Vaccine and antiviral development against SARS-CoV-2 infection or COVID-19 disease would benefit from validated small animal models. Here, we show that transgenic mice expressing human angiotensin-converting enzyme 2 (hACE2) by the human cytokeratin 18 promoter (K18 hACE2) represent a susceptible rodent model. K18 hACE2 transgenic mice succumbed to SARS-CoV-2 infection by day 6, with virus detected in lung airway epithelium and brain. K18 ACE2 transgenic mice produced a modest TH1/2/17 cytokine storm in the lung and spleen that peaked by day 2, and an extended chemokine storm that was detected in both lungs and brain. This chemokine storm was also detected in the brain at day 6. K18 hACE2 transgenic mice are, therefore, highly susceptible to SARS-CoV-2 infection and represent a suitable animal model for the study of viral pathogenesis, and for identification and characterization of vaccines (prophylactic) and antivirals (therapeutics) for SARS-CoV-2 infection and associated severe COVID-19 disease.

Microglial cells are difficult to track during development due to the lack of specific reagents for myeloid sub-populations. To further understand how myeloid lineages differentiate during development to give rise to microglial cells, we investigated CX3CR1 and CCR2 transcription unit activation in Cx3cr1+/GFPCCR2+/RFP knock-in fluorescent protein reporter mice. The principal findings include: 1) CX3CR1+ cells localized to the AGM region, and visualized at E9.0 in the yolk sac and neuroectoderm, 2) At E10.5 CX3CR1 single positive microglial cells were visualized penetrating the neuroepithelium, 3) CX3CR1 and CCR2 distinguished infiltrating macrophages from resident surveillant or activated microglia within tissue sections and by flow cytometric analyses. Our results support the contribution of the yolk sac as source of microglial precursors. We provide a novel model to monitor chemokine receptor expression changes in microglia and myeloid cells early (E8.0-E10.5) in development and during inflammatory conditions, which have been challenging to visualize in mammalian tissues.

The goal of the study was to determine the association between diabetes and inflammation in clinically diagnosed diabetes patients. We hypothesized that low-grade inflammation in diabetes is associated with the level of glucose control. Using a cross-sectional design we compared pro and anti-inflammatory cytokines in a community recruited cohort of 367 Mexican Americans with type 2-diabetes having a wide range blood glucose levels. Cytokines (IL-6, TNF-α, IL-1β, IL-8) and adipokines (adiponectin, resistin and leptin) were measured using multiplex ELISA. Our data indicated that diabetes as whole was strongly associated with elevated levels of IL-6, leptin, CRP and TNF-α, whereas worsening of glucose control was positively and linearly associated with high levels of IL-6, leptin. The associations remained statistically significant even after controlling for BMI and age (p = 0.01). The association between TNF-α, however, was attenuated when comparisons were performed based on glucose control. Strong interaction effects between age and BMI and diabetes were observed for IL-8, resistin, and CRP. The cytokine/adipokine profiles of Mexican Americans with diabetes suggest an association between low-grade inflammation and quality of glucose control. Unique to in our population is that the chronic inflammation is accompanied by lower levels of leptin.

New antibiotics are needed to combat rising resistance, with new Mycobacterium tuberculosis (Mtb) drugs of highest priority. Conventional whole-cell and biochemical antibiotic screens have failed. We developed a novel strategy termed PROSPECT (PRimary screening Of Strains to Prioritize Expanded Chemistry and Targets) in which we screen compounds against pools of strains depleted for essential bacterial targets. We engineered strains targeting 474 Mtb essential genes and screened pools of 100-150 strains against activity-enriched and unbiased compounds libraries, measuring > 8.5-million chemical-genetic interactions. Primary screens identified > 10-fold more hits than screening wild-type Mtb alone, with chemical-genetic interactions providing immediate, direct target insight. We identified > 40 novel compounds targeting DNA gyrase, cell wall, tryptophan, folate biosynthesis, and RNA polymerase, as well as inhibitors of a novel target EfpA. Chemical optimization yielded EfpA inhibitors with potent wild-type activity, thus demonstrating PROSPECT's ability to yield inhibitors against novel targets which would have eluded conventional drug discovery.

Background Although the biological basis for the increased susceptibility of diabetic patients to tuberculosis remains unclear, the world is undergoing a type 2 diabetes pandemic. We hypothesize that chronic hyperglycemia leads to immunocompromise that facilitates progression to active tuberculosis. To assess this possibility, we determined whether patients with tuberculosis and diabetes (particularly those with chronic hyperglycemia), compared with patients with tuberculosis who did not have diabetes, presented altered cytokine responses to a mycobacterial antigen. Methods Samples of whole blood from patients with tuberculosis and diabetes and from patients with tuberculosis who did not have diabetes was stimulated in vitro with purified protein derivative from Mycobacterium tuberculosis. We then determined whether there was an association between the levels of innate and adaptive cytokines secreted in response to the antigen and diabetes status, or diabetes with chronic hyperglycemia (measured by glycosylated hemoglobin level), after controlling for possible confounders. Results Innate and type 1 cytokine responses were significantly higher in patients with tuberculosis who had diabetes than in nondiabetic control subjects. The effect was consistently and significantly more marked in diabetic patients with chronic hyperglycemia. Conclusions These data provide preliminary evidence that type 2 diabetes, especially type 2 diabetes involving chronic hyperglycemia, is associated with an altered immune response to M. tuberculosis. More-detailed knowledge of the underlying mechanisms should focus on the effect of chronic hyperglycemia on the immune response to help in understanding the enhanced susceptibility of diabetic patients to tuberculosis.

