The Phagocyte Oxidase Controls Tolerance to Mycobacterium tuberculosis Infection.

Protection from infectious disease relies on two distinct strategies: antimicrobial resistance directly inhibits pathogen growth, whereas infection tolerance protects from the negative impact of infection on host health. A single immune mediator can differentially contribute to these strategies in distinct contexts, confounding our understanding of protection to different pathogens. For example, the NADPH-dependent phagocyte oxidase (Phox) complex produces antimicrobial superoxide and protects from tuberculosis (TB) in humans. However, Phox-deficient mice display no sustained resistance defects to Mycobacterium tuberculosis, suggesting a more complicated role for NADPH Phox complex than strictly controlling bacterial growth. We examined the mechanisms by which Phox contributes to protection from TB and found that mice lacking the Cybb subunit of Phox suffered from a specific defect in tolerance, which was caused by unregulated Caspase-1 activation, IL-1ß production, and neutrophil influx into the lung. These studies imply that a defect in tolerance alone is sufficient to compromise immunity to M. tuberculosis and highlight a central role for Phox and Caspase-1 in regulating TB disease progression.

Cutting Edge: Plasmodium falciparum Induces Trained Innate Immunity.

Malarial infection in naive individuals induces a robust innate immune response. In the recently described model of innate immune memory, an initial stimulus primes the innate immune system to either hyperrespond (termed training) or hyporespond (tolerance) to subsequent immune challenge. Previous work in both mice and humans demonstrated that infection with malaria can both serve as a priming stimulus and promote tolerance to subsequent infection. In this study, we demonstrate that initial stimulation with Plasmodium falciparum-infected RBCs or the malaria crystal hemozoin induced human adherent PBMCs to hyperrespond to subsequent ligation of TLR2. This hyperresponsiveness correlated with increased H3K4me3 at important immunometabolic promoters, and these epigenetic modifications were also seen in Kenyan children naturally infected with malaria. However, the use of epigenetic and metabolic inhibitors indicated that the induction of trained immunity by malaria and its ligands may occur via a previously unrecognized mechanism(s).

Spinal Cord Stimulation for Intractable Testicular Pain: Case Report and Review of the Literature.

OBJECTIVE: Treating chronic testicular pain is often challenging, and few treatment options have been reported. We report a case of intractable testicular pain successfully treated with spinal cord stimulation (SCS). CASE: A 59-year-old male with a 40-year history of bilateral testicular pain after ruptured epididymitis presented for consultation after failing multiple medical and surgical treatments. Repeat genitofemoral nerve block gave him temporary relief. SCS trial to target this distribution resulted in complete pain relief, and the patient was referred for implantation. He reported continued relief nine months after implantation. DISCUSSION: This is the third reported case of intractable chronic testicular pain successfully treated with SCS. Although evidence is scarce, SCS appears to be a potential treatment for patients with testicular pain presenting with a clear distribution of pain.

The clinical potential of targeted nanomedicine: delivering to cancer stem-like cells.

Cancer stem-like cells (CSCs) have been implicated in recurrence and treatment resistance in many human cancers. Thus, a CSC-targeted drug delivery strategy to eliminate CSCs is a desirable approach for developing a more effective anticancer therapy. We have developed a tumor-targeting nanodelivery platform (scL) for systemic administration of molecular medicines. Following treatment with the scL nanocomplex carrying various payloads, we have observed exquisite tumor-targeting specificity and significant antitumor response with long-term survival benefit in numerous animal models. We hypothesized that this observed efficacy might be attributed, at least in part, to elimination of CSCs. Here, we demonstrate the ability of scL to target both CSCs and differentiated nonstem cancer cells (non-CSCs) in various mouse models including subcutaneous and intracranial xenografts, syngeneic, and chemically induced tumors. We also show that systemic administration of scL carrying the wtp53 gene was able to induce tumor growth inhibition and the death of both CSCs and non-CSCs in subcutaneous colorectal cancer xenografts suggesting that this could be an effective method to reduce cancer recurrence and treatment resistance. This scL nanocomplex is being evaluated in a number of clinical trials where it has been shown to be well tolerated with indications of anticancer activity.

Diffusion-weighted imaging of the liver: comparison of image quality between monopolar and bipolar acquisition schemes at 3T.

