Circular RNA: a new star in neurological diseases.

Circular RNAs (circRNAs) are novel endogenous non-coding RNAs characterized by the presence of a covalent bond linking the 3' and 5' ends generated by backsplicing. In this review, we summarize a number of the latest theories regarding the biogenesis, properties and functions of circRNAs. Specifically, we focus on the advancing characteristics and functions of circRNAs in the brain and neurological diseases. CircRNAs exhibit the characteristics of species conservation, abundance and tissue/developmental-stage-specific expression in the brain. We also describe the relationship between circRNAs and several neurological diseases and highlight their functions in neurological diseases.

Successful treatment of murine autoimmune cholangitis by parabiosis: Implications for hematopoietic therapy.

There is a significant unmet need in the treatment of primary biliary cirrhosis (PBC) despite significant data on the effector pathways that lead to biliary duct damage. We focused attention on a murine model of PBC, the dominant negative transforming growth factor ß receptor II (Tg) mice. To further define the pathways that lead to biliary pathology in these mice, we developed Tg mice deleted of CD4 cells (CD4(-/-)Tg). Interestingly, these mice developed more severe cholangitis than control Tg mice. These mice, which lack CD4 cells, manifested increased levels of IFN-γ produced by effector CD8 cells. It appears that increased cholangitis is due to the absence of CD4 Treg cells. Based on these data, we parabiosed CD4(-/-)Tg mice with established disease at 8-9 weeks of age with C57BL/6 control mice. Such parabiotic "twins" had a significant reduction in autoimmune cholangitis, even though they had established pathology at the time of surgery. We prepared mixed bone marrow chimera mice constructed from CD4(-/-)Tg and CD8(-/-) mice and not only was cholangitis improved, but a decrease in terminally differentiated CD8(+) T effector cells in the presence of wild type CD4 cells was noted. In conclusion, "correcting" the CD4 T cell subset, even in the presence of pathogenic CD8 T cells, is effective in treating autoimmune cholangitis.

Systems biologic analysis of T regulatory cells genetic pathways in murine primary biliary cirrhosis.

CD4(+)Foxp3(+) regulatory T cells (Tregs) play a non-redundant role in control of excessive immune responses, and defects in Tregs have been shown both in patients and murine models of primary biliary cirrhosis (PBC), a progressive autoimmune biliary disease. Herein, we took advantage of a murine model of PBC, the dominant negative transforming growth factor ß receptor II (dnTGFßRII) mice, to assess Treg genetic defects and their functional effects in PBC. By using high-resolution microarrays with verification by PCR and protein expression, we found profound and wide-ranging differences between dnTGFßRII and normal, wild type Tregs. Critical transcription factors were down-regulated including Eos, Ahr, Klf2, Foxp1 in dnTGFßRII Tregs. Functionally, dnTGFßRII Tregs expressed an activated, pro-inflammatory phenotype with upregulation of Ccl5, Granzyme B and IFN-γ. Genetic pathway analysis suggested that the primary effect of loss of TGFß pathway signaling was to down regulate immune regulatory processes, with a secondary upregulation of inflammatory processes. These findings provide new insights into T regulatory genetic defects; aberrations of the identified genes or genetic pathways should be investigated in human PBC Tregs. This approach which takes advantage of biologic pathway analysis illustrates the ability to identify genes/pathways that are affected both independently and dependent on abnormalities in TGFß signaling. Such approaches will become increasingly useful in human autoimmunity.

[A preliminary study of plasma microRNA levels in children with methylmalonic acidemia].

OBJECTIVE: To screen out differentially expressed microRNAs (miRNAs) in the plasma of children with methylmalonic acidemia (MMA), to determine the expression of miR-9-1 in plasma and to preliminarily evaluate the significance of miR-9-1 as a biomarker in MMA. METHODS: Plasma was obtained from 17 MMA children, 10 hyperhomocysteinemia (HHcy) children without MMA (HHcy group), and 10 normal controls. Of 17 MMA children, 12 had HHcy (MMA+HHcy group), and 5 had no HHcy (MMA group). The differentially expressed miRNAs were screened out by miRNA microarray. Differentially expressed miR-9-1 was selected, and plasma miR-9-1 levels were determined by RT-PCR. Urine was collected from MMA patients who received vitamin B12 treatment, and plasma miR-9-1 levels were determined by RT-PCR after treatment. RESULTS: The miRNA microarray analysis showed that 26 miRNAs were differentially expressed, among which 16 miRNAs (including miR-9-1) were down-regulated over 2 times, while 10 miRNAs were up-regulated over 2 times. The MMA+HHcy , MMA and HHcy groups had significantly down-regulated miR-9-1 compared with the normal control group (P<0.01). The patients who showed a good response to vitamin B12 treatment had significantly increased plasma miR-9-1 levels, without significant difference compared with the normal control group. CONCLUSIONS: Plasma miR-9-1 is significantly down-regulated in MMA patients, but it is significantly up-regulated after vitamin B12 treatment, suggesting that miR-9-1 may act as a biomarker in monitoring the progression of MMA.

