Cancer Cells Promote Immune Regulatory Function of Macrophages by Upregulating Scavenger Receptor MARCO Expression.

Expression of macrophage receptor with collagenous structure (MARCO) by tumor-associated macrophages is associated with poor prognosis of multiple types of cancer. In this article, we report that cancer cells (e.g., breast cancer and glioblastoma cell lines) can upregulate surface MARCO expression on human macrophages not only via IL-6-induced STAT3 activation but also via sphingosine-1-phosphate receptor (S1PR)-mediated IL-6 and IL-10 expression followed by STAT3 activation. We further found that MARCO ligation induces activation of the MEK/ERK/p90RSK/CREB signaling cascade, leading to IL-10 expression followed by STAT3-dependent PD-L1 upregulation. Such MARCO-induced macrophage polarization is accompanied by increased expression of PPARG, IRF4, IDO1, CCL17, and CCL22. Ligation of surface MARCO can thus result in decreased T cell responses mainly by reduction of their proliferation. Taken together, cancer cell-induced MARCO expression and its intrinsic regulatory function within macrophages are, to our knowledge, new aspects of cancer immune evasion mechanisms that need to be further studied in the future.

OX40 Ligand Contributes to Human Lupus Pathogenesis by Promoting T Follicular Helper Response.

Increased activity of T follicular helper (Tfh) cells plays a major pathogenic role in systemic lupus erythematosus (SLE). However, the mechanisms that cause aberrant Tfh cell responses in SLE remain elusive. Here we showed the OX40 ligand (OX40L)-OX40 axis contributes to the aberrant Tfh response in SLE. OX40L was expressed by myeloid antigen-presenting cells (APCs), but not B cells, in blood and in inflamed tissues in adult and pediatric SLE patients. The frequency of circulating OX40L-expressing myeloid APCs positively correlated with disease activity and the frequency of ICOS(+) blood Tfh cells in SLE. OX40 signals promoted naive and memory CD4(+) T cells to express multiple Tfh cell molecules and were sufficient to induce them to become functional B cell helpers. Immune complexes containing RNA induced OX40L expression on myeloid APCs via TLR7 activation. Our study provides a rationale to target the OX40L-OX40 axis as a therapeutic modality for SLE.

Linking biomarkers with healthy lifestyle outcomes after stroke: Supplementary results of a 12-month randomized controlled trial.

BACKGROUND AND AIMS: Participation in a healthy lifestyle intervention such as the Diabetes Prevention Program Group Lifestyle Balance-adapted for stroke (GLB-CVA) may reduce stroke burden. Identifying biomarkers associated with lifestyle changes may enhance an individualized approach to stroke recovery. We investigated metabolic biomarkers related to cardiovascular and neurological function in individuals with stroke in the GLB-CVA study and healthy (non-stroke) individuals. METHODS AND RESULTS: Participants with chronic (>12 months) stroke were recruited to this wait-list randomized controlled trial if they were overweight (BMI ≥25 kg/m2). Participants were randomized to (1) the GLB-CVA program to complete 22 educational sessions addressing behavioral principals of dietary and physical activity or (2) a 6 month wait-list control (WLC). Biomarkers [Plasma irisin, vascular endothelial growth factor, lipoprotein-associated phospholipase A2 (Lp-PLA2), insulin-like growth factor 1 and brain-derived neurotrophic factor (BDNF)] were collected at baseline, 3, and 6 months. Age-matched healthy individuals were recruited for biomarker assessment. Compared to healthy adults (n = 19), participants with stroke (GLB-CVA = 24; WLC = 24) at baseline had higher tHcy levels (p < 0.001) and lower PLA2 levels (p = 0.016). No statistically significant interactions were observed for any biomarkers between the GLB-CVA and WLC or between people who achieved 5% weight loss and those who did not. CONCLUSION: Participation in a 6-month healthy lifestyle program did not result in statistically significant changes to select metabolic biomarker levels for our participants with chronic stroke. However, participants with stroke demonstrated a unique biomarker profile compared to age-matched healthy individuals.

C-type lectin-like receptor LOX-1 promotes dendritic cell-mediated class-switched B cell responses.

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a pattern-recognition receptor for a variety of endogenous and exogenous ligands. However, LOX-1 function in the host immune response is not fully understood. Here, we report that LOX-1 expressed on dendritic cells (DCs) and B cells promotes humoral responses. On B cells LOX-1 signaling upregulated CCR7, promoting cellular migration toward lymphoid tissues. LOX-1 signaling on DCs licensed the cells to promote B cell differentiation into class-switched plasmablasts and led to downregulation of chemokine receptor CXCR5 and upregulation of chemokine receptor CCR10 on plasmablasts, enabling their exit from germinal centers and migration toward local mucosa and skin. Finally, we found that targeting influenza hemagglutinin 1 (HA1) subunit to LOX-1 elicited HA1-specific protective antibody responses in rhesus macaques. Thus, LOX-1 expressed on B cells and DC cells has complementary functions to promote humoral immune responses.

Early SIV and HIV infection promotes the LILRB2/MHC-I inhibitory axis in cDCs.

