A thalamic-primary auditory cortex circuit mediates resilience to stress.

Resilience enables mental elasticity in individuals when rebounding from adversity. In this study, we identified a microcircuit and relevant molecular adaptations that play a role in natural resilience. We found that activation of parvalbumin (PV) interneurons in the primary auditory cortex (A1) by thalamic inputs from the ipsilateral medial geniculate body (MG) is essential for resilience in mice exposed to chronic social defeat stress. Early attacks during chronic social defeat stress induced short-term hyperpolarizations of MG neurons projecting to the A1 (MGA1 neurons) in resilient mice. In addition, this temporal neural plasticity of MGA1 neurons initiated synaptogenesis onto thalamic PV neurons via presynaptic BDNF-TrkB signaling in subsequent stress responses. Moreover, optogenetic mimicking of the short-term hyperpolarization of MGA1 neurons, rather than merely activating MGA1 neurons, elicited innate resilience mechanisms in response to stress and achieved sustained antidepressant-like effects in multiple animal models, representing a new strategy for targeted neuromodulation.

Intermittent Hypobaric Hypoxia Ameliorates Autistic-Like Phenotypes in Mice.

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by persistent deficits in social communication and stereotyped behaviors. Although major advances in basic research on autism have been achieved in the past decade, and behavioral interventions can mitigate the difficulties that individuals with autism experience, little is known about the many fundamental issues of the interventions, and no specific medication has demonstrated efficiency for the core symptoms of ASD. Intermittent hypobaric hypoxia (IHH) is characterized by repeated exposure to lowered atmospheric pressure and oxygen levels, which triggers multiple physiological adaptations in the body. Here, using two mouse models of ASD, male Shank3B -/- and Fmr1 -/y mice, we found that IHH training at an altitude of 5,000 m for 4 h per day, for 14 consecutive days, ameliorated autistic-like behaviors. Moreover, IHH training enhanced hypoxia inducible factor (HIF) 1α in the dorsal raphe nucleus (DRN) and activated the DRN serotonergic neurons. Infusion of cobalt chloride into the DRN, to mimic IHH in increasing HIF1α expression or genetically knockdown PHD2 to upregulate HIF1α expression in the DRN serotonergic neurons, alleviated autistic-like behaviors in Shank3B -/- mice. In contrast, downregulation of HIF1α in DRN serotonergic neurons induced compulsive behaviors. Furthermore, upregulating HIF1α in DRN serotonergic neurons increased the firing rates of these neurons, whereas downregulation of HIF1α in DRN serotonergic neurons decreased their firing rates. These findings suggest that IHH activated DRN serotonergic neurons via upregulation of HIF1α, and thus ameliorated autistic-like phenotypes, providing a novel therapeutic option for ASD.

LncRNA-AC006129.1 reactivates a SOCS3-mediated anti-inflammatory response through DNA methylation-mediated CIC downregulation in schizophrenia.

Schizophrenia is a complex genetic disorder, the non-Mendelian features of which are likely complicated by epigenetic factors yet to be elucidated. Here, we performed RNA sequencing of peripheral blood RNA from monozygotic twins discordant for schizophrenia, and identified a schizophrenia-associated upregulated long noncoding RNA (lncRNA, AC006129.1) that participates in the inflammatory response by enhancing SOCS3 and CASP1 expression in schizophrenia patients and further validated this finding in AC006129.1-overexpressing mice showing schizophrenia-related abnormal behaviors. We find that AC006129.1 binds to the promoter region of the transcriptional repressor Capicua (CIC), facilitates the interactions of DNA methyltransferases with the CIC promoter, and promotes DNA methylation-mediated CIC downregulation, thereby ameliorating CIC-induced SOCS3 and CASP1 repression. Derepression of SOCS3 enhances the anti-inflammatory response by inhibiting JAK/STAT-signaling activation. Our findings reveal an epigenetic mechanism with etiological and therapeutic implications for schizophrenia.