PURPOSE: To compare image quality of monopolar and bipolar diffusion-weighted imaging (DWI) sequences of the liver at 3T. METHODS: 32 healthy volunteers (mean 27 ± 8 years; 27 M/5F) and 11 patients (mean age 58 ± 14 years; 8 M/3F) underwent liver MRI using a 3T system incorporating 2-channel parallel transmission for B1-shimming and reduced B1-inhomogeneity. Scans included free-breathing DWI sequences (b-value 0, 400, 800 s/mm(2)) acquired using both monopolar and bipolar techniques. Estimated signal-to-noise ratio (eSNR), apparent diffusion coefficient (ADC), and measures of subjective image quality on b-800 images, scored on a 1-5 scale by two independent radiologists, were compared between sequences. RESULTS: Monopolar sequence demonstrated significantly higher eSNR (volunteers: 12.7 ± 4.0 vs. 11.3 ± 3.5, patients: 11.4 ± 4.0 vs. 10.2 ± 3.3; p ≤ 0.013) compared with the bipolar sequence. Monopolar sequence also achieved significantly higher scores for reader 1 in volunteers and patients in terms of clarity of right lobe edge, clarity of intra-hepatic vessels, conspicuity of the left lobe, and overall diagnostic quality (p ≤ 0.031), as well as significantly higher scores for reader 2 in volunteers in terms of clarity of intra-hepatic vessels, conspicuity of the left lobe, and overall diagnostic quality (p ≤ 0.035). Respiratory motion artifact was not significantly different between sequences in patients or volunteers for either reader (p ≥ 0.191). Hepatic ADC was significantly lower using monopolar technique only in volunteers (1.28 ± 0.12 vs. 1.43 ± 0.15, p < 0.001). CONCLUSION: In comparison with past studies performed at 1.5T, when using a modern 3T system, we observed improved image quality of liver DWI using a monopolar, rather than a bipolar, acquisition scheme, largely attributed to higher eSNR.

Colocating Teleophthalmology Within Primary Care Settings to Improve Access to Diabetic Retinopathy Screening: Retrospective Descriptive Evaluation.

BACKGROUND: Annual retinal exams for patients with diabetes are critical as diabetic retinopathy is the number one cause of preventable blindness in working-age adults in the United States. Currently, most patients with diabetes in the United States receive a referral from their primary care provider to see an ophthalmologist for their annual dilated eye exam, which can be an added inconvenience and expense. As such, there is a need for alternative screening strategies within an outpatient network. The use of a telemedicine platform in a primary care setting serves as a novel strategy to increase diabetic retinopathy screening rates. In order to provide better access to diabetic retinopathy screening for our patients, cameras were placed in 3 primary care practices in October 2017 as part of an 8-month pilot program. Specialized cameras from Intelligent Retinal Imaging Systems (IRIS) were used to acquire images that could be interpreted remotely by ophthalmologists within the LifeBridge Health network for the diagnosis of diabetic retinopathy and the detection of other types of pathology (eg, macular edema). OBJECTIVE: The aim of this retrospective descriptive study was to examine whether a telemedicine platform can be used as a cost-effective way to increase diabetic retinopathy screening rates in the primary care setting. METHODS: Aggregate screening volume and diagnostic data were collected for each of the 3 practice locations for the 8-month pilot period (October 30, 2017, through June 30, 2018). Additionally, payor reimbursement data and equipment cost data were used to determine the payback period for each of the 3 practice locations. RESULTS: The pilot program proved the business case that implementation of the IRIS camera in 3 practice locations could result in enough patients being screened to pay for the cost of the camera within a maximum of 2 years. The 3 practices showed increased diabetic retinopathy screening rates of 1%, 6%, and 24%, respectively, and were all able to screen enough patients to be on track to pay off the cost of the camera within 2 years of implementation. Aggregate data from the pilot period showed that of the 1213 patients who were screened, approximately 17.1% (n=207) were diagnosed with diabetic retinopathy and an additional 17.7% (n=215) were suspected of having some other form of pathology. Of note, 10.1% (n=123) were also identified as being "IRIS saves," defined as having pathology identified that was severe enough to be considered an imminent threat to their vision. CONCLUSIONS: This retrospective descriptive study suggests that a telemedicine platform can be used to improve diabetic retinopathy screening rates in the primary care setting within a large health care system in a cost-effective way that allows for the cost of the equipment to be recouped through billing within a maximum of 2 years.

Host-pathogen genetic interactions underlie tuberculosis susceptibility in genetically diverse mice.

The outcome of an encounter with Mycobacterium tuberculosis (Mtb) depends on the pathogen's ability to adapt to the variable immune pressures exerted by the host. Understanding this interplay has proven difficult, largely because experimentally tractable animal models do not recapitulate the heterogeneity of tuberculosis disease. We leveraged the genetically diverse Collaborative Cross (CC) mouse panel in conjunction with a library of Mtb mutants to create a resource for associating bacterial genetic requirements with host genetics and immunity. We report that CC strains vary dramatically in their susceptibility to infection and produce qualitatively distinct immune states. Global analysis of Mtb transposon mutant fitness (TnSeq) across the CC panel revealed that many virulence pathways are only required in specific host microenvironments, identifying a large fraction of the pathogen's genome that has been maintained to ensure fitness in a diverse population. Both immunological and bacterial traits can be associated with genetic variants distributed across the mouse genome, making the CC a unique population for identifying specific host-pathogen genetic interactions that influence pathogenesis.

