RESUMEN
Severe aplastic anemia (SAA) is a rare, fatal disease characterized by severe cytopenias and loss of hematopoietic stem cells (HSCs). Immune-mediated destruction and inflammation are known drivers of SAA, however, the underlying mechanisms driving persistent inflammation are unknown. Current treatments for SAA rely on immunosuppressive therapies or HSC transplantation, however, these treatments are not always effective. Using an established mouse model of SAA, we observed a significant increase in apoptotic cells within the bone marrow (BM) and impaired efferocytosis in SAA mice, relative to radiation controls. Single-cell transcriptomic analysis revealed heterogeneity among BM monocytes and unique populations emerged during SAA characterized by increased inflammatory signatures and significantly increased expression of Sirpa and Cd47. CD47, a "don't eat me" signal, was increased on both live and apoptotic BM cells, concurrent with markedly increased expression of signal regulatory protein alpha (SIRPα) on monocytes. Functionally, SIRPα blockade improved cell clearance and reduced accumulation of CD47-positive apoptotic cells. Lipidomic analysis revealed a reduction in the precursors of specialized pro-resolving lipid mediators (SPMs) and increased prostaglandins in the BM during SAA, indicative of impaired inflammation resolution. Specifically, 18-HEPE, a precursor of E-series resolvins, was significantly reduced in SAA-induced mice relative to radiation controls. Treatment of SAA mice with Resolvin E1 (RvE1) improved efferocytic function, BM cellularity, platelet output, and survival. Our data suggest that impaired efferocytosis and inflammation resolution contributes to SAA progression and demonstrate that SPMs, such as RvE1, offer new and/or complementary treatments for SAA that do not rely on immune suppression.
Asunto(s)
Anemia Aplásica , Antígeno CD47 , Ácido Eicosapentaenoico , Animales , Anemia Aplásica/patología , Ratones , Ácido Eicosapentaenoico/análogos & derivados , Ácido Eicosapentaenoico/farmacología , Antígeno CD47/metabolismo , Antígeno CD47/genética , Apoptosis/efectos de los fármacos , Fagocitosis/efectos de los fármacos , Modelos Animales de Enfermedad , Ratones Endogámicos C57BL , Receptores Inmunológicos/metabolismo , Receptores Inmunológicos/genética , Monocitos/metabolismo , Monocitos/efectos de los fármacos , Inflamación/patología , Masculino , EferocitosisRESUMEN
Sepsis survivors exhibit immune dysfunction, hematological changes, and increased risk of infection. The long-term impacts of sepsis on hematopoiesis were analyzed using a surgical model of murine sepsis, resulting in 50% survival. During acute disease, phenotypic hematopoietic stem and progenitor cells (HSPCs) were reduced in the bone marrow (BM), concomitant with increased myeloid colony-forming units and extramedullary hematopoiesis. Upon recovery, BM HSPCs were increased and exhibited normal function in the context of transplantation. To evaluate hematopoietic responses in sepsis survivors, we treated recovered sham and cecal ligation and puncture mice with a mobilizing regimen of granulocyte colony-stimulating factor (G-CSF) at day 20 post-surgery. Sepsis survivors failed to undergo emergency myelopoiesis and HSPC mobilization in response to G-CSF administration. G-CSF is produced in response to acute infection and injury to expedite the production of innate immune cells; therefore, our findings contribute to a new understanding of how sepsis predisposes to subsequent infection.
Asunto(s)
Factor Estimulante de Colonias de Granulocitos , Movilización de Célula Madre Hematopoyética , Células Madre Hematopoyéticas , Mielopoyesis , Sepsis , Animales , Masculino , Ratones , Modelos Animales de Enfermedad , Factor Estimulante de Colonias de Granulocitos/farmacología , Factor Estimulante de Colonias de Granulocitos/uso terapéutico , Células Madre Hematopoyéticas/citología , Células Madre Hematopoyéticas/efectos de los fármacos , Células Madre Hematopoyéticas/metabolismo , Ratones Endogámicos C57BL , Mielopoyesis/efectos de los fármacos , Sepsis/complicaciones , SobrevivientesRESUMEN
Current treatments for severe aplastic anemia (SAA) rely on hematopoietic stem cell (HSC) transplantation and immunosuppressive therapies, however these treatments are not always effective. While immune-mediated destruction and inflammation are known drivers of SAA, the underlying mechanisms that lead to persistent inflammation are unknown. Using an established mouse model of SAA, we observed a significant increase in apoptotic cells within the bone marrow (BM) and demonstrate impaired efferocytosis in SAA mice, as compared to radiation controls. Single-cell transcriptomic analysis revealed heterogeneity among BM monocytes and unique populations emerged during SAA characterized by increased inflammatory signatures and significantly increased expression of Sirpa and Cd47. CD47, a "don't eat me" signal, was increased on both live and apoptotic BM cells, concurrent with markedly increased expression of signal regulatory protein alpha (SIRPα) on monocytes. Functionally, SIRPα blockade improved cell clearance and reduced accumulation of CD47-positive apoptotic cells. Lipidomic analysis revealed a reduction in the precursors of specialized pro-resolving lipid mediators (SPMs) and increased prostaglandins in the BM during SAA, indicative of impaired inflammation resolution. Specifically, 18-HEPE, a precursor of E-series resolvins, was significantly reduced in SAA-induced mice relative to radiation controls. Treatment of SAA mice with Resolvin E1 (RvE1) improved efferocytic function, BM cellularity, platelet output, and survival. Our data suggest that impaired efferocytosis and inflammation resolution contributes to SAA progression and demonstrate that SPMs, such as RvE1, offer new and/or complementary treatments for SAA that do not rely on immune suppression.
RESUMEN
The interaction between the immune system and the nervous system remains an intriguing enigma. Recent studies indicate that innate lymphoid cells (ILCs), a unique family of innate effector cells, participate in intense cross talk with the nervous system. In the mucosal barrier sites, ILCs have been found to co-localize with neurons, nerves, glial cell projectors, and neuroendocrine cells. The cross talk between ILCs and peripheral nervous system orchestrates mucosal homeostasis and immunity. In addition, the barrier tissues of the central nervous system (CNS) also provide conductive microenvironment for ILC development and maintenance. Activities of CNS-associated ILCs impact the outcome of various CNS disorders. In this chapter, we review and discuss the intricate and bidirectional interaction between ILCs and nervous system.