Axonal iron transport in the brain modulates anxiety-related behaviors.

Iron is essential for a broad range of biochemical processes in the brain, but the mechanisms of iron metabolism in the brain remain elusive. Here we show that iron functionally translocates among brain regions along specific axonal projections. We identified two pathways for iron transport in the brain: a pathway from ventral hippocampus (vHip) to medial prefrontal cortex (mPFC) to substantia nigra; and a pathway from thalamus (Tha) to amygdala (AMG) to mPFC. While vHip-mPFC transport modulates anxiety-related behaviors, impairment of Tha-AMG-mPFC transport did not. Moreover, vHip-mPFC iron transport is necessary for the behavioral effects of diazepam, a well-known anxiolytic drug. By contrast, genetic or pharmacological promotion of vHip-mPFC transport produced anxiolytic-like effects and restored anxiety-like behaviors induced by repeated restraint stress. Taken together, these findings provide key insights into iron metabolism in the brain and identify the mechanisms underlying iron transport in the brain as a potential target for development of novel anxiety treatments.

Vitamin D Status and Patient Outcomes after Knee or Hip Surgery: A Meta-Analysis.

BACKGROUND: This study evaluates the effect of vitamin D status in patient outcomes after hip or knee joint surgery. METHOD: Literature search was carried out in electronic databases, and study selection followed predetermined eligibility criteria. Data were extracted from relevant studies and meta-analyses of standardized mean differences between hypovitaminosis D (vitamin D deficiency or insufficiency) and euvitaminosis D in assessment scores of patient-reported outcomes were performed. RESULTS: A total of 12 studies (2,593 patients; age 69.89 years [95% CI 68.07-71.70]; 35.95% [29.43-42.46] males) were included in the meta-analysis. The prevalence of hypovitaminosis D (vitamin D deficiency or insufficiency) was 33.18% [25.10-41.26], but the combined prevalence of deficiency and insufficiency was 46.99 [34.02-59.96]. Hospital stay was 1.09 days [-0.39 to 2.56] longer in the hypovitaminosis D group compared to the euvitaminosis D group. Preoperatively, Harris Hip Score (HHS) and Knee Society Score were significantly lower (p = 0.001 and p = 0.00001, respectively) in the hypovitaminosis D group than in the euvitaminosis D group. Postoperatively, HHS (p = 0.004) score was significantly lower in the hypovitaminosis D group than in the euvitaminosis D group. CONCLUSION: The prevalence of hypovitaminosis D is high in osteoarthritis patients undergoing knee or hip surgery. Vitamin D deficiency may affect the outcomes of orthopedic joint surgery. However, randomized trial/s will be required to confirm these findings.

Astrocytic adenosine 5'-triphosphate release regulates the proliferation of neural stem cells in the adult hippocampus.

Astrocytes are key components of the niche for neural stem cells (NSCs) in the adult hippocampus and play a vital role in regulating NSC proliferation and differentiation. However, the exact molecular mechanisms by which astrocytes modulate NSC proliferation have not been identified. Here, we identified adenosine 5'-triphosphate (ATP) as a proliferative factor required for astrocyte-mediated proliferation of NSCs in the adult hippocampus. Our results indicate that ATP is necessary and sufficient for astrocytes to promote NSC proliferation in vitro. The lack of inositol 1,4,5-trisphosphate receptor type 2 and transgenic blockage of vesicular gliotransmission induced deficient ATP release from astrocytes. This deficiency led to a dysfunction in NSC proliferation that could be rescued via the administration of exogenous ATP. Moreover, P2Y1-mediated purinergic signaling is involved in the astrocyte promotion of NSC proliferation. As adult hippocampal neurogenesis is potentially involved in major mood disorder, our results might offer mechanistic insights into this disease.

Discovery of a novel lead characterized by a stilbene-extended scaffold against sepsis as soluble epoxide hydrolase inhibitors.