Mitochondrial respiration contributes to the interferon gamma response in antigen-presenting cells.

The immunological synapse allows antigen-presenting cells (APCs) to convey a wide array of functionally distinct signals to T cells, which ultimately shape the immune response. The relative effect of stimulatory and inhibitory signals is influenced by the activation state of the APC, which is determined by an interplay between signal transduction and metabolic pathways. While pathways downstream of toll-like receptors rely on glycolytic metabolism for the proper expression of inflammatory mediators, little is known about the metabolic dependencies of other critical signals such as interferon gamma (IFNγ). Using CRISPR-Cas9, we performed a series of genome-wide knockout screens in murine macrophages to identify the regulators of IFNγ-inducible T cell stimulatory or inhibitory proteins MHCII, CD40, and PD-L1. Our multiscreen approach enabled us to identify novel pathways that preferentially control functionally distinct proteins. Further integration of these screening data implicated complex I of the mitochondrial respiratory chain in the expression of all three markers, and by extension the IFNγ signaling pathway. We report that the IFNγ response requires mitochondrial respiration, and APCs are unable to activate T cells upon genetic or chemical inhibition of complex I. These findings suggest a dichotomous metabolic dependency between IFNγ and toll-like receptor signaling, implicating mitochondrial function as a fulcrum of innate immunity.

Sirtuin 3 Downregulation in Mycobacterium tuberculosis-Infected Macrophages Reprograms Mitochondrial Metabolism and Promotes Cell Death.

Mycobacterium tuberculosis induces metabolic reprogramming in macrophages like the Warburg effect. This enhances antimicrobial performance at the expense of increased inflammation, which may promote a pathogen-permissive host environment. Since the NAD+-dependent protein deacetylase Sirtuin 3 (SIRT3) is an important regulator of mitochondrial metabolism and cellular redox homeostasis, we hypothesized that SIRT3 modulation mediates M. tuberculosis-induced metabolic reprogramming. Infection of immortalized and primary murine macrophages resulted in reduced levels of SIRT3 mRNA and protein and perturbation of SIRT3-regulated enzymes in the tricarboxylic acid cycle, electron transport chain, and glycolytic pathway. These changes were associated with increased reactive oxygen species and reduced antioxidant scavenging, thereby triggering mitochondrial stress and macrophage cell death. Relevance to tuberculosis disease in vivo was indicated by greater bacterial burden and immune pathology in M. tuberculosis-infected Sirt3-/- mice. CD11b+ lung leukocytes isolated from infected Sirt3-/- mice showed decreased levels of enzymes involved in central mitochondrial metabolic pathways, along with increased reactive oxygen species. Bacterial burden was also greater in lungs of LysMcreSirt3L2/L2 mice, demonstrating the importance of macrophage-specific SIRT3 after infection. These results support the model of SIRT3 as a major upstream regulatory factor, leading to metabolic reprogramming in macrophages by M. tuberculosisIMPORTANCE Tuberculosis, the disease caused by the bacterium M. tuberculosis, remains one of the top 10 causes of death worldwide. Macrophages, the first cells to encounter M. tuberculosis and critical for defense against infection, are hijacked by M. tuberculosis as a protected growth niche. M. tuberculosis-infected macrophages undergo metabolic reprogramming where key mitochondrial pathways are modulated, but the mechanisms driving this metabolic shift is unknown. Our study demonstrates that M. tuberculosis downregulates Sirtuin 3 (SIRT3), an important regulator of mitochondrial metabolism, leading to SIRT3-dependent transcriptional downregulation of mitochondrial metabolic proteins, which is followed by oxidative stress and macrophage necrosis. This study identifies SIRT3 modulation as a key event in M. tuberculosis-induced metabolic reprograming in macrophages that defend against tuberculosis.

A genetic screen in macrophages identifies new regulators of IFNγ-inducible MHCII that contribute to T cell activation.

