Differential inflammatory macrophage response to rutile and titanium particles.

Titanium and its alloys are widely used as implant materials for dental and orthopaedic applications due to their advantageous bulk mechanical properties and biocompatibility, compared to other metallic biomaterials. In order to improve their wear and corrosion resistance, several surface modifications that give rise to an outer ceramic layer of rutile have been developed. The ability of rutile wear debris to stimulate the release of inflammatory cytokines from macrophages has not been addressed to date. We have compared the in vitro biocompatibility of sub-cytotoxic doses of rutile and titanium particles in THP-1 cells driven to the monocyte/macrophage differentiation pathway as well as in primary cultures of human macrophages. Confocal microscopy experiments indicated that differentiated THP-1 cells and primary macrophages efficiently internalised rutile and titanium particles. Treatment of THP-1 cells with rutile particles stimulated the release of TNF-alpha, IL-6 and IL-1beta to a lesser extent than titanium. The influence of osteoblasts on the particle-induced stimulation of TNF-alpha and IL-1beta was analysed by co-culturing differentiated THP-1 cells with human primary osteoblasts. Under these conditions, secretion levels of both cytokines after treatment of THP-1 cells with rutile particles were lower than after exposure to titanium. Finally, we observed that primary macrophages released higher amounts of TNF-alpha, IL-6 and IL-1beta after incubation with titanium particles than with rutile. Taken together, these data indicate that rutile particles are less bioreactive than titanium particles and, therefore, a higher biocompatibility of titanium-based implants modified with an outer surface layer of rutile is expected.

Molecular basis of cholestatic diseases of surgical interest.

Cholestasis constitutes one of the most common and severe manifestations of acquired or inherited liver disease. When manifest in early infancy, it is often life-threatening and usually requires surgical management. In many cases, liver transplantation is the only effective therapy. Extensive knowledge about the molecular mechanisms underlying several pediatric cholestatic disorders has been gained in recent years from studies in both experimental models and clinical forms. In this review, we focus on recent contributions to the knowledge of molecular basis of main pediatric cholestatic disorders, such as biliary atresia, Alagille syndrome, and familial intrahepatic cholestasis. For some of them, putative targets of therapeutic interest, such as interferon-gamma and Farnesoid X receptor, have been proposed.

Reduced hepatic expression of farnesoid X receptor in hereditary cholestasis associated to mutation in ATP8B1.

Farnesoid X receptor (FXR) is a transcription factor that controls bile acid homeostasis. The phenotype of Fxr null mice is characterized by hypercholanaemia, impaired secretion of bile acids and failure to thrive. Human disorders with these characteristics include FIC1 disease (caused by mutations in ATP8B1, which encodes a putative aminophospholipid translocase, FIC1, whose function in bile handling is unknown) and bile salt export pump (BSEP) disease (caused by mutation in ABCB11, which encodes BSEP, the primary canalicular bile salt export pump). We investigated the possibility of hepatic down-regulation of FXR in FIC1 disease and BSEP disease. Three siblings with this phenotype, born to consanguine parents, were initially studied. The children were demonstrated to be compound heterozygotes for missense and nonsense mutations in ATP8B1. Expression of specific genes in liver was analysed, comparing one of these siblings with a child homozygous for missense mutation in ABCB11, as well as with a child having idiopathic cholestatic liver disease, a child with extrahepatic biliary atresia and a normal organ donor. The expression of two main FXR isoforms was specifically decreased in the liver of the FIC1 disease patient. A consistent and concomitant reduction in messenger RNA levels of FXR targets, such as BSEP and small heterodimer partner, was also found. Gene-profiling experiments identified 163 transcripts whose expression changed significantly in FIC1-disease liver. Of note was that several genes involved in synthesis, conjugation and transport of bile acids were down-regulated. A cluster of genes involved in lipid metabolism was also differentially expressed. Our findings suggest that hepatic down-regulation of FXR contributes to the severe cholestasis of FIC1 disease.

Involvement of CCL27-CCR10 interactions in drug-induced cutaneous reactions.

