The role of CRMP4 in LPS-induced neuroinflammation.

Neuroinflammation has been gaining attention as one of the potential causes of neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis in recent years. The suppression of excessive proinflammatory responses is expected to be a target for the treatment and prevention of neurodegenerative diseases. Collapsin response mediator protein 4 (CRMP4) is involved in cytoskeleton-associated axonal guidance in the developing brain. Recently, the involvement of CRMP4 in several pathological conditions, including inflammation induced by lipopolysaccharide (LPS), a widely used inflammatory molecule, has been reported. However, the role of CRMP4 in LPS-induced inflammation in vivo remains largely unknown. In this study, we generated microglia-specific CRMP4 knockout mice for the first time and examined the role of CRMP4 in an LPS-induced brain inflammation model. We found that microglia after LPS injection in substantia nigra was significantly reduced in Crmp4-/- mice compared to Crmp4+/+mice. The increased expression of IL-10 in striatum samples was downregulated in Crmp4-/- mice. A significant reduction in Iba1 expression was also observed in microglia-specific Crmp4 knockout mice compared with that in control mice. In contrast, the expression of IL-10 did not change in these mice, whereas arginase 1 (Arg1) expression was significantly suppressed. These results demonstrate the involvement of CRMP4 in LPS-induced inflammation in vivo, that CRMP4 suppresses microglial proliferation in a cell-autonomous manner.

Forebrain commissure formation in zebrafish embryo requires the binding of KLC1 to CRMP2.

Formation of the corpus callosum (CC), anterior commissure (AC), and postoptic commissure (POC), connecting the left and right cerebral hemispheres, is crucial for cerebral functioning. Collapsin response mediator protein 2 (CRMP2) has been suggested to be associated with the mechanisms governing this formation, based on knockout studies in mice and knockdown/knockout studies in zebrafish. Previously, we reported two cases of non-synonymous CRMP2 variants with S14R and R565C substitutions. Among the, the R565C substitution (p.R565C) was caused by the novel CRMP2 mutation c.1693C > T, and the patient presented with intellectual disability accompanied by CC hypoplasia. In this study, we demonstrate that crmp2 mRNA could rescue AC and POC formation in crmp2-knockdown zebrafish, whereas the mRNA with the R566C mutation could not. Zebrafish CRMP2 R566C corresponds to human CRMP2 R565C. Further experiments with transfected cultured cells indicated that CRMP2 with the R566C mutation could not bind to kinesin light chain 1 (KLC1). Knockdown of klc1a in zebrafish resulted in defective AC and POC formation, revealing a genetic interaction with crmp2. These findings suggest that the CRMP2 R566C mutant fails to bind to KLC1, preventing axonal elongation and leading to defective AC and POC formation in zebrafish and CC formation defects in humans. Our study highlights the importance of the interaction between CRMP2 and KLC1 in the formation of the forebrain commissures, revealing a novel mechanism associated with CRMP2 mutations underlying human neurodevelopmental abnormalities.

[Long-Term Suppression with First-Line Chemotherapy(FOLFIRI plus BV)for Peritoneal Metastasis].

A 72-year-old man underwent right hemicolectomy for transverse colon cancer(pT4aN1aM0, Stage ⅢB), after which he received adjuvant chemotherapy(capecitabine plus oxaliplatin[CAPOX])for 6 months. Three years after the first surgery, FDG-PET/CT revealed a tumor in the abdomen. He underwent a tumorectomy and adjuvant chemotherapy(CAPOX plus bevacizumab[BV])performed for 6 months. Two years after a tumorectomy, the CEA level rose again. He was diagnosed peritoneal metastasis again. A central venous(CV)port was implanted for access to the right internal jugular vein, and he received systemic chemotherapy(fluorouracil, Leucovorin, and irinotecan[FOLFIRI]plus BV)as an outpatient. One year after this recurrence, no peritoneal dissemination was detected by CT. Thereafter, total 49 courses of FOLFIRI plus BV were introduced, but chemotherapy was discontinued due to CV port-related infection. Three months later, low back pain appeared and became a diagnosis of spondylodiscitis. He had surgery, but follow-up CT performed 8 years after the first surgery detected multiple liver metastasis. It was considered necessary to take infection control measures during long-term chemotherapy.

Simultaneous removal of fluoride and phosphate from semiconductor wastewater via chemical precipitation of calcium fluoride and hydroxyapatite using byproduct of recycled aggregate.

