Modulation of Anti-Tumor Necrosis Factor Alpha (TNF-α) Antibody Secretion in Mice Immunized with TNF-α Kinoid

Tumor necrosis factor alpha (TNF-α) blockade is an effective treatment for patients with TNF-α-dependent chronic inflammatory diseases, such as rheumatoid arthritis, Crohn''s disease, and psoriasis. TNF-α kinoid, a heterocomplex of human TNF-α and keyhole limpet hemocyanin (KLH) (TNF-K), is an active immunotherapy targeting TNF-α. Since the TNF-K approach is an active immunization, and patients receiving this therapy also receive immunosuppressant treatment, we evaluated the effect of some immunosuppressive drugs on the generation of anti-TNF-α antibodies produced during TNF-K treatment. BALB/c mice were injected intramuscularly with TNF-K in ISA 51 adjuvant. Mice were also injected intraperitoneally with one of the following: phosphate-buffered saline, cyclophosphamide, methylprednisolone, or methotrexate. Anti-TNF-α and anti-KLH antibody levels were assessed by enzyme-linked immunosorbent assay and the anti-TNF-α neutralizing capacity of sera by L929 bioassay. Our results showed that current treatments used in rheumatoid arthritis, such as methylprednisolone and methotrexate, do not significantly alter anti-TNF-α antibody production after TNF-K immunization. In contrast, the administration of cyclophosphamide (200 mg/kg) after immunization significantly reduced anti-TNF-α antibody titers and their neutralizing capacity.     

Lymphoid neogenesis in chronic rejection: the murderer is in the house

Although chronic rejection is currently the main cause of long-term allograft failure, its pathogenesis remains elusive, hereby preventing the development of effective therapy. Recent advances in the comprehension of the pathophysiology of chronic inflammatory diseases could shed new light on the pathogenesis of chronic rejection. Lymphoid neogenesis is a mechanism responsible for the progressive organization of chronic inflammatory infiltrates into functional ectopic germinal centers, and has been evidenced recently in various pathological situations sharing a common feature: the failure of the immune response to eradicate the targeted antigen(s). Chronic rejection is such a situation as it results from a sustained alloimmune response against the donor's antigens that are constantly replenished by the grafted tissue. Accordingly, functional ectopic germinal centers develop within chronically rejected organs. This implies that, during chronic rejection, graft is at the same time the target and the site of elicitation of the alloimmune response.     

12/15-lipoxygenase orchestrates the clearance of apoptotic cells and maintains immunologic tolerance

Noninflammatory clearance of apoptotic cells (ACs) is crucial to maintain self-tolerance. Here, we have reported a role for the enzyme 12/15-lipoxygenase (12/15-LO) as a central factor governing the sorting of ACs into differentially activated monocyte subpopulations. During inflammation, uptake of ACs was confined to a population of 12/15-LO-expressing, alternatively activated resident macrophages (resMΦ), which blocked uptake of ACs into freshly recruited inflammatory Ly6C(hi) monocytes in a 12/15-LO-dependent manner. ResMΦ exposed 12/15-LO-derived oxidation products of phosphatidylethanolamine (oxPE) on their plasma membranes and thereby generated a sink for distinct soluble receptors for ACs such as milk fat globule-EGF factor 8, which were essential for the uptake of ACs into inflammatory monocytes. Loss of 12/15-LO activity, in turn, resulted in an aberrant phagocytosis of ACs by inflammatory monocytes, subsequent antigen presentation of AC-derived antigens, and a lupus-like autoimmune disease. Our data reveal an unexpected key role for enzymatic lipid oxidation during the maintenance of self-tolerance.     

Validation of the Face Name Associative Memory Exam in cognitively normal older individuals

The recently developed Face Name Associative Memory Exam (FNAME), a challenging paired associative learning task, shows promise in detecting the subtle cognitive changes characteristic of preclinical Alzheimer's disease. In this study, we evaluated the validity and reliability of the FNAME in 210 cognitively normal older individuals (58-90 years of age). Construct validity of the measure was assessed by principal components analysis, which revealed two independent factors. Correlations between the FNAME subtests and another episodic memory test were significant. The results indicated strong test-retest reliability in a subsample (n = 41). Normative data stratified by age were also generated.     

