Human bone marrow contains high levels of extracellular vesicles with a tissue-specific subtype distribution

Association between venous thromboembolism rates and different prophylactic anticoagulation regimens in patients undergoing free flap reconstruction of the head and neck region

BACKGROUND

Venous Thromboembolism (VTE) is a serious complication after free tissue transfer to the head and neck (H&N). However, an optimal antithrombotic prophylaxis protocol is not defined in the literature. Enoxaparin 30 mg twice daily (BID) and heparin 5000 IU three times daily (TID) are among the most commonly used regimens for chemoprophylaxis. However, no studies compare these two agents in the H&N population.

METHODS

A cohort study of patients who underwent free tissue transfer to H&N from 2012 to 2021 and received either enoxaparin 30 mg BID or Heparin 5000 IU TID postoperatively. Postoperative VTE and hematoma events were recorded within 30 days of index surgery. The cohort was divided into two groups based on chemoprophylaxis. VTE and hematoma rates were compared between the groups.

RESULTS

Out of 895 patients, 737 met the inclusion criteria. The mean age and Caprini score were 60.6 [SD 12.5] years and 6.5 [SD 1.7], respectively. 234 [31.88%] were female. VTE and hematoma rates among all patients were 4.47% and 5.56%, respectively. The mean Caprini score between the enoxaparin (n = 664) and heparin (n = 73) groups was not statistically significant (6.5 ± 1.7 vs.6.3 ± 1.3, p = 0.457). The VTE rate in the enoxaparin group was significantly lower than in the heparin group (3.9% vs. 9.6%; OR: 2.602, 95% CI: 1.087-6.225). Hematoma rates were similar between the two groups (5.5% vs. 5.6%; OR: 0.982, 95% CI: 0.339-2.838).

CONCLUSIONS

Enoxaparin 30 mg BID was associated with a lower VTE rate while maintaining a similar hematoma rate compared to heparin 5000 units TID. This association may support the use of enoxaparin over heparin for VTE chemoprophylaxis in H&N reconstruction.

Erythropoiesis and Malaria, a Multifaceted Interplay

One of the major pathophysiologies of malaria is the development of anemia. Although hemolysis and splenic clearance are well described as causes of malarial anemia, abnormal erythropoiesis has been observed in malaria patients and may contribute significantly to anemia. The interaction between inadequate erythropoiesis and Plasmodium parasite infection, which partly occurs in the bone marrow, has been poorly investigated to date. However, recent findings may provide new insights. This review outlines clinical and experimental studies describing different aspects of ineffective erythropoiesis and dyserythropoiesis observed in malaria patients and in animal or in vitro models. We also highlight the various human and parasite factors leading to erythropoiesis disorders and discuss the impact that Plasmodium parasites may have on the suppression of erythropoiesis.

Heat Shock Proteins and PD-1/PD-L1 as Potential Therapeutic Targets in Myeloproliferative Neoplasms

Simple Summary

Myeloproliferative neoplasms (MPN), which are a heterogeneous group of rare disorders that affect blood cell production in bone marrow, present many significant challenges for clinicians. Though considerable progress has been made, in particular with the JAK1/2 inhibitor ruxolitinib, more effective alternative therapeutic approaches are needed. In the search for new and more efficient therapies, heat shock proteins, also known as stress proteins, and the programmed cell death 1 (PD-1)/programmed death ligand 1 (PD-L1) immune checkpoint axis have been found to be of great interest in hematologic malignancies. Here, we review the therapeutic potential of stress protein inhibitors in the management of patients diagnosed with MPN and summarize the accumulating evidence of the role of the PD-1/PD-L1 axis in MPN in order to provide perspectives on future therapeutic opportunities relative to the inhibition of these targets.

Abstract

Myeloproliferative neoplasms (MPN) are a group of clonal disorders that affect hematopoietic stem/progenitor cells. These disorders are often caused by oncogenic driver mutations associated with persistent Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling. While JAK inhibitors, such as ruxolitinib, reduce MPN-related symptoms in myelofibrosis, they do not influence the underlying cause of the disease and are not curative. Due to these limitations, there is a need for alternative therapeutic strategies and targets. Heat shock proteins (HSPs) are cytoprotective stress-response chaperones involved in protein homeostasis and in many critical pathways, including inflammation. Over the last decade, several research teams have unraveled the mechanistic connection between STAT signaling and several HSPs, showing that HSPs are potential therapeutic targets for MPN. These HSPs include HSP70, HSP90 (chaperoning JAK2) and both HSP110 and HSP27, which are key factors modulating STAT3 phosphorylation status. Like the HSPs, the PD-1/PD-L1 signaling pathway has been widely studied in cancer, but the importance of PD-L1-mediated immune escape in MPN was only recently reported. In this review, we summarize the role of HSPs and PD-1/PD-L1 signaling, the modalities of their experimental blockade, and the effect in MPN. Finally, we discuss the potential of these emerging targeted approaches in MPN therapy.

Characterization of Cellular Sources and Circulating Levels of Extracellular Vesicles in a Dietary Murine Model of Nonalcoholic Steatohepatitis

Circulating extracellular vesicles (EVs) are a novel and emerging biomarker for nonalcoholic steatohepatitis (NASH). It has been demonstrated that total circulating EVs and hepatocyte‐derived EVs are elevated in male mice with diet‐induced NASH. How hepatocyte‐derived EVs change over time and other cellular sources of EVs in NASH have not been determined. Our objective was to define the quantitative evolution of hepatocyte‐derived, macrophage‐derived, neutrophil‐derived, and platelet‐derived EVs in male and female mice with dietary NASH. Fluorescently labeled antibodies and a nanoscale flow cytometer were used to detect plasma levels of EVs. Asialoglycoprotein receptor 1 (ASGR1) and cytochrome P450 family 2 subfamily E member 1 (CYP2E1) are markers of hepatocyte‐derived EVs; galectin 3 is a marker of macrophage‐derived EVs; common epitope on lymphocyte antigen 6 complex, locus G/C1 (Ly‐6G and Ly‐6C) is a marker of neutrophil‐derived EVs; and clusters of differentiation 61 (CD61) is a marker of platelet‐derived EVs. Nonalcoholic fatty liver disease activity score (NAS) was calculated using hematoxylin and eosin‐stained liver sections, and magnetic resonance imaging (MRI) was used for measurement of the fat fraction and elastography. Hepatocyte‐derived EVs increased in both male and female mice at 12 and 10 weeks of feeding, respectively, and remained elevated at 24 weeks in both male and female mice and at 48 weeks in male mice and 36 weeks in female mice. Macrophage‐ and neutrophil‐derived EVs were significantly elevated at 24 weeks of dietary feeding concomitant with the histologic presence of inflammatory foci in the liver. In fat‐, fructose‐, and cholesterol‐ (FFC) fed male mice, platelet‐derived EVs were elevated at 12, 24, and 48 weeks, whereas in female mice, platelet derived EVs were significantly elevated at 24 weeks. Hepatocyte‐, macrophage‐ and neutrophil‐derived EVs correlated well with the histologic NAS. Conclusion: Circulating cell‐type‐specific EVs may be a novel biomarker for NASH diagnosis and longitudinal follow up.