Recently, some inhibitors of soluble epoxide hydrolase (sEH) showed limited potential in treating sepsis by increasing survival time, but they have unfortunately failed to improve survival rates. In this study, we initially identified a new hit 11D, belonging to a natural skeleton known as stilbene and having an IC50 of 644 nM on inhibiting murine sEH. Natural scaffold-based sEH inhibitors are paid less attention. A combination of structure-activity relationships (SARs)-guided structural optimization and computer-aided skeleton growth led to a highly effective lead compound 70P (IC50: 4.0 nM). The dose-response study indicated that 70P (at doses of 0.5-5 mg/kg, ip.) significantly increased survival rates and survival time by reducing the levels of the inflammatory factors TNF-α and IL-6 in the liver. Interestingly, 70P exhibited much higher accumulation in the liver than in plasma (AUC ratio: 175). In addition, 70P exhibits equal IC50 value (1.5 nM) on inhibiting human sEH as EC5026 (1.7 nM). In conclusion, the natural scaffold-extended sEH inhibitor 70P has the potential to become a new promising lead for addressing the unmet medical need in sepsis treatment, which highlighted the importance of natural skeleton in developing sEH inhibitors.

Enhancing HIF-1α-P2X2 signaling in dorsal raphe serotonergic neurons promotes psychological resilience.

Major depressive disorder (MDD) is a devastating condition. Although progress has been made in the past seven decades, patients with MDD continue to receive an inadequate treatment, primarily due to the late onset of first-line antidepressant drugs and to their acute withdrawal symptoms. Resilience is the ability to rebound from adversity in a healthy manner and many people have psychological resilience. Revealing the mechanisms and identifying methods promoting resilience will hopefully lead to more effective prevention strategies and treatments for depression. In this study, we found that intermittent hypobaric hypoxia training (IHHT), a method for training pilots and mountaineers, enhanced psychological resilience in adult mice. IHHT produced a sustained antidepressant-like effect in mouse models of depression by inducing long-term (up to 3 months after this treatment) overexpression of hypoxia-inducible factor (HIF)-1α in the dorsal raphe nucleus (DRN) of adult mice. Moreover, DRN-infusion of cobalt chloride, which mimics hypoxia increasing HIF-1α expression, triggered a rapid and long-lasting antidepressant-like effect. Down-regulation of HIF-1α in the DRN serotonergic (DRN5-HT) neurons attenuated the effects of IHHT. HIF-1α translationally regulated the expression of P2X2, and conditionally knocking out P2rx2 (encodes P2X2 receptors) in DRN5-HT neurons, in turn, attenuated the sustained antidepressant-like effect of IHHT, but not its acute effect. In line with these results, a single sub-anesthetic dose of ketamine enhanced HIF-1α-P2X2 signaling, which is essential for its rapid and long-lasting antidepressant-like effect. Notably, we found that P2X2 protein levels were significantly lower in the DRN of patients with MDD than that of control subjects. Together, these findings elucidate the molecular mechanism underlying IHHT promoting psychological resilience and highlight enhancing HIF-1α-P2X2 signaling in DRN5-HT neurons as a potential avenue for screening novel therapeutic treatments for MDD.

Neuregulin 1 regulates pyramidal neuron activity via ErbB4 in parvalbumin-positive interneurons.

Neuregulin 1 (NRG1) is a trophic factor thought to play a role in neural development. Recent studies suggest that it may regulate neurotransmission, mechanisms of which remain elusive. Here we show that NRG1, via stimulating GABA release from interneurons, inhibits pyramidal neurons in the prefrontal cortex (PFC). Ablation of the NRG1 receptor ErbB4 in parvalbumin (PV)-positive interneurons prevented NRG1 from stimulating GABA release and from inhibiting pyramidal neurons. PV-ErbB4(-/-) mice exhibited schizophrenia-relevant phenotypes similar to those observed in NRG1 or ErbB4 null mutant mice, including hyperactivity, impaired working memory, and deficit in prepulse inhibition (PPI) that was ameliorated by diazepam, a GABA enhancer. These results indicate that NRG1 regulates the activity of pyramidal neurons by promoting GABA release from PV-positive interneurons, identifying a critical function of NRG1 in balancing brain activity. Because both NRG1 and ErbB4 are susceptibility genes of schizophrenia, our study provides insight into potential pathogenic mechanisms of schizophrenia and suggests that PV-ErbB4(-/-) mice may serve as a model in the study of this and relevant brain disorders.