Semiconductor wastewater with high concentrations of fluoride and phosphate is an environmental issue that cannot be ignored. Moreover, the byproduct of recycled aggregates, concrete fines, cannot be reused in concrete manufacturing, which is a key issue to address for the sustainable development of the concrete industry. The objective of this study was to tackle the crucial environmental issues of these two industries by developing concrete fines as an alternative material to treat semiconductor wastewater. The chemical precipitation of calcium fluoride and hydroxyapatite in the presence of concrete fines was determined as the mechanism underpinning the removal of fluoride and phosphate in wastewater. Owing to the wide range of contaminant concentration and solution pH and the possibility of multi-stage treatment, the effects of the initial contaminant concentration (F: 100-1000 mg/L; P: 20-200 mg/L) and solution pH (pH: 2-7) on the removal reactions were determined. The highest F and P removal percentages were more than 99%, and the final F and P concentrations met the effluent standard (F: 15 mg/L, P: 1.3 mg/L). The removal reactions of F and P are generally in competition, and the removal of F has priority over the removal of P. The pseudo-second-order model can describe the kinetics of the removal reactions well. The formation of fluorapatite can reduce the F concentration below the concentration achievable by CaF2 precipitation alone. Furthermore, using the byproduct of recycled aggregates instead of conventional chemicals to treat semiconductor wastewater is promising in terms of reducing CO2 emissions, and prospective applications are discussed. This study can lead to the development of a sustainable and clean process for semiconductor wastewater treatment using byproducts from the concrete industry.

[Three Cases of Conversion Surgery Resulted in Pathological Complete Response for Unresectable Pancreatic Cancer].

Conversion surgery(CS)post chemotherapy for unresectable pancreatic cancer is often reported recently. Although it is still controversial about adaptation of CS, it could possibly be one of the useful choices of treatment for unresectable pancreatic cancer. We report 3 cases of CS which eventually turned out to be pathological complete response.

The Japanese Epidemiologic Study for Perioperative Anaphylaxis, a prospective nationwide study: allergen exposure, epidemiology, and diagnosis of anaphylaxis during general anaesthesia.

BACKGROUND: Diagnosis of perioperative anaphylaxis is often challenging. This study describes the utility of a newly developed tool for identifying patients with a high possibility of anaphylaxis, and aimed to investigate the frequency of anaphylaxis with each drug during the perioperative period in Japan. METHODS: This study included patients with anaphylaxis of Grade 2 or higher severity during general anaesthesia at 42 facilities across Japan in 2019 and 2020. We developed and adopted a unique objective evaluation tool yielding a composite score for diagnosing anaphylaxis, which includes the results of skin tests and basophil activation tests, and clinical scores for perioperative anaphylaxis. The number of cases using each drug and the total number of anaphylaxis cases were investigated to calculate the frequency of anaphylaxis. RESULTS: General anaesthesia was performed in 218 936 cases, which included 55 patients with suspected perioperative anaphylaxis. The developed composite score diagnosed 43 of them with a high probability of anaphylaxis. The causative agent was identified in 32 cases. Plasma histamine levels showed high diagnostic accuracy for anaphylaxis. The top causative agents were rocuronium (10 cases in 210 852 patients, 0.005%), sugammadex (7 cases in 150 629 patients, 0.005%), and cefazolin (7 cases in 106 005 patients, 0.007%). CONCLUSIONS: We developed a composite tool to diagnose anaphylaxis, and found that the combination of tryptase levels, skin testing, and basophil activation testing results and clinical score improved the certainty of anaphylaxis diagnosis. The incidence of perioperative anaphylaxis in our study was 1 in about 5000 general anaesthesia cases. CLINICAL TRIAL REGISTRATION: UMIN000035350.

[A Case of Jejunal Ectopic Pancreas Incidentally Found in Laparoscopic Rectal Cancer Surgery].

In laparoscopic surgery, intraabdominal examination is occasionally difficult due to restriction of operative field and palpation. This is a case report of a jejunal ectopic pancreas which was incidentally found during laparoscopic surgery. A 49-year- old male underwent endoscopic mucosal resection for a rectal polyp which pathologically resulted in 5,000 µm invasion in submucosa and lymphatic invasion. Laparoscopic low anterior resection was planned for the patient as an additional treatment. During the surgery, irregular shaped tumor-like lesion was incidentally found in jejunum which was located 30 cm distal side from the ligament of Treitz. Partial resection of jejunum was also performed for pathological diagnosis. Resected jejunal lesion was pathologically diagnosed as an ectopic pancreas of Heinrich classification type Ⅰ. Ectopic pancreas is defined as pancreatic tissue which is discontinuous to pancreas, asymptomatic in most cases, but some reported cases of pancreatitis, forming fistula or cancerous change. Reporting with some literature review.

