Fabian Crespo

Soluble cytokine receptors in biological therapy.

Due to their fundamental involvement in the pathogenesis of many diseases, cytokines constitute key targets for biotherapeutic approaches. The discovery that soluble forms of cytokine receptors are involved in the endogenous regulation of cytokine activity has prompted substantial interest in their potential application as immunotherapeutic agents. As such, soluble cytokine receptors have many advantages, including specificity, low immunogenicity and high affinity. Potential disadvantages, such as low avidity and short in vivo half-lifes, have been addressed by the use of genetically-designed receptors, hybrid proteins or chemical modifications. The ability of many soluble cytokine receptors to inhibit the binding and biological activity of their ligands makes them very specific cytokine antagonists. Several pharmaceutical companies have generated a number of therapeutic agents based on soluble cytokine receptors and many of them are undergoing clinical trials. The most advanced in terms of clinical development is etanercept (Enbrel™, Immunex), a fusion protein between soluble TNF receptor Type II and the Fc region of human IgG1. This TNF-α antagonist was the first soluble cytokine receptor to receive approval for use in humans. In general, most agents based on soluble cytokine receptors have been safe, well-tolerated and have shown only minor side effects in the majority of patients. Soluble cytokine receptors constitute a new generation of therapeutic agents with tremendous potential for applications in a wide variety of human diseases. Two current areas of research are the identification of their most promising applications and characterisation of their long-term effects.

Targeting of glycosaminoglycan-cytokine interactions as a novel therapeutic approach in allotransplantation.

Background. Glycosaminoglycans (GAGs) are heteropolysaccharides present as integral components of the extracellular matrix (ECM), cell and basement membranes. GAGs play an important role in immune and inflammatory responses because of their ability to interact with cytokines and chemokines, promoting the localization of these molecules onto the ECM or cell membranes at specific anatomical sites. The main goal of these studies was to test the hypothesis that interference with the binding of cytokines/chemokines to GAGs will interfere with a graft rejection response. Methods. MC-2, a cationic peptide derived from the sequence of the heparin-binding domain of mouse interferon gamma, was used as an inhibitor of the binding of cytokines/chemokines to GAGs. The effects of this peptide were studied in an allogeneic transplantation model involving vascularized rat skin flaps. Results. The MC-2 peptide was found to inhibit binding of interferon-&ggr;, as well as that of the chemokines, interleukin-8, interferon gamma inducible protein-10, and regulated on activation normal T cell expressed and secreted (RANTES), to GAGs in vitro. Direct administration of MC-2 in an allogeneic skin flap transplantation model resulted in a significantly delayed time of rejection, from 5.4 ± 0.5 days (control; n=6) to 12.6 ± 1.6 days (treated animals; n=10). Histopathologic analysis of the skin biopsies was consistent with the delayed rejection process in those animals receiving the peptide, showing only mild signs of rejection up to day 11 (in contrast, all control animals had rejected their flaps by day 6). Conclusions. These results are consistent with the idea that GAG-cytokine interactions constitute valid therapeutic targets and suggest the potential applicability of such an approach in the prevention of graft rejection.

Cytokine expression and microglial activation in progressive supranuclear palsy

Although little is known about the etiology of progressive supranuclear palsy (PSP), genetic and epigenetic factors, oxidative injury and inflammation are thought to contribute to its development and/or progression. Evidence for activated glia involvement in PSP has raised the possibility that neuroinflammation may contribute to its pathogenesis. To investigate the correlation between neuroinflammation and PSP, a comparative study was conducted on the patterns of cytokine expression in different regions of the brains of PSP, Alzheimers disease (AD) patients and normal controls. Our results show different patterns of cytokine expression in each disease, with the expression of IL-1β transcripts being significantly higher in the substantia nigra of PSP than in AD and controls, while AD brains had significantly higher IL-1β expression in the parietal cortex compared to PSP and controls. In addition, expression of TGFβ was significantly higher in the cortical areas (particularly frontal and parietal lobes) of AD compared to PSP and controls. These results show a disease-specific topographical relationship among the expression of certain cytokines (IL-1β and TGFβ), microglial activation and neurodegenerative changes, suggesting that these cytokines may contribute to the pathologic process. If so, the use of cytokine-inhibitors and/or other anti-inflammatory agents may be able to slow disease progression in PSP.

