Thrombotic Complications in Patients with Immune-Mediated Hemolysis

Extremely Rare Case of Successful Treatment of Foot Ulcer Associated with Evans' Syndrome and Buerger's Disease

Evans Syndrome (ES) is a rare autoimmune disorder characterized by the simultaneous occurrence of immune thrombocytopenia (ITP) and autoimmune hemolytic anemia (AIHA). Thrombotic complications in ES patients are uncommon, particularly involving Buerger's Disease (BD). We report a case of a 49-year-old male with ES and a history of diabetes and heavy smoking, presenting with a necrotic wound on his right great toe. Diagnostic evaluations revealed severe stenosis and thrombosis in the lower limb arteries, diagnosed as BD. The patient underwent successful popliteal-tibioperoneal artery bypass surgery and the subsequent disarticulation and revision of the distal phalanx, followed by the application of an acellular dermal matrix (ADM) to promote healing. Post-surgery, the patient showed significant improvement in blood flow and complete epithelialization without complications. This case highlights the importance of a multidisciplinary approach to managing complex wounds in ES patients, suggesting potential treatment pathways for future cases involving BD.

A novel acid-responsive polymer coating with antibacterial and antifouling properties for the prevention of biofilm-associated infections

Chronic infections caused by the pathogenic biofilms on implantable medical devices pose an increasing challenge. To combat long-term biofilm-associated infections, we developed a novel dual-functional polymer coating with antibacterial and antifouling properties. The coating consists of N-vinylpyrrolidone (NVP) and 3-(acrylamido)phenylboronic acid (APBA) copolymer brushes, which bind to curcumin (Cur) as antibacterial molecules through acid-responsive boronate ester bonds. In this surface design, the hydrophilic poly (N-vinylpyrrolidone) (PVP) component improved antifouling performance and effectively prevented bacterial adhesion and aggregation during the initial phases. The poly (3-(acrylamido) phenylboronic acid) (PAPBA, abbreviated PB) component provided binding sites for Cur by forming acid-responsive boronate ester bonds. When fewer bacteria overcame the anti-adhesion barrier and colonized, the surface responded to the decreased microenvironmental pH by breaking the boronate ester bonds and releasing curcumin. This responsive mechanism enabled Cur to interfere with biofilm formation and provide a multilayer anti-biofilm protection system. The coating showed excellent antibacterial properties against Escherichia coli and Staphylococcus aureus, preventing biofilm formation for up to 7 days. The coating also inhibited protein adsorption and platelet adhesion significantly. This coating also exhibited high biocompatibility with animal erythrocytes and pre-osteoblasts. This research offers a promising approach for developing novel smart anti-biofilm coating materials.

Cutting-Edge Techniques and Drugs for the Treatment of Pulmonary Embolism: Current Knowledge and Future Perspectives

Pulmonary embolism (PE) is a potentially life-threatening condition requiring prompt diagnosis and treatment. Recent advances have led to the development of newer techniques and drugs aimed at improving PE management, reducing its associated morbidity and mortality and the complications related to anticoagulation. This review provides an overview of the current knowledge and future perspectives on PE treatment. Anticoagulation represents the first-line treatment of hemodynamically stable PE, direct oral anticoagulants being a safe and effective alternative to traditional anticoagulation: these drugs have a rapid onset of action, predictable pharmacokinetics, and low bleeding risk. Systemic fibrinolysis is suggested in patients with cardiac arrest, refractory hypotension, or shock due to PE. With this narrative review, we aim to assess the state of the art of newer techniques and drugs that could radically improve PE management in the near future: (i) mechanical thrombectomy and pulmonary embolectomy are promising techniques reserved to patients with massive PE and contraindications or failure to systemic thrombolysis; (ii) catheter-directed thrombolysis is a minimally invasive approach that can be suggested for the treatment of massive or submassive PE, but the lack of large, randomized controlled trials represents a limitation to widespread use; (iii) novel pharmacological approaches, by agents inhibiting thrombin-activatable fibrinolysis inhibitor, factor Xia, and the complement cascade, are currently under investigation to improve PE-related outcomes in specific settings.

cGMP modulates hemin-mediated platelet death

BACKGROUND AND AIMS

Hemolysis is a known risk factor for thrombosis resulting in critical limb ischemia and microcirculatory disturbance and organ failure. Intravasal hemolysis may lead to life-threatening complications due to uncontrolled thrombo-inflammation. Until now, conventional antithrombotic therapies failed to control development and progression of these thrombotic events. Thus, the pathophysiology of these thrombotic events needs to be investigated to unravel underlying pathways and thereby identify targets for novel treatment strategies.

METHODS

Here we used classical experimental set-ups as well as high-end flow cytometry, metabolomics and lipidomic analysis to in-depth analyze the effects of hemin on platelet physiology and morphology.