Ferroptosis: a critical player and potential therapeutic target in traumatic brain injury and spinal cord injury.

Ferroptosis, a new non-necrotizing programmed cell death (PCD), is driven by iron-dependent phospholipid peroxidation. Ferroptosis plays a key role in secondary traumatic brain injury and secondary spinal cord injury and is closely related to inflammation, immunity, and chronic injuries. The inhibitors against ferroptosis effectively improve iron homeostasis, lipid metabolism, redox stabilization, neuronal remodeling, and functional recovery after trauma. In this review, we elaborate on the latest molecular mechanisms of ferroptosis, emphasize its role in secondary central nervous trauma, and update the medicines used to suppress ferroptosis following injuries.

[miR-124-1 promotes neural differentiation of rat bone marrow mesenchymal stem cells].

OBJECTIVE: To study the effects of miR-124-1 on neuronal differentiation of rat bone marrow mesenchymal stem cells (MSCs). METHODS: MSCs cells were assigned into three groups: control (uninfected and untransfected), miR-124-1+ (infected with miR-124-1), and miR-124-1- (transfected with Anti-rno-miR-124* Inhibitor). MSCs were induced by ß-mercaptoethanol (ß-ME) to differentiate into neurons. The fluorescence expressed by infected MSCs was observed under an inverted fluorescence microscope. MTT method was used to measure cell survival rate after transfection or infection. Immunocytochemistry, RT-PCR and Western blot methods were used to detect the expression of ß3 tubulin, MAP-2 and GFAP 6 days after ß-ME induction. RESULTS: The expression of miR-124-1 in the miR-124-1+ group was significantly higher 2 days after infection of lentivirus vector compared with the control group (P<0.01). In the miR-124-1- group, the cell survival rate and the miR-124-1 expression level decreased significantly 24 hrs after transfection of anti-rno-miR-124* inhibitor (P<0.01). After 6 days of ß-ME induction, the protein and mRNA expression levels of ß3 tubulin and MAP-2 in the miR-124-1+ group were much higher than the other two groups (P<0.01); while the expression levels of ß3 tubulin and MAP-2 in the miR-124-1-group were lower than the control group (P<0.01). The expression of GFAP in the three groups was weak (<1%). CONCLUSIONS: miR-124 might promote neuronal differentiation of rat MSCs.

Exosomes derived from bone marrow mesenchymal stem cells protect the injured spinal cord by inhibiting pericyte pyroptosis.

Mesenchymal stem cell (MSC) transplantation is a promising treatment strategy for spinal cord injury, but immunological rejection and possible tumor formation limit its application. The therapeutic effects of MSCs mainly depend on their release of soluble paracrine factors. Exosomes are essential for the secretion of these paracrine effectors. Bone marrow mesenchymal stem cell-derived exosomes (BMSC-EXOs) can be substituted for BMSCs in cell transplantation. However, the underlying mechanisms remain unclear. In this study, a rat model of T10 spinal cord injury was established using the impact method. Then, 30 minutes and 1 day after spinal cord injury, the rats were administered 200 µL exosomes via the tail vein (200 µg/mL; approximately 1 × 106 BMSCs). Treatment with BMSC-EXOs greatly reduced neuronal cell death, improved myelin arrangement and reduced myelin loss, increased pericyte/endothelial cell coverage on the vascular wall, decreased blood-spinal cord barrier leakage, reduced caspase 1 expression, inhibited interleukin-1ß release, and accelerated locomotor functional recovery in rats with spinal cord injury. In the cell culture experiment, pericytes were treated with interferon-γ and tumor necrosis factor-α. Then, Lipofectamine 3000 was used to deliver lipopolysaccharide into the cells, and the cells were co-incubated with adenosine triphosphate to simulate injury in vitro. Pre-treatment with BMSC-EXOs for 8 hours greatly reduced pericyte pyroptosis and increased pericyte survival rate. These findings suggest that BMSC-EXOs may protect pericytes by inhibiting pyroptosis and by improving blood-spinal cord barrier integrity, thereby promoting the survival of neurons and the extension of nerve fibers, and ultimately improving motor function in rats with spinal cord injury. All protocols were conducted with the approval of the Animal Ethics Committee of Zhengzhou University on March 16, 2019.