The immunoregulatory effects of gangliosides involve immune deviation favoring type‐2 T cell responses

Gangliosides, sialic acid‐containing glycosphingolipids present in most cell membranes, are thought to participate in the maintenance of immune privilege and tumor‐induced immunosuppression. However, the mechanisms responsible for their immunomodulatory activity remain poorly understood. The purpose of this study was to investigate whether gangliosides are able to modulate the balance of type‐1/type‐2 T cell responses and to characterize the cellular mechanisms involved. The effects of different gangliosides on anti‐CD3‐stimulated murine splenocytes and purified T cells were studied. The presence of gangliosides during T cell activation reduced the expression of interferon‐γ (IFN‐γ) and enhanced that of interleukin (IL)‐4, suggesting a shift toward a type‐2 response. Intracellular cytokine staining demonstrated that gangliosides inhibited IFN‐γ production in CD4+, CD8+, and natural killer (NK)1.1+ cell populations and enhanced IL‐4 in CD4+ T cells. The ganglioside‐mediated enhancement in IL‐4 production was independent of changes in endogenous IFN‐γ, did not occur with cells from CD1d‐deficient mice, and was partially inhibited by anti‐CD1d antibodies. The inhibitory effects on IFN‐γ were independent of endogenous IL‐4 or the presence of NKT cells and were unaffected by anti‐CD1d antibodies. These results suggest that gangliosides may modify the immunological environment by promoting immune deviation in favor of type‐2 T cell responses.

Revascularización miocárdica arterial completa con ambas arterias mamarias sin circulación extracorpórea

Introduccion. Tector ha descrito la tecnica de revascularizacion arterial completa usando multiples anastomosis con ambas arterias mamarias internas. Para reducir la morbimortalidad quirurgica nos hemos propuesto realizar esta tecnica sin circulacion extracorporea. Pacientes y metodos. Desde abril de 1998 hemos realizado revascularizacion «tipo Tector» sin circulacion extracorporea en 92 pacientes, 74 varones (80%) y 18 mujeres (20%), con una edad media de 64,9 ± 8,1 anos (rango, 42-78). La angiografia preoperativa puso de manifiesto que diecinueve (20,5%) pacientes tenian lesion significativa de tronco comun y 58 (63%) triple vaso. Cuarenta pacientes (43,5%) presentaban angina inestable, 24 (26%) enfermedad vascular periferica significativa y 26 (28%) diabetes. Ambas mamarias fueron disecadas sin pediculo, y anastomosadas como injerto en «Y» o «T». La permeabilidad de las anastomosis se evaluo con Doppler intraoperatorio en 24 (26%) pacientes mediante

Failure to deplete anti-Galalpha1-3Gal antibodies after pig-to-baboon organ xenotransplantation by immunoaffinity columns containing multiple Galalpha1-3Gal oligosaccharides.

Abstract:  Background:  The impact of anti‐Galα1‐3Gal (αGal) antibodies on the acute humoral xenograft rejection (AHXR) of pig organs transplanted in baboons is unclear.

Do leprosy and tuberculosis generate a systemic inflammatory shift? Setting the ground for a new dialogue between experimental immunology and bioarchaeology

It is possible that during long lasting chronic infections such as tuberculosis (TB) and leprosy individuals who generate a stronger immune response will produce a chronic shift in the systemic levels of inflammatory proteins. Consequently, the systemic immunological shift could affect inflammatory responses against other persistent pathogens such as Porphyromonas gingivalis associated with periodontal disease (PD). OBJECTIVE To determine if in vitro exposure to Mycobacterium tuberculosis or M. leprae lysates impacts subsequent immune responses to P. gingivalis; and to propose a new dialogue between experimental immunology and paleopathology. MATERIAL AND METHODS We sequentially (2 days protocol) exposed peripheral blood mononuclear cells (PBMCs) from healthy donors to bacterial lysates either from M. tuberculosis, or M. leprae, or P. gingivalis. After collecting all supernatants, we measured the expression of immune proteins TNFα and IFNγ using an enzyme-linked immunosorbent assay. RESULTS Early exposure (day 1) of PBMCs to M. leprae or M. tuberculosis lysates induces an inflammatory shift detected by the increase of TNFα and IFNγ when the same cells are subsequently (day 2) exposed to oral pathogen P. gingivalis. DISCUSSION By extrapolating these results, we suggest that chronic infections, such as TB and leprosy, could generate a systemic immunological shift that can affect other inflammatory processes such the one present in PD. We propose that the presence and severity of PD should be explored as a proxy for inflammatory status or competence when reconstructing the health profile in past populations.