ErbB4 in parvalbumin-positive interneurons is critical for neuregulin 1 regulation of long-term potentiation.

Neuregulin 1 (NRG1) is a trophic factor that acts by stimulating ErbB receptor tyrosine kinases and has been implicated in neural development and synaptic plasticity. In this study, we investigated mechanisms of its suppression of long-term potentiation (LTP) in the hippocampus. We found that NRG1 did not alter glutamatergic transmission at SC-CA1 synapses but increased the GABA(A) receptor-mediated synaptic currents in CA1 pyramidal cells via a presynaptic mechanism. Inhibition of GABA(A) receptors blocked the suppressing effect of NRG1 on LTP and prevented ecto-ErbB4 from enhancing LTP, implicating a role of GABAergic transmission. To test this hypothesis further, we generated parvalbumin (PV)-Cre;ErbB4(-/-) mice in which ErbB4, an NRG1 receptor in the brain, is ablated specifically in PV-positive interneurons. NRG1 was no longer able to increase inhibitory postsynaptic currents and to suppress LTP in PV-Cre;ErbB4(-/-) hippocampus. Accordingly, contextual fear conditioning, a hippocampus-dependent test, was impaired in PV-Cre;ErbB4(-/-) mice. In contrast, ablation of ErbB4 in pyramidal neurons had no effect on NRG1 regulation of hippocampal LTP or contextual fear conditioning. These results demonstrate a critical role of ErbB4 in PV-positive interneurons but not in pyramidal neurons in synaptic plasticity and support a working model that NRG1 suppresses LTP by enhancing GABA release. Considering that NRG1 and ErbB4 are susceptibility genes of schizophrenia, these observations contribute to a better understanding of how abnormal NRG1/ErbB4 signaling may be involved in the pathogenesis of schizophrenia.

Hepatic soluble epoxide hydrolase activity regulates cerebral Aß metabolism and the pathogenesis of Alzheimer's disease in mice.

Alzheimer's disease (AD) is caused by a complex interaction between genetic and environmental factors. However, how the role of peripheral organ changes in response to environmental stimuli during aging in AD pathogenesis remains unknown. Hepatic soluble epoxide hydrolase (sEH) activity increases with age. Hepatic sEH manipulation bidirectionally attenuates brain amyloid-ß (Aß) burden, tauopathy, and cognitive deficits in AD mouse models. Moreover, hepatic sEH manipulation bidirectionally regulates the plasma level of 14,15-epoxyeicosatrienoic acid (-EET), which rapidly crosses the blood-brain barrier and modulates brain Aß metabolism through multiple pathways. A balance between the brain levels of 14,15-EET and Aß is essential for preventing Aß deposition. In AD models, 14,15-EET infusion mimicked the neuroprotective effects of hepatic sEH ablation at biological and behavioral levels. These results highlight the liver's key role in AD pathology, and targeting the liver-brain axis in response to environmental stimuli may constitute a promising therapeutic approach for AD prevention.

[Recent progress in neurobiological mechanisms of depression].

Revealing the neurobiological mechanism of depression has always been a big challenge in the field of neuroscience. Not only are depressive syndromes heterogeneous and their aetiologies diverse, but also some symptoms are impossible to reproduce in animal models. Nevertheless, great progress has been made on the understanding and treatment of depression in recent years. In this review, we focus on key leading hypotheses in the neurobiological mechanism of depression, examine their strengths and weaknesses critically, and also highlight new insights that promise to extend the understanding of depression and its treatment.

A hippocampus dependent neural circuit loop underlying the generation of auditory mismatch negativity.