De novo non-synonymous DPYSL2 (CRMP2) variants in two patients with intellectual disabilities and documentation of functional relevance through zebrafish rescue and cellular transfection experiments.

Collapsin response mediator protein 2 (Crmp2) is an evolutionarily well-conserved tubulin-binding cytosolic protein that plays critical roles in the formation of neural circuitry in model organisms including zebrafish and rodents. No clinical evidence that CRMP2 variants are responsible for monogenic neurogenic disorders in humans presently exists. Here, we describe two patients with de novo non-synonymous variants (S14R and R565C) of CRMP2 and intellectual disability associated with hypoplasia of the corpus callosum. We further performed various functional assays of CRMP2 variants using zebrafish and zebrafish Crmp2 (abbreviated as z-CRMP2 hereafter) and an antisense morpholino oligonucleotide [AMO]-based experimental system in which crmp2-morphant zebrafish exhibit the ectopic positioning of caudal primary (CaP) motor neurons. Whereas the co-injection of wild-type z-CRMP2 mRNA suppressed the ectopic positioning of CaP motor neurons in Crmp2-morphant zebrafish, the co-injection of R566C or S15R, z-CRMP2, which corresponds to R565C and S14R of human CRMP2, failed to rescue the ectopic positioning. Transfection experiments of zebrafish or rat Crmp2 using plasmid vectors in HeLa cells, with or without a proteasome inhibitor, demonstrated that the expression levels of mutant Crmp2 protein encoded by R565C and S14R CRMP2 variants were decreased, presumably because of increased degradation by proteasomes. When we compared CRMP2-tubulin interactions using co-immunoprecipitation and cellular localization studies, the R565C and S14R mutations weakened the interactions. These results collectively suggest that the CRMP2 variants detected in the present study consistently led to the loss-of-function of CRMP2 protein and support the notion that pathogenic variants in CRMP2 can cause intellectual disabilities in humans.

Valproic Acid-Induced Anxiety and Depression Behaviors are Ameliorated in p39 Cdk5 Activator-Deficient Mice.

Valproic acid (VPA) is a drug used for the treatment of epilepsy, seizures, migraines, and bipolar disorders. Cyclin-dependent kinase 5 (Cdk5) is a Ser/Thr kinase activated by p35 or p39 in neurons and plays a role in a variety of neuronal functions, including psychiatric behaviors. We previously reported that VPA suppressed Cdk5 activity by reducing the expression of p35 in cultured cortical neurons, leaving p39 unchanged. In this study, we asked for the role of Cdk5 in VPA-induced anxiety and depression behaviors. Wild-type (WT) mice displayed increased anxiety and depression after chronic administration of VPA for 14 days, when the expression of p35 was decreased. To clarify their relationship, we used p39 knockout (KO) mice, in which p35 is the only Cdk5 activator. When p39 KO mice were treated chronically with VPA, unexpectedly, they exhibited fewer anxiety and depression behaviors than WT mice. The effects were p39 cdk5r2 gene-dosage dependent. Together, these results indicate that Cdk5-p39 plays a specific role in VPA-induced anxiety and depression behaviors.

Involvement of Cdk5 activating subunit p35 in synaptic plasticity in excitatory and inhibitory neurons.

Cyclin-dependent kinase 5 (Cdk5) /p35 is involved in many developmental processes of the central nervous system. Cdk5/p35 is also implicated in synaptic plasticity, learning and memory. Several lines of conditional Cdk5 knockout mice (KO) have been generated and have shown different outcomes for learning and memory. Here, we present our analysis of p35 conditional KO mice (p35cKO) in hippocampal pyramidal neurons or forebrain GABAergic neurons using electrophysiological and behavioral methods. In the fear conditioning task, CamKII-p35cKO mice showed impaired memory retention. Furthermore, NMDAR-dependent long-term depression (LTD) induction by low-frequency stimuli in hippocampal slices from CamkII-p35cKO mice was impaired compared to that in control mice. In contrast, Dlx-p35cKO mice showed no abnormalities in behavioral tasks and electrophysiological analysis in their hippocampal slices. These results indicated that Cdk5/p35 in excitatory neurons is important for the hippocampal synaptic plasticity and associative memory retention.

