokine receptor (TCCR) pathway plays an important role in develop-

To compare the roles of programmed death 1 ligand 1 (PD‐L1) and PD‐L2 in regulating immunity to infection, we investigated responses of mice lacking PD‐L1 or PD‐L2 to infection with Leishmania mexicana. PD‐L1–/– and PD‐L2–/– mice exhibited distinct disease outcomes following infection with L. mexicana. In comparison to susceptible WT mice, PD‐L1–/– mice showed resistance to L. mexicana, as demonstrated by reduced growth of cutaneous lesions and parasite burden. In contrast, PD‐L2–/– mice developed exacerbated disease with increased parasite burden. Host resistance to L. mexicana is partly associated with the development of a Th1 response and down‐regulation of the Th2 response. Both PD‐L1–/– and PD‐L2–/– mice produced levels of IFN‐γ similar to WT mice. However, the development of IL‐4‐producing cells was reduced in PD‐L1–/– mice, demonstrating a role for PD‐L1 in regulating Th cell differentiation. This inadequate Th2 response may explain the increased resistance of PD‐L1–/– mice. Although no alterations in Th1/Th2 skewing were observed in PD‐L2–/– mice, PD‐L2–/– mice exhibited a marked increase in L. mexicana‐specific antibody production. Increased Leishmania‐specific IgG production may suppress the healing response through FcγR ligation on macrophages. Taken together, our results demonstrate that PD‐L1 and PD‐L2 have distinct roles in regulating the immune response to L. mexicana.

Recombinant adeno-associated virus (rAAV) vectors have gained an extensive record of safety and efficacy in animal models of human disease. Infrequent reports of genotoxicity have been limited to specific vectors associated with excess hepatocellular carcinomas (HCC) in mice. In order to understand potential mechanisms of genotoxicity, and identify patterns of insertion that could promote tumor formation, we compared a self-complementary AAV (scAAV) vector designed to promote insertional activation (scAAV-CBA-null) to a conventional scAAV-CMV-GFP vector. HCC-prone C3H/HeJ mice and severe combined immunodeficiency (SCID) mice were infected with vector plus secondary treatments including partial hepatectomy (HPX) and camptothecin (CPT) to determine the effects of cell cycling and DNA damage on tumor incidence. Infection with either vector led to a significant increase in HCC incidence in male C3H/HeJ mice. Partial HPX after infection reduced HCC incidence in the cytomegalovirus-green fluorescent protein (CMV-GFP)-infected mice, but not in the cognate chicken β-actin (CBA)-null infected group. Tumors from CBA-null infected, hepatectomized mice were more likely to contain significant levels of vector DNA than tumors from the corresponding CMV-GFP-infected group. Most CBA-null vector insertions recovered from tumors were associated with known proto-oncogenes or tumor suppressors. Specific patterns of insertion suggested read-through transcription, enhancer effects, and disruption of tumor suppressors as likely mechanisms for genotoxicity.

Chemokines play a critical role in recruitment of leukocytes to the site of infection, which is essential for host defense. We analyzed the role of CXC chemokine receptor 3 (CXCR3) in the control of cutaneous leishmaniasis using CXCR3 -/-C57BL/6 mice. We found that Leishmania major-infected CXCR3 -/-mice mount an efficient Th1 response as evident by markedly increased serum levels of Th1-associated IgG2a and significant production of IFN-c and IL-12 by the draining lymph node cells, restrict systemic spread of infection, but fail to control parasite replication at the site of infection and develop chronic non-healing lesions. Furthermore, the inability of CXCR3 -/-mice to control cutaneous L. major growth was associated with fewer CD4 + and CD8 + T cells and significantly lower levels of IFN-c in their lesions as compared to CXCR3 +/+ mice. These results demonstrate that CXCR3 plays a critical role in the host defense against cutaneous leishmaniasis caused by L. major. Furthermore, they also suggest that the susceptibility of CXCR3 -/-mice to L. major is due to impaired CD4 + and CD8 + T cell trafficking and decreased production of IFN-c at the site of infection rather than to their inability to mount a parasite-specific Th1 response. IntroductionLeishmania species are obligate intracellular parasites that are of extensive public health importance in the tropical and subtropical regions of the world [1]. In humans, cutaneous leishmaniasis caused by Leishmania major commonly manifests as a self-healing skin lesion followed by the development of long-term immunity. Several studies have shown that an IL-12-driven Th1 response and IFN-c production are critical for the control of L. major infection in genetically resistant mice, such as CBA/J, C57BL/6, and C3H [2][3][4][5]. On the other hand, the development of non-healing lesions in susceptible BALB/c mice is associated with the preferential induction of a Th2-like response associated with production of 6].The chemokine superfamily comprises a large number of small soluble proteins that are involved in the development and homeostasis of the hematopoietic system, angiogenesis, tissue repair, and regulation of the host immune response [7,8]. Recent studies have shown that chemokines play a critical role in the development of innate as well as acquired immunity against a variety [18]. Three CXC chemokines, CXCL9 (Mig), CXCL10 (IFN-inducible protein 10, IP-10) and CXCL11 (IFN-inducible T cell alpha chemoattractant, I-TAC), signal via CXCR3 [19,20], activate Ras/extracellular signal-regulated kinase (ERK), Src, and the phosphatidylinositol 3-kinase/Akt pathway, and mediate their biological functions such as cell migration and proliferation [21]. Many clinical studies have implicated a role for CXCR3 in the pathogenesis of several inflammatory diseases such as multiple sclerosis, psoriasis, and rheumatoid arthritis by facilitating the recruitment of pathogenic T cells to the site of inflammation [22][23][24][25]. Moreover, experimental studies using a cardiac transplanta...