Extracting relevant information and transforming it into appropriate behavior, is a fundamental brain function, and requires the coordination between the sensory and cognitive systems, however, the underlying mechanisms of interplay between sensory and cognition systems remain largely unknown. Here, we developed a mouse model for mimicking human auditory mismatch negativity (MMN), a well-characterized translational biomarker for schizophrenia, and an index of early auditory information processing. We found that a subanesthetic dose of ketamine decreased the amplitude of MMN in adult mice. Using pharmacological and chemogenetic approaches, we identified an auditory cortex-entorhinal cortex-hippocampus neural circuit loop that is required for the generation of MMN. In addition, we found that inhibition of dCA1→MEC circuit impaired the auditory related fear discrimination. Moreover, we found that ketamine induced MMN deficiency by inhibition of long-range GABAergic projection from the CA1 region of the dorsal hippocampus to the medial entorhinal cortex. These results provided circuit insights for ketamine effects and early auditory information processing. As the entorhinal cortex is the interface between the neocortex and hippocampus, and the hippocampus is critical for the formation, consolidation, and retrieval of episodic memories and other cognition, our results provide a neural mechanism for the interplay between the sensory and cognition systems.

[Treatment of acetabular fracture involving quadrilateral body by external rectus abdominis incision combined with calcaneal profiled plate internal fixation].

OBJECTIVE: To investigate the therapeutic effect of lateral rectus abdominis incision combined with winged calcaneal plate on pelvic and acetabular fractures involving quadrilateral body. METHODS: From January 2017 to April 2021, 21 cases of pelvic and acetabular fractures involving quadrilateral bodies were retrospectively analyzed, including 12 males and 9 females. The age ranged from 21 to 73 years with an average of (43.23±6.45) years. All patients were treated by lateral incision of rectus abdominis combined with open reduction and internal fixation with aerofoil plate, including 12 cases of pelvis with anterior and posterior column fractures, 7 cases of acetabular fractures with quadrilateral involvement, and 2 cases of acetabular fractures with central dislocation. RESULTS: All 21 patients were followed up for 12 to 36 months with an average of (18.60±6.45) months. All fractures healed. According to Matta's image reduction evaluation after operation, 11 cases of pelvic anterior and posterior column fractures were all anatomic reduction, 1 case was satisfactory reduction, 7 cases of acetabular fractures involving quadrilateral were anatomic reduction, 1 case with central dislocation was anatomic reduction, and 1 case was satisfactory reduction. The modified Merle D'Aubigne Postel hip joint score was 13 to 17 points. CONCLUSION: Lateral incision approach of rectus abdominis combined with wing-shaped steel plate can obtain good radiological and clinical results in the treatment of complex pelvic and acetabular fractures involving quadrilateral bodies, and has advantages in the treatment of complex pelvic fractures and acetabular quadrilateral fractures.

Loss of schizophrenia-related miR-501-3p in mice impairs sociability and memory by enhancing mGluR5-mediated glutamatergic transmission.

Schizophrenia is a polygenetic disease, the heterogeneity of which is likely complicated by epigenetic modifications yet to be elucidated. Here, we performed transcriptomic analysis of peripheral blood RNA from monozygotic twins discordant for schizophrenia and identified a schizophrenia-associated down-regulated microRNA, miR-501-3p. We showed that the loss of miR-501-3p in germline knockout (KO) male mice resulted in dendritic structure defects, glutamatergic transmission enhancement, and sociability, memory, and sensorimotor gating disruptions, which were attenuated when miR-501 expression was conditionally restored in the nervous system. Combining the results of proteomic analyses with the known genes linked to schizophrenia revealed that metabotropic glutamate receptor 5 (mGluR5) was one of the miR-501-3p targets and was elevated in vivo upon loss of miR-501. Treatment with the mGluR5 negative allosteric modulator 3-2((-methyl-4-thiazolyl) ethynyl) pyridine or the N-methyl-d-aspartate receptor antagonist 2-amino-5-phosphonopentanoic acid ameliorated the deficits observed in Mir501-KO mice. The epigenetic and pathophysiological mechanism that links miR-501-3p to the modulation of glutamatergic transmission provides etiological implications for schizophrenia.

