The role of pulse dexamethasone in acquired idiopathic thrombotic thrombocytopenic purpura

[Treatment of thrombotic thrombocytopenic purpura]

The review discusses approaches to treatment of acquired thrombotic thrombocytopenic purpuгa (aTTP). In patients with aTTP plasma exchanges, glucocorticosteroids allow to stop an acute attack of TTP, and use of rituximab allows to achieve remission. In recent years, caplacizumab has been used. Treatment options such as cyclosporin A, bortezomib, splenectomy, N-acetylcysteine, recombinant ADAMTS13 are also described. Separately discussed issues of management of patients with TTP during pregnancy, and pediatric patients with TTP.

Evaluation and Management of Patients With Thrombotic Thrombocytopenic Purpura

Thrombotic thrombocytopenic purpura (TTP) describes syndromes with multiple etiologies, some of which are rapidly fatal without plasma exchange treatment. Although there have been advances in understanding the pathogenesis of TTP, evaluation and management remain difficult because there are no specific diagnostic criteria, as TTP can be clinically similar to other acute disorders, such as sepsis, disseminated malignancy, malignant hypertension, and preeclampsia, and because urgent treatment is required. An unexpected observation of anemia and thrombocytopenia should trigger consideration of TTP; evidence that the anemia is due to microangiopathic hemolysis, suggested by the presence of red cell fragmentation on the blood smear, supports the diagnosis. When the diagnostic criteria of microangiopathic hemolytic anemia and thrombocytopenia without an apparent alternative etiology are fulfilled, plasma exchange treatment is appropriate. However, plasma exchange has risks for severe complications and death; therefore, this management decision must be balanced against the confidence in the diagnosis. With plasma exchange treatment, approximately 80% of patients survive, in contrast to only 10% in the era prior to the availability of plasma exchange. The continuing mortality from TTP, the risks of plasma exchange treatment, and the potential for recurrent episodes of TTP are clinical challenges that remain to be solved.

Therapeutic plasma exchange in patients with thrombotic thrombocytopenic purpura: a retrospective multicenter study

Thrombotic thrombocytopenic purpura (TTP) is a particular form of thrombotic microangiopathy typically characterized by thrombocytopenia, microangiopathic hemolytic anemia, fever, neurological abnormalities, and renal dysfunction. TTP requires a rapid diagnosis and an adapted management in emergency. Daily sessions of therapeutic plasma exchange (TPE) remain the basis of management of TTP. Also, TTP is a rare disease that is fatal if it is not treated. TPE has resulted in excellent remission and survival rates in TTP patients.

AIM

We aimed to present our experience in 163 patients with TTP treated with TPE during the past 5years from 10 centers of Turkey.

PATIENTS AND METHODS

One hundered and sixty-three patients with TTP treated with TPE during the past 5years from 10 centers of Turkey were retrospectively evaluated. TPE was carried out 1-1.5times plasma volume. Fresh frozen plasma (FFP) was used as the replacement fluid. TPE was performed daily until normalization of serum lactate dehydrogenase (LDH) and recovery of the platelet count to >150×10(9)/dL. TPE was then slowly tapered. Clinical data, the number of TPE, other given therapy modalities, treatment outcomes, and TPE complications were recorded.

