Presence of adherent Escherichia coli strains in ileal mucosa of patients with Crohn's disease

Background & Aims: Infectious agents are suspected of being involved in the pathogenesis of Crohn's disease. This study was designed to look for the presence of virulent Escherichia coli strains associated with the ileal mucosa of patients with Crohn's disease. Methods:E. coli strains were recovered from resected chronic ileal lesions (n = 20), neoterminal ileum after surgery from patients with (n = 19) and without (n = 11) endoscopic recurrence, and controls (n = 13). Bacterial adhesion was determined in vitro using intestinal cell lines; other associated virulence factors were assessed by DNA hybridization and polymerase chain reaction experiments. Results: None of the strains harbored any of the virulence factor–encoding genes of E. coli involved in acute enteric diseases. However, mannose-resistant adhesion to differentiated Caco-2 cells was found for 84.6% and 78.9% of the E. coli strains isolated from chronic and early recurrent lesions, respectively, compared with 33% of controls (P < 0.02). In addition, 21.8% of the strains induced a cytolytic effect by synthesis of an α-hemolysin. Conclusions:E. coli strains isolated from the ileal mucosa of patients with Crohn's disease adhere to differentiated intestinal cells and may disrupt the intestinal barrier by synthesizing an α-hemolysin.GASTROENTEROLOGY 1998;115:1405-1413     

Impact of CD34+ cell dose on the outcome of patients undergoing reduced-intensity-conditioning allogeneic peripheral blood stem cell transplantation

We analyzed the impact of CD34+ cell dose on the outcome of 86 patients undergoing reduced-intensity conditioning (RIC) allogeneic peripheral blood stem cell transplantation. The RIC was based on fludarabine 150 mg/m2 and melphalan 140 mg/m2 or busulphan 10 mg/kg. A median of 5.68 x 106 CD34+ cells/kg and 2.86 x 108 CD3+ cells/kg were infused. All patients receiving more than percentile 75 (p75) of CD34+ cells reached complete chimerism in T lymphocytes by days 21 to 28, compared with 44% among those receiving p75 or fewer cells (P =.046). Overall, 30.3% patients developed grade 2 to 4 acute graft-versus-host disease (aGVHD). Among 83 evaluable patients, 55.8% developed chronic GVHD (cGVHD). The dose of CD34+ cells infused did influence the development of cGVHD, with a cumulative incidence of extensive cGVHD of 74% vs 47% (P =.02) among patients receiving more than p75 CD34+ cells vs those receiving p75 or fewer. Projected overall survival (OS) and event-free survival (EFS) at 43 months were 60% and 46%, respectively. Neither the dose of CD34+ cells nor the dose of CD3+ cells infused significantly influenced OS and EFS, although among patients categorized as high-risk, 36% of those receiving p75 or fewer CD34+ cells relapsed or progressed, compared with only 9% among those receiving more than p75 CD34+ cells (P =.07). Among patients receiving p75 or fewer CD34+ cells, 36% of high-risk patients relapsed, compared with 10% of low- and intermediate-risk patients (P =.004), while relapse rates were not significantly different between both subgroups when we infused more than p75 CD34+ cells, thus indicating that infusing high doses of CD34+ cells ameliorates the negative effect of advanced disease status at transplantation. cGVHD was associated with better EFS (63% vs 16% at 43 months for patients with and without cGVHD; P <.0001) and better OS (78% vs 28% for patients with and without cGHVD; P <.001). The number of CD34+ cells infused should be tailored to prevent extensive cGVHD among patients categorized as low-risk, while high-risk patients, in whom the graft-versus-leukemia effect may determine disease outcome, should receive high doses of CD34+ cells.     