Classical dendritic cells (cDCs) play a pivotal role in the early events that tip the immune response toward persistence or viral control. In vitro studies indicate that HIV infection induces the dysregulation of cDCs through binding of the LILRB2 inhibitory receptor to its MHC-I ligands and the strength of this interaction was proposed to drive disease progression. However, the dynamics of the LILRB2/MHC-I inhibitory axis in cDCs during early immune responses against HIV are yet unknown. Here, we show that early HIV-1 infection induces a strong and simultaneous increase of LILRB2 and MHC-I expression on the surface of blood cDCs. We further characterized the early dynamics of LILRB2 and MHC-I expression by showing that SIVmac251 infection of macaques promotes coordinated up-regulation of LILRB2 and MHC-I on cDCs and monocytes/macrophages, from blood and lymph nodes. Orientation towards the LILRB2/MHC-I inhibitory axis starts from the first days of infection and is transiently induced in the entire cDC population in acute phase. Analysis of the factors involved indicates that HIV-1 replication, TLR7/8 triggering, and treatment by IL-10 or type I IFNs increase LILRB2 expression. Finally, enhancement of the LILRB2/MHC-I inhibitory axis is specific to HIV-1 and SIVmac251 infections, as expression of LILRB2 on cDCs decreased in naturally controlled chikungunya virus infection of macaques. Altogether, our data reveal a unique up-regulation of LILRB2 and its MHC-I ligands on cDCs in the early phase of SIV/HIV infection, which may account for immune dysregulation at a critical stage of the anti-viral response.

Brucella ß 1,2 cyclic glucan is an activator of human and mouse dendritic cells.

Bacterial cyclic glucans are glucose polymers that concentrate within the periplasm of alpha-proteobacteria. These molecules are necessary to maintain the homeostasis of the cell envelope by contributing to the osmolarity of Gram negative bacteria. Here, we demonstrate that Brucella ß 1,2 cyclic glucans are potent activators of human and mouse dendritic cells. Dendritic cells activation by Brucella ß 1,2 cyclic glucans requires TLR4, MyD88 and TRIF, but not CD14. The Brucella cyclic glucans showed neither toxicity nor immunogenicity compared to LPS and triggered antigen-specific CD8(+) T cell responses in vivo. These cyclic glucans also enhanced antigen-specific CD4(+) and CD8(+) T cell responses including cross-presentation by different human DC subsets. Brucella ß 1,2 cyclic glucans increased the memory CD4(+) T cell responses of blood mononuclear cells exposed to recombinant fusion proteins composed of anti-CD40 antibody and antigens from both hepatitis C virus and Mycobacterium tuberculosis. Thus cyclic glucans represent a new class of adjuvants, which might contribute to the development of effective antimicrobial therapies.

Alirocumab and Lipid Levels, Inflammatory Biomarkers, Metabolomics, and Safety in Patients Receiving Maintenance Dialysis: The ALIrocumab in DIALysis Study (A Phase 3 Trial to Evaluate the Efficacy and Safety of Biweekly Alirocumab in Patients on a Stable Dialysis Regimen).

Rationale & Objective: The proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor alirocumab is used in the general population to treat dyslipidemia, but little is known about the effects of alirocumab on lipid levels, biomarkers, the metabolome, and safety in individuals receiving maintenance dialysis. Study Design: Patients receiving maintenance dialysis for at least 3 months and with a low-density lipoprotein cholesterol level of >70 mg/dL were treated with alirocumab for 12 weeks. Laboratory measurements, drug levels, and safety assessments were obtained at baseline and every 4 weeks during the trial. Setting & Participants: In an outpatient setting, 14 patients completed the trial. Intervention: The patients were treated with alirocumab at a full dose of 150 mg every 2 weeks for 12 weeks. The patients were asked to report any adverse events every 2 weeks. Outcomes: There were no unexpected adverse events or laboratory abnormalities in this population receiving dialysis. The drug levels were the same as those for a population not receiving dialysis. Results: Alirocumab resulted in a 45% reduction in the low-density lipoprotein cholesterol level (P = 0.005) and a 35% reduction in the apolipoprotein B level (P = 0.06). There were no significant decreases in the levels of triglycerides, C-reactive protein, fibrinogen, or other inflammatory biomarkers tested. There were significant decreases in the levels of 7 ceramide, 5 sphingomyelin, and 5 cholesterol ester species. Limitations: This study was performed in only 14 patients who were administered alirocumab for only 12 weeks. This study did not address alirocumab treatment in patients with chronic kidney disease not receiving maintenance dialysis. Conclusions: Individuals receiving maintenance dialysis had a similar response to the PCSK9 inhibitor alirocumab as patients not receiving dialysis. The levels of inflammatory biomarkers were not clearly decreased by alirocumab, but the levels of ceramides, sphingomyelins, and cholesterol esters were significantly reduced. Trial Registration: Clinical Trials.gov as NCT03480568.

A novel vaccine for mantle cell lymphoma based on targeting cyclin D1 to dendritic cells via CD40.

BACKGROUND: Mantle cell lymphoma (MCL) is a distinct clinical pathologic subtype of B cell non-Hodgkin's lymphoma often associated with poor prognosis. New therapeutic approaches based on boosting anti-tumor immunity are needed. MCL is associated with overexpression of cyclin D1 thus rendering this molecule an interesting target for immunotherapy. METHODS: We show here a novel strategy for the development of recombinant vaccines carrying cyclin D1 cancer antigens that can be targeted to dendritic cells (DCs) via CD40. RESULTS: Healthy individuals and MCL patients have a broad repertoire of cyclin D1-specific CD4(+) and CD8(+) T cells. Cyclin D1-specific T cells secrete IFN-γ. DCs loaded with whole tumor cells or with selected peptides can elicit cyclin D1-specific CD8(+) T cells that kill MCL tumor cells. We developed a recombinant vaccine based on targeting cyclin D1 antigen to human DCs via an anti-CD40 mAb. Targeting monocyte-derived human DCs in vitro with anti-CD40-cyclin D1 fusion protein expanded a broad repertoire of cyclin D1-specific CD4(+) and CD8(+) T cells. CONCLUSIONS: This study demonstrated that cyclin D1 represents a good target for immunotherapy and targeting cyclin D1 to DCs provides a new strategy for mantle cell lymphoma vaccine.