RESULTS

Fifty-eight percent (95/163) of the patients were females. The median age of the patients was 42years (range; 16-82). The median age of male patients was significantly higher than female (53 vs. 34years; p<0.001). All patients had thrombocytopenia and microangiopathic hemolytic anemia. At the same time, 82.8% (135/163) of patients had neurological abnormalities, 78.5% (128/163) of patients had renal dysfunction, and 89% (145/163) of patients had fever. Also, 10.4% (17/163) of patients had three of the five criteria, 10.4% (17/163) of patients had four of the five criteria, and 6.1% (10/163) of patients had all of the five criteria. Primary TTP comprised of 85.9% (140/163) of the patients and secondary TTP comprised of 14.1% (23/163) of the patients. Malignancy was the most common cause in secondary TTP. The median number of TPE was 13 (range; 1-80). The number of TPE was significantly higher in complete response (CR) patients (median 15.0 vs. 3.5; p<0.001). CR was achieved in 85.3% (139/163) of the patients. Similar results were achieved with TPE in both primary and secondary TTP (85% vs. 87%, respectively; p=0.806). There was no advantage of TPE+prednisolone compared to TPE alone in terms of CR rates (82.1% vs. 76.7%; p=0.746). CR was not achieved in 14.7% (24/163) of the patients and these patients died of TTP related causes. There were no statistical differences in terms of mortality rate between patients with secondary and primary TTP [15% (21/140) vs. 13% (3/23); p=0.806]. But, we obtained significant statistical differences in terms of mortality rate between patients on TPE alone and TPE+prednisolone [14% (12/86) vs. 3% (2/67), p<0.001].

CONCLUSIONS

TPE is an effective treatment for TTP and is associated with high CR rate in both primary and secondary TTP. Thrombocytopenia together with microangiopathic hemolytic anemia is mandatory for the diagnosis of TTP and if these two criteria met in a patient, TPE should be performed immediately.

Lipopolysaccharide renders transgenic mice expressing human serum amyloid P component sensitive to Shiga toxin 2

Transgenic C57BL/6 mice expressing human serum amyloid P component (HuSAP) are resistant to Shiga toxin 2 (Stx2) at dosages that are lethal in HuSAP-negative wild-type mice. However, it is well established that Stx2 initiates extra-intestinal complications such as the haemolytic-uremic syndrome despite the presence of HuSAP in human sera. We now demonstrate that co-administering purified Escherichia coli O55 lipopolysaccharide (LPS), at a dosage of 300 ng/g body weight, to HuSAP-transgenic mice increases their susceptibility to the lethal effects of Stx2. The enhanced susceptibility to Stx2 correlated with an increased expression of genes encoding the pro-inflammatory cytokine TNFα and chemokines of the CXC and CC families in the kidneys of LPS-treated mice, 48 hours after the Stx2/LPS challenge. Co-administering the glucocorticoid dexamethasone, but not the LPS neutralizing cationic peptide LL-37, protected LPS-sensitized HuSAP-transgenic mice from lethal doses of Stx2. Dexamethasone protection was specifically associated with decreased expression of the same inflammatory mediators (CXC and CC-type chemokines and TNFα) linked to enhanced susceptibility caused by LPS. The studies reveal further details about the complex cascade of host-related events that are initiated by Stx2 as well as establish a new animal model system in which to investigate strategies for diminishing serious Stx2-mediated complications in humans infected with enterohemorrhagic E. coli strains.

High versus standard dose methylprednisolone in the acute phase of idiopathic thrombotic thrombocytopenic purpura: a randomized study

Therapeutic plasma exchange (PE) is the accepted therapy for thrombotic thrombocytopenic purpura (TTP). Because not all patients achieve remission, other treatment modalities have been used in addition to PE, but no randomized clinical trial evaluated their efficacy. The aim of this multicentric study was to compare the effectiveness of standard- versus high-dose methylprednisolone as an adjunctive treatment to PE in the acute phase of TTP. Sixty patients with idiopathic TTP were randomized to receive methylprednisolone 1 mg/kg/die intravenous or 10 mg/kg/die for 3 days, thereafter, 2.5 mg/kg/die in addition to PE. Both dosages of steroids were well tolerated. At the end of induction therapy (day 23), the percentage of patients failing to achieve complete remission was significantly higher in the standard dose (16 of 30) than in the high-dose group (seven of 30). Also, the number of cases without a good response at day 9 and the number of deaths were higher in the standard-dose arm, but the differences did not reach the statistical significance. Results of present study indicate that the association of PE with high-dose instead of standard-dose steroids reduces the percentage of TTP patients that fail to achieve complete remission.