Injury-induced Immune Response Research Articles

MicroRNA sequencing analysis reveals injury-induced immune responses of Scylla paramamosain against cheliped autotomy

During pond culture or intensive culture system of crabs (mainly Eriocheir sinensis, Portunus trituberculatus and Scylla paramamosain), high-density farming has typically contributed to a higher limb autotomy level in juvenile animals, especially in S. paramamosain which has a high level of cannibalism. Due to the high limb autotomy level, the survival and growth rates in S. paramamosain farming are restricted, which limit the growth of the mud crab farming industry. MicroRNAs (miRNAs) are small noncoding RNAs that regulate a series of biological processes including innate immune responses by post-transcriptional suppression of their target genes. MiRNAs are believed to be crucial for innate immune process of host wound healing. Many miRNAs have been verified to be required in host immune responses to repair wound and to defense pathogen after tissue damage. However, to our best knowledge, the miRNAs functions of crustacean innate immune reactions against injury induced by limb autotomy have not been studied yet. Here in this study, for the first time, miRNAs involved in the S. paramamosain immune reactions against injury induced by cheliped autotomy were obtained by high-throughput sequencing. A total of 575 miRNAs (518 known miRNAs and 57 novel predicted miRNAs) were obtained, of which 141 differentially expressed microRNAs (93 up-regulated microRNAs and 48 down-regulated microRNAs) were revealed to be modified against cheliped autotomy, and the qPCR results of randomly selected miRNAs confirmed the expression patterns in the miRNAs sequencing data. Numerous immune-related target genes associated with innate immune system were mediated by miRNAs to induce host humoral immune and cellular immune defense to minimize acute physical damage. Furthermore, the genes expression in hemolymph coagulation and melanization pathways, as well as Toll and Imd signaling pathways were mediated by miRNAs to activate host immune responses including melanization and antimicrobial peptides for rapid wound healing and killing invaded pathogens. These results will help to understand injury-induced immune responses in crabs and to develop an effective control strategy of autotomy rate in crabs farming.

Spatial transcriptomics reveals asymmetric cellular responses to injury in the regenerating spiny mouse (Acomys) ear.

In contrast to other mammals, the spiny mouse (Acomys) regenerates skin and ear tissue, which includes hair follicles, glands, and cartilage, in a scar-free manner. Ear punch regeneration is asymmetric with only the proximal wound side participating in regeneration. Here, we show that cues originating from the proximal side are required for normal regeneration and use spatially resolved transcriptomics (tomo-seq) to understand the molecular and cellular events underlying this process. Analyzing gene expression across the ear and comparing expression modules between proximal and distal wound sides, we identify asymmetric gene expression patterns and pinpoint regenerative processes in space and time. Moreover, using a comparative approach with nonregenerative rodents (Mus, Meriones), we strengthen a hypothesis in which particularities in the injury-induced immune response may be one of the crucial determinants for why spiny mice regenerate whereas their relatives do not. Our data are available in SpinyMine, an easy-to-use and expandable web-based tool for exploring Acomys regeneration-associated gene expression.

Immune Profiling Demonstrates a Common Immune Signature of Delayed Acquired Immunodeficiency in Patients With Various Etiologies of Severe Injury.

