IGH 3'RR recombination uncovers a non-germinal center imprint and c-MYC-dependent IGH rearrangement in unmutated chronic lymphocytic leukemia.

Chronic lymphocytic leukemia (CLL) is an incurable indolent non-Hodgkin lymphoma characterized by tumor B cells that weakly express a B-cell receptor. The mutational status of the variable region (IGHV) within the immunoglobulin heavy chain (IGH) locus is an important prognosis indicator and raises the question of the CLL cell of origin. Mutated IGHV gene CLL are genetically imprinted by activation-induced cytidine deaminase (AID). AID is also required for IGH rearrangements: class switch recombination and recombination between switch Mu (Sµ) and the 3' regulatory region (3'RR) (Sµ-3'RRrec). The great majority of CLL B cells being unswitched led us to examine IGH rearrangement blockade in CLL. Our results separated CLL into two groups on the basis of Sµ-3'RRrec counts per sample: Sµ-3'RRrecHigh cases (mostly unmutated CLL) and Sµ-3'RRrecLow cases (mostly mutated CLL), but not based on the class switch recombination junction counts. Sµ-3'RRrec appeared to be ongoing in Sµ-3'RRrecHigh CLL cells and comparison of Sµ-3'RRrec junction structural features pointed to different B-cell origins for both groups. In accordance with IGHV mutational status and PIM1 mutation rate, Sµ-3'RRrecHigh CLL harbor a non-germinal center experienced B-cell imprint while Sµ-3'RRrecLow CLL are from AID-experienced B cells from a secondary lymphoid organ. In addition to the proposals already made concerning the CLL cell of origin, our study highlights that analysis of IGH recombinatory activity can identify CLL cases from different origins. Finally, on-going Sµ-3'RRrec in Sµ-3'RRrecHigh cells appeared to presumably be the consequence of high c-MYC expression, as c-MYC overexpression potentiated IGH rearrangements and Sµ-3'RRrec, even in the absence of AID for the latter.

Demultiplexing Ig repertoires by parallel mRNA/DNA sequencing shows major differential alterations in severe COVID-19.

To understand the fine differential elements that can lead to or prevent acute respiratory distress syndrome (ARDS) in COVID-19 patients, it is crucial to investigate the immune response architecture. We herein dissected the multiple layers of B cell responses by flow cytometry and Ig repertoire analysis from acute phase to recovery. Flow cytometry with FlowSOM analysis showed major changes associated with COVID-19 inflammation such as an increase of double-negative B-cells and ongoing plasma cell differentiation. This paralleled COVID-19-driven expansion of two disconnected B-cell repertoires. Demultiplexing successive DNA and RNA Ig repertoire patterns characterized an early expansion of IgG1 clonotypes with atypically long and uncharged CDR3, the abundance of this inflammatory repertoire being correlated with ARDS and likely pejorative. A superimposed convergent response included convergent anti-SARS-CoV-2 clonotypes. It featured progressively increasing somatic hypermutation together with normal-length or short CDR3 and it persisted until a quiescent memory B-cell stage after recovery.

[Feedback from the establishment of a psychiatric regulation line at SAMU 62 in the context of Covid-19]. / Retour d'expérience de la mise en place d'une ligne de régulation psychiatrique au SAMU 62 dans le contexte Covid-19.

The epidemic context of Covid-19 and the containment measures, put in place since 16 March 2020, has significantly increased the number of emergencies calls in call center (SAMU). In the department of Pas-de-Calais, one step of the crisis measures was setting up a psychiatric regulation line, which aims to manage calls with strong emotional valence (in connexion with containment, anxiety related to the epidemic context, or break in psychiatric cares for people suffering of mental disorders). This psychiatric hotline was provided from 20 March 2020 to 15 May 2020 by fifteen psychiatric careers (psychiatrists, psychologists and psychiatric nurses) from the network of the medical-psychological emergency unit (unit of the emergency call center which aims to manage people involved in psychotraumatic events). In total, 556 calls were answered, i.e. an average of 9,8 calls per day. The typology of calls was in a quarter of the cases anxiety related to the fear of being infected, in the second quarter, adjustment disorders related to containment, and for about half of the calls, psychiatrics symptoms whether it was preexisting and increased by the discontinuation of care, or context-induced. The benefits identified by this device were as follows: -the discharge of time-consuming calls for the medical dispatcher assistant, -the expertise of a mental health professional, knowing the mental health network, to make the decision more fluid. Last but not least, it is interesting to note that the presence of the psychiatric regulator in the regulation room allowed a transfer of calls and a reciprocal acculturation. In view of the relevance of the establishment of a psychiatric regulation line in the epidemic context of Covid-19, it seems interesting to consider the sustainability of this system, which is part of a global context of evolution of the provision of emergency care.

Autophagy Targeting and Hematological Mobilization in FLT3-ITD Acute Myeloid Leukemia Decrease Repopulating Capacity and Relapse by Inducing Apoptosis of Committed Leukemic Cells.

Targeting FLT3-ITD in AML using TKI against FLT3 cannot prevent relapse even in the presence of complete remission, suggesting the resistance and/or the persistence of leukemic-initiating cells in the hematopoietic niche. By mimicking the hematopoietic niche condition with cultures at low oxygen concentrations, we demonstrate in vitro that FLT3-ITD AML cells decrease their repopulating capacity when Vps34 is inhibited. Ex vivo, AML FLT3-ITD blasts treated with Vps34 inhibitors recovered proliferation more slowly due to an increase an apoptosis. In vivo, mice engrafted with FLT3-ITD AML MV4-11 cells have the invasion of the bone marrow and blood in 2 weeks. After 4 weeks of FLT3 TKI treatment with gilteritinib, the leukemic burden had strongly decreased and deep remission was observed. When treatment was discontinued, mice relapsed rapidly. In contrast, Vps34 inhibition strongly decreased the relapse rate, and even more so in association with mobilization by G-CSF and AMD3100. These results demonstrate that remission offers the therapeutic window for a regimen using Vps34 inhibition combined with mobilization to target persistent leukemic stem cells and thus decrease the relapse rate.