Gamma-delta T cells suppress microbial metabolites that activate striatal neurons and induce repetitive/compulsive behavior in mice.

Intestinal γδ T cells play an important role in shaping the gut microbiota, which is critical not only for maintaining intestinal homeostasis but also for controlling brain function and behavior. Here, we found that mice deficient for γδ T cells (γδ-/-) developed an abnormal pattern of repetitive/compulsive (R/C) behavior, which was dependent on the gut microbiota. Colonization of WT mice with γδ-/- microbiota induced R/C behavior whereas colonization of γδ-/- mice with WT microbiota abolished the R/C behavior. Moreover, γδ-/- mice had elevated levels of the microbial metabolite 3-phenylpropanoic acid in their cecum, which is a precursor to hippurate (HIP), a metabolite we found to be elevated in the CSF. HIP reaches the striatum and activates dopamine type 1 (D1R)-expressing neurons, leading to R/C behavior. Altogether, these data suggest that intestinal γδ T cells shape the gut microbiota and their metabolites and prevent dysfunctions of the striatum associated with behavior modulation.

Myeloid cell subsets that express latency-associated peptide promote cancer growth by modulating T cells.

Myeloid suppressor cells promote tumor growth by a variety of mechanisms which are not fully characterized. We identified myeloid cells (MCs) expressing the latency-associated peptide (LAP) of TGF-ß on their surface and LAPHi MCs that stimulate Foxp3+ Tregs while inhibiting effector T cell proliferation and function. Blocking TGF-ß inhibits the tolerogenic ability of LAPHi MCs. Furthermore, adoptive transfer of LAPHi MCs promotes Treg accumulation and tumor growth in vivo. Conversely, anti-LAP antibody, which reduces LAPHi MCs, slows cancer progression. Single-cell RNA-Seq analysis on tumor-derived immune cells revealed LAPHi dominated cell subsets with distinct immunosuppressive signatures, including those with high levels of MHCII and PD-L1 genes. Analogous to mice, LAP is expressed on myeloid suppressor cells in humans, and these cells are increased in glioma patients. Thus, our results identify a previously unknown function by which LAPHi MCs promote tumor growth and offer therapeutic intervention to target these cells in cancer.

Robotic-Assisted Trajectory Into Kambin's Triangle During Percutaneous Transforaminal Lumbar Interbody Fusion-Initial Case Series Investigating Safety and Efficacy.

BACKGROUND: Minimally invasive spine surgery (MISS) has the potential to further advance with the use of robot-assisted (RA) techniques. While RA pedicle screw placement has been extensively investigated, there is a lack of literature on the use of the robot for other tasks, such as accessing Kambin's triangle in percutaneous lumbar interbody fusion (percLIF). OBJECTIVE: To characterize the surgical feasibility and preliminary outcomes of an initial case series of 10 patients receiving percLIF with RA cage placement via Kambin's triangle. METHODS: We performed a single-center, retrospective review of patients undergoing RA percLIF using robot-guided trajectory to access Kambin's triangle for cage placement. Patients undergoing RA percLIF were eligible for enrollment. Baseline health and demographic information in addition to peri- and postoperative data was collected. The dimensions of each patient's Kambin's triangle were measured. RESULTS: Ten patients and 11 levels with spondylolisthesis were retrospectively reviewed. All patients successfully underwent the planned procedure without perioperative complications. Four patients underwent their procedure with awake anesthesia. The average dimension of Kambin's triangle was 66.3 m2. With the exception of 1 patient who stayed in the hospital for 7 d, the average length of stay was 1.2 d, with 2 patients discharged the day of surgery. No patients suffered postoperative motor or sensory deficits. Spinopelvic parameters and anterior and posterior disc heights were improved with surgery. CONCLUSION: As MISS continues to evolve, further exploration of robot-guided surgical practice, such as our technique, will lead to creative solutions to challenging anatomical variation and overall improved patient care.

Endovascular treatment of a ruptured posterior fossa pure arterial malformation: illustrative case.

BACKGROUND: Pure arterial malformations (PAMs) are rare vascular anomalies that are commonly mistaken for other vascular malformations. Because of their purported benign natural history, PAMs are often conservatively managed. The authors report the case of a ruptured PAM leading to subarachnoid hemorrhage (SAH) with intraventricular extension that was treated endovascularly. OBSERVATIONS: A 38-year-old man presented with a 1-day history of headaches and nausea. A computed tomography scan demonstrated diffuse SAH with intraventricular extension, and angiography revealed a right posterior inferior cerebellar artery-associated PAM. The PAM was treated with endovascular Onyx embolization. LESSONS: To the authors' knowledge, only 2 other cases of SAH associated with PAM have been reported. In those 2 cases, surgical clipping was pursued for definitive treatment. Here, the authors report the first case of a ruptured PAM treated using an endovascular approach, showing its feasibility as a treatment option particularly in patients in whom open surgery is too high a risk.