Isolation of immune cells that infiltrate the central nervous system (CNS) during infection, trauma, autoimmunity or neurodegeneration, is often required to define their phenotype and effector functions. Histochemical approaches are instrumental to determine the location of the infiltrating cells and to analyze the associated CNS pathology. However, in-situ histochemistry and immunofluorescent staining techniques are limited by the number of antibodies that can be used at a single time to characterize immune cell subtypes in a particular tissue. Therefore, histological approaches in conjunction with immune-phenotyping by flow cytometry are critical to fully characterize the composition of local CNS infiltration. This protocol is based on the separation of CNS cellular suspensions over discontinous percoll gradients. The current article describes a rapid protocol to efficiently isolate mononuclear cells from brain and spinal cord tissues that can be effectively utilized for identification of various immune cell populations in a single sample by flow cytometry. Video LinkThe video component of this article can be found at http://www.jove.com/video/2348/ Protocol Preparation of reagentsPrepare stock isotonic percoll (SIP), 4 ml per brain, by mixing 9 parts of percoll with one part of 10X HBSS without Ca++ and Mg++.Prepare SIP at 70% in 1X HBSS without Ca++ and Mg++, 2 ml per brain dispensed into a 15 ml polypropylene conical tube.Note: It is recommended that percoll should be used at room temperature, if used cold, cells tend to clump and cell separation is less efficient. Tissue collection and homogenizationAnesthetize mice and perfuse through the left ventricle with ice-cold 1X HBSS. Dissect brain and spinal cord and maintain in RPMI without phenol red until all mice are sacrificed.Place tissues in 7 or 15 ml dounce homogenizer containing 3 ml of RPMI, gently make a cell suspension with a loose-fitting pestle (A size) followed by a tigh-fitting pestle (B size) to further dissociate the tissues. Complete the volume of the cell suspensions to 7 ml with RPMI. Gradient set upAdd 3 ml of SIP to the cell suspension to make a final 30% SIP Slowly layer the 10 mL cell suspension on top of the 70% SIP. This is the most critical step of the procedure, use a pipette-aid set in the gravity mode avoiding mixing of the 70% and 30% solutions. A very clear flat line should be visible at the 70%-30% junction.Centrifuge 30 min at 500G 18°C. Make sure centrifuge will stop with minimal or no brake so that the interphase is not disturbed.Using a transfer pipet, gently remove the layer of debris from the top of the tube and collect 2.0-3.0 ml of the 70%-30% interphase into a clean conical tube containing 8 ml of 1X HBSS. Ensure that the percoll containing the interphase is diluted about three fold, mix a few times by inversion and centrifugre 7 min at 500G at 18°C.Resuspend pellet in 1 ml of cell staining buffer and transfer it to a 1.5 ml tube and wash one more time using a micro-centrifuge at 10,000G 1 min at 4°C.

Fractalkine, a chemokine anchored to neurons or peripheral endothelial cells, serves as an adhesion molecule or as a soluble chemoattractant. Fractalkine binds CX3CR1 on microglia and circulating monocytes, dendritic cells and NK cells. The aim of this study is to determine the role of CX3CR1 in the trafficking and function of myeloid cells to the central nervous system (CNS) during experimental autoimmune encephalomyelitis (EAE). Our results show that in models of active EAE Cx3cr1–/– mice exhibited more severe neurological deficiencies. Bone marrow chimeric mice confirmed that CX3CR1-deficiency in bone marrow enhanced EAE severity. Notably, CX3CR1 deficiency was associated with an increased accumulation of CD115+Ly6C–CD11c+ dendritic cells into EAE affected brains which correlated with enhanced demyelination and neuronal damage. Furthermore, higher IFN-γ and IL-17 levels were detected in cerebellar and spinal cord tissues of CX3CR1-deficient mice. Analyses of peripheral responses during disease initiation revealed a higher frequency of IFN-γ and IL-17 producing T cells in lymphoid tissues of CX3R1-deficient as well as enhanced T cell proliferation induced by CX3CR1-deficient DCs. In addition, adoptive transfer of MOG35-55 reactive wild type T cells induced substantially more severe EAE in CX3CR1-deficient recipients when compared to wild type recipients. Collectively, the data demonstrate that besides its role in chemoattraction, CX3CR1 is a key regulator of myeloid cell activation contributing to the establishment of adaptive immune responses.

ObjectiveTo describe early functional outcomes of nerve transfer surgery in a relatively large cohort of patients with acute flaccid myelitis (AFM).MethodsA retrospective case analysis was made of patients with AFM treated with nerve transfer surgery between 2007 and 2018. Surgical criteria were persistent motor deficits after 6 months from onset and available donor nerves. Thirty‐two patients with AFM were evaluated; 16 underwent nerve transfer surgeries. Motor function was evaluated by a licensed occupational therapist using the Active Movement Scale preoperatively and during follow‐up examinations. Patients with 6 or more months of follow‐up were included in the analysis. Patients with procedures other than nerve transfers were excluded.ResultsSixteen patients with AFM had nerve transfers, with a male predominance (75%) and median age of 2.5 years (range = 4 months–12 years). Eleven patients had a minimum 6 months of follow‐up. Nerve transfers to restore elbow function had 87% excellent recovery for elbow flexion and 67% for elbow extension. Finger and thumb extension were full against gravity in 1 patient (100%). Shoulder external rotation was excellent in 50% of patients and shoulder abduction in only 20%. Nine of 10 patients (90%) had resolution of shoulder pseudosubluxation following nerve transfer to the suprascapular nerve.InterpretationPatients with AFM with persistent motor deficits 6 to 9 months after onset benefit from nerve transfer surgery. Restoration of elbow function was more reliable than restoration of shoulder function. We recommend early referral of patients with incomplete recovery to a center experienced in nerve transfers for timely evaluation and treatment. ANN NEUROL 2019;86:607–615