ABSTRACT
Although infiltrating macrophages influence many pathological processes after spinal cord injury (SCI), the intrinsic molecular mechanisms that regulate their function are poorly understood. A major hurdle has been dissecting macrophage-specific functions from those in other cell types as well as understanding how their functions change over time. Therefore, we used the RiboTag method to obtain macrophage-specific mRNA directly from the injured spinal cord in mice and performed RNA sequencing to investigate their transcriptional profile. Our data show that at 7 d after SCI, macrophages are best described as foam cells, with lipid catabolism representing the main biological process, and canonical nuclear receptor pathways as their potential mediators. Genetic deletion of a lipoprotein receptor, CD36, reduces macrophage lipid content and improves lesion size and locomotor recovery. Therefore, we report the first macrophage-specific transcriptional profile after SCI and highlight the lipid catabolic pathway as an important macrophage function that can be therapeutically targeted after SCI.SIGNIFICANCE STATEMENT The intrinsic molecular mechanisms that regulate macrophage function after spinal cord injury (SCI) are poorly understood. We obtained macrophage-specific mRNA directly from the injured spinal cord and performed RNA sequencing to investigate their transcriptional profile. Our data show that at 7 d after SCI, macrophages are best described as foam cells, with lipid catabolism representing the main biological process and canonical nuclear receptor pathways as their potential mediators. Genetic deletion of a lipoprotein receptor, CD36, reduces macrophage lipid content and improves lesion size and locomotor recovery. Therefore, we report the first macrophage-specific transcriptional profile after SCI and highlight the lipid catabolic pathway as an important macrophage function that can be therapeutically targeted after SCI.
Subject(s)
Lipid Metabolism/physiology , Macrophages/metabolism , Spinal Cord Injuries/pathology , Animals , Bone Marrow Transplantation , CD36 Antigens/genetics , CD36 Antigens/metabolism , Cell Movement/genetics , Cytokines/genetics , Cytokines/metabolism , Disease Models, Animal , Female , Gene Expression Regulation/genetics , Hemagglutinins/metabolism , Leukocyte Common Antigens/genetics , Leukocyte Common Antigens/metabolism , Lipid Metabolism/genetics , Locomotion , Male , Mice , Mice, Inbred C57BL , Mice, Transgenic , RNA, Ribosomal/administration & dosage , Ribosomal Proteins/genetics , Ribosomal Proteins/metabolism , Signal Transduction/genetics , Spinal Cord Injuries/physiopathology , Spinal Cord Injuries/surgeryABSTRACT
In this study we investigated the mechanism of enhanced resistance against Listeria monocytogenes induced with Listeria ribosomal RNA and the adjuvant dimethyldioctadecylammonium bromide (DDA). Mice immunized with DDA alone (which were not protected against Listeria-infection) were used as negative controls. Mice immunized with RNA plus DDA were found to have an increased capacity to mobilize polymorphonuclear leukocytes (PMNs) and macrophages to the inflamed peritoneal cavity compared to mice immunized with adjuvant alone. Intraperitoneal (i.p.) inflammation was induced by injection of the sterile irritant proteose peptone. The protective capacity of various cell-populations was investigated by i.p. transfer of cells to normal recipient mice and concomitant challenge of recipient animals with a lethal dose of viable Listeria. Inflammatory PMNs as well as inflammatory macrophages from mice immunized with RNA plus DDA protected recipient animals against listeriosis whereas cells from mice immunized with DDA alone failed to do so. Therefore, enhanced mobilization as well as activation of PMNs and macrophages may have contributed to the expression of protection against L. monocytogenes induced with RNA plus DNA.
Subject(s)
Immunity, Innate/drug effects , Immunization, Passive , Listeriosis/immunology , Quaternary Ammonium Compounds/immunology , RNA, Ribosomal/immunology , Adjuvants, Immunologic/immunology , Animals , Inflammation/immunology , Macrophages/immunology , Male , Mice , Mice, Inbred BALB C , Neutrophils/immunology , Peritoneal Cavity/cytology , Quaternary Ammonium Compounds/administration & dosage , RNA, Ribosomal/administration & dosageABSTRACT
Ribosomal preparation obtained from Salmonella typhimurium, used as a vaccine, was able to induce protection of 100% on mice challenged with 5.5 X 10(9) CFU of S. typhimirium administered by oral route. Effective dose at 50% was of 0.1085 mug, expressed as ribonucleic acid (RNA). This vaccine induced an important humoral response as soon as in nine days. The ribosomal preparation used in this work was maintained at 4 degrees C at least for eighty two days. This fact shows an adequate stability of this biological product.
