Activation of toll-like receptor-2 by endogenous matrix metalloproteinase-2 modulates dendritic-cell-mediated inflammatory responses.

Matrix metalloproteinase-2 (MMP-2) is involved in several physiological mechanisms, including wound healing and tumor progression. We show that MMP-2 directly stimulates dendritic cells (DCs) to both upregulate OX40L on the cell surface and secrete inflammatory cytokines. The mechanism underlying DC activation includes physical association with Toll-like receptor-2 (TLR2), leading to NF-κB activation, OX40L upregulation on DCs, and ensuing TH2 differentiation. Significantly, MMP-2 polarizes T cells toward type 2 responses in vivo, in a TLR2-dependent manner. MMP-2-dependent type 2 polarization may represent a key immune regulatory mechanism for protection against a broad array of disorders, such as inflammatory, infectious, and autoimmune diseases, which can be hijacked by tumors to evade immunity.

Delayed HIV diagnosis and initiation of antiretroviral therapy: inequalities by educational level, COHERE in EuroCoord.

OBJECTIVES: In Europe and elsewhere, health inequalities among HIV-positive individuals are of concern. We investigated late HIV diagnosis and late initiation of combination antiretroviral therapy (cART) by educational level, a proxy of socioeconomic position. DESIGN AND METHODS: We used data from nine HIV cohorts within COHERE in Austria, France, Greece, Italy, Spain and Switzerland, collecting data on level of education in categories of the UNESCO/International Standard Classification of Education standard classification: non-completed basic, basic, secondary and tertiary education. We included individuals diagnosed with HIV between 1996 and 2011, aged at least 16 years, with known educational level and at least one CD4 cell count within 6 months of HIV diagnosis. We examined trends by education level in presentation with advanced HIV disease (AHD) (CD4 <200 cells/µl or AIDS within 6 months) using logistic regression, and distribution of CD4 cell count at cART initiation overall and among presenters without AHD using median regression. RESULTS: Among 15 414 individuals, 52, 45,37, and 31% with uncompleted basic, basic, secondary and tertiary education, respectively, presented with AHD (P trend <0.001). Compared to patients with tertiary education, adjusted odds ratios of AHD were 1.72 (95% confidence interval 1.48-2.00) for uncompleted basic, 1.39 (1.24-1.56) for basic and 1.20 (1.08-1.34) for secondary education (P < 0.001). In unadjusted and adjusted analyses, median CD4 cell count at cART initiation was lower with poorer educational level. CONCLUSIONS: Socioeconomic inequalities in delayed HIV diagnosis and initiation of cART are present in European countries with universal healthcare systems and individuals with lower educational level do not equally benefit from timely cART initiation.

Reversal of NK-cell exhaustion in advanced melanoma by Tim-3 blockade.

The immunoregulatory protein T-cell immunoglobulin- and mucin-domain-containing molecule-3 (Tim-3) mediates T-cell exhaustion and contributes to the suppression of immune responses in both viral infections and tumors. Tim-3 blockade reverses the exhausted phenotype of CD4+ and CD8+ T cells in several chronic diseases, including melanoma. Interestingly, natural killer (NK) cells constitutively express Tim-3; however, the role of Tim-3 in modulating the function of these innate effector cells remains unclear, particularly in human diseases. In this study, we compared the function of Tim-3 in NK cells from healthy donors and patients with metastatic melanoma. NK cells from the latter were functionally impaired/exhausted, and Tim-3 blockade reversed this exhausted phenotype. Moreover, Tim-3 expression levels were correlated with the stage of the disease and poor prognostic factors. These data indicate that Tim-3 can function as an NK-cell exhaustion marker in advanced melanoma and support the development of Tim-3-targeted therapies to restore antitumor immunity.

Reversal of natural killer cell exhaustion by TIM-3 blockade.

Natural killer (NK) cells are innate immune cells that become progressively exhausted in advanced stage cancer, crippling their ability to execute antitumor functions. We previously characterized the nature of NK cell exhaustion in metastatic melanoma patients, reporting a correlation with high expression of TIM-3. Blockade of this immune checkpoint molecule reversed the exhausted phenotype and improved NK cell function.

Dendritic cell-targeted approaches to modulate immune dysfunction in the tumor microenvironment.

There has been enormous progress this past decade in the understanding of the biology of dendritic cells (DCs) along with increasing attention for the development of novel dendritic cell (DC)-based cancer therapies. However, the clinical impact of DC-based vaccines remains to be established. This limited success could be explained by suboptimal conditions for generating potent immunostimulatory DCs as well as immune suppression mediated by the tumor microenvironment (TME). Therefore, strategies that optimize the potency of DC vaccines along with newly described therapies that target the TME in order to overcome immune dysfunction may provide durable tumor-specific immunity. These novel interventions hold the most promise for successful cancer immunotherapies.

