Current Drug Targets - Immune, Endocrine & Metabolic Disorders - Volume 4, Issue 2, 2004

Over the last decade it has become apparent that common pathogenic mechanisms are shared between many human chronic inflammatory diseases of unrelated pathology and manifestation. These mechanisms include common inflammatory networks that control tissue destructive and repair processes and their study is of major therapeutic potential as recently demonstrated for TNFα. Thus, early studies in rheumatoid arthritis defined TNFα as a major therapeutic target, the blockade of which was subsequently proved to be of great efficacy in the clinic. This paved the way for the successful blockade of TNFα in various other diseases including Crohn's disease, psoriasis, spondyloarthropathies and juvenile arthritis, although no similar networks with anti-TNFα at their apex had previously been demonstrated. In this article, we review the current knowledge of the pathogenic mechanisms involved in rheumatoid arthritis and chronic obstructive pulmonary disease with particular emphasis on the role of inflammatory cytokines, chemokines, and tissue degrading enzymes as revealed by studies in the laboratory and the clinic. Direct comparison of these mechanisms may provide clues for a future therapy for these painful and incurable diseases.

It is not unusual to meet increased levels of ferritinaemia in patients apparently healthy. Among other causes of hyperferritinaemia, recently was described the Hereditary Hyperferritinemia Cataract Syndrome, a genetic condition characterized by increased serum ferritin values without iron overload and bilateral nuclear cataract, both of early onset. It has been demonstrated that single or double point mutations or deletions in the stem-loop structure of the iron regulatory element (I.R.E.) located in the 5 untranslated regions of the ferritin L-subunit gene (19q13.1) are responsible for the upregulation of ferritin. This overexpression only for the L-chain gives rise to typical piles in several tissues. When this altered ferritin accumulates in lens it causes bilateral nuclear cataracts, that is the peculiar sign of this syndrome. It is essential to differentiate true iron overload from Hereditary Hyperferritinaemia Cataract Syndrome (H.H.C.S.), because these patients rapidly develop iron deficient anaemia when venosectioned. Here we describe a case report about a 40 years old healthy female blood donor who presented isolated hyperferritinaemia without iron overload, in the absence of concomitant pathologies. Anamnestic, biochemical, instrumental and clinical investigations led us to diagnose H.H.C.S., a pathology first described in 1995. From 1995 to date about 40 cases concerning patients showing the characteristics of this syndrome from Europe, U.S.A., and Australia were described. Biochemical, genetical and clinical investigations led finally to understand every matter of this pathology, providing conclusive and exhaustive explanations.

Heterotrimeric G-protein-coupled receptors (GPCRs) mediate a wide variety of organismal functions ranging from vision, olfaction, and gustation to the development and physiology of the cardiovascular, neuronal, and immune system. Naturally they are targets of a large number of therapeutic drugs. The regulators of G protein signaling (RGS) are a family of diverse proteins that regulate the GPCR-mediated signaling pathways principally by acting as GTPase activating proteins (GAPs) for the α subunit of the heterotrimeric Gproteins. Certain members of the RGS family contain multiple domains and motifs that mediate interactions with other signaling molecules, thus linking GPCR-dependent and GPCR-independent signaling pathways. Because of their ability to fine-tune vital GPCR-mediated processes and recent findings linking them to brain disorders, retinitis pigmentosa, and cancer RGS proteins have become excellent candidates for new drug discovery. The focus of this review is to discuss the roles of the RGS proteins in the development and normal physiology of cardiovascular and immune system, and to explore their potential as drug targets useful for the treatment of pathological conditions of the cardiovascular and immune systems.

Structure-modifying osteoarthritis (OA) drugs are agents that reverse, retard, or stabilize the pathology of OA, thereby providing symptomatic relief in the long-term treatment. The objective of this review is to evaluate the literature on chondroitin sulfate (CS) with respect to the pathobiology of OA to ascertain whether this agent should be classified as a symptomatic slow-acting drug (SYSADOA), a compound that has a slow onset of action and improve OA symptoms after a couple of weeks. CS exhibits a wide range of biological activities and from a pharmacological point of view it produces a slow but gradual decrease of the clinical symptoms of OA and these benefits last for a long period after the end of treatment. Many literature data show that CS could have an anti-inflammatory activity and a chondroprotective action by modifying the structure of cartilage. These properties are also related to the oral adsorption of this molecule as high-molecular mass compounds having clusters of sulfate groups and high charge density capable of exert their chondroprotective activity in vivo.

The existence of an immune-endocrine interaction has been demonstrated decades ago. An immunomodulatory effect was reported for a wide range of hormones. The best known example for this interaction is the glucocorticoids released by the adrenal cortex. Apart of the glucocorticoids several hormones and neurotransmitters released by these systems are capable of altering immune functions. This includes the catecholamines epinephrine, norepinephrine and dopamine, the pituitary hormone prolactin, and the adrenal hormone dehydroepiandrosterone (DHEA). Several pathological states are paralleled by an activation of the endocrine system leading to an increased hormone release. In line with this an elevated release of catecholamines, of prolactin, and of DHEA has been demonstrated after major surgery, during systemic inflammation and following trauma hemorrhage. Furthermore, due to their pharmacologic properties several neurotransmitters are used as pharmaceutical agents to stabilize cardiovascular function or to prevent organ failure (e.g. epinephrine, norepinephrine, dopamine). Several pharmacological substances interact with the release of immunomodulatory hormones (e.g. metoclopramid and prolactin, dopamine and prolactin) and some hormones are available as over-the counter self medications like DHEA. Therefore, alterations of the serum concentrations of these hormones may affect the immunocompetence of the organism and may thereby affect the clinical course of critically ill patients. The clinical and pharmacological implications of this complex relationship between the endocrine and the immune system will be provided on the background of a review of the recent literature and of our research work.