Intermittent hypoxia promotes hippocampal neurogenesis and produces antidepressant-like effects in adult rats.

Increasing evidence indicates that stimulating hippocampal neurogenesis could provide novel avenues for the treatment of depression, and recent studies have shown that in vitro neurogenesis is enhanced by hypoxia. The aim of this study was to investigate the potential regulatory capacity of an intermittent hypobaric hypoxia (IH) regimen on hippocampal neurogenesis and its possible antidepressant-like effect. Here, we show that IH promotes the proliferation of endogenous neuroprogenitors leading to more newborn neurons in hippocampus in adult rats. Importantly, IH produces antidepressant-like effects in multiple animal models screening for antidepressant activity, including the forced swimming test, chronic mild stress paradigm, and novelty-suppressed feeding test. Hippocampal x-ray irradiation blocked both the neurogenic and behavioral effects of IH, indicating that IH likely produces antidepressant-like effects via promoting neurogenesis in adult hippocampus. Furthermore, IH stably enhanced the expression of BDNF in hippocampus; both the antidepressant-like effect and the enhancement of cell proliferation induced by IH were totally blocked by pharmacological and biological inhibition of BDNF-TrkB (tyrosine receptor kinase B) signaling, suggesting that the neurogenic and antidepressant-like effects of IH may involve BDNF signaling. These observations might contribute to both a better understanding of physiological responses to IH and to developing IH as a novel therapeutic approach for depression.

The Ghrelin/Growth Hormone Secretagogue Receptor System Is Involved in the Rapid and Sustained Antidepressant-Like Effect of Paeoniflorin.

Major depressive disorder (MDD) is a debilitating mental illness affecting people worldwide. Although significant progress has been made in the development of therapeutic agents to treat this condition, fewer than half of all patients respond to currently available antidepressants, highlighting the urgent need for the development of new classes of antidepressant drugs. Here, we found that paeoniflorin (PF) produced rapid and sustained antidepressant-like effects in multiple mouse models of depression, including the forced swimming test and exposure to chronic mild stress (CMS). Moreover, PF decreased the bodyweight of mice without affecting food intake and glucose homeostasis, and also reduced the plasma levels of total ghrelin and the expression of ghrelin O-acyltransferase in the stomach; however, the plasma levels of ghrelin and the ghrelin/total ghrelin ratio were unaffected. Furthermore, PF significantly increased the expression of growth hormone secretagogue receptor 1 alpha (GHSR1α, encoded by the Ghsr gene) in the intestine, whereas the levels of GHSR1α in the brain were only marginally downregulated following subchronic PF treatment. Finally, the genetic deletion of Ghsr attenuated the antidepressant-like effects of PF in mice exposed to CMS. These results suggested that increased GHSR1α expression in the intestine mediates the antidepressant-like effects of PF. Understanding peripheral ghrelin/GHSR signaling may provide new insights for the screening of antidepressant drugs that produce fast-acting and sustained effects.

Decreasing hyaluronic acid combined with drug-loaded nanoprobes improve the delivery and efficacy of chemotherapeutic drugs for pancreatic cancer.

Pancreatic cancer is one of the common malignant tumors of the digestive system, and its clinical treatment is still very challenging. Most of the pancreatic cancer chemotherapeutic drugs have poor plasma stability, low cell uptake efficiency, and are prone to developing drug resistance and toxic side effects. Besides, pancreatic cancer often has a dense extracellular matrix, which consists of collagens, hyaluronic acid, and other proteoglycans. Among them, hyaluronic acid is a key component of the dense matrix, which results in vascular compression and insufficient perfusion, and hinders the delivery of chemotherapeutic drugs. In this study, we explore using hyaluronidase in tumor-bearing mice to eliminate the hyaluronic acid barrier, to reduce blood vessel compression and reshape the tumor microenvironment. In addition, we evaluate using doxorubicin-loaded nanoprobes to improve the stability and local tumor-killing effect of the drug. The nanoprobes have the characteristics of near-infrared optical imaging, which are used to monitor the tumor size in real-time during the treatment process, and dynamically observe the tumor inhibitory effect. The results show that elimination of the hyaluronic acid barrier combined with the doxorubicin-loaded nanoprobes can greatly increase drug penetration into tumor tissue and improve the effectiveness of chemotherapy drugs. This study provides a novel strategy for the treatment of pancreatic cancer.