Hck contributes to bone homeostasis by controlling the recruitment of osteoclast precursors.

In osteoclasts, Src controls podosome organization and bone degradation, which leads to an osteopetrotic phenotype in src(-/-) mice. Since this phenotype was even more severe in src(-/-)hck(-/-) mice, we examined the individual contribution of Hck in bone homeostasis. Compared to wt mice, hck(-/-) mice exhibited an osteopetrotic phenotype characterized by an increased density of trabecular bone and decreased bone degradation, although osteoclastogenesis was not impaired. Podosome organization and matrix degradation were found to be defective in hck(-/-) osteoclast precursors (preosteoclast) but were normal in mature hck(-/-) osteoclasts, probably through compensation by Src, which was specifically overexpressed in mature osteoclasts. As a consequence of podosome defects, the 3-dimensional migration of hck(-/-) preosteoclasts was strongly affected in vitro. In vivo, this translated by altered bone homing of preosteoclasts in hck(-/-) mice: in metatarsals of 1-wk-old mice, when bone formation strongly depends on the recruitment of these cells, reduced numbers of osteoclasts and abnormal developing trabecular bone were observed. This phenotype was still detectable in adults. In summmary, Hck is one of the very few effectors of preosteoclast recruitment described to date and thereby plays a critical role in bone remodeling.

Comparison of corneal thickness and curvature in myopic and keratoconic eyes of patients from French Caribbean Isles and continental France.

PURPOSE: To evaluate the corneal thickness and curvature of myopic and patients with keratoconus from two countries. METHODS: This cross-sectional study was conducted at Cabinet Opale, Fort de France, French West Indies and University Hospital of Bordeaux, France. Corneal thickness and curvature were assessed in 170 keratoconic eyes of 89 residents of the French Caribbean Islands (FCI) and 159 keratoconic eyes of 91 residents of the Aquitaine region of southwest France. A group of age-matched keratoconus-free patients who had been referred for refractive surgery owing to myopia (173 FCI [173 eyes; 87 individuals] and Aquitaine [181 eyes; 93 individuals]) were also assessed. RESULTS: The mean age at keratoconus diagnosis was significantly higher among FCI than Aquitaine residents (p = 0.009). The mean keratometric (Km) reading was statistically higher for keratoconic FCI than Aquitaine patients, at 48.06 versus 46.21 diopters (p = 0.001). This difference was more pronounced among patients aged >40 years than those ≤40 years (p = 0.009). Patients with keratoconus showed no significant difference in mean central corneal thickness and thinnest corneal point values, irrespective of region. Myopic individuals from the FCI, however, had significantly lower mean central corneal thickness and thinnest corneal point measurements than Aquitaine myopics, irrespective of age group (p ≤ 0.0008). CONCLUSION: The corneas of patients with keratoconus of African-Caribbean and Caucasian origins are of similar thickness. Myopic African-Caribbean patients referred for refractive surgery tend to present with thinner corneas than Caucasians.

Outcomes of deep anterior lamellar keratoplasty for keratoconus: learning curve and advantages of the big bubble technique.

PURPOSE: To evaluate retrospectively the outcomes of a case series of deep anterior lamellar keratoplasties by air dissection (DALK-AD) using the big bubble (BB) technique, in the surgical treatment of keratoconus (KC). METHODS: Forty-four consecutive keratoplasties of 42 patients for KC were performed at the French National Reference Center for KC from January 2008 to June 2010 by the same surgeon with the aim of systematically performing DALK-AD with the BB technique. The outcomes of the DALK-AD not converted to penetrating keratoplasty were analyzed, and a learning curve was established to successfully achieve the DALK-AD using the BB technique. RESULTS: Thirty-two DALK-AD procedures were successfully performed among 44 consecutively operated keratoplasties, with 12 being converted to penetrating keratoplasty during the surgical procedure. At 12 months, the mean best-corrected logarithm of the minimum angle of resolution visual acuity was 0.88 ± 0.14 with 93.3% seeing best-corrected visual acuity ≥ 20/30 and 100% seeing best-corrected visual acuity ≥ 20/40. The mean gain of visual acuity in logarithm of the minimum angle of resolution lines at 6 and 12 months was 6.12 ± 3.97 (P < 0.0001) and 6.94 ± 4.18 (P < 0.005), respectively. The rate for intraoperative and postoperative complications was 31.8% and 4.5%, respectively. CONCLUSION: Despite a learning period needed to successfully perform deep lamellar anterior keratoplasty with the BB technique, this approach is safe and provides very good visual outcomes when adequate baring of Descemet membrane is achieved. The learning curve showed that complications related to this technique decrease significantly after the first 10 cases.

