Dissecting Allo-Sensitization After Local Administration of Human Allogeneic Adipose Mesenchymal Stem Cells in Perianal Fistulas of Crohn's Disease Patients.

Adipose mesenchymal stem cells (ASC) are considered minimally immunogenic. This is due to the low expression of human leukocyte antigens I (HLA-I), lack of HLA-II expression and low expression of co-stimulatory molecules such as CD40 and CD80. The low rate of observed immunological rejection as well as the immunomodulatory qualities, position ASC as a promising cell-based therapy for the treatment of a variety of inflammatory indications. Yet, few studies have addressed relevant aspects of immunogenicity such as ASC donor-to-patient HLA histocompatibility or assessment of immune response triggered by ASC administration, particularly in the cases of presensitization. The present study aims to assess allo-immune responses in a cohort of Crohn's disease patients administered with allogeneic ASC (darvadstrocel formerly Cx601) for the treatment of complex perianal fistulas. We identified donor-specific antibodies (DSA) generation in a proportion of patients and observed that patients showing preexisting immunity were prone to generating DSA after allogeneic therapy. Noteworthy, naïve patients generating DSA at week 12 (W12) showed a significant reduction in DSA titer at week 52 (W52), whereas DSA titer was reduced in pre-sensitized patients only with no specificities against the donor administered. Remarkably, we did not observe any correlation of DSA generation with ASC therapeutic efficacy. In vitro complement-dependent cytotoxicity (CDC) studies have revealed limited cytotoxic levels based upon HLA-I expression and binding capacity even in pro-inflammatory conditions. We sought to identify CDC coping mechanisms contributing to the limited cytotoxic killing observed in ASC in vitro. We found that ASC express membrane-bound complement regulatory proteins (mCRPs) CD55, CD46, and CD59 at basal levels, with CD46 more actively expressed in pro-inflammatory conditions. We demonstrated that CD46 is a main driver of CDC signaling; its depletion significantly enhances sensitivity of ASC to CDC. In summary, despite relatively high clearance, DSA generation may represent a major challenge for allogeneic cell therapy management. Sensitization may be a significant concern when evaluating re-treatment or multi-donor trials. It is still unknown whether DSA generation could potentially be the consequence of donor-to-patient interaction and, therefore, subsequently link to efficacy or biological activity. Lastly, we propose that CDC modulators such as CD46 could be used to ultimately link CDC specificity with allogeneic cell therapy efficacy.

Intralymphatic Administration of Adipose Mesenchymal Stem Cells Reduces the Severity of Collagen-Induced Experimental Arthritis.

Mesenchymal stem cells (MSCs) are multipotent stromal cells with immunomodulatory properties. They have emerged as a very promising treatment for autoimmunity and inflammatory diseases such as rheumatoid arthritis. Previous studies have demonstrated that MSCs, administered systemically, migrate to lymphoid tissues associated with the inflammatory site where functional MSC-induced immune cells with a regulatory phenotype were increased mediating the immunomodulatory effects of MSCs. These results suggest that homing of MSCs to the lymphatic system plays an important role in the mechanism of action of MSCs in vivo. Thus, we hypothesized that direct intralymphatic (IL) (also referred as intranodal) administration of MSCs could be an alternative and effective route of administration for MSC-based therapy. Here, we report the feasibility and efficacy of the IL administration of human expanded adipose mesenchymal stem cells (eASCs) in a mouse model of collagen-induced arthritis (CIA). IL administration of eASCs attenuated the severity and progression of arthritis, reduced bone destruction and increased the levels of regulatory T cells (CD25+Foxp3+CD4+ cells) and Tr1 cells (IL10+CD4+), in spleen and draining lymph nodes. Taken together, these results indicate that IL administration of eASCs is very effective in modulating established CIA and may represent an alternative treatment modality for cell therapy with eASCs.

Fatal Campylobacter jejuni ileocolitis.

Campylobacter infection usually starts in the jejunum and ileum and progresses distally. The case fatality rate is low and most occur in elderly or patients with comorbidity as in this case. Antibiotics should be used in severe cases or patients at risk. The choices are macrolides and fluoroquinolones. However, in some countries quinolone resistance is increasing, as in Spain. We shouldn´t forget this fact for the proper treatment approach and specifically in refractory cases.

Ileocolitis fatal por Campylobacter jejuni / Fatal Campylobacter jejuni ileocolitis

No disponible

Shunt extrahepático. Causa rara de encefalopatía hepática / Extrahepatic shunt. Unusual cause of hepatic encephalopathy

No disponible

T Lymphocyte Prestimulation Impairs in a Time-Dependent Manner the Capacity of Adipose Mesenchymal Stem Cells to Inhibit Proliferation: Role of Interferon γ, Poly I:C, and Tryptophan Metabolism in Restoring Adipose Mesenchymal Stem Cell Inhibitory Effect.

