Contribution of classical complement activation and IgM to the control of Rickettsia infection.

Pathogenic Rickettsia are obligate intracellular bacteria and the etiologic agents of many life-threatening infectious diseases. Due to the serious nature of these infections, it is imperative to both identify the responsive immune sensory pathways and understand the associated immune mechanisms that restrict Rickettsia proliferation. Previous studies have demonstrated that the mammalian complement system is both activated during Rickettsia infection and contributes to the immune response to infection. To further define this component of the mammalian anti-Rickettsia immune response, we sought to identify the mechanism(s) of complement activation during Rickettsia infection. We have employed a series of in vitro and in vivo models of infection to investigate the role of the classical complement activation pathway during Rickettsia infection. Depletion or elimination of complement activity demonstrates that both C1q and pre-existing IgM contribute to complement activation; thus implicating the classical complement system in Rickettsia-mediated complement activation. Elimination of the classical complement pathway from mice increases susceptibility to R. australis infection with both increased bacterial loads in multiple tissues and decreased immune activation markers. This study highlights the role of the classical complement pathway in immunity against Rickettsia and implicates resident Rickettsia-responsive IgM in the response to infection.

Identification of Zika Virus Inhibitors Using Homology Modeling and Similarity-Based Screening to Target Glycoprotein E.

The World Health Organization has designated Zika virus (ZIKV) as a dangerous, mosquito-borne pathogen that can cause severe developmental defects. The primary goal of this work was identification of small molecules as potential ZIKV inhibitors that target the viral envelope glycoprotein (ZIKV E) involved in membrane fusion and viral entry. A homology model of ZIKV E containing the small molecule ß-octyl glucoside (BOG) was constructed, on the basis of an analogous X-ray structure from dengue virus, and >4 million commercially available compounds were computationally screened using the program DOCK6. A key feature of the screen involved the use of similarity-based scoring to identify inhibitor candidates that make similar interaction energy patterns (molecular footprints) as the BOG reference. Fifty-three prioritized compounds underwent experimental testing using cytotoxicity, cell viability, and tissue culture infectious dose 50% (TCID50) assays. Encouragingly, relative to a known control (NITD008), six compounds were active in both the cell viability assay and the TCID50 infectivity assay, and they showed activity in a third caspase activity assay. In particular, compounds 8 and 15 (tested at 25 µM) and compound 43 (tested at 10 µM) appeared to provide significant protection to infected cells, indicative of anti-ZIKV activity. Overall, the study highlights how similarity-based scoring can be leveraged to computationally identify potential ZIKV E inhibitors that mimic a known reference (in this case BOG), and the experimentally verified hits provide a strong starting point for further refinement and optimization efforts.

Are movement-based classification systems more effective than therapeutic exercise or guideline based care in improving outcomes for patients with chronic low back pain? A systematic review.

Objectives: The purpose of this systematic review was to determine if movement-based classification (MBC) systems are more effective than therapeutic exercise or guideline-based care (GBC) in improving outcomes in patients with low back pain (LBP) based upon randomized clinical trials (RCT) with moderate to high methodological quality and low to moderate risk of bias. Methods: The search strategy was developed by a librarian experienced in systematic review methodology and peer reviewed by a second research librarian. The following databases were searched from their inception to May 17, 2018: PubMed, Embase, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, and the WHO International Clinical Trials Registry Platform. The identified RCTs with a PEDro score of ≥6 were screened and assessed for risk of bias by two blinded individual reviewers using Covidence. Results: Seven studies were identified that had moderate-to-high methodological quality. One of the studies was identified as having a high risk of bias. Of the six studies that remained, only one study reported finding a statistically significant difference at the immediate follow-up that was not clinically significant. There was no significance at 6 and 12 months. Discussion: There is a paucity of moderate to high methodological quality RCTs with similar methodology that compare MBC to standard of care treatments for patients with LBP. Studies with moderate to high methodological quality that have a low risk of bias do not support MBCs as being superior to general exercise or GBC in the treatment of nonradicular LBP. Level of Evidence: 1a.