Selective tumor antigen vaccine delivery to human CD169+ antigen-presenting cells using ganglioside-liposomes

Priming of CD8⁺ T cells by dendritic cells (DCs) is crucial for the generation of effective antitumor immune responses. Here, we describe a liposomal vaccine carrier that delivers tumor antigens to human CD169/Siglec-1⁺ antigen-presenting cells using gangliosides as targeting ligands. Ganglioside-liposomes specifically bound to CD169 and were internalized by in vitro-generated monocyte-derived DCs (moDCs) and macrophages and by ex vivo-isolated splenic macrophages in a CD169-dependent manner. In blood, high-dimensional reduction analysis revealed that ganglioside-liposomes specifically targeted CD14⁺ CD169⁺ monocytes and Axl⁺ CD169⁺ DCs. Liposomal codelivery of tumor antigen and Toll-like receptor ligand to CD169⁺ moDCs and Axl⁺ CD169⁺ DCs led to cytokine production and robust cross-presentation and activation of tumor antigen-specific CD8⁺ T cells. Finally, Axl⁺ CD169⁺ DCs were present in cancer patients and efficiently captured ganglioside-liposomes. Our findings demonstrate a nanovaccine platform targeting CD169⁺ DCs to drive antitumor T cell responses.

The major breakthrough of immune-checkpoint inhibitors, such as anti-CTLA4 and anti–PD-L1, in cancer therapy is still limited to a minority of patients who respond to this treatment (1). Patients with pancreatic cancer, for example, failed to respond to monotherapies of checkpoint inhibitors in multiple trials (2, 3). Factors such as poor tumor immunogenicity, tumor-immunosuppressive microenvironment, and the lack of an existing tumor-specific immune response are thought to contribute to patients’ lack of response to these immune-checkpoint inhibitors (2, 4, 5). Nevertheless, the abundance of intratumoral CD8⁺ T cells is associated with longer survival of pancreatic cancer patients, suggesting these patients may benefit from a better antitumor immunity (6–8). Therefore, new strategies aiming to boost patients’ antitumor CD8⁺ T cell responses should be explored to improve current therapies.Dendritic cells (DCs) play a crucial role in eliciting immune responses against tumor-specific antigens and have therefore generated significant interest as a therapeutic target in the context of cancer immunotherapy (9). The most commonly used DC-based immunotherapy utilizes monocyte-derived DCs (moDCs) due to the large numbers that can be generated ex vivo. In general, moDC-based vaccines have shown some survival benefit and appear to be well-tolerated; however, the objective response rate in most studies is still relatively low (9, 10). Moreover, since generating DCs ex vivo is a laborious, time-consuming, and costly process, research is shifting toward targeting tumor antigens to naturally circulating or tissue-resident DCs in vivo as a vaccine strategy to induce immune responses (11). Both in mice and humans, DCs can be divided into several subsets, of which the conventional DCs (CD141⁺ cDC1 and CD1c⁺ cDC2) have been shown to be responsible for T cell priming (12, 13).In vivo DC targeting can be achieved by using antibodies or ligands that bind to DC-specific receptors and are directly conjugated to tumor antigen or to nanoparticles harboring tumor antigen. Targeting C-type lectin receptors in particular, such as DEC-205, Clec-9A, and DC-SIGN, has been demonstrated to induce antigen-specific and antitumor responses in mouse and human models (14–17). Recently, we compared two vaccination strategies of antigen–antibody conjugates directed to either DEC-205⁺ DCs or to CD169⁺ macrophages, a type of macrophage that acts as sentinel in secondary lymphoid organs (18). Remarkably, we observed that antigen targeting toward CD169⁺ macrophages led to a significant antigen-specific CD8⁺ T cell response that was as efficient as DEC-205 targeting and capable of suppressing tumor cell outgrowth (18–20). Stimulation of antigen-specific immune responses by targeting to CD169 has also been demonstrated using HLA-A2.1 transgenic mice and human CD169-expressing moDCs (21), indicating the immunotherapy potential of antigen targeting to CD169.In a resting state, CD169/Siglec-1 is highly expressed by a specific subtype of macrophages that are located bordering the marginal zone in the spleen and the subcapsular sinus of lymph nodes (22, 23). Their strategic location allows them to be among the first cells to encounter and to capture blood and lymph-borne pathogens, and, in conjunction with DCs, to initiate the appropriate immune responses (18, 19, 24, 25). In addition to combating infection, CD169⁺ macrophages have been implicated in antitumor immunity. They have been shown to