Murine CD27(?) Vγ6(+) γδ T cells producing IL-17A promote ovarian cancer growth via mobilization of protumor small peritoneal macrophages

Cancer-associated inflammation mobilizes a variety of leukocyte populations that can inhibit or enhance tumor cell growth in situ. These subsets include γδ T cells, which can infiltrate tumors and typically provide large amounts of antitumor cytokines, such as IFN-γ. By contrast, we report here that in a well-established transplantable (ID8 cell line) model of peritoneal/ovarian cancer, γδ T cells promote tumor cell growth. γδ T cells accumulated in the peritoneal cavity in response to tumor challenge and could be visualized within solid tumor foci. Functional characterization of tumor-associated γδ T cells revealed preferential production of interleukin-17A (IL-17), rather than IFN-γ. Consistent with this finding, both T cell receptor (TCR)δ-deficient and IL-17–deficient mice displayed reduced ID8 tumor growth compared with wild-type animals. IL-17 production by γδ T cells in the tumor environment was essentially restricted to a highly proliferative CD27⁽⁻⁾ subset that expressed Vγ6 instead of the more common Vγ1 and Vγ4 TCR chains. The preferential expansion of IL-17–secreting CD27⁽⁻⁾ Vγ6⁽⁺⁾ γδ T cells associated with the selective mobilization of unconventional small peritoneal macrophages (SPMs) that, in comparison with large peritoneal macrophages, were enriched for IL-17 receptor A, and for protumor and proangiogenic molecular mediators, which were up-regulated by IL-17. Importantly, SPMs were uniquely and directly capable of promoting ovarian cancer cell proliferation. Collectively, this work identifies an IL-17–dependent lymphoid/myeloid cross-talk involving γδ T cells and SPMs that promotes tumor cell growth and thus counteracts cancer immunosurveillance.Developing tumors are infiltrated by a variety of leukocyte subsets that can either promote or inhibit inflammation, and thus impact on cancer progression (1). Among such populations are γδ T cells, which are major players in lymphoid stress surveillance likely due to their recognition of stress-inducible molecules independently of MHC-mediated antigen presentation (2). Moreover, abundant IFN-γ secretion and cytotoxic effector functions endow γδ T cells with potent antitumor activity. This has been clearly documented in murine models of spontaneous (3), chemically induced (4), transgenic (5), and transplantable (6, 7) tumors. For example, in the widely used B16 melanoma model, γδ T cells were shown to infiltrate tumors very early and provided a critical source of IFN-γ that significantly delayed tumor growth (6, 7).Human γδ T cells also possess IFN-γ–secreting potential, which is displayed immediately at birth (8) and display cytotoxicity against tumor lines of diverse origin, including epithelial (9, 10) and hematological (11, 12) tumors. This has prompted the development of cancer clinical trials targeting γδ T cells, which have produced encouraging, albeit highly variable, degrees of therapeutic responses (13–15). There is therefore great interest in maximizing the antitumor functions of γδ T cells for cancer immunotherapy.Despite these highly promising reports, a clinical study on breast cancer tissue revealed a surprising inverse correlation between infiltrating γδ T cells and overall patient survival (16). In fact, γδ T cells represented the most significant independent prognostic factor for assessing severity of breast cancer (16). Similarly, a recent report on colorectal cancer showed a positive correlation between clinopathological parameters and the infiltration of γδ T cells specifically producing interleukin-17 (IL-17) (17). A tumor-promoting function of γδ T cells was also suggested in murine fibrosarcoma (18) and hepatocellular carcinoma (19) models, in which γδ T cells were the major cellular source of IL-17, which was required for optimal tumor growth in vivo. These data raise the interesting question as to whether distinct functional attributes of γδ T cells, for example differential cytokine production, may associate with markedly different outcomes for tumor growth.Along these lines, we have pioneered the identification of two distinct functional subsets of murine γδ T cells based on the expression levels of the CD27 coreceptor (20). We showed that robust IFN-γ production is associated with the CD27⁽⁺⁾ phenotype, whereas secretion of IL-17 is restricted to CD27⁽⁻⁾ γδ T cells. This dichotomy of hard-wired commitment to specific cytokine production is established during thymic development and maintained during the immune response to various infection agents (21, 22). Thus, the overall impact of γδ T cells in a given disease may depend on the balance between distinct proinflammatory effector cell subsets.Building on these foundations, we have here analyzed the overall and subset-specific contributions of γδ T cells to a well-established murine syngeneic model of ovarian cancer (ID8; transplantable cell line) that has a strong inflammatory component (23–25), akin to that observed in human patients with high-grade serous ovarian cancer (25, 26). In this murine model, we demonstrate that γδ T cells are major sources of IL-17, and both T cell receptor (TCR)δ-deficient and IL-17–deficient mice display reduced ID8 tumor growth. Interestingly, IL-17 production by γδ T cells in the tumor environment is essentially restricted to a CD27⁽⁻⁾ subset that does not express the commonly used Vγ1 or Vγ4 TCR chains, but rather Vγ6; these Vγ6⁽⁺⁾ cells are highly biased toward IL-17 production, in contrast to their IFN-γ–producing Vγ1⁽⁺⁾ and Vγ4⁽⁺⁾ counterparts. The ID8 tumor environment gets progressively enriched in the IL-17–promoting factor IL-7, whose receptor is highly expressed on Vγ6⁽⁺⁾ cells. This associates with preferential Vγ6⁽⁺⁾ cell proliferation and accumulation of IL-17 in the tumor bed, which in turn induces the mobilization of (recently described) small peritoneal macrophages (SPMs) that are enriched in IL-17 receptor A (IL-17RA) and in protumor and proangiogenic molecular mediators. Importantly, in comparison with large peritoneal macrophages (LPMs), SPMs can strongly and directly promote ovarian cancer cell proliferation. In summary, our work identifies an IL-17–dependent γδ T-cell/SPM axis that promotes tumor cell growth and thus opposes the widely accepted antitumor (and IFN-γ mediated) function of γδ T cells.     