[Significance of soluble DLL1 in diagnosis of intracranial infectious diseases in children].

OBJECTIVE: To investigate the significance of soluble DLL1 (Delta-like-1) levels of cerebrospinal fluid (CSF) and serum in the diagnosis of intracranial infection in children. METHODS: Fifty children with intracranial infection, including 20 cases of tuberculous meningitis (TM), 20 cases of viral meningitis (VM) and 10 cases of purulent meningitis (PM), and 20 children without intracranial infection (control group) were enrolled. The levels of soluble DLL1 in CSF and serum were measured using ELISA. RESULTS: The level of CSF soluble DLL1 in the TM group was significantly higher than that in the VM, PM and control groups (2.89 ± 1.72 ng/mL vs 0.14 ± 0.14 ng/mL, 0.27 ± 0.21 ng/mL, 0.13 ± 0.12 ng/mL; P<0.01). The level of serum soluble DLL1 in the TM group was also significantly higher than that in the VM, PM and control groups (12.61 ± 6.45 ng/mL vs 2.28 ± 2.27 ng/mL, 2.38 ± 1.79 ng/mL, 2.26 ± 2.10 ng/mL; P<0.01). The levels of soluble DLL1 in the CSF and serum in the VM and PM groups were not significantly different from those in the control group. CONCLUSIONS: Soluble DLL1 as a novel indicator might have potentially important value in the diagnosis of TM.

[Protective effect of musk extract on rat's cerebral cortical neurons with inflammatory injury].

OBJECTIVE: To investigate the protective effects of musk extract (ME) and its possible mechanism on rat's cerebral cortical neurons with inflammatory injury induced by lipopolysaccharide (LPS). METHODS: Neurons and astrocytes from newborn rat cerebral cortex were cultured in vitro respectively, and the astrocyte conditioned medium (ACM), obtained by treating astrocytes with 10 mg/L LPS and different concentrations of ME for 24 h, was added in the culture fluid of neurons. The survival rate and apoptotic rate of neurons were measured by MTT method and AO/EB stain; and the changes of inflammatory factors in the ACM were determined by ELISA. RESULTS: The survival rate (%) of neurons treated by ACM with ME in concentrations of 18 mg/L, 36 mg/L, 72 mg/L and 144 mg/L was 52.55 +/- 3.52, 55.77 +/- 2.36, 64.89 +/- 3.45 and 73.67 +/- 1.80, respectively, significantly higher than that in the model neurons (43.62 +/- 4. 51, P < 0.05), while the apoptotic rate (%) in them, 68.11 +/- 2.16, 44.27 +/- 3.68, 32.56 +/- 2.14 and 21.89 +/- 2.46, respectively, was significantly lower than that in model neurons (71.33 +/- 3.25, P < 0.05 or P < 0.01). Level of IL-6 was decreasing along with the raising of ME concentration in the ACM, showing a concentration-dependent state. CONCLUSION: ME shows apparent protective effect on neurons against inflammatory injury, especially in a high concentration (144 mg/L), which may be associated with the reduction of IL-6 secreted by astrocytes.

[Expression of microRNA in neonatal rats with hypoxic-ischemic brain damage].

OBJECTIVE: To study the changes of microRNA expression in cortex tissues in neonatal rats with hypoxic-ischemic brain damage (HIBD)and the possible roles of microRNA in the pathogenesis of HIBD. METHODS Rat HIBD model was prepared. The cortex tissues were obtained 14 days after the HIBD event. The microRNA expression profiles were measured using microRNA microarray. Expression of 9 microRNAs (miR-126,-26a,-674-5p,-21,-25,-290, miR-124,-125b-5p and microRNA-9a) was determined by quantitative real-time PCR. RESULTS: he results of microRNA expression profiles indicated that 27 pieces of microRNA were up-regulated more than 2 folds and 60 pieces were down-regulated more than 2 folds compared with the normal control group. The results of the 9 microRNAs detected by quantitative real-time PCR were consistent with those detected by microRNA microarray. CONCLUSIONS: HIBD rats have significant changes in microRNA expression, suggesting that microRNA expression may play important roles in the pathogenesis of HIBD.