Loss of CRMP1 and CRMP2 results in migration defects of Purkinje cells in the X lobule of the mouse cerebellum.

The three-layered structure of the mammalian cerebellar cortex is generated through the coordinated migration of cerebellar neurons. Purkinje cells migrate and form a three- to four-cell-thick aggregate below the external granule cell layer during the embryonic stage, and align to form a monocellular arrangement in the Purkinje cell layer during the postnatal period. We previously reported the involvement of Cdk5-mediated CRMP2 phosphorylation in Purkinje cell migration and the synergistic roles of two other CRMPs, CRMP1 and CRMP4. In the present study, we investigated the loss of function of CRMP2 along with the synergistic function of CRMP1 in the migration and alignment of Purkinje cells. We found deficits in the migration and alignment of Purkinje cells in lobule X of the cerebella of CRMP1 and CRMP2 double knockout mice. Because lobule X, also called the flocculonodular lobe, is involved in the maintenance of balance equilibrium and muscle tone, we conducted balance beam and grip power tests in these mice and found impaired performance on the balance beam test and lower grip power in CRMP1 and CRMP2 double knockout mice, indicating the importance of these genes in proper cerebellar development.

[A Case of Descending Colon Cancer with Virchow and Axillary Lymph Node Metastasis].

A 72-year-old man was referred to our department with suspected intestinal obstruction. CT showed irregular descending colon wall thickening. Lower endoscopy showed severe descending colon stenosis. Biopsy results were group 1. FDG accumulation of significant SUV was found in the lymph nodes on the left supraclavicular region, left axilla, right mediastinum, posterior part of the right diaphragmatic leg, around the abdominal aorta, and in the liver. The accumulation in the descending colon was not definitely neoplastic. Consequently of left axillary lymph node biopsy, axillary lymph node metastasis of colorectal cancer was suspected, and laparoscopic left semicolon resection was performed. Among the simultaneous distant colorectal cancer metastases, Virchow's and left axillary lymph node metastases are extremely rare(0.1%). We report a case of descending colon cancer with simultaneous Virchow's and left axillary lymph node metastases, with some literature discussion.

[A Case of Meningeal Carcinomatosis of Gastric Cancer Successfully Controlled with Nab-Paclitaxel].

We report a 76-year-old woman with meningeal carcinomatosis after gastric cancer surgery. During adjuvant chemotherapy, metastasis to the left axillary and Virchow's lymph node was suspected. A resection biopsy revealed gastric cancer metastasis, and PTX plus RAM therapy was started. Due to RAM adverse events, the treatment was changed to weekly nab- PTX, which was continued for about 6 months. During the 8th course, she was hospitalized due to worsening headache and lightheadedness. Meningeal carcinomatosis was diagnosed by cytology of CSF examination and MRI findings. She died on the 16th day after admission. Meningeal carcinomatosis has a rapidly progressive course with poor prognosis. This case shows nab-PTX may have been able to control the progression.

An ectopic thymoma arising in the middle mediastinum that was difficult to distinguish from a lymph node metastasis.

BACKGROUND: Ectopic thymomas often occur in the upper mediastinum; however, they rarely arise in the middle mediastinum, especially on the dorsal side of the innominate vein and superior vena cava in the peribronchial region. CASE PRESENTATION: Six years prior, a 27-year-old female presented to our department and was diagnosed with locally advanced left breast cancer. First, we administered chemotherapy including an anti-human epidermal growth factor receptor 2 antibody. The size of the tumor was markedly reduced, and a radical operation involving mastectomy and axillary lymph node dissection was then performed. The patient underwent radiotherapy after the mastectomy, followed by trastuzumab therapy; she continued to receive endocrine therapy thereafter. She underwent computed tomography once a year after the surgery, and a nodule in the middle mediastinum on the dorsal side of the innominate vein and superior vena cava in the parabronchial region was detected at 4 years. We speculated that the nodule was a solitary mediastinal lymph node metastasis from her breast cancer; therefore, we performed thoracoscopic resection of the tumor. We diagnosed the tumor as a thymoma. Currently, the patient visits our hospital to receive continuous hormone therapy for her breast cancer, and the latest computed tomography scan demonstrated no metastases from or recurrence of her breast cancer or thymoma. CONCLUSIONS: We report a case of ectopic thymoma in the middle mediastinum. The tumor, which was detected during systemic therapy for locally advanced breast cancer, was located on the dorsal side of the innominate vein and superior vena cava in the parabronchial region and was indistinguishable from a lymph node metastasis from breast cancer.