The host response plays a central role in the pathophysiology of sepsis and severe injuries. So far, no study has comprehensively described the overtime changes of the injury-induced immune profile in a large cohort of critically ill patients with different etiologies. Prospective observational cohort study. Adult ICU in a University Hospital in Lyon, France. Three hundred fifty-three septic, trauma, and surgical patients and 175 healthy volunteers were included in the REAnimation Low Immune Status Marker study. None. Extensive immune profiling was performed by assessing cellular phenotypes and functions, protein, and messenger RNA levels at days 1-2, 3-4, and 5-7 after inclusion using a panel of 30 standardized immune markers. Using this immunomonitoring panel, no specificity in the immune profile was observed among septic, trauma, and surgical patients. This common injury-induced immune response was characterized by an initial adaptive (i.e., physiologic) response engaging all constituents of the immune system (pro- and anti-inflammatory cytokine releases, and innate and adaptive immune responses) but not associated with increased risk of secondary infections. In contrary, the persistence in a subgroup of patients of profound immune alterations at the end of the first week after admission was associated with increased risk of secondary infections independently of exposure to invasive devices. The combined monitoring of markers of pro-/anti-inflammatory, innate, and adaptive immune responses allowed a better enrichment of patients with risk of secondary infections in the selected population. Using REAnimation Low Immune Status Marker immunomonitoring panel, we detected delayed injury-acquired immunodeficiency in a subgroup of severely injured patients independently of primary disease. Critically ill patients' immune status could be captured through the combined monitoring of a common panel of complementary markers of pro-/anti-inflammatory, innate, and adaptive immune responses. Such immune monitoring needs to be incorporated in larger study cohorts with more extensive immune surveillance to develop specific hypothesis allowing for identification of biological systems affecting altered immune function related to late infection in the setting of acute systemic injury.

Molecular and cellular identification of the immune response in peripheral ganglia following nerve injury

BackgroundNeuroinflammation accompanies neural trauma and most neurological diseases. Axotomy in the peripheral nervous system (PNS) leads to dramatic changes in the injured neuron: the cell body expresses a distinct set of genes known as regeneration-associated genes, the distal axonal segment degenerates and its debris is cleared, and the axons in the proximal segment form growth cones and extend neurites. These processes are orchestrated in part by immune and other non-neuronal cells. Macrophages in ganglia play an integral role in supporting regeneration. Here, we explore further the molecular and cellular components of the injury-induced immune response within peripheral ganglia.MethodsAdult male wild-type (WT) and Ccr2−/− mice were subjected to a unilateral transection of the sciatic nerve and axotomy of the superior cervical ganglion (SCG). Antibody arrays were used to determine the expression of chemokines and cytokines in the dorsal root ganglion (DRG) and SCG. Flow cytometry and immunohistochemistry were utilized to identify the cellular composition of the injury-induced immune response within ganglia.ResultsChemokine expression in the ganglia differed 48 h after nerve injury with a large increase in macrophage inflammatory protein-1γ in the SCG but not in the DRG, while C-C class chemokine ligand 2 was highly expressed in both ganglia. Differences between WT and Ccr2−/− mice were also observed with increased C-C class chemokine ligand 6/C10 expression in the WT DRG compared to C-C class chemokine receptor 2 (CCR2)−/− DRG and increased CXCL5 expression in CCR2−/− SCG compared to WT. Diminished macrophage accumulation in the DRG and SCG of Ccr2−/− mice was found compared to WT ganglia 7 days after nerve injury. Interestingly, neutrophils were found in the SCG but not in the DRG. Cytokine expression, measured 7 days after injury, differed between ganglion type and genotype. Macrophage activation was assayed by colabeling ganglia with the anti-inflammatory marker CD206 and the macrophage marker CD68, and an almost complete colocalization of the two markers was found in both ganglia.ConclusionsThis study demonstrates both molecular and cellular differences in the nerve injury-induced immune response between DRG and SCG and between WT and Ccr2−/− mice.

Peripheral macrophage infiltration and complement-initiation lead to synaptic loss and cognitive decline following traumatic brain injury