RESULTS

Hemin does strongly and swiftly induce platelet activation and this process is modulated by the sGC-cGMP-cGKI signaling axis. cGMP modulation also reduced the pro-aggregatory potential of plasma derived from patients with hemolysis. Furthermore, hemin-induced platelet death evokes distinct platelet subpopulations. Typical cell death markers, such as ROS, were induced by hemin-stimulation and the platelet lipidome was specifically altered by high hemin concentration. Specifically, arachidonic acid derivates, such as PGE2, TXB2 or 12-HHT, were significantly increased. Balancing the cGMP levels by modulation of the sGC-cGMP-cGKI axis diminished the ferroptotic effect of hemin.

CONCLUSION

We found that cGMP modulates hemin-induced platelet activation and thrombus formation in vitro and cGMP effects hemin-mediated platelet death and changes in the platelet lipidome. Thus, it is tempting to speculate that modulating platelet cGMP levels may be a novel strategy to control thrombosis and critical limb ischemia in patients with hemolytic crisis.

Severe autoimmune hemolytic anemia; epidemiology, clinical management, outcomes and knowledge gaps

Autoimmune hemolytic anemia (AIHA) is an acquired hemolytic disorder, mediated by auto-antibodies, and has a variable clinical course ranging from fully compensated low grade hemolysis to severe life-threatening cases. The rarity, heterogeneity and incomplete understanding of severe AIHA complicate the recognition and management of severe cases. In this review, we describe how severe AIHA can be defined and what is currently known of the severity and outcome of AIHA. There are no validated predictors for severe clinical course, but certain risk factors for poor outcomes (hospitalisation, transfusion need and mortality) can aid in recognizing severe cases. Some serological subtypes of AIHA (warm AIHA with complement positive DAT, mixed, atypical) are associated with lower hemoglobin levels, higher transfusion need and mortality. Currently, there is no evidence-based therapeutic approach for severe AIHA. We provide a general approach for the management of severe AIHA patients, incorporating monitoring, supportive measures and therapeutic options based on expert opinion. In cases where steroids fail, there is a lack of rapidly effective therapeutic options. In this era, numerous novel therapies are emerging for AIHA, including novel complement inhibitors, such as sutimlimab. Their potential in severe AIHA is discussed. Future research efforts are needed to gain a clearer picture of severe AIHA and develop prediction models for severe disease course. It is crucial to incorporate not only clinical characteristics but also biomarkers that are associated with pathophysiological differences and severity, to enhance the accuracy of prediction models and facilitate the selection of the optimal therapeutic approach. Future clinical trials should prioritize the inclusion of severe AIHA patients, particularly in the quest for rapidly acting novel agents.

A novel role of acellular hemoglobin in hemolytic thrombosis

BACKGROUND

Hemolytic thrombosis has been associated with acellular hemoglobin released from damaged red blood cells during hemolysis. However, the precise molecular mechanism underlying acellular hemoglobin-induced thrombosis remains arguable. In this study, we examined the interaction between hemoglobin and the A1 domain of von Willebrand factor (VWF), which is a critical mediator of platelet activation.

METHODS

Previous studies have suggested that the interaction between hemoglobin and the A1 domain of VWF enhances VWF's hemostatic activity. We employed a multidisciplinary investigation to re-examine this interaction, and identified significant differences in binding affinity between the active and inactive forms of A1.

RESULTS

We found that hemoglobin binds more strongly to the active A1 than the inactive form. Using hydrogen‑deuterium exchange mass spectrometry, we identified the specific residues involved in this interaction, which are located on the α1-β2 and β3-α2 loops that are typically covered by the "autoinhibitory module" in the inactive A1. This observation provides a structural explanation for the differential binding affinity between the active and inactive forms of A1. We demonstrated that the binding of hemoglobin to A1 blocks the interaction between GPIbα and VWF, and inhibits VWF-mediated thrombosis in vivo. Furthermore, we found that administration of hemoglobin led to similar levels of thrombocytopenia and microthrombosis in both wildtype and VWF-deficient mice, indicating that the mechanism underlying acellular hemoglobin-induced thrombosis is VWF-independent.

CONCLUSIONS

These findings challenge the previous theory that hemoglobin-induced thrombosis occurs solely through binding with VWF, and provide evidence supporting a novel role for hemoglobin in hemolytic thrombosis.

Thrombosis in Pregnant Women with Hemolytic Anemia

Hemolytic anemias are a group of uncommon disorders affecting both genders, frequently occurring at the reproductive age. While a link between hemolysis and hypercoagulability has been suggested based on the elucidation of certain involved pathophysiological mechanisms, the extent of thrombotic risk in pregnant women with hemolytic anemia remains debatable. Due to the paucity of pregnancy-related data, risk assessment of gestations in women with hemolytic anemia is complicated. This review will highlight the latest advances in the diagnosis and management of these challenging disorders in pregnancy.

Thromboembolism Early After Glucocorticoid Administration in Patients with Autoimmune Hemolytic Anemia

Pulmonary embolism and deep venous thrombosis (PE/DVT) are well-known lethal complications in autoimmune hemolytic anemia (AIHA). However, the impact of their treatment is unclear. Here, we describe three elderly Japanese patients with AIHA who developed PE/DVT early after glucocorticoid administration. All patients presented with active hemolysis and high D-dimer levels upon admission. Thromboembolism was confirmed within 2 weeks after starting glucocorticoid, suggesting that both active hemolysis and glucocorticoid administration synergistically contributed to the development of PE/DVT. Clinicians should consider that such synergism may increase the risk of thromboembolism in patients with AIHA, and prophylactic anticoagulation is worth considering in patients after starting glucocorticoid.