Acute microglia ablation induces neurodegeneration in the somatosensory system.

Previous studies have reported that microglia depletion leads to impairment of synapse formation and these cells rapidly repopulate from CNS progenitors. However, the impact of microglia depletion and repopulation in the long-term state of the CNS environment has not been characterized. Here, we report that acute and synchronous microglia depletion and subsequent repopulation induces gray matter microgliosis, neuronal death in the somatosensory cortex and ataxia-like behavior. We find a type 1 interferon inflammatory signature in degenerating somatosensory cortex from microglia-depleted mice. Transcriptomic and mass cytometry analysis of repopulated microglia demonstrates an interferon regulatory factor 7-driven activation state. Minocycline and anti-IFNAR1 antibody treatment attenuate the CNS type 1 interferon-driven inflammation, restore microglia homeostasis and reduce ataxic behavior. Neither microglia depletion nor repopulation impact neuropathology or T-cell responses during experimental autoimmune encephalomyelitis. Together, we found that acute microglia ablation induces a type 1 interferon activation state of gray matter microglia associated with acute neurodegeneration.

Clinical Problem-Solving: Lethargy and Fever in an Immunocompromised Patient.

We present the case of a 63-year-old woman with a glioblastoma multiforme on immunosuppressive steroid doses who developed lethargy and fever. We review the differential diagnosis and emphasize the importance of reframing the case when the clinical course differs from expectation. Once the diagnosis is evident, we discuss the incidence and clinical course in different patient populations.

Disruption of the ATP/adenosine balance in CD39-/- mice is associated with handling-induced seizures.

Seizures are due to excessive, synchronous neuronal firing in the brain and are characteristic of epilepsy, the fourth most prevalent neurological disease. We report handling-induced and spontaneous seizures in mice deficient for CD39, a cell-surface ATPase highly expressed on microglial cells. CD39-/- mice with handling-induced seizures had normal input-output curves and paired-pulse ratio measured from hippocampal slices and lacked microgliosis, astrogliosis or overt cell loss in the hippocampus and cortex. As expected, however, the cerebrospinal fluid of CD39-/- mice contained increased levels of ATP and decreased levels of adenosine. To determine if immune activation was involved in seizure progression, we challenged mice with lipopolysaccharide (LPS) and measured the effect on microglia activation and seizure severity. Systemic LPS challenge resulted in increased cortical staining of Iba1/CD68 and gene array data from purified microglia predicted increased expression of interleukin-8, triggering receptor expressed on myeloid cells 1, p38, pattern recognition receptors, death receptor, nuclear factor-κB , complement, acute phase, and interleukin-6 signalling pathways in CD39-/- versus CD39+/+ mice. However, LPS treatment did not affect handling-induced seizures. In addition, microglia-specific CD39 deletion in adult mice was not sufficient to cause seizures, suggesting instead that altered expression of CD39 during development or on non-microglial cells such as vascular endothelial cells may promote the seizure phenotype. In summary, we show a correlation between altered extracellular ATP/adenosine ratio and a previously unreported seizure phenotype in CD39-/- mice. This work provides groundwork for further elucidation of the underlying mechanisms of epilepsy.

Minimally Invasive Muscle Sparing Posterior-Only Approach for Lumbar Circumferential Decompression and Stabilization to Treat Spine Metastasis--Technical Report.