[Clinical analysis of 322 cases of non-epileptic cerebral palsy].

OBJECTIVE: To study the clinical features of non-epileptic seizures associated with cerebral palsy (CP) in children. METHODS: A total of 1 198 children with CP (age: 9 months to 6 years) were enrolled. The children with paroxysmal events were monitored by 24 hrs video-EEG (VEEG) to make sure the seizures were epileptic or non-epileptic. The symptoms, age, CP types and EEG features were observed in children with non-epileptic CP. RESULTS: Five hundred and seventy-eight children (48.24%) presented paroxysmal events. The seizures were epileptic in 231 children (19.28%) and non-epileptic in 322 cases (26.88%). In the 322 cases of non-epileptic CP, the paroxysmal events were of various kinds, including non-epileptic seizure tonic, seizure shake head, shrug shoulder or head hypsokinesis, cry or scream, panic attacks, sleep myoclonic and stereotyped movement. One hundred and fifty-eight (49.1%) out of the 322 children demonstrated nonspecific EEG abnormalities. One hundred and eleven children (34.5%) were misdiagnosed as epilepsy in primary hospitals. The CP children less than one year old showed higher frequency of non-epileptic seizures than the age groups over 1 year and 3 to 6 years. The frequency of non-epileptic seizures was the highest in children with spastic CP (168 cases, 52.2%), followed by dyskinetic CP (69 cases, 21.4%) and mixed type CP (65 cases, 20.2%). CONCLUSIONS: The paroxysmal events in children with CP partially are non-epileptic seizures and it is important to differentiate non-epileptic from epileptic seizures. The frequencies of non-epileptic seizures may be associated with a child's age and CP type.

[Effects of DSCAM on differentiation of rat marrow mesenchymal stem cells into neurons in vitro].

OBJECTIVE: To study the effects of Down syndrome cellular adhesion molecule (DSCAM) on differentiation of rat marrow mesenchymal stem cells (MSCs) into neurons in vitro. METHODS: MSCs from Sprague-Dawley rats were induced into neurons by baicalin. The expression of DSCAM before and after induction was evaluated by immunocytochemical staining and Western blot assay. After knockdown of DSCAM by siRNA transfection, the differentiation rate of neurons derived from MSCs was measured. RESULTS: Before induction, the expression of DSCAM was not detectable in MSCs. After bFGF preinduction for 24 hrs, DSCAM was slightly expressed in MSCs (1.71+/- 0.67%). The DSCAM expression increased 6 hrs after baicalin induction (15.79+/- 4.24%), reached a peak at 3 days (53.16+/- 5.94%) and then decreased gradually. The DSCAM expression 6 days after baicalin induction (28.99+/- 6.72%) was significantly lower than that at 3 days (P<0.01). However, after DSCAM-siRNA transfection, the DSCAM expression in MSCs was significantly reduced. MSCs did not express neuron-specific beta-III-tubulin before induction. After baicalin induction for 6 hrs, 3 days and 6 days, the expression of beta-III-tubulin was 1.40+/- 0.79%, 41.59+/- 3.17% and 59.11+/- 4.76% respectively. But the beta-III-tubulin expression significantly decreased 3 and 6 days after DSCAM-siRNA transfection (28.57+/- 2.91% and 43.90+/- 12.31% respectively). CONCLUSIONS: DSCAM may play an important role in MSCs differentiation into neural cells.

The risk factors and prognosis of delayed perihematomal edema in patients with spontaneous intracerebral hemorrhage.

PURPOSE: We hypothesize delayed perihematomal edema (DHE) leads to secondary injury after spontaneous intracerebral hemorrhage (sICH) with a poor prognosis. Hence, we need to investigate the risk factors of DHE and identify whether DHE will predict the poor outcome of sICH. METHODS: We retrospectively recruited 121 patients with sICH admitted to the Department of Neurology from January 2014 to August 2018. After dividing all these patients into DHE group and non-DHE group, we analyzed the potential risk factors and outcome of DHE using a multivariate logistic regression model. RESULTS: We conclude DHE after sICH associates with age, hospitalization time, hematoma shape, blood pressure upon admission, alcohol consumption, blood sodium level, and baseline hematoma volume within 24 hours after symptom onset, among which differences were statistically significant (P < .05). Logistic regression analysis finally identified that age (OR = 0.958, 95% CI = 0.923-0.995) and the baseline hematoma volume (OR = 1.161, 95% CI = 1.089-1.238) were the most significant risk factors for DHE, and moreover, the DHE (OR = 3.062, 95% CI = 1.196-7.839) was also a risk factor for poor prognosis in sICH patients. CONCLUSION: We suggest DHE is a clinical predictor of secondary injury following sICH and poor prognosis. In addition, age and baseline hematoma volume are considered significant high-risk factors for DHE in patients with sICH.