Infrequent Thrombotic Complications in Japanese Patients with Warm Autoimmune Hemolytic Anemia

Objective Patients with autoimmune hemolytic anemia (AIHA) are considered to be at an increased risk of thrombosis, and prophylaxis for venous thromboembolism (VTE) is often recommended. However, the occurrence of thrombosis in Asian patients has not been specifically studied. Thrombotic complications and features of Japanese warm AIHA (WAIHA) patients were studied to see if Japanese patients were at an increased risk of thrombosis and should receive prophylaxis for VTE. Patients and Methods Forty-seven consecutive patients with warm WAIHA were retrospectively studied. Twenty-nine patients were diagnosed as primary cases and 18 as secondary cases, and 10 patients were diagnosed with Evans syndrome. Results No patient presented with thrombosis, and over a median observation period of 15 months, 3 patients had ischemic cerebral vascular accidents. However, all three of those patients had other known risks for thrombosis, with only one taking thrombotic prophylaxis. No venous thrombosis occurred in any patients during the follow-up period. There was no mortality associated with thrombosis. D-dimer levels were often elevated in patients with WAIHA, indicating that the coagulation was activated in a considerable number of patients, but not to such a level as to be associated with clinically overt thrombosis. Conclusion Thrombotic complications occur infrequently in Japanese WAIHA patients, and these individuals do not appear to be at a particularly increased risk of thrombosis because of WAIHA. The indication of VTE prophylaxis should be determined individually, considering other risks.

Intravascular hemolysis and multitreatment predict thrombosis in patients with autoimmune hemolytic anemia

BACKGROUND

Thrombosis may complicate autoimmune hemolytic anemia (AIHA), but its predictors are still lacking, and no clear-cut indications for anticoagulant prophylaxis are available.

OBJECTIVES

To characterize frequency and severity of thromboses in AIHA patients and identify risk factors for thrombosis that may advise primary anticoagulant prophylaxis.

PATIENTS/METHODS

A total of 287 consecutive AIHA patients diagnosed and followed from 1978 at a tertiary Italian center were retrospectively studied; 174 of them were prospectively evaluated from January 2020 until December 2021. AIHA relapse, thrombosis occurrence, and primary anticoagulant prophylaxis were evaluated.

RESULTS

Thirty-three AIHA patients (11.4%) experienced thrombosis, 70% of whom hospitalized. The cumulative thrombosis incidence was higher in patients with lactate dehydrogenase (LDH) ≥ 1.5 (hazard ratio [HR] 3.22), in those experiencing infections (HR 3.57), receiving transfusions (HR 3.06), rituximab (HR 3.3), or cyclophosphamide (HR 2.67). By multivariable analysis, LDH, transfusions, rituximab, and cyclophosphamide treatment emerged as independent factors associated with thrombosis. Among 174 patients prospectively followed in the past 2 years, we observed 70 acute hemolytic episodes in 45 patients; 33/45 displayed LDH ≥1.5 × upper limit of normal, and 17 received anticoagulant prophylaxis with low molecular weight heparin for a median of 70 days (30-300). In those receiving prophylaxis no thrombotic complications occurred, whereas five thrombotic episodes were registered in the remaining 16 cases.

CONCLUSIONS

Thrombosis was observed in about 11% of AIHA patients, mainly grade 3, and associated with intravascular hemolysis, need of transfusions, multitreatment, and infections, advising primary anticoagulant prophylaxis in these settings.

Iron deficiency anemia and thrombosis risk in children-revisiting an old hypothesis

Iron deficiency anemia has a high prevalence in children and has repeatedly been implicated as a risk factor for arterial and venous thrombosis. As an effective therapy for iron deficiency anemia is available, understanding the association between this form of anemia and the potentially severe thrombosis phenotype is of major clinical interest. Recent findings shed light on pathophysiology of hypercoagulability resulting from iron-restricted erythropoiesis. Specifically, an animal model of induced iron deficiency allowed identifying multiple mechanisms, by which iron deficiency anemia results in increased thrombus formation and thrombus progression both in arterial and venous thrombosis. These findings complement and support conclusions derived from clinical data. The purpose of this mini review is to summarize current evidence on the association of iron deficiency anemia and thrombosis. We want to increase the awareness of iron deficiency as a risk factor for thrombosis in the pediatric population. We discuss how novel pathophysiological concepts can be translated into the clinical settings and suggest clinical studies on prevention and treatment strategies in high-risk patient groups.

Concomitant autoimmune hemolytic anemia and pulmonary embolism associated with mild COVID-19: A case report

Despite its rarity, AIHA can be associated with COVID-19. It should be suspected in a patient with recent COVID-19 presenting with unexplained anemia.