Long-term follow-up of children with risk organ-negative Langerhans cell histiocytosis after 2-chlorodeoxyadenosine treatment

The nucleoside analogue, 2-chlorodeoxyadenosine (2CDA), was reported to be an active treatment for childhood Langerhans cell histiocytosis (LCH) without risk organ (RO−) involvement. However, we lack data on long-term effects of 2CDA treatment, including the disease reactivation rate, permanent sequelae and long-term tolerance. This study included 44 children from the French LCH registry, treated for a RO− LCH with 2CDA monotherapy (median number of six courses). The median age at the beginning of 2CDA was 3·6 years (range, 0·3–19·7 years) and the median follow-up after was 5·4 years (range, 0·6–15·1 years). Objective response to 2CDA was observed in 25 patients (56·8%), while six patients (13·6%) had stable disease and 13 patients (29·5%) exhibited progressive disease. Among patients without progression, only two experienced disease reactivation after 2CDA discontinuation. The five-year cumulative incidence of disease progression or reactivation after 2CDA therapy initiation was 34·3%. The lymphopenia reported in all cases [72% below absolute lymphocyte count (ALC) of 0·5 G/l], was addressed with appropriate prophylactic measures. Other toxicities above grade 2 were uncommon, and no second malignant neoplasm or neuropathy was reported. The five-year overall survival was 97·7%. In conclusion, we could confirm that 2CDA monotherapy was a beneficial long-term therapy for treating patients with RO− LCH. Appropriate management of induced immune deficiency is mandatory.