Traumatic brain injury (TBI) is a highly prevalent and extremely debilitating problem with nearly 2 million new cases reported annually and over 5 million individuals living with long-term injury-induced deficits. Critical changes that affect cognition take place over time following the initial insult and the innate immune system is a key mechanism that contributes to chronic neurodegeneration. Two at risk populations for TBI are adolescents and the elderly; two populations with vastly different immune parameters. In this work we compared injury-induced immune responses and cognitive decline from young and aged animals. In both young and aged animals significant increases in inflammatory responses in the brain were measured immediately following injury. In the aged animals, there are exacerbated and prolonged inflammatory responses, characterized by macrophage infiltration, microglia activation and robust cytokine/chemokine profiles. This exacerbated immune response corresponds with worsened cognitive decline in the aged animals. Furthermore, we found complement initiation (C1q, C3) increases corresponding with synapse loss in aged-injured animals. Complement initiation can lead to microglia mediated pruning in development and neurodegenerative disease. Thus we investigated if microglia and/or macrophages interacted with C1q in aged-injured animals. We measured co-localization between Iba-1, CD68 and C1q suggesting that these immune cells may be causing synaptic loss. Currently, we are testing if interference of these pathways (macrophage infiltration, microglia activation and/or complement initiation) can reverse injury-induced cognitive decline.

Trends in tissue repair and regeneration.

The 6th EMBO conference on the Molecular and Cellular Basis of Regeneration and Tissue Repair took place in Paestum (Italy) on the 17th-21st September, 2016. The 160 scientists who attended discussed the importance of cellular and tissue plasticity, biophysical aspects of regeneration, the diverse roles of injury-induced immune responses, strategies to reactivate regeneration in mammals, links between regeneration and ageing, and the impact of non-mammalian models on regenerative medicine.

Axonal and Glial Responses to a Mid-Thoracic Spinal Cord Hemisection in the Macaca fascicularis Monkey

A comprehensive understanding of the pathology of spinal cord injury (SCI) in non-human primates may facilitate greatly the development of new strategies to promote recovery in humans with SCI. Relatively few studies, however, have been conducted to systemically examine pathological changes in the monkey, a non-human primate, after SCI. We report axonal, glial, and fibrotic responses in the spinal cord of monkey Macaca fascicularis after a thoracic (T) 8-9 lateral hemisection. We examined these changes at three regions--i.e., the lesion epicenter, the peri-lesion area, and the lateral white matter of the intact, contralateral hemicord at 7 (subacute) and 30 (early chronic) days post-injury. The lateral hemisection resulted in a marked axon and myelin loss, along with tissue loss, at the lesion epicenter at both time points. Unexpectedly, axonal loss and myelin degeneration, along with reactive gliosis and microglia/macrophages activation, were also observed in the contralateral spared hemicord, indicating a spread of the initial damage to the contralateral side. In addition, activated microglia/macrophages were found both within the injury epicenter and the peri-lesion area, indicating that they participate in injury-induced immune responses that may exacerbate the secondary damage. In contrast to rodents, substantial reactive astrocytic responses at the lesion border were not observed in the monkey. Conversely, a deposit of robust fibrotic scar was observed at the injury epicenter, which filled the space originally created by the hemisection. Thus, understanding the pathology of monkey SCI may provide clinically relevant information in designing repair strategies targeting specific problems associated with human SCIs.

Concomitant upregulation of nuclear factor-kB activity, proinflammatory cytokines and ICAM-1 in the injured brain after cortical contusion trauma in a rat model

Nuclear factor kappa B (NF-kB), proinflammatory cytokines and intercellular adhesion molecule 1 (ICAM-1) are frequently upregulated in the injured brain after traumatic brain injury (TBI). However, the temporal pattern of upregulation is not well defined. The current study was undertaken to investigate the temporal profile of the expression of NF-kB, proinflammatory cytokines and ICAM-1 in the injured brain after cortical contusion trauma of the rat brain. A rat model of cortical contusion was produced by a free-falling weight on the exposed dura of right parietal lobe. The rats were randomly divided into control group and TBI groups at hours 3, 12, 24 and 72, and on day 7. NF-kB binding activity in the surrounding brain of injured area was studied by electrophoretic mobility shift assay (EMSA). The levels of TNF-alpha and IL-6 were detected using ELISA and ICAM-1 expression studied by immunohistochemistry. The data were analyzed by one-way ANOVA followed by Student-Newman-Keuls post hoc test. Relation between variables was analyzed using bivariate correlation with two-tailed test. Compared with that of control group, NF-kB binding activity in the injured brain was significantly increased through 12 h and 7 days postinjury, with the maximum at 72 h. The concentrations of TNF-alpha and IL-6 in the injured brain were significantly increased from 3 h to 7 days and maximal at 24 h postinjury. The number of ICAM-1 immunostained microvessels was significantly increased in the injured brain from 24 h to 7 days postinjury, with its peak at 72 h. Concomitant upregulation of TNF-alpha, IL-6, ICAM-1 and the cytokine mediators NF-kB in the injured brain was observed in the injured brain after cortical contusion, and there was a highly positive relation among these variables. Cortical contusion trauma could induce a concomitant and persistent upregulation of NF-kB binding activity, TNF-alpha, IL-6 and ICAM-1 in the injured rat brain which might play a central role in the injury-induced immune response of brain.