The immunomodulatory properties of mesenchymal stem/stromal cells (MSCs) make them an attractive therapeutic tool to treat chronic inflammatory diseases, such as rheumatoid arthritis or Crohn's disease. These indications are characterized by a chronic activation of immune cells that perpetuates the disease. In vitro, when adipose mesenchymal stem cells (ASCs) are cultured with T lymphocytes at the time of stimulation, their proliferation is inhibited. However, these experimental settings do not necessarily fit with what ASCs will face in inflammatory conditions in vivo, where ASCs will likely encounter and interact with already activated immune cells which might affect their immunomodulatory capacity. In most in vitro studies, MSCs have been cultured with peripheral blood mononuclear cells at the time of lymphocyte stimulation and information about the interaction between MSCs and prestimulated lymphocytes in vitro is scarce. Therefore, a better understanding of the capacity of MSCs to modulate the responses of preactivated immune cells is needed. In this study we focused on the effects of ASCs on prestimulated lymphocytes and systematically investigated the potential mechanisms involved. We report that prestimulation of T lymphocytes 48 h before the coculture with ASCs impairs the capacity of ASCs to inhibit proliferation. Preactivation of ASCs with interferon γ or the toll-like receptor ligand Poly I:C, but not other stimuli tested, enhanced the ability to inhibit the proliferation of 48 h-stimulated T lymphocytes. The inhibitory effect of ASCs was shown to be time dependent and mediated through the actual magnitude of tryptophan degradation by indoleamine 2,3-dioxygenase.

Tryptophan concentration is the main mediator of the capacity of adipose mesenchymal stromal cells to inhibit T-lymphocyte proliferation in vitro.

BACKGROUND AIMS: Mesenchymal stromal cells (MSCs) have immunomodulatory properties that are mediated by cell-to-cell interactions and paracrine effects through soluble factors, among which tryptophan (Trp) conversion into kynurenine (Kyn) through the enzymatic activity of indoleamine 2,3-dioxygenase has been proven to be of special relevance. However, the respective role of Trp depletion and/or Kyn accumulation on the inhibition of T-cell proliferation by MSCs remains unclear. METHODS: The effect of supplementation with increasing concentrations of Trp on the capacity of MSCs to inhibit T-lymphocyte proliferation in vitro was investigated. RESULTS: We report that Trp supplementation impairs the capacity of adipose mesenchymal stromal cells (ASCs) to inhibit T-cell proliferation, despite the accumulation of very high concentrations of Kyn in the medium (>200 µmol/L). Moreover, Trp supplementation after 72 h of peripheral blood mononuclear cell:ASC co-culture, once the inhibitory effect of ASCs was established, reverted ASC inhibition and restored T-cell proliferation. Addition to stimulated lymphocytes of Kyn inhibited T proliferation in 3 of 10 peripheral blood mononuclear cell donors, but at different concentrations, suggesting that sensitivity of lymphocytes to Kyn might be donor-dependent. CONCLUSIONS: Our results confirm the relevance of Trp metabolism as a key mediator of the immunomodulatory properties of ASCs and clarify the respective roles of the Trp/Kyn balance.

Human adipose-derived stem cells impair natural killer cell function and exhibit low susceptibility to natural killer-mediated lysis.

Human adipose-derived stem cells (hASCs) have been successfully used in treating numerous diseases. However, several aspects need to be considered, particularly in the context of allogeneic cell therapy. To better understand hASCs-host interactions, we studied the phenotype of hASCs and their modulatory effect on natural killer (NK) cells by using bone marrow-mesenchymal stem cells (hBM-MSCs) as a reference. The hASCs displayed a lower susceptibility to NK cell-mediated lysis and a lower expression of ligands for DNAM-1 when compared with hBM-MSCs. Moreover, here we demonstrated that hASCs and hBM-MSCs can modulate NK cells through the action of soluble factors such as indoleamine 2,3-dioxygenase. Altogether, these results suggest that for an adoptive cell therapy based on the transfer of allogeneic hASCs, the NK-hASCs crosstalk will not result in an immediate recognition of the transferred cells. Thus, hASCs may remain in the tissue long enough to balance the immune response before being cleared.

A population of CD19highCD45R-/lowCD21low B lymphocytes poised for spontaneous secretion of IgG and IgA antibodies.

Ab responses to selected Ags are produced by discrete B cell populations whose presence and functional relevance vary along the ontogeny. The earliest B lineage-restricted precursors in gestational day 11 mouse embryos display the CD19(+)CD45R/B220(-) phenotype. Phenotypically identical cells persist throughout gestation and in postnatal life, in parallel to the later-arising, CD19(+)CD45R(+) B cells. Very early after birth, the CD19(+)CD45R(-) B cell subset included high frequencies of spontaneously Ig-secreting cells. In the adult spleen, a small subset of CD19(high)CD45R(-/low)IgM(+/-)IgD(-)CD21/Cr2(-/low) cells, which was detected in perifollicular areas, displayed genetic and phenotypical traits of highly differentiated B cells, and was enriched in IgG- and IgA-secreting plasma cells. In vitro differentiation and in vivo adoptive transfer experiments of multipotent hemopoietic progenitors revealed that these CD19(high)CD45R(-/low) B cells were preferentially regenerated by embryo-, but not by adult bone marrow-, derived progenitors, except when the latter were inoculated into newborn mice. Both the early ontogenical emergence and the natural production of serum Igs, are shared features of this CD19(high)CD45R(-/low) B cell population with innate-like B lymphocytes such as B1 and marginal zone B cells, and suggest that the new population might be related to that category.