Immunity against the Obligate Intracellular Bacterial Pathogen Rickettsia australis Requires a Functional Complement System.

The complement system has a well-defined role in deterring blood-borne infections. However, complement is not entirely efficacious, as several bacterial pathogens, including some obligate intracellular pathogens, have evolved mechanisms for resistance. It is presumed that obligate intracellular bacteria evade complement attack by residing within a host cell; however, recent studies have challenged this presumption. Here, we demonstrate that the complement system is activated during infection with the obligate intracellular bacterium Rickettsia australis and that genetic ablation of complement increases susceptibility to infection. Interaction of Rickettsia australis with serum-borne complement leads to activation of the complement cascade, producing three effector mechanisms that could negatively influence R. australis. The C9-dependent membrane attack complex can lead to deposition of a bacteriolytic membrane pore on the bacteria, but this system does not contribute to control of rickettsial infection. Similarly, complement receptor (CR1/2)-dependent opsonophagocytosis may lead to engulfment and killing of the bacteria, but this system is also dispensable for immunity. Nevertheless, intact complement is essential for naturally acquired and antibody-mediated immunity to Rickettsia infection. Comparison of infection in mice lacking the central complement protein C3 with infection in their wild-type counterparts demonstrated decreases in gamma interferon (IFN-γ) production, IgG secretion, and spleen hyperplasia in animals lacking complement. The correlation between loss of secondary immune functions and loss of complement indicates that the proinflammatory signaling components of the complement system, and not membrane attack complex or opsonophagocytosis, contribute to the immune response to this pathogen.

Nonselective Persistence of a Rickettsia conorii Extrachromosomal Plasmid during Mammalian Infection.

Scientific analysis of the genus Rickettsia is undergoing a rapid period of change with the emergence of viable genetic tools. The development of these tools for the mutagenesis of pathogenic bacteria will permit forward genetic analysis of Rickettsia pathogenesis. Despite these advances, uncertainty still remains regarding the use of plasmids to study these bacteria in in vivo mammalian models of infection, namely, the potential for virulence changes associated with the presence of extrachromosomal DNA and nonselective persistence of plasmids in mammalian models of infection. Here, we describe the transformation of Rickettsia conorii Malish 7 with the plasmid pRam18dRGA[AmTrCh]. Transformed R. conorii stably maintains this plasmid in infected cell cultures, expresses the encoded fluorescent proteins, and exhibits growth kinetics in cell culture similar to those of nontransformed R. conorii. Using a well-established murine model of fatal Mediterranean spotted fever, we demonstrate that R. conorii(pRam18dRGA[AmTrCh]) elicits the same fatal outcomes in animals as its untransformed counterpart and, importantly, maintains the plasmid throughout infection in the absence of selective antibiotic pressure. Interestingly, plasmid-transformed R. conorii was readily observed both in endothelial cells and within circulating leukocytes. Together, our data demonstrate that the presence of an extrachromosomal DNA element in a pathogenic rickettsial species does not affect either in vitro proliferation or in vivo infectivity in models of disease and that plasmids such as pRam18dRGA[AmTrCh] are valuable tools for the further genetic manipulation of pathogenic rickettsiae.

RC1339/APRc from Rickettsia conorii is a novel aspartic protease with properties of retropepsin-like enzymes.