Corneal collagen crosslinking in progressive keratoconus: multicenter results from the French National Reference Center for Keratoconus.

PURPOSE: To report refractive, topographic, and biomechanical outcomes, efficiency, and safety of corneal collagen crosslinking (CXL) 1, 3, 6, and 12 months after treatment. SETTING: National Reference Centre for Keratoconus, Bordeaux and Toulouse, France. DESIGN: Case series. METHODS: This retrospective uncontrolled double-center study comprised eyes with progressive keratoconus. Uncorrected distance visual acuity, corrected distance visual acuity (CDVA), corneal pachymetry, endothelial cell count, and corneal hysteresis and corneal resistance factor were evaluated at baseline and at 1, 3, 6, and 12 months. RESULTS: One hundred forty-two eyes were enrolled in the study. At 6 months, the CDVA had stabilized in 53 eyes (48.1%), improved in 36 eyes (32.7%), and decreased in 18 eyes (16.3%). At 12 months, the CDVA had stabilized in 31 eyes (47.6%), improved in 26 eyes (40.0%), and decreased in 8 eyes (12%). At 6 months, keratoconus progression had stopped in 51 eyes (49.03%) and the maximum keratometry (K) value had decreased by more than 1.0 diopter (D) in 37 eyes (35.5%); it continued to progress in 16 eyes (15.3%). At 12 months, keratoconus progression had stopped in 42 eyes (68.8%) and the maximum K value had decreased by more than 2.0 D in 13 eyes (21.3%). The complication rate with loss of vision was 3.5%. CONCLUSIONS: Ultraviolet-A light associated with riboflavin CXL is an efficient procedure to stabilize and improve progressive keratoconus. The results reinforce previous studies highlighting the efficacy and safety of the procedure. A large prospective randomized clinical trial is needed.

Early biomechanical keratoconus pattern measured with an ocular response analyzer: curve analysis.

PURPOSE: To estimate the ability of the Ocular Response Analyzer parameters to aid in the diagnosis of keratoconus in pre-laser in situ keratomileusis (LASIK) patients. SETTING: Department of Ophthalmology, Bordeaux 2 University, Bordeaux Cedex, France. DESIGN: Evaluation of diagnostic test. METHODS: This study compared eyes with mild stages of keratoconus (study group) with preoperative eyes that later had LASIK (control group). Corneas with a central thickness within 500 to 600 µm were targeted. The biomechanical measurements were acquired, and 12 parameters were analyzed after extraction from the signal data. RESULTS: The study group comprised 103 eyes and the control group, 97 eyes. The mean corneal hysteresis (CH) was 9.2 mm Hg in study eyes and 10.1 mm Hg in control eyes and the mean corneal resistance factor (CRF), 8.9 mm Hg and 10.6 mm Hg, respectively. For a threshold of 9.6, CH had a sensitivity of 66% with a specificity of 67%. For a threshold of 9.7, the CRF had a sensitivity of 72% and a specificity of 77%. For 6 biomechanical parameters, the probability that a patient would present with keratoconus was 3 in 1000 if 1 parameter was over the chosen threshold. CONCLUSIONS: If 1 of 6 parameters were over a chosen threshold, the probability that a patient would present with keratoconus would be almost 3 in 1000 instead of 9 in 1000 in a LASIK surgery cohort. Despite low sensitivity and specificity, some parameters provided by the corneal analyzer offered high negative likelihood ratios and deserve more study with bigger samples.

TLR4 engagement during TLR3-induced proinflammatory signaling in dendritic cells promotes IL-10-mediated suppression of antitumor immunity.

Toll-like receptor (TLR) agonists are promising adjuvants for immune therapy of cancer, but their potential efficacy as single or combinatorial agents has yet to be fully evaluated. Here, we report that among all TLR agonists tested, dendritic cells (DC) stimulated with the TLR3 agonist polyI:C displayed the strongest activity in stimulating proinflammatory responses and the production of melanoma antigen-specific CD8(+) T cells. Simultaneous treatment with TLR7/8 agonists further improved these responses, but the inclusion of bacterial lipopolysaccharide (LPS), a TLR4 agonist, suppressed proinflammatory cytokine production. This inhibition was contingent upon rapid induction of the suppressive cytokine interleukin (IL)-10 by LPS, leading to dysregulated immune responses and it could be reversed by signal transducers and activators of transcription 3 knockdown, p38 blockade or antibodies to IL-10 and its receptor. Our findings show how certain TLR agonist combinations can enhance or limit DC responses associated with antitumor immunity, through their relative ability to induce IL-10 pathways that are immune suppressive.