Expression of nuclear factor kappaB and tumor necrosis factor alpha in the mouse brain after experimental thermal ablation injury.

Nuclear factor kappa B (NFkappaB) participates in the regulation of a diverse range of genes involved in inflammation and acute phase responses. We investigated the expression of the activated form of NFkappaB and tumor necrosis factor alpha (TNFalpha), an inflammatory cytokine, in experimental brain injury. We generated focal brain injury in mice using radiofrequency thermal ablation at the caudate putamen in mice. Intracerebral expression of TNFalpha and the p50 and p65 subunits of NFkappaB were studied using immunohistochemistry at 1, 4, and 8 hours and at 1, 2, 4, 8, 14, and 28 days postinjury. Coagulative necrosis approximately 2 mm in diameter was produced at the site of injury. No immunoreactivity for TNFalpha, NFkappaB p50, or NFkappaB p65 was detected in the injured area in the early phase postinjury. On posttrauma Day 2, however, weak expression of TNFalpha, NFkappaB p50, and NFkappaB p65 was detected in mononuclear cells that infiltrated edematous tissue surrounding the lesion. On posttrauma Days 4 to 8, the expression of TNFalpha, NFkappaB p50, and NFkappaB p65 was prominently increased in infiltrating and proliferating mononuclear cells (macrophages and microglia) and in proliferating reactive astrocytes surrounding the lesion. Nuclear subcellular localization of the expression of NFkappaB p50 and p65 was observed, which indicated that these subunits might be activated in these cells. On posttrauma Day 14, the expression of TNFalpha, NFkappaB p50, and NFkappaB p65 decreased and was limited to mononuclear cells, and it finally disappeared on Day 28. The temporal profiles of TNFalpha, NFkappaB p50, and NFkappaB p65 were closely associated with the occurrence of secondary insults and the tissue-remodeling process in wound healing. These results suggest that TNFalpha, NFkappaB p50, and NFkappaB p65 may play a central role in the injury-induced immune response that leads to secondary insults or wound healing after brain injury. Inappropriate and deregulated activation of NFkappaB in injured brain tissue may be implicated in the development of secondary brain damage.

Altered neuronal and microglial responses to excitotoxic and ischemic brain injury in mice lacking TNF receptors.

Brain injury, as occurs in stroke or head trauma, induces a dramatic increase in levels of tumor necrosis factor-alpha (TNF), but its role in brain injury response is unknown. We generated mice genetically deficient in TNF receptors (TNFR-KO) to determine the role of TNF in brain cell injury responses. Damage to neurons caused by focal cerebral ischemia and epileptic seizures was exacerbated in TNFR-KO mice, indicating that TNF serves a neuroprotective function. Oxidative stress was increased and levels of an antioxidant enzyme reduced in brain cells of TNFR-KO mice, indicating that TNF protects neurons by stimulating antioxidant pathways. Injury-induced microglial activation was suppressed in TNFR-KO mice, demonstrating a key role for TNF in injury-induced immune response. Drugs that target TNF signaling pathways may prove beneficial in treating stroke and traumatic brain injury.