Multicenter Retrospective Study of Invasive Fusariosis in Intensive Care Units, France

Invasive fusariosis can be life-threatening, especially in immunocompromised patients who require intensive care unit (ICU) admission. We conducted a multicenter retrospective study to describe clinical and biologic characteristics, patient outcomes, and factors associated with death and response to antifungal therapy. We identified 55 patients with invasive fusariosis from 16 ICUs in France during 2002----2020. The mortality rate was high (56%). Fusariosis-related pneumonia occurred in 76% of patients, often leading to acute respiratory failure. Factors associated with death included elevated sequential organ failure assessment score at ICU admission or history of allogeneic hematopoietic stem cell transplantation or hematologic malignancies. Neither voriconazole treatment nor disseminated fusariosis were strongly associated with response to therapy. Invasive fusariosis can lead to multiorgan failure and is associated with high mortality rates in ICUs. Clinicians should closely monitor ICU patients with a history of hematologic malignancies or stem cell transplantation because of higher risk for death.

Tumor Lysis Syndrome and AKI: Beyond Crystal Mechanisms

BACKGROUND

The pathophysiology of AKI during tumor lysis syndrome (TLS) is not well understood due to the paucity of data. We aimed to decipher crystal-dependent and crystal-independent mechanisms of TLS-induced AKI.

METHODS

Crystalluria, plasma cytokine levels, and extracellular histones levels were measured in two cohorts of patients with TLS. We developed a model of TLS in syngeneic mice with acute myeloid leukemia, and analyzed ultrastructural changes in kidneys and endothelial permeability using intravital confocal microscopy. In parallel, we studied the endothelial toxicity of extracellular histones in vitro. RESULTS: The study provides the first evidence that previously described crystal-dependent mechanisms are insufficient to explain TLS-induced AKI. Extracellular histones that are released in huge amounts during TLS caused profound endothelial alterations in the mouse model. The mechanisms of histone-mediated damage implicates endothelial cell activation mediated by Toll-like receptor 4. Heparin inhibits extracellular histones and mitigates endothelial dysfunction during TLS.

CONCLUSION

This study sheds new light on the pathophysiology of TLS-induced AKI and suggests that extracellular histones may constitute a novel target for therapeutic intervention in TLS when endothelial dysfunction occurs.

Endothelial Cells Activated by Extracellular Histones Promote Foxp3+ Suppressive Treg Cells In Vitro

Histones are widely recognized as pro-inflammatory mediators upon their release from the nucleus into the extracellular space. However, their impact on endothelial cell immunogenicity is unknown. Endothelial cells, Human Microvascular Endothelial cells 1 (HMEC1), have been exposed to recombinant histones in order to study their effect on the endothelial phenotype. We then studied the differentiation of CD4⁺-T lymphocytes subpopulations after three days of interaction with endothelial cells in vitro and observed that histone-treated endothelial cells differentiate a suppressive FoxP3⁺ T regulator subpopulation that expressed Human Leucocyte Antigen DR (HLA-DR) and Cytotoxic T-Lymphocyte-Associated protein 4 (CTLA4). Toll-Like Receptor 4 (TLR4) inhibition significantly decreased the expansion of these Treg cells. Moreover, blockade of Interleukin (IL)-6 and Intercellular Adhesion Molecule (ICAM)-1 in cocultures significantly decreased the expansion of Tregs, suggesting an IL-6 and ICAM-1 dependent pathway. Thus, beyond their inflammatory effects, extracellular histones may induce an increase of immunosuppressive Treg population via their action on endothelial cells. Further studies are needed to evaluate the impact on immunosuppression of an increase of peripheral suppressive Treg via endothelial cell activation by histones in vivo.

Deregulation and Targeting of TP53 Pathway in Multiple Myeloma

Multiple Myeloma (MM) is an incurable disease characterized by a clonal evolution across the course of the diseases and multiple lines of treatment. Among genomic drivers of the disease, alterations of the tumor suppressor TP53 are associated with poor outcomes. In physiological situation, once activated by oncogenic stress or DNA damage, p53 induces either cell-cycle arrest or apoptosis depending on the cellular context. Its inactivation participates to drug resistance in MM. The frequency of TP53 alterations increases along with the progression of the disease, from 5 at diagnosis to 75% at late relapses. Multiple mechanisms of regulation lead to decreased expression of p53, such as deletion 17p, TP53 mutations, specific microRNAs overexpression, TP53 promoter methylations, and MDM2 overexpression. Several therapeutic approaches aim to target the p53 pathway, either by blocking its interaction with MDM2 or by restoring the function of the altered protein. In this review, we describe the mechanism of deregulation of TP53 in MM, its role in MM progression, and the therapeutic options to interact with the TP53 pathway.