Ly108, a glycoprotein of the signaling lymphocytic activation molecule family of cell surface receptors expressed by T, B, NK, and APCs has been shown to have a role in NK cell cytotoxicity and T cell cytokine responses. In this study, we describe that CD4+ T cells from mice with a targeted disruption of exons 2 and 3 of Ly108 (Ly108ΔE2+3) produce significantly less IL-4 than wild-type CD4+ cells, as judged by in vitro assays and by in vivo responses to cutaneous infection with Leishmania mexicana. Surprisingly, neutrophil functions are controlled by Ly108. Ly108ΔE2+3 mice are highly susceptible to infection with Salmonella typhimurium, bactericidal activity of Ly108ΔE2+3 neutrophils is defective, and their production of IL-6, IL-12, and TNF-α is increased. The aberrant bactericidal activity by Ly108ΔE2+3 neutrophils is a consequence of severely reduced production of reactive oxygen species following phagocytosis of bacteria. Thus, Ly108 serves as a regulator of both innate and adaptive immune responses.

T-bet and STAT1 regulate IFN-γ gene transcription in CD4+ T cells, which mediate protection against Leishmania. Here we show that T-bet and STAT1 are required for the induction of an efficient Th1 response during Leishmania donovani infection, but they play distinct roles in determining disease outcome. Both STAT1−/− and T-bet−/− mice failed to mount a Th1 response, but STAT1−/− mice were highly resistant to L. donovani and developed less immunopathology, whereas T-bet−/− mice were highly susceptible and eventually developed liver inflammation. Adoptive cell transfer studies showed that RAG2−/− recipients receiving STAT1+/+ or STAT1−/− T cells developed comparable liver pathology, but those receiving STAT1−/− T cells were significantly more susceptible to infection. These unexpected findings reveal distinct roles for T-bet and STAT1 in mediating host immunity and liver pathology during visceral leishmaniasis.

The experimental model of high-dose Leishmania mexicana infection is used frequently to study molecular mechanisms regulating Th2 response since most inbred mice regardless of their genetic background display Th2 cytokine-dependent susceptibility to L. mexicana unlike Leishmania major. Here, we analyzed the course of L. mexicana infection in BALB/c, C57BL/6 and CBA/J mouse strains using low-dose ear infection model that mimics natural transmission. Although all three strains were equally susceptible to high-dose back rump L. mexicana infection, they displayed marked differences in their ability to control parasite growth after low-dose ear infection. Leishmania mexicana-infected BALB/c mice produced high levels of Th2-associated cytokines and developed non-healing lesions full of parasites, whereas CBA/J mice preferentially produced Th1-associated IFN-gamma but low levels of IL-4, and developed small self-resolving lesions. Both BALB/c and C57BL/6 mice produced comparable amounts of IFN-gamma following L. mexicana infection, but later produced less Th2-associated cytokines, and exhibited an 'intermediate' susceptibility phenotype characterized by lesion sizes that were significantly smaller than BALB/c mice but larger than CBA/J mice. Interestingly, all three strains also showed marked differences in trafficking of macrophages, CD4+ T cells and CD8+ T cells into their lesions. Finally, we analyzed the course of low-dose L. mexicana infection in signal transducers and activators of transcription (STAT) 6-/- and STAT6+/+ BALB/c mice. We found that STAT6-/- mice mount a Th1 response, produce high levels of IL-12 and IFN-gamma and develop smaller lesions containing fewer parasites as compared with STAT6+/+ mice. Our findings demonstrate that genetic background plays a critical role in determining susceptibility of inbred mice to low-dose L. mexicana infection. Furthermore, together with our previous findings, they show that STAT6-mediated signaling is involved in mediating susceptibility to L. mexicana following both high-dose back rump and low-dose ear dermis infection.