Cytokine-mediated activation of host immunity is central to the control of pathogens. Interferon-gamma (IFNγ) is a key cytokine in protective immunity that induces major histocompatibility complex class II molecules (MHCII) to amplify CD4+ T cell activation and effector function. Despite its central role, the dynamic regulation of IFNγ-induced MHCII is not well understood. Using a genome-wide CRISPR-Cas9 screen in murine macrophages, we identified genes that control MHCII surface expression. Mechanistic studies uncovered two parallel pathways of IFNγ-mediated MHCII control that require the multifunctional glycogen synthase kinase three beta (GSK3ß) or the mediator complex subunit 16 (MED16). Both pathways control distinct aspects of the IFNγ response and are necessary for IFNγ-mediated induction of the MHCII transactivator Ciita, MHCII expression, and CD4+ T cell activation. Our results define previously unappreciated regulation of MHCII expression that is required to control CD4+ T cell responses.

Functionally Overlapping Variants Control Tuberculosis Susceptibility in Collaborative Cross Mice.

Host genetics plays an important role in determining the outcome of Mycobacterium tuberculosis infection. We previously found that Collaborative Cross (CC) mouse strains differ in their susceptibility to M. tuberculosis and that the CC042/GeniUnc (CC042) strain suffered from a rapidly progressive disease and failed to produce the protective cytokine gamma interferon (IFN-γ) in the lung. Here, we used parallel genetic and immunological approaches to investigate the basis of CC042 mouse susceptibility. Using a population derived from a CC001/Unc (CC001) × CC042 intercross, we mapped four quantitative trait loci (QTL) underlying tuberculosis immunophenotypes (Tip1 to Tip4). These included QTL that were associated with bacterial burden, IFN-γ production following infection, and an IFN-γ-independent mechanism of bacterial control. Further immunological characterization revealed that CC042 animals recruited relatively few antigen-specific T cells to the lung and that these T cells failed to express the integrin alpha L (αL; i.e., CD11a), which contributes to T cell activation and migration. These defects could be explained by a CC042 private variant in the Itgal gene, which encodes CD11a and is found within the Tip2 interval. This 15-bp deletion leads to aberrant mRNA splicing and is predicted to result in a truncated protein product. The ItgalCC042 genotype was associated with all measured disease traits, indicating that this variant is a major determinant of susceptibility in CC042 mice. The combined effect of functionally distinct Tip variants likely explains the profound susceptibility of CC042 mice and highlights the multigenic nature of tuberculosis control in the Collaborative Cross.IMPORTANCE The variable outcome of Mycobacterium tuberculosis infection observed in natural populations is difficult to model in genetically homogeneous small-animal models. The newly developed Collaborative Cross (CC) represents a reproducible panel of genetically diverse mice that display a broad range of phenotypic responses to infection. We explored the genetic basis of this variation, focusing on a CC line that is highly susceptible to M. tuberculosis infection. This study identified multiple quantitative trait loci associated with bacterial control and cytokine production, including one that is caused by a novel loss-of-function mutation in the Itgal gene, which is necessary for T cell recruitment to the infected lung. These studies verify the multigenic control of mycobacterial disease in the CC panel, identify genetic loci controlling diverse aspects of pathogenesis, and highlight the utility of the CC resource.

Strategies for Avoiding Recommendations for Additional Imaging Through a Comprehensive Comparison With Prior Studies.

PURPOSE: To determine the frequency and characteristics of recommendations for additional imaging and/or intervention (RAIs) in abdominal CT and MRI interpretations that might be avoided through comprehensive comparison with all available prior examinations. METHODS: A total of 1,006 RAIs in abdominopelvic CT and MRI reports were retrospectively evaluated. Reports and images from each patient's prior imaging examinations, including those of all relevant body parts and modalities, were reviewed to determine if the RAI could have been avoided based on prior imaging. Frequency and characteristics of such "avoidable" RAIs were evaluated. RESULTS: A total of 41 of 1,006 (4.1%) RAIs were avoidable. The key prior examination that established the RAI as avoidable was a different modality in 53.7% (22 of 41) and on a different body area in 41.5% (17 of 41) of cases, including chest imaging in 31.7% (13 of 41). A total of 83.3% (5 of 6) adrenal RAIs, and 80.0% (4 of 5) liver RAIs were avoidable based on prior chest imaging. The key finding was present on the prior images but was not described in the report in 46.3% (19 of 41) of cases. A greater number of prior examinations were available in cases of avoidable RAIs (mean, 12.2 ± 16.7) than in those of nonavoidable RAIs (mean, 5.7 ± 9.5) (P < .001). CONCLUSIONS: A small fraction of RAIs can be avoided by performing a thorough evaluation of all prior imaging examinations, including different modalities and body parts. Nearly half of the key prior examinations did not report the finding, highlighting the importance of directly reviewing relevant images, particularly chest imaging for evaluation of indeterminate upper-abdominal findings. Configuration of PACS for optimized selection and display of relevant examination reports and images may facilitate such comparisons.