BACKGROUND: Drug-induced skin reactions, including toxic epidermal necrolysis and Stevens-Johnson syndrome, are severe bullous cutaneous diseases of uncertain etiology, although cytotoxic T cells seem to be involved. Cutaneous T cell-attracting chemokine (CTACK/CCL27) is selectively expressed in skin and attracts CCR10-expressing cells. Exclusive CTACK expression by keratinocytes suggests its involvement in inflammatory skin diseases. OBJECTIVE: We addressed whether CTACK/CCL27 production by the epidermis and CCR10+ lymphocytes are involved in toxic epidermal necrolysis and Stevens-Johnson syndrome. METHODS: We measured CTACK expression by epidermal cells in 2 patients with drug-induced bullous skin reactions and compared it to lesional skin from several drug-induced exanthemas. In parallel we measured CCR10 mRNA in peripheral blood mononuclear cells from the patients during the course of the disease and in lymphocytes infiltrating the skin. RESULTS: CTACK expression levels in skin biopsies from the 2 patients with drug-induced bullous reactions were higher than those found in healthy subjects or in other drug-induced exanthemas. CCR10 mRNA levels were also elevated in peripheral blood lymphocytes and in lesional skin during the acute phase of the disease. Moreover, resolution was associated with a return to baseline of both CTACK and CCR10 receptor expression. CONCLUSION: CTACK-CCR10 interactions may be involved in the selective recruitment to the skin of cytotoxic lymphocytes in toxic epidermal necrolysis and Stevens-Johnson syndrome, as well as in less severe drug-induced cutaneous diseases.

Improvement of toxic epidermal necrolysis after the early administration of a single high dose of intravenous immunoglobulin.

BACKGROUND: Toxic epidermal necrolysis (TEN) is a severe disease often induced by drugs. Treatment is controversial, although intravenous immunoglobulins (IVIGs) have been effective. OBJECTIVE: To report the case of a child with TEN after lamotrigine treatment, who improved 24 hours after IVIG administration. METHODS: Sequential blood and blister fluid samples were obtained for flow cytometry and reverse transcriptase-polymerase chain reaction analyses. RESULTS: The first blood sample, taken before IVIG administration, showed normal levels of lymphocyte subsets and CLA (4.0%) but high levels of activated lymphocytes (CD69) (18.0%). After treatment, the CLA+, CD69+, and memory cells increased until day 7, decreasing to normal values at days 15 and 30. In the blister fluid samples, taken on day 1, there were high levels of CD8+ (70.2%; CD4/CD8 ratio, 1:5), CLA+ (18.8%), and CD69+ (70%) cells, decreasing 24 hours after IVIG administration. In the blood samples, there was a Th1 cytokine pattern initially, tending to Th0 with time. Perforin, granzyme B, and Fas ligand were only observed before IVIG administration. CONCLUSIONS: A single high dose of IVIG interrupted the progression of skin disease and reduced the expression of the apoptotic markers. The immunologic changes, first seen in blister fluid and remaining several days in peripheral blood, indicate that T cells were first recruited to the skin and then recirculated to blood.

Anaphylactic reaction to diphtheria-tetanus vaccine in a child: specific IgE/IgG determinations and cross-reactivity studies.

The present study describes the occurrence of an anaphylactic reaction after the administration of the fifth booster dose of DT vaccine in a six-year-old child. Skin test, in vitro determinations of specific IgE antibodies and immunoblotting assays showed that the IgE response was directed against tetanus and diphtheria toxoids (Dtx). IgG antibodies were also detected by ELISA and immunoblotting. The RAST and immunoblotting inhibitions showed no cross-reactivity between the two toxoids, indicating the presence of co-existing but non-cross-reacting IgE and IgG antibodies. This was maintained in two subsequent determinations done 18 and 30 months after the episode. To our knowledge, this is the first study of cross-reactivity between tetanus and diphtheria antigens. We show that simultaneous IgE antibodies to two different toxoids may occur, indicating that after an immediate reaction to DT, a search for IgE antibodies to both tetanus and Dtx should be undertaken.