CD52 is a novel target for the treatment of FLT3-ITD-mutated myeloid leukemia.

Internal tandem duplication (ITD) of FMS-like tyrosine kinase 3 (FLT3) confers poor prognosis and is found in approximately 25% of cases of acute myeloid leukemia (AML). Although FLT3 inhibitors have shown clinical benefit in patients with AML harboring FLT3-ITD, the therapeutic effect is limited. Here, to explore alternative therapeutics, we established a cellular model of monoallelic FLT3ITD/WT cells using the CRISPR-Cas9 system in a human myeloid leukemia cell line, K562. cDNA microarray analysis revealed elevated CD52 expression in K562-FLT3ITD/WT cells compared to K562-FLT3WT/WT cells, an observation that was further confirmed by quantitative real-time-PCR and flow cytometric analyses. The elevated expression of CD52 in K562-FLT3ITD/WT cells was decreased in wild-type FLT3 (FLT3-WT) knock-in K562-FLT3ITD/WT cells. In K562-FLT3ITD/WT cells, a STAT5 inhibitor, pimozide, downregulated CD52 protein expression while an AKT inhibitor, afuresertib, did not affect CD52 expression. Notably, an anti-CD52 antibody, alemtuzumab, induced significant antibody-dependent cell-mediated cytotoxicity (ADCC) in K562-FLT3ITD/WT cells compared to K562-FLT3WT/WT cells. Furthermore, alemtuzumab significantly suppressed the xenograft tumor growth of K562-FLT3ITD/WT cells in severe combined immunodeficiency (SCID) mice. Taken together, our data suggested that genetically modified FLT3-ITD knock-in human myeloid leukemia K562 cells upregulated CD52 expression via activation of STAT5, and alemtuzumab showed an antitumor effect via induction of ADCC in K562-FLT3ITD/WT cells. Our findings may allow establishment of a new therapeutic option, alemtuzumab, to treat leukemia with the FLT3-ITD mutation.

[A Case Report of Carcinoma of the Appendix Which Was Diagnosed with Ascites One Year after Appendicitis Operation].

A 68-year-old man visited our hospital in October 201X, giving abdominal bloating as his primary symptom. We found tenderness at McBurney's point, high WBC values from a blood test, and swelling of the appendix in a CT scan, so he was diagnosed with acute appendicitis. On the same day, he had an emergency laparoscopic appendectomy, and he made good progress and was discharged from the hospital on the fourth day after the surgery. In the histopathological examination, he was diagnosed with acute gangrenous appendicitis and examination was concluded. August of the following year, ascites accumulation was found by CT scan, and he was introduced to the department of gastroenterology of this hospital for further testing. Lower endoscopy showed swelling of the appendix root, and he was diagnosed with adenocarcinoma in the biopsy. A CT scan found increased granular concentration in the omentum. Because of a diagnosis of appendix cancer/peritoneal dissemination, he underwent laparoscopic examination in October. Nodules were found scattered in the small intestinal mesentery and the omentum, and peritoneal dissemination was suspected during intraoperative rapid diagnosis. The operation was concluded with only laparoscopic examination. Because of the diagnosis of appendix cancer/peritoneal dissemination, mFOLFOX6 plus bevacizumab was implemented. Primary appendix cancer is a relatively rare disease, often diagnosed after surgery for appendicitis, reported of here 0.03% to 0.5% of cases undergoing appendectomy. We report a case of primary appendix cancer diagnosed 1 year after appendectomy, with the discussion of the literature.

[A Case of Neuroendocrine Tumor of the Second Part of the Duodenum].

A 69-year-old woman was referred to our hospital when the upper gastrointestinal endoscopy performed by the previous physician for detailed examination of upper abdominal discomfort indicated a duodenal tumor. Upper gastrointestinal endoscopy revealed a submucosal tumor with a central depression in the descending part of the duodenum. Contrast- enhanced computed tomography of the abdomen revealed a 23 mm tumor with contrast effect in the descending part of the duodenum contralateral to the Vater papilla. There was no lymphadenopathy or distant metastasis. Duodenal gastrointestinal stromal tumor was suspected, and localized duodenectomy was planned. Intraoperative findings showed that the tumor was located in the descending part contralateral to the Vater papilla with no evidence of surrounding invasion. Localized duodenectomy was performed, and on intraoperative rapid histopathological examination, an adenocarcinoma was suspected. As a result, the surgery was changed into pancreaticoduodenectomy. Based on the results of immunostaining, neuroendocrine tumor grade 2 was diagnosed. No lymph node metastasis was observed. The patient did not have recurrence of lesion 7 months after surgery.