[Osteoimmunology: an integrated vision of immune and bone systems]. / Ostéo-immunologie: une vision globale et intégrée du tissu squelettique et du sytème immunitaire. Implication pour la recherche en rhumatologie.

Study of dysregulations of the immune system resulting in abnormal bone homeostasis has led to the emergence of the field of osteoimmunology. Among the interactions between the immune system and bone, several signaling molecules and pathways previously identified in immune cells have been shown to be key players in the osteoclast, the bone resorbing cell. Osteoclast differentiation requires two signaling pathways: the RANK/RANKL pathway and the signal initiated by the ITAM-harboring adaptor proteins DAP12 and FcRgamma. Until recently, it was unclear how RANK and ITAM signals merge to cooperatively stimulate activation of NFATc1, the master transcription factor in osteoclastogenesis. A recent study from H. Takayanagi's group has shown that the tyrosine kinases Btk and Tec form a multiprotein complex with adaptor molecules such as BLNK, that is able to integrate these two signaling pathways and thus stimulate osteoclastogenesis. Taken together, these new data open novel clinical perspectives especially for osteoarticular inflammatory diseases.

Osteoclasts control osteoblast chemotaxis via PDGF-BB/PDGF receptor beta signaling.

BACKGROUND: Bone remodeling relies on the tightly regulated interplay between bone forming osteoblasts and bone digesting osteoclasts. Several studies have now described the molecular mechanisms by which osteoblasts control osteoclastogenesis and bone degradation. It is currently unclear whether osteoclasts can influence bone rebuilding. METHODOLOGY/PRINCIPAL FINDINGS: Using in vitro cell systems, we show here that mature osteoclasts, but not their precursors, secrete chemotactic factors recognized by both mature osteoblasts and their precursors. Several growth factors whose expression is upregulated during osteoclastogenesis were identified by DNA microarrays as candidates mediating osteoblast chemotaxis. Our subsequent functional analyses demonstrate that mature osteoclasts, whose platelet-derived growth factor bb (PDGF-bb) expression is reduced by siRNAs, exhibit a reduced capability of attracting osteoblasts. Conversely, osteoblasts whose platelet-derived growth factor receptor beta (PDGFR-beta) expression is reduced by siRNAs exhibit a lower capability of responding to chemotactic factors secreted by osteoclasts. CONCLUSIONS/SIGNIFICANCE: We conclude that, in vitro mature osteoclasts control osteoblast chemotaxis via PDGF-bb/PDGFR-beta signaling. This may provide one key mechanism by which osteoclasts control bone formation in vivo.

Murine dendritic cell transdifferentiation into osteoclasts is differentially regulated by innate and adaptive cytokines.

Dendritic cells (DC) are the mononuclear cells that initiate adaptive immune responses. Osteoclasts (OC) are the multinucleated giant cells that resorb bone. As previously described for human conventional DC (cDC), we demonstrate that murine cDC, either in vitro generated from Fms-like tyrosine kinase 3 (Flt3)+ bone marrow progenitors or ex vivo purified from spleen, are able to develop into OC in response to M-CSF and receptor activator of NF-kappaB ligand (RANKL) in vitro. This transdifferentiation is driven by the immune environment that controls cDC maturation, cell fusion, tartrate-resistant acid phosphatase (TRAP) and bone resorption activities. Only immature cDC have the capacity to become OC since mature cDC or plasmacytoid DC do not. Additions of the pro-inflammatory cytokines, such as IL-1beta and TNF-alpha, or human rheumatoid synovial fluid, increase murine cDC transdifferentiation into OC, whereas IFN-alpha inhibits it. The adaptive cytokine, IFN-gamma, inhibits cDC fusion while IL-4 increases it. IL-2, IFN-gamma and IL-4 inhibit TRAP and bone resorption activities contrary to IL-10, which enhances both activities. A putative new "immune multinucleated giant cell" unable to resorb bone, which is formed owing to IL-4, is underlined. The future analysis of cDC transdifferentiation into OC in murine models of inflammatory arthritis will give us the quantitative importance of this phenomenon in vivo.