Correlation between tumor necrosis factor alpha mRNA and microRNA-155 expression in rat models and patients with temporal lobe epilepsy.

Accumulative evidence demonstrates that there is an inseparable connection between inflammation and temporal lobe epilepsy (TLE). Some recent studies have found that the multifunctional microRNA-155 (miR-155) is a key regulator in controlling the neuroinflammatory response of TLE rodent animals and patients. The aim of the present study was to investigate the dynamic expression pattern of tumor necrosis factor alpha (TNF-α) as a pro-inflammatory cytokine and miR-155 as a posttranscriptional inflammation-related miRNA in the hippocampus of TLE rat models and patients. We performed real-time quantitative PCR (qRT-PCR) on the rat hippocampus 2 h, 7 days, 21 days and 60 days following kainic acid-induced status epilepticus (SE) and on hippocampi obtained from TLE patients and normal controls. To further characterize the relationship between TNF-α and miR-155, we examined the effect of antagonizing miR-155 on TNF-α secretion using its antagomir. Here, we found that TNF-α secretion and miR-155 expression levels were correlated after SE. The expression of TNF-α reached peak levels in the acute phase (2h post-SE) of seizure and then gradually decreased; however, it rose again in the chronic phase (60 days post-SE). miR-155 expression started to increase 2 h post-SE, reached peak levels in the latent phase (7 days post-SE) of seizure and then gradually decreased. The variation in the trend of miR-155 lagged behind that of TNF-α. In patients with TLE, the expression levels of both TNF-α and miR-155 were also significantly increased. Furthermore, antagonizing miR-155 inhibited the production of TNF-α in the hippocampal tissues of TLE rat models. Our findings demonstrate a critical role for miR-155 in the physiological regulation of the TNF-α pro-inflammatory response and elucidate the role of neuroinflammation in the pathogenesis of TLE. Therefore, regulation of the miR-155/TNF-α axis may be a new therapeutic target for TLE.

The role of the microRNA-146a/complement factor H/interleukin-1ß-mediated inflammatory loop circuit in the perpetuate inflammation of chronic temporal lobe epilepsy.

Increasing evidence indicates that neuroinflammation plays a crucial role in the pathogenesis of temporal lobe epilepsy (TLE). However, it is unclear how the perpetuate inflammation develops. Some recent studies have suggested the possible involvement of microRNA-146a (miR-146a) in the modulation of inflammatory signaling occurring in TLE. To understand how miR-146a modulates inflammatory signaling in TLE, we investigated the role of interleukin-1ß (IL-1ß), miR-146a and human complement factor H (CFH) in the perpetuate inflammation in rat models of chronic TLE and U251 cells. We found that enhancive miR-146a could upregulate the expression of IL-1ß and downregulate the expression of CFH, whereas reductive miR-146a could downregulate the expression of IL-1ß and upregulate the expression of CFH, in hippocampi of chronic TLE rat models. Meanwhile, enhancive miR-146a could increase the abnormal wave forms in the chronic TLE rat models. Additionally, enhancive IL-1ß could feedback downregulate the expression of CFH, upregulate the expression of miR-146a and increase the abnormal wave forms in chronic TLE rat models. After CFH gene knockdown in U251 cells, enhancive miR-146a did not upregulate the expression of IL-1ß. In summary, this study shows that enhancive miR-146a can upregulate the inflammatory factor IL-1ß in chronic TLE by downregulating CFH, and that upregulation of IL-1ß plays an important feedback-regulating role in the expression of miR-146a and CFH, forming a miR-146a-CFH-IL-1ß loop circuit that initiates a cascade of inflammation and then leads to the perpetuate inflammation in TLE. Therefore, modulation of the miR-146a-CFH-IL-1ß loop circuit could be a novel therapeutic target for TLE.

[The best site of transplantation of neural stem cells into brain in treatment of hypoxic-ischemic damage: experiment with newborn rats].