Hyperactive and impulsive behaviors of LMTK1 knockout mice.

Lemur tail kinase 1 (LMTK1), previously called Apoptosis-Associated Tyrosine Kinase (AATYK), remains an uncharacterized Ser/Thr protein kinase that is predominantly expressed in the brain. It is recently reported that LMTK1A, an isoform of LMTK1, binds to recycling endosomes through its palmitoylation and regulates endosomal trafficking by suppressing the activity of Rab11 small GTPase. In neurons, knockdown or knockout of LMTK1 results in longer axons, greater branching of dendrites and increased number of spines, suggesting that LMTK1 plays a role in neuronal circuit formation. However, its in vivo function remained to be investigated. Here, we examined the brain structures and behaviors of LMTK1 knockout (KO) mice. LMTK1 was expressed in most neurons throughout the brain. The overall brain structure appeared to be normal in LMTK1 KO mice, but the numbers of synapses were increased. LMTK1 KO mice had a slight impairment in memory formation and exhibited distinct psychiatric behaviors such as hyperactivity, impulsiveness and high motor coordination without social interaction deficits. Some of these abnormal behaviors represent core features of attention deficit hyperactive disorder (ADHD), suggesting the possible involvement of LMTK1 in the pathogenesis of ADHD.

[Bladder-Infiltrating Sigmoid Colon Cancer Successfully Treated with Neoadjuvant Chemotherapy and Radical Resection-A Case Report].

A 71-year-old man presented with the chief complaints of constipation, melena, and weight loss, and sigmoid colon cancer was suspected on lower gastrointestinal endoscopy. The cancer was diagnosed as RAS wild type adenocarcinoma(tub2)on biopsy. Abdominal contrast-enhanced CT revealed a mass with a maximum diameter of 55mm in the sigmoid colon; therefore, bladder infiltration was suspected. The Group 1 lymph nodes were bulky, with a maximum diameter of 50 mm, and No. 253 lymph node was enlarged. No fistulas were found on cystoscopy. The sigmoid colon cancer was cT4b(bladder), N3, M0, cStage Ⅲc. After performing a colostomy, neoadjuvant chemotherapy with mFOLFOX6 plus panitumumab was started. Radical surgery was performed after 3 courses of chemotherapy. The clinical treatment effect was PR, and the final histopathologi- cal examination revealed ypT3, ypN0(0/17), R0, ypStageⅡa. The therapeutic effect was Grade 2a. Postoperative adjuvant chemotherapy was performed for 6 months with mFOLFOX, and there have been no signs of cancer recurrence for 9 postoperative months. We experienced a case of colon cancer with suspected bladder infiltration, successfully treated with neoadjuvant chemotherapy and radical surgery.

Lanthionine ketimine ester improves outcome in an MPTP-induced mouse model of Parkinson's disease via suppressions of CRMP2 phosphorylation and microglial activation.

Parkinson's disease (PD) is characterized by progressive degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNc). Levodopa (L-Dopa), the current main treatment for PD, reduces PD symptoms by partially replacing dopamine, but it does not slow neurodegeneration. Recent studies have evidenced that neuroinflammatory processes contribute to the degeneration of dopaminergic neurons in the SNc under cytopathic conditions, while other lines of inquiry have implicated phosphorylation of collapsin response mediator protein 2 (CRMP2) as a causal factor in axonal retraction after neural injury. We recently reported on the therapeutic effect of lanthionine ketimine ester (LKE) which associates with CRMP2 following axonal injury in the spinal cord. In the present study, we report that LKE protects SNc dopaminergic neurons after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) challenge, a common model for PD, and reduces the number of activated microglia proximal to the damaged SNc. The results also show that MPTP-induced motor impairment was suppressed in LKE treatment. Furthermore, the results show that LKE inhibits the elevation of CRMP2 phosphorylation in dopaminergic neurons in the SNc after MPTP injection. These data suggest that modification of CRMP2 phosphorylation and suppression of microglial activation with LKE administration may represent a novel strategy for slowing progress of pathological processes in PD.