Activation of the Innate Immune Checkpoint CLEC5A on Myeloid Cells in the Absence of Danger Signals Modulates Macrophages' Function but Does Not Trigger the Adaptive T Cell Immune Response.

C-Type lectin receptor 5A (CLEC5A) is a spleen tyrosine kinase- (Syk-) coupled pattern recognition receptor expressed on myeloid cells and involved in the innate immune response to viral and bacterial infections. Activation of the CLEC5A receptor with pathogen-derived antigens leads to a secretion of proinflammatory mediators such as TNF-α and IL-6 that may provoke a systemic cytokine storm, and CLEC5A gene polymorphisms are associated with the severity of DV infection. In addition, the CLEC5A receptor was mentioned in the context of noninfectious disorders like chronic obstructive pulmonary disease (COPD) or arthritis. Altogether, CLEC5A may be considered as an innate immune checkpoint capable to amplify proinflammatory signals, and this way contributes to infection or to aseptic inflammation. In this study, we determined CLEC5A receptor expression on different macrophage subsets (in vitro and ex vivo) and the functional consequences of its activation in aseptic conditions. The CLEC5A surface expression appeared the highest on proinflammatory M1 macrophages while intermediate on tumor-associated phenotypes (M2c or TAM). In contrast, the CLEC5A expression on ex vivo-derived alveolar macrophages from healthy donors or macrophages from ovarian cancer patients was hardly detectable. Targeting CLEC5A on noninflammatory macrophages with an agonistic α-CLEC5A antibody triggered a release of proinflammatory cytokines, resembling a response to dengue virus, and led to phenotypic changes in myeloid cells that may suggest their reprogramming towards a proinflammatory phenotype, e.g., upregulation of CD80 and downregulation of CD163. Interestingly, the CLEC5A agonist upregulated immune-regulatory molecules like CD206, PD-L1, and cytokines like IL-10, macrophage-derived chemokine (MDC/CCL22), and thymus and activation chemokine (TARC/CCL17) which are associated with an anti-inflammatory or a protumorigenic macrophage phenotype. In the absence of concomitant pathogenic or endogenous danger signals, the CLEC5A receptor activation did not amplify an autologous T cell response, which may represent a protective innate mechanism to avoid an undesirable autoimmune adaptive response.

Usefulness of ambulatory blood pressure measurement for hypertension management in India: the India ABPM study.

The present paper reports differences between office blood pressure (BP) measurement (OBPM) and ambulatory blood pressure measurement (ABPM) in a large multi-centre Indian all comers' population visiting primary care physicians. ABPM and OBPM data from 27,472 subjects (aged 51 ± 14 years, males 68.2%, treated 45.5%) were analysed and compared. Patients were classified based on the following hypertension thresholds: systolic BP (SBP) ≥ 140 and/or diastolic BP (DBP) ≥90 mmHg for OBPM, and SBP ≥ 130 and/or DBP ≥ 80 mmHg for 24-h ABPM, and SBP ≥ 120 and/or DBP ≥ 70 mmHg for night-time ABPM and SBP ≥ 135 and/or DBP ≥ 85 mmHg for daytime ABPM, all together. White coat hypertension (WCH) was seen in 12.0% (n = 3304), masked hypertension (MH) in 19.3% (n = 5293) and 55.5% (n = 15,246) had sustained hypertension. Isolated night-time hypertension (INH) was diagnosed in 11.9% (n = 3256). Untreated subjects had MH relatively more often than treated subjects (23.0% vs. 14.8%, p < 0.0001; respectively). Females had higher relative risk (RR) of having WCH than males (RR 1.16 [CI 95, 1.07-1.25], p < 0.0001). Whereas, males had higher RR of MH than females (RR 1.09 [CI 95, 1.02-1.17] p < 0.01). INH subjects had lower average systolic and diastolic dipping percentages (0.7 ± 6.6/ 2.2 ± 7.9 vs. 9.0 ± 7.3/11.9 ± 8.5, p < 0.001) than those without INH. In conclusion, for diagnosis of hypertension there was a contradiction between OBPM and ABPM in approximately one-third of all patients, and a substantial number of patients had INH. Using ABPM in routine hypertension management can lead to a reduction in burden and associated costs for Indian healthcare.

Blood pressure related to age: The India ABPM study.