OBJECTIVE: To investigate the best site of transplantation of neural stem cells (NSCs) into the brain to treat hypoxic-ischemic damage (HIBD). METHODS: Forty-eight 7-day-old Spraque-Dawley rats underwent ligation of the left common carotid artery and exposure to 8% oxygen at 37 degrees C for 2 hours to establish HIBD models and then were randomly divided into 4 equal groups 3 days later: HIBD control group, HIBD + cortex transplantation group (CT group) undergoing NSC transplantation into the sensorimotor cortex, HIBD + hippocampus transplantation group (HT group) undergoing NSC transplantation into the hippocampus, and HIBD + ventricle transplantation group (VT group), undergoing NSC transplantation into the lateral ventricle. Since the rats were 40-day-old, they underwent radial maze water-seeking test and 4 sensorimotor tests. Then the brains of the rats were taken out to undergo histological examination by Nissl staining and immunohistochemistry to observer the 5-bromodeoxyuridine (BrdU) expression. RESULTS: The times the rats took to find the water in all 3 arms of the maze were arranged form short to long in the order HT group < VT group < CT group < HIBD group with significant differences between the HT, VT, and CT groups and HIBD group (All P < 0.05) and between the groups HT and VT and the group CT (both P < 0.05). The results of the 4 sensorimotor tests were arranged from the best to the worst in the order CT group > VT group > HT group > HIBD group with significant differences between the groups CT and VT and the group HIBD (both P < 0.05). Nissl staining showed that the number of normal neurons in the cortex area from more to less were arranged in the order CT group > VT group > HT group > HIBD group; and the number of normal neurons in the CAI area from more to less were arranged in the order HT group > VT group > CT group > HIBD group. CONCLUSION: Transplantation of NSC attenuates the brain damage and the cognitive and sensorimotor dysfunction after HIBD. Transplantation into the lateral ventricle is the most effective.

[Clinical analysis of families with generalized epilepsy with febrile seizures plus].

OBJECTIVE: To investigate the clinical phenotypes and hereditary patterns of the generalized epilepsy with febrile seizures plus (GEFS+). METHODS: Detailed family trees were constructed by inquire and physical examinations for the probands of the 15 pedigrees of GEFS+. Some patients received electroencephalography, cranial CT or MRI examination. The seizures and epilepsy syndromes were classified according to the 2001 Seizure International Classification. The clinical data of GEFS+ were reviewed. RESULTS: The 15 families consisted of 196 individuals. Seventy-five individuals were confirmed with epilepsy. The phenotypes of 64 out of the 75 patients with epilepsy conformed to GEFS+. The 64 patients included 38 males and 26 females (1 deceased) and there was no gender difference in the morbility of GEFS+. The age at onset was all in childhood. GEFS+ had a diversity of phenotypes. Febrile seizures (FS) were confirmed in 44 patients, FS and myoclonic seizure in 1, febrile seizures plus (FS+) in 13, FS+ and absence seizure in 2, FS+ and myoclonic seizure in 1, and FS+ and focal seizure in 3. CONCLUSIONS: The heterogeneity of phenotypes and genetics may be the hallmarks of GEFS+. FS and FS+ are common phenotypes while FS+ and absence seizure, FS+ and myoclonic seizure, and FS+ and focal seizure are rare. If one of the parents is affected in a GEFS+ family, the susceptibility of their children to GEFS+ is the same no matter what gender of their children is. It is speculated that the hereditary pattern of GEFS+ conforms to autosomal dominant inheritance.

Modulation of liver regeneration via myeloid PTEN deficiency.

Molecular mechanisms that modulate liver regeneration are of critical importance for a number of hepatic disorders. Kupffer cells and natural killer (NK) cells are two cell subsets indispensable for liver regeneration. We have focused on these two populations and, in particular, the interplay between them. Importantly, we demonstrate that deletion of the myeloid phosphatase and tensin homolog on chromosome 10 (PTEN) leading to an M2-like polarization of Kupffer cells, which results in decreased activation of NK cells. In addition, PTEN-deficient Kupffer cells secrete additional factors that facilitate the proliferation of hepatocytes. In conclusion, PTEN is critical for inhibiting M2-like polarization of Kupffer cells after partial hepatectomy, resulting in NK cell activation and thus the inhibition of liver regeneration. Furthermore, PTEN reduces growth factor secretion by Kupffer cells. Our results suggest that targeting PTEN on Kupffer cells may be useful in altering liver regeneration in patients undergoing liver resection.