Fuzi polysaccharide-1 produces antidepressant-like effects in mice.

Current antidepressants are clinically effective only after several weeks of administration. We show that Fuzi polysaccharide-1 (FPS), a new water-soluble polysaccharide isolated from Fuzi, which has been used to treat mood disorders in traditional Chinese medicine for centuries, increases the number of newborn cells in the dentate gyrus in adult mice, and most of these cells subsequently differentiate into new neurons. We also found that FPS administration reduces immobility in the forced swim test, and latency in the novelty suppressed-feeding test. Moreover, a 14-d regimen with FPS reverses avoidance behaviour and inhibition of hippocampal neurogenesis induced by chronic defeat stress. In contrast, imipramine, a well known antidepressant, reverses this avoidance behaviour only after 4 wk of continuous administration. Finally, acute treatment with FPS had no effect on brain monoamine levels in frontal cortex but significantly increases BDNF in the hippocampus, while the antidepressant effect and enhancement of cell proliferation induced by FPS administration were totally blocked by K252a, an inhibitor of trkB in a chronic social defeat depression model, suggesting that the neurogenic and antidepressant effects of FPS may involve BDNF signalling. In conclusion, our findings suggest that FPS could be developed as a putative antidepressant with a rapid onset of action.

[Bridging system for severe comminuted femoral fracture].

OBJECTIVE: To explore the clinical effect of bridging system in the treatment of severe comminuted femoral fracture. METHODS: From March 2016 to October 2018, 50 patients with severe comminuted femoral fracture including 35 males and 15 females, aged 48 to 72(54.6±8.7) years, were admitted. All cases were comminuted fractures of the femoral shaft, 16 with proximal femur fractures and 7 with distal femur fractures. All cases were all unilateral fractures, 23 on the left and 27 on the right. The time from injury to operation was 5 to 60 (26.7±13.3) hours. The cause of injury was traffic accident, 12 cases with high fall, 35 cases fell and 3 cases fell accidentally. The patients were treated with bridge combined internal fixation system, and the operative effect and fracture healing were analyzed. RESULTS: The operation was successful in all patients. There was no change to other fixed operation. The operation time was (75.8±12.3) min, the amount of bleeding was(356.4±64.8) ml, and there was no serious postoperative complications such as infection, internal fixation displacement, re fracture and nonunion. After 6 to 36 months follow-up, the fracture healing was evaluated by Warden's score. With the extension of observation time, Warden's score gradually increased, and the time of bone healing was(5.5±0.9) months. Harris score and HSS score were used to evaluate the function of hip and knee joint respectively. With the extension of time, Harris score and HSS score increased gradually. Six months after operation, Harris score was 83.5±11.2, HSS score was 79.7±10.5. During the follow-up period, there were no serious complications such as internal fixation displacement, re-fracture, nonunion of fracture and deep vein thrombosis of lower extremity. CONCLUSION: The bridge combined internalfixation system has better safety and effectiveness in the treatment of severe comminuted femoral fracture. As long as the requirements of local anatomy and biomechanics are strictly mastered and the operation risks are fully evaluated in combination with imaging, the better fixation effect can be achieved. The operation has less trauma, fewer complications and simple operation, which is believed to have a wider application potential. Due to the limited sample size and follow-up time, no clinical control was set up, the results of the study still need to be further verified by prospective trials.