The present paper reports trends in office blood pressure (BP) measurement (OBPM) and ambulatory blood pressure measurement (ABPM) with age in a large multi-center Indian all comers' population visiting primary care physicians. ABPM and OBPM data from 27 472 subjects (aged 51 ± 14 years, males 68.2%, treated 45.5%) were analyzed and compared. Individual differences between OBPM and ABPM patterns were compared for patients according to 10-year age categories. Results showed that systolic (S) BP values started to increase with age from the age of 40, BP variability (SD) increased from the age of 30 years. Diastolic (D) BP values started to decrease from the age of 50 years. Mean OBPM values were higher than daytime ABPM values (all P < .001) in all age-groups. The prevalence of white coat hypertension (WCH) and masked hypertension (MH) was based on OBPM and daytime, 24-hour, and nighttime average BPs together. WCH decreased with age from 15.1% and 12.4% in treated and untreated subjects at the youngest age to 7.2% and 6.9% in the oldest age, respectively. MH prevalence was higher for untreated than for treated subjects but remained similar for all age-groups (range of 18.6%-21.3%). The prevalence of reverse dippers increased with age from the youngest to oldest group with 7.3%-34.2% (P < .001 for trend). Dippers prevalence decreased from 42.5% to 17.9% from the youngest to oldest age-groups, respectively (P < .001 for trend). These findings confirm that BP patterns show clear differences in trends with age, particularly regarding nighttime BP.

Decitabine enhances anti-CD33 monoclonal antibody BI 836858-mediated natural killer ADCC against AML blasts.

Acute myeloid leukemia (AML) is the most common type of acute leukemia, affecting older individuals at a median age of 67 years. Resistance to intensive induction chemotherapy is the major cause of death in elderly AML; hence, novel treatment strategies are warranted. CD33-directed antibody-drug conjugates (gemtuzumab ozogamicin) have been shown to improve overall survival, validating CD33 as a target for antibody-based therapy of AML. Here, we report the in vitro efficacy of BI 836858, a fully human, Fc-engineered, anti-CD33 antibody using AML cell lines and primary AML blasts as targets. BI 836858-opsonized AML cells significantly induced both autologous and allogeneic natural killer (NK)-cell degranulation and NK-cell-mediated antibody-dependent cellular cytotoxicity (ADCC). In vitro treatment of AML blasts with decitabine (DAC) or 5-azacytidine, 2 hypomethylating agents that show efficacy in older patients, did not compromise BI 836858-induced NK-cell-mediated ADCC. Evaluation of BI 836858-mediated ADCC in serial marrow AML aspirates in patients who received a 10-day course of DAC (pre-DAC, days 4, 11, and 28 post-DAC) revealed significantly higher ADCC in samples at day 28 post-DAC when compared with pre-DAC treatment. Analysis of ligands to activating receptors (NKG2D) showed significantly increased NKG2D ligand [NKG2DL] expression in day 28 post-DAC samples compared with pre-DAC samples; when NKG2DL receptor was blocked using antibodies, BI 836858-mediated ADCC was significantly decreased, suggesting that DAC enhances AML blast susceptibility to BI 836858 by upregulating NKG2DL. These data provide a rationale for combination therapy of Fc-engineered antibodies such as BI 836858 with azanucleosides in elderly patients with AML.

Pharmacodynamic and antineoplastic activity of BI 836845, a fully human IGF ligand-neutralizing antibody, and mechanistic rationale for combination with rapamycin.

Insulin-like growth factor (IGF) signaling is thought to play a role in the development and progression of multiple cancer types. To date, therapeutic strategies aimed at disrupting IGF signaling have largely focused on antibodies that target the IGF-I receptor (IGF-IR). Here, we describe the pharmacologic profile of BI 836845, a fully human monoclonal antibody that utilizes an alternative approach to IGF signaling inhibition by selectively neutralizing the bioactivity of IGF ligands. Biochemical analyses of BI 836845 demonstrated high affinity to human IGF-I and IGF-II, resulting in effective inhibition of IGF-induced activation of both IGF-IR and IR-A in vitro. Cross-reactivity to rodent IGFs has enabled rigorous assessment of the pharmacologic activity of BI 836845 in preclinical models. Pharmacodynamic studies in rats showed potent reduction of serum IGF bioactivity in the absence of metabolic adverse effects, leading to growth inhibition as evidenced by reduced body weight gain and tail length. Moreover, BI 836845 reduced the proliferation of human cell lines derived from different cancer types and enhanced the antitumor efficacy of rapamycin by blocking a rapamycin-induced increase in upstream signaling in vitro as well as in human tumor xenograft models in nude mice. Our data suggest that BI 836845 represents a potentially more effective and tolerable approach to the inhibition of IGF signaling compared with agents that target the IGF-I receptor directly, with potential for rational combinations with other targeted agents in clinical studies.

A novel Fc-engineered monoclonal antibody to CD37 with enhanced ADCC and high proapoptotic activity for treatment of B-cell malignancies.