Acquired demyelinating and inflammatory neuropathies encompass a number of acute and chronic autoimmune conditions characterized by variable degrees of clinical involvement. These disorders, including Guillain-Barré syndrome (GBS), chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), multifocal motor neuropathy (MMN), and paraprotein-associated neuropathy, have an overall annual incidence of 2-4 / 100,000 worldwide and are potentially treatable. Over the last few years, several investigations have helped clarify the pathogenesis of immune neuropathies and the definition of molecular targets involved in these diseases, thus providing firmer grounds for treatment with classical immunosuppressive drugs and new biological agents. In GBS and related variants, which are characterized by cellular inflammation and alterations of the blood-nerve barrier, randomized clinical trials show that plasma exchange (PE) and intravenous immunoglobulin (IVIg) are equally effective as disease-modifying treatments, although IVIg has been adopted as the favourite treatment in most centres. In CIDP, controlled clinical trials have established the efficacy of oral prednisone, PE and IVIg, with intermittent IVIg treatment or corticosteroids being usually preferred. Adding azathioprine can help keep lower the required dose of prednisone, while other immunosuppressive agents, such as cyclophosphamide and cyclosporin A may have side effects, limiting their use to selected cases. Currently, the efficacy of interferon beta and alfa is under evaluation. Controlled trials support the view that IVIg is the treatment of choice in MMN. Patients resistant to IVIg administration may benefit of treatments which deplete B cells, such as cyclophosphamide and rituximab. Demyelinating neuropathies associated with circulating paraproteins are clinically heterogeneous, depending on the reactivity and type of the monoclonal (M) protein. In many cases, neuropathies associated with IgM M proteins are not treated because of their slow progression. In patients with a disabling or rapid progression, small trials have shown short-term benefits from IVIg or PE. Recently, fludarabine and rituximab have been reported as beneficial in selected cases.

Fms-like tyrosine kinase 3 ligand (Flt3L) has multiple effects on the hematopoietic and immune systems. Further, preclinical studies have suggested potential therapeutic activity against cancer. Flt3L is a potent hematopoietic cytokine, capable of stimulating the expansion and differentiation of hematopoietic progenitor and stem cells. Administration of Flt3L mobilizes hematopoietic cells from the bone marrow (BM) into the blood, lymphoid organs, and parenchymal tissues. This mobilization activity, especially effective in combination with granulocyte colony stimulating factor (G-CSF), has stimulated studies of Flt3L in hematopoietic stem cell (HSC) transplantation. In addition to its effects on hematopoietic stem and progenitor cells, Flt3L has been shown to increase the frequency and number of dendritic cells (DCs) within the circulatory system and solid organs. DC expansion by Flt3L has been the focus of preclinical and clinical studies on antigen (Ag) specific T-cell mediated immunity. The mechanism for the augmentation of T-cell mediated immunity has yet to be completely identified, although Flt3L's ability to expand DCs in lymphoid and non-lymphoid tissues is involved. This expansion occurs primarily with DCs, which secrete interleukin (IL) 12. Consistent with the expansion of this DC population, treatment with Flt3L enhances T-cell mitogenesis and preferentially induces type 1 T-cell responses. However, the DCs resulting from Flt3L administration are immature, leading in some studies to the induction of tolerance. This review focuses on the effects of Flt3L on DCs and other effector populations, and on its potential activity as a therapeutic agent for cancer, alone and in combination with vaccines.

Activins and inhibins were first identified by virtue of their ability to regulate follicle-stimulating hormone (FSH) secretion from the anterior pituitary. Activins are also powerful regulators of gonadal functions. However, the physiological functions of activins are not restricted to reproductive tissues. Activins are involved in apoptosis of hepatocytes and B cells, fibrosis, inflammation and neurogenesis. Activins are regarded as novel drug targets since blocking activins would provide benefits by preventing apoptosis, fibrosis, inflammation and growth of several cancers. Activins are members of the transforming growth factor-β (TGF-β) family, which has numerous peptide growth and differentiation factors including activins, bone morphogenetic proteins (BMPs), growth and differentiation factors (GDFs) and TGF-βs. Among them, GDF8 is also known as myostatin and is structurally related to activins. Myostatin is specifically expressed in the skeletal muscle lineage and is a candidate for muscle chalone negatively regulating the growth of myoblasts. Myostatin is regarded as a good drug target since therapeutics that modulate skeletal muscle growth would be useful for disease conditions such as muscular dystrophy, sarcopenia, cachexia and even diabetes. Recent studies have revealed that activins and myostatin signal through activin type II receptors (ActRIIA and ActRIIB) and their activities are regulated by extracellular binding proteins, follistatins and follistatin-related gene (FLRG). Furthermore, signaling of activins, myostatin and related ligands is also controlled by intracellular receptor-interacting proteins by novel mechanisms. In this review, I would like to show the current progress in the field emphasizing the importance of activins and myostatin as novel drug targets for immune, endocrine and metabolic disorders.