Transferrin Saturation Inversely Correlates with Platelet Function.

BACKGROUND: The association between iron overload (IO) and risk of cardiovascular disease is controversial. Epidemiological studies have found a significant negative association of transferrin (Tf) saturation and cardiovascular events suggesting that higher body iron possibly confer a protective effect towards developing cardiovascular events. The biological mechanisms of this phenomenon are unknown. OBJECTIVE: This article investigates the role of IO on platelet reactivity. MATERIALS AND METHODS: This study was a prospective case-control study comparing 45 patients with IO, mostly characterized by the HFE gene mutations C282Y and/or H63D, with 32 healthy controls. We evaluated: (1) platelet aggregation in both platelet-rich plasma and whole blood, (2) platelet membrane expression of the activation marker CD62P, (3) activation of platelet signalling phosphoinositide 3-kinase /Akt and mitogen-activated protein kinase/extracellular signal-regulated kinases (Erk)-1/2 pathways, (4) a pattern of in vivo platelet activation markers, and (5) iron biomarker predictors of platelet reactivity. RESULTS: IO patients had significantly lower platelet aggregability, expression of CD62P and phosphorylation amounts of pAkt and pErk-2 in response to agonists. Furthermore, patients with higher Tf saturation levels were characterized by lower circulating levels of sCD40L, PDGF-BB and thromboxane B2. Platelet aggregation and activation parameters inversely correlated with Tf saturation and the stepwise multivariate regression analysis underlined the role of Tf saturation in predicting platelet reactivity. We also found that in vitro platelet exposure to diferric Tf, but not to iron-depleted TF, dose-dependently inhibited platelet function in all investigated subjects. CONCLUSION: Tf saturation is inversely associated with platelet reactivity and this could explain, at least in part, the association of high Tf and lower risk of cardiovascular diseases in IO.

Rituximab in cryoglobulinemic peripheral neuropathy.

Type II mixed cryoglobulinemia is sustained by an oligoclonal production of IgM sharing rheumatoid activity and can be associated with renal, cutaneous, rheumatologic or neurological manifestations. Peripheral neuropathy is a major cause of morbidity in hepatitis C virus-associated mixed cryoglobulinemia and is often refractory to any treatment. Rituximab induces a selective depletion of IgM-producing B cells, and both case reports on monoclonal IgM-related polyneuropathy as well as studies on small series of patients with interferon alpha-resistant mixed cryoglobulinemia have suggested that it may be beneficial. Thirteen patients affected by type II mixed cryoglobulinemia with polyneuropathy were treated. Rituximab was administered intravenously at a dose of 375 mg/m(2) on days 1, 8, 15 and 22. Two more doses were given 1 and 2 months later. No other immunosuppressive drugs were added. Response was evaluated by assessing the changes in the clinical neurological condition, in electromyographic indices and in laboratory parameters (including cryocrit, viral load, complement levels and rheumatoid factor) over at least 12 months. Sensory symptoms disappeared or improved following treatment. A significant improvement in the clinical neuropathy disability score was observed. Electromyography examination revealed that the amplitude of compound motor action potential had increased. Viral load did not significantly change. Side effects were negligible. In this open prospective study, rituximab appeared to be effective and safe in the treatment of patients with type II cryoglobulinemia-associated neuropathy.

Rituximab as a therapeutic tool in severe mixed cryoglobulinemia.

Type II mixed cryoglobulinemia (MC) is a systemic vasculitis, associated in most cases with hepatitis C virus (HCV) infection, sustained by proliferation of oligoclonal cells. Systemic B cell depletion and clinical remission can be achieved in non-Hodgkin lymphoma by human/mouse chimeric monoclonal antibody that specifically reacts with the CD20 antigen (rituximab). Similar effects could be expected in type II MC. Twelve patients, mean age 61.9 years (range 37-76), 11 with HCV infection genotype 2a2c (4 cases) or 1b (6 cases) and 3 (1 case) and symptomatic type II MC with systemic manifestations, including renal involvement, marrow clonal restriction, large necrotizing ulcers, and polyneuropathy, were considered eligible for rituximab therapy because of resistance or intolerance to conventional therapy or important bone marrow infiltration. Rituximab was administered intravenously at a dose of 375 mg/m2 on days 1, 8, 15, and 22. Two more doses were administered 1 and 2 months later. No other immunosuppressive drugs were added. Response was evaluated by assessing the changes in clinical signs, symptoms, and laboratory parameters. Levels of proteinuria, hematuria, erythrocyte sedimentation rate, cryocrit, rheumatoid factor, and IgM decreased while C4 values increased and HCV viral load remained stable during short- and medium-term observation. Bone marrow abnormalities were found to reverse to normal. Constitutional symptoms disappeared or ameliorated. No acute or delayed side effects were seen. Based on this experience and a number of reports published in the last 5 years, Rituximab appears to be a safe and effective therapeutic option in symptomatic patients with HCV-associated MC with signs of systemic vasculitis.