The tetraspanin CD37 is widely expressed in B-cell malignancies and represents an attractive target for immunotherapy with mAbs. We have chimerized a high-affinity mouse Ab to CD37 and engineered the CH2 domain for improved binding to human Fcγ receptors. The resulting mAb 37.1 showed high intrinsic proapoptotic activity on malignant B cells accompanied by homotypic aggregation. Furthermore, the Ab-mediated high Ab-dependent cell-mediated cytotoxicity (ADCC) on lymphoma and primary CLL cells. mAb 37.1 strongly depleted normal B cells as well as spiked B-lymphoma cells in blood samples from healthy donors as well as malignant B cells in blood from CLL patients. In all assays, mAb 37.1 was superior to rituximab in terms of potency and maximal cell lysis. A single dose of mAb CD37.1 administered to human CD37-transgenic mice resulted in a reversible, dose-dependent reduction of peripheral B cells. In a Ramos mouse model of human B-cell lymphoma, administration of mAb 37.1 strongly suppressed tumor growth. Finally, a surrogate Fc-engineered Ab to macaque CD37, with in vitro proapoptotic and ADCC activities very similar to those of mAb 37.1, induced dose-dependent, reversible B-cell depletion in cynomolgus monkeys. In conclusion, the remarkable preclinical pharmacodynamic and antitumor effects of mAb 37.1 warrant clinical development for B-cell malignancies.

Human combinatorial Fab library yielding specific and functional antibodies against the human fibroblast growth factor receptor 3.

The human combinatorial antibody library Fab 1 (HuCAL-Fab 1) was generated by transferring the heavy and light chain variable regions from the previously constructed single-chain Fv library (Knappik, A., Ge, L., Honegger, A., Pack, P., Fischer, M., Wellnhofer, G., Hoess, A., Wölle, J., Plückthun, A., and Virnekäs, B. (2000) J. Mol. Biol. 296, 57-86), diversified in both complementarity-determining regions 3 into a novel Fab display vector, yielding 2.1 x 10(10) different antibody fragments. The modularity has been retained in the Fab display and screening plasmids, ensuring rapid conversion into various antibody formats as well as antibody optimization using prebuilt maturation cassettes. HuCAL-Fab 1 was challenged against the human fibroblast growth factor receptor 3, a potential therapeutic antibody target, against which, to the best of our knowledge, no functional antibodies could be generated so far. A unique screening mode was designed utilizing recombinant functional proteins and cell lines differentially expressing fibroblast growth factor receptor isoforms diversified in expression and receptor dependence. Specific Fab fragments with subnanomolar affinities were isolated by selection without any maturation steps as determined by fluorescence flow cytometry. Some of the selected Fab fragments completely inhibit target-mediated cell proliferation, rendering them the first monoclonal antibodies against fibroblast growth factor receptors having significant function blocking activity. This study validates HuCAL-Fab 1 as a valuable source for the generation of target-specific antibodies for therapeutic applications.

Immature mouse dendritic cells enter inflamed tissue, a process that requires E- and P-selectin, but not P-selectin glycoprotein ligand 1.

Inflammatory processes are associated with the rapid migration of dendritic cells (DCs) to regional lymph nodes and depletion of these potent antigen-presenting cells (APCs) from the inflamed tissue. This study examined whether sites of cutaneous inflammation can be repopulated with DCs from a pool of immature DCs circulating in the blood. In adoptive transfer experiments with ex vivo-generated radioactively labeled primary bone marrow-derived DCs injected into mice challenged by an allergic contact dermatitis reaction, immature DCs were actively recruited from the blood to sites of cutaneous inflammation, whereas mature DCs were not. Immature, but not mature, DCs were able to adhere specifically to immobilized recombinant E- and P-selectin under static as well as under flow conditions. P-selectin-dependent adhesion of immature DCs correlates with their higher level of expression of the carbohydrate epitope cutaneous lymphocyte-associated antigen (CLA) and is blocked by a novel inhibitory antibody against mouse P-selectin glycoprotein ligand 1 (PSGL-1). Surprisingly, however, emigration of immature DCs into inflamed skin is retained in the presence of this anti-PSGL-1 antibody and is also normal when immature DCs are generated from fucosyltransferase (Fuc-T) Fuc-TVII-deficient mice. By contrast, emigration of wild-type immature DCs is reduced by adhesion-blocking anti-E- and P-selectin antibodies, and immature DCs generated ex vivo from Fuc-TVII/Fuc-TIV double-deficient mice emigrate poorly. Thus, fucosylated ligands of the endothelial selectins, determined in part by Fuc-TIV, and independent of PSGL-1, are required for extravasation of DCs into sites of cutaneous inflammation.