capture tumor-derived materials in mouse and human (26, 27), and their frequency in tumor-draining lymph nodes is clearly associated with better clinical outcomes in several types of cancer (28–30). Although the exact mechanism is unclear, these observations suggest that lymphoid-resident CD169⁺ macrophages can positively contribute to antitumor immunity. Next to lymphoid tissue-resident macrophages, CD169 is also constitutively expressed by a recently described Axl⁺ Siglec6⁺ DC subset (Axl⁺ DCs, AS DCs, or pre-DCs) present in peripheral blood and lymphoid tissues (31–34). Axl⁺ DCs have been proposed as a distinct DC subset that has the capacity to produce inflammatory cytokines and to stimulate CD4⁺ and CD8⁺ T cells (31–33). In addition to these constitutively CD169-expressing macrophages and DCs, during inflammatory conditions, monocytes can up-regulate CD169 in response to type I interferons (IFN-Is) (35, 36).CD169 is a member of the sialic acid-binding Ig-like lectin (Siglec) receptor family that recognizes sialic acids present on glycoproteins or glycolipids on the cell surface and mediates cell–cell interactions and adhesion (37). Sialic acid-containing glycosphingolipids, such as GM3, GT1b, and GD1a gangliosides, are known to be endogenous ligands for CD169 molecules (38, 39). However, the CD169–sialic acid axis can be hijacked as a receptor entry molecule by viral pathogens, including murine leukemia virus (MLV), HIV, and Ebola virus to infect DCs or macrophages (40–43). The CD169-mediated entry and transinfection is dependent on gangliosides, including GM3, that are present on the viral lipid membrane (40, 44, 45). Interestingly, Axl⁺ DCs have been recently demonstrated to be the predominant DC subset to capture HIV in a CD169-dependent manner.In this study, we aimed to exploit ganglioside–CD169 interactions to develop a novel tumor antigen vaccination strategy that directs tumor antigens to human CD169⁺ antigen-presenting cells (APCs) using liposomes containing gangliosides. We generated liposomes with different types of gangliosides and assessed the binding and uptake by different types of human CD169⁺ APCs, including monocytes and primary and monocyte-derived macrophages and DCs. High-dimensionality mapping revealed the specificity of ganglioside-liposome targeting exclusively to circulating CD169⁺ monocytes and Axl⁺ DCs. To determine the efficacy of ganglioside-liposomes for antigen presentation, we encapsulated peptides derived from the pancreatic cancer-associated tumor antigen Wilms tumor 1 (WT1) or melanoma-associated gp100 antigen into the ganglioside-liposomes. CD169⁺ moDCs and Axl⁺ DCs loaded with these ganglioside-liposomes efficiently activated CD8⁺ T cells specific for these epitopes. Moreover, Axl⁺ DCs were present in patients with four different cancers and could be targeted by ganglioside-liposomes. Our data demonstrate that ganglioside-liposomes can be used as nanovaccine carriers that efficiently target CD169⁺ DCs for cross-presentation and antigen-specific T cell activation. In conclusion, our studies support the concept that cancer vaccines targeting to CD169 can be applied to boost CD8⁺ T cell responses in cancer patients.     

The randomized shortened dental arch study: influence of two different treatments on interdental spacing over 5 years

Clinical Oral Investigations - Being a secondary outcome in a multicenter randomized controlled trial, the present analysis focused on interdental spacing in the shortened dental arch (SDA). The...     

Do we need ‘new’ omega-3 polyunsaturated fatty acids formulations?

The therapeutic value of omega-3 polyunsaturated fatty acids (PUFAs), mainly (but not only) found in fish oils, eicosapentaenoic and docosahexaenoic acids (EPA and DHA, respectively), has been extensively studied in a wide variety of disease conditions, predominantly in cardiovascular disease. However, the significant difference in efficacy observed in various conditions with different dosages seems to be at least partly related to the large discrepancy in quality of the product and to the bioavailability of the omega-3 PUFA. The research of new sources (e.g., from arctic Krill oil) and pharmaceutical forms of omega-3 PUFA (e.g., omega-3 carboxylic acids) is needed in order to detect the one with the best bioavailability and efficacy, and with a parallel reduction in the production costs. There is also the need to understand if long-term PUFA supplementation could increase the efficacy of the already-available evidence–based therapies for cardiovascular disease prevention and for the management of the diseases where the use of PUFA could have a possible improving effect.