Members of the species Rickettsia are obligate intracellular, gram-negative, arthropod-borne pathogens of humans and other mammals. The life-threatening character of diseases caused by many Rickettsia species and the lack of reliable protective vaccine against rickettsioses strengthens the importance of identifying new protein factors for the potential development of innovative therapeutic tools. Herein, we report the identification and characterization of a novel membrane-embedded retropepsin-like homologue, highly conserved in 55 Rickettsia genomes. Using R. conorii gene homologue RC1339 as our working model, we demonstrate that, despite the low overall sequence similarity to retropepsins, the gene product of rc1339 APRc (for Aspartic Protease from Rickettsia conorii) is an active enzyme with features highly reminiscent of this family of aspartic proteases, such as autolytic activity impaired by mutation of the catalytic aspartate, accumulation in the dimeric form, optimal activity at pH 6, and inhibition by specific HIV-1 protease inhibitors. Moreover, specificity preferences determined by a high-throughput profiling approach confirmed common preferences between this novel rickettsial enzyme and other aspartic proteases, both retropepsins and pepsin-like. This is the first report on a retropepsin-like protease in gram-negative intracellular bacteria such as Rickettsia, contributing to the analysis of the evolutionary relationships between the two types of aspartic proteases. Additionally, we have also shown that APRc is transcribed and translated in R. conorii and R. rickettsii and is integrated into the outer membrane of both species. Finally, we demonstrated that APRc is sufficient to catalyze the in vitro processing of two conserved high molecular weight autotransporter adhesin/invasion proteins, Sca5/OmpB and Sca0/OmpA, thereby suggesting the participation of this enzyme in a relevant proteolytic pathway in rickettsial life-cycle. As a novel bona fide member of the retropepsin family of aspartic proteases, APRc emerges as an intriguing target for therapeutic intervention against fatal rickettsioses.

A systematic review of orthopaedic manual therapy randomized clinical trials quality.

Study Design: Systematic review and meta-analysis. Objectives: To conduct a systematic review and meta-analysis of randomized clinical trials (RCTs) in the orthopaedic manual therapy (OMT) literature from January 2010 to June 2014 in order to determine if the CONSORT checklist and Cochrane Risk of Bias (RoB) assessment tools: (1) are reliable; (2) have improved the reporting and decreased the risk of bias in RCTs in the OMT literature; (3) differ based on journal impact factor (JIF); and (4) scores are associated with each other. Background: The CONSORT statement is used to improve the accuracy of reporting within RCTs. The Cochrane RoB tool was designed to assess the risk of bias within RCTs. To date, no evaluation of the quality of reporting and risk of bias in OMT RCTs has been published. Methods: Relevant RCTs were identified by a literature review from January 2010 to June 2014. The identified RCTs were assessed by two individual reviewers utilizing the 2010 CONSORT checklist and the RoB tool. Agreement and a mean composite total score for each tool were attained in order to determine if the CONSORT and RoB tools were reliable and varied by year and impact factor. Results: A total of 72 RCTs in the OMT literature were identified. A number of categories within the CONSORT and RoB tools demonstrated prevalence-adjusted bias-adjusted kappa (PABAK) scores of less than 0.20 and from 0.20 to 0.40. The total CONSORT and RoB scores were correlated to each other (r = 0.73; 95% CI 0.60 to 0.82; p < 0.0001). There were no statistically significant differences in CONSORT or RoB scores by year. There was a statistically significant correlation between both CONSORT scores and JIF (r = 0.64, 95% CI 0.47 to 0.76; p < 0.0001), and between RoB scores and JIF (r = 0.42, 95% confidence interval 0.21-0.60; p < 0.001). There was not a statistically significant correlation between JIF and year of publication. Conclusion: Our findings suggest that the CONSORT and RoB have a number of items that are unclear and unreliable, and that the quality of reporting in OMT trials has not improved in recent years. Improvements in reporting are necessary to allow advances in OMT practice. Level of Evidence: 1A.

Manual unloading of the lumbar spine: can it identify immediate responders to mechanical traction in a low back pain population? A study of reliability and criterion referenced predictive validity.

BACKGROUND: To date, no research has examined the reliability or predictive validity of manual unloading tests of the lumbar spine to identify potential responders to lumbar mechanical traction. PURPOSE: To determine: (1) the intra and inter-rater reliability of a manual unloading test of the lumbar spine and (2) the criterion referenced predictive validity for the manual unloading test. METHODS: Ten volunteers with low back pain (LBP) underwent a manual unloading test to establish reliability. In a separate procedure, 30 consecutive patients with LBP (age 50·86±11·51) were assessed for pain in their most provocative standing position (visual analog scale (VAS) 49·53±25·52 mm). Patients were assessed with a manual unloading test in their most provocative position followed by a single application of intermittent mechanical traction. Post traction, pain in the provocative position was reassessed and utilized as the outcome criterion. RESULTS: The test of unloading demonstrated substantial intra and inter