OBJECTIVE: Palliative tumor resection and subsequent stabilization are important for maximizing function and quality of life for patients suffering from spinal metastases. However, traditional operative techniques for spinal metastases with vertebral body destruction involve extensive soft tissue dissection. In the lumbar spine, open 2-staged spine procedures are routinely required with an anterior retroperitoneal approach for corpectomy and cage insertion and posterior decompression and stabilization with pedicle screws and rods. Both stages require extensive soft tissue dissection that results in significant surgical morbidity, long recovery time, and subsequent delay in initiating postoperative chemoradiotherapy, as well as initially hampering patients' overall quality of life. A minimally invasive approach is desirable for achieving spinal stability, pain control, functional recovery, rapid initiation of adjuvant therapies, and overall patient satisfaction, especially in patients whose medical and surgical therapies are aimed at palliation rather than cure. PRESENTATION: A 59-year-old man with renal cell carcinoma and a known L1 vertebral body metastasis presented with severe progressive low back pain and was found to have a pathologic L1 vertebral body fracture with focal kyphosis. INTERVENTION: Here, we describe a minimally invasive muscle-sparing, posterior-only approach for L1 transpedicular hemicorpectomy and expandable cage placement, L1 laminectomy, and T11-L3 posterior instrumented stabilization. The surgical corridor was achieved through the Wiltse muscle plane between the multifidus and longissimus muscles so that minimal muscle detachment was required to achieve transpedicular access to the anterior and middle spinal columns. The L1 nerve root was completely skeletonized to allow adequate lumbar hemicorpectomy, tumor resection, and expandable titanium cage insertion. Lastly, percutaneous pedicle screws and rods were inserted from T11 to L3 for stabilization. RESULT: The patient tolerated the procedure well with no complications and less than 200 mL estimated blood loss. Postoperative computed tomography revealed restoration of intervertebral height and adequate tumor resection with excellent placement of the expandable cage and posterior construct. The patient was discharged on postoperative day 4 and had nearly no back pain 3 weeks after surgery. Adjuvant therapies were started soon after. At the 6-month follow-up, the patient required minimal narcotic pain medication. Computed tomography scan demonstrated stable hardware with no evidence of failure. CONCLUSION: A minimally invasive muscle-sparing, posterior-only approach is a promising surgical strategy for 360-degree decompression and stabilization for the treatment of lumbar spinal metastases with minimized blood loss, muscle detachment and postoperative pain, and fast postoperative recovery and initiation of adjuvant therapy.

Deficient CX3CR1 signaling promotes recovery after mouse spinal cord injury by limiting the recruitment and activation of Ly6Clo/iNOS+ macrophages.

Macrophages exert divergent effects in the injured CNS, causing either neurotoxicity or regeneration. The mechanisms regulating these divergent functions are not understood but can be attributed to the recruitment of distinct macrophage subsets and the activation of specific intracellular signaling pathways. Here, we show that impaired signaling via the chemokine receptor CX3CR1 promotes recovery after traumatic spinal cord injury (SCI) in mice. Deficient CX3CR1 signaling in intraspinal microglia and monocyte-derived macrophages (MDMs) attenuates their ability to synthesize and release inflammatory cytokines and oxidative metabolites. Also, impaired CX3CR1 signaling abrogates the recruitment or maturation of MDMs with presumed neurotoxic effects after SCI. Indeed, in wild-type mice, Ly6C(lo)/iNOS(+)/MHCII(+)/CD11c(-) MDMs dominate the lesion site, whereas CCR2(+)/Ly6C(hi)/MHCII(-)/CD11c(+) monocytes predominate in the injured spinal cord of CX3CR1-deficient mice. Replacement of wild-type MDMs with those unable to signal via CX3CR1 resulted in anatomical and functional improvements after SCI. Thus, blockade of CX3CR1 signaling represents a selective anti-inflammatory therapy that is able to promote neuroprotection, in part by reducing inflammatory signaling in microglia and MDMs and recruitment of a novel monocyte subset.

Spinal cord injury therapies in humans: an overview of current clinical trials and their potential effects on intrinsic CNS macrophages.

INTRODUCTION: Macrophage activation is a hallmark of spinal cord injury (SCI) pathology. CNS macrophages, derived from resident microglia and blood monocytes, are ubiquitous throughout the injured spinal cord, and respond to signals in the lesion environment by changing their phenotype and function. Depending on their phenotype and activation status, macrophages may initiate secondary injury mechanisms and/or promote CNS regeneration and repair. AREAS COVERED: This review provides a comprehensive overview of current SCI clinical trials that are intended to promote neuroprotection, axon regeneration or cell replacement. None of these potential therapies were developed with the goal of influencing macrophage function; however, it is likely that each will have direct or indirect effects on CNS macrophages. The potential impact of each trial is discussed in the context of CNS macrophage biology. EXPERT OPINION: Activation of CNS macrophages is an inevitable consequence of traumatic SCI. Given that these cells are exquisitely sensitive to changes in microenvironment, any intervention that affects tissue integrity and/or the composition of the cellular milieu will undoubtedly affect CNS macrophages. Thus, it is important to understand how current clinical trials will affect intrinsic CNS macrophages.

Identification of two distinct macrophage subsets with divergent effects causing either neurotoxicity or regeneration in the injured mouse spinal cord.

Macrophages dominate sites of CNS injury in which they promote both injury and repair. These divergent effects may be caused by distinct macrophage subsets, i.e., "classically activated" proinflammatory (M1) or "alternatively activated" anti-inflammatory (M2) cells. Here, we show that an M1 macrophage response is rapidly induced and then maintained at sites of traumatic spinal cord injury and that this response overwhelms a comparatively smaller and transient M2 macrophage response. The high M1/M2 macrophage ratio has significant implications for CNS repair. Indeed, we present novel data showing that only M1 macrophages are neurotoxic and M2 macrophages promote a regenerative growth response in adult sensory axons, even in the context of inhibitory substrates that dominate sites of CNS injury (e.g., proteoglycans and myelin). Together, these data suggest that polarizing the differentiation of resident microglia and infiltrating blood monocytes toward an M2 or "alternatively" activated macrophage phenotype could promote CNS repair while limiting secondary inflammatory-mediated injury.

An efficient and reproducible method for quantifying macrophages in different experimental models of central nervous system pathology.

Historically, microglia/macrophages are quantified in the pathological central nervous system (CNS) by counting cell profiles then expressing the data as cells/mm(2). However, because it is difficult to visualize individual cells in dense clusters and in most cases it is unimportant to know the absolute number of macrophages within lesioned tissue, alternative methods may be more efficient for quantifying the magnitude of the macrophage response in the context of different experimental variables (e.g., therapeutic intervention or time post-injury/infection). The present study provides the first in-depth comparison of different techniques commonly used to quantify microglial/macrophage reactions in the pathological spinal cord. Individuals from the same and different laboratories applied techniques of digital image analysis (DIA), standard cell profile counting and a computer-assisted cell counting method with unbiased sampling to quantify macrophages in focal inflammatory lesions, disseminated lesions caused by autoimmune inflammation or at sites of spinal trauma. Our goal was to find a simple, rapid and sensitive method with minimal variability between trials and users. DIA was consistently the least variable and most time-efficient method for assessing the magnitude of macrophage responses across lesions and between users. When used to evaluate the efficacy of an anti-inflammatory treatment, DIA was 5-35 x faster than cell counting and was sensitive enough to detect group differences while eliminating inter-user variability. Since lesions are clearly defined and single profiles of microglia/macrophages are difficult to discern in most pathological specimens of brain or spinal cord, DIA offers significant advantages over other techniques for quantifying activated macrophages.

Particle-tethered NADH for production of methanol from CO(2) catalyzed by coimmobilized enzymes.

Efficient cofactor regeneration and reuse are highly desired for many important biotransformation applications. Here we show for the first time that cofactor NAD(H) covalently attached to micro particles, which can be easily recovered and reused, effectively mediated multistep reactions catalyzed by enzymes that were also immobilized with the micro particles. Such an immobilized enzyme-cofactor catalytic system was examined for the production of methanol from CO(2) with in situ cofactor regeneration. Four enzymes including formate, formaldehyde, alcohol, and glutamate dehydrogenases were coimmobilized using the same particles as that used for cofactor immobilization (enzymes and cofactor were immobilized separately). Reactions were performed by bubbling CO(2) in a suspension solution of the particle-attached enzymes and cofactor. It appeared that the collision among the particles afforded sufficient interactions between the cofactor and enzymes, and thus enabled the sequential transformation of CO(2) to methanol along with cofactor regeneration. For a 30-min batch reaction, a productivity of 0.02 micromol methanol/h/g-enzyme was achieved. That was lower than but comparable to the 0.04 micromol methanol/h/g-enzyme observed for free enzymes and cofactor at the same reaction conditions. The immobilized system showed fairly good stabilities in reusing. Over 80% of their original productivity was retained after 11 reusing cycles, with a cumulative methanol yield based on the amount of cofactor reached 127%. That was a promising enhancement in cofactor utilization as compared to the single-batch yield of 12% observed with free enzymes and free cofactor.

Inflammation and its role in neuroprotection, axonal regeneration and functional recovery after spinal cord injury.

Trauma to the central nervous system (CNS) triggers intraparenchymal inflammation and activation of systemic immunity with the capacity to exacerbate neuropathology and stimulate mechanisms of tissue repair. Despite our incomplete understanding of the mechanisms that control these divergent functions, immune-based therapies are becoming a therapeutic focus. This review will address the complexities and controversies of post-traumatic neuroinflammation, particularly in spinal cord. In addition, current therapies designed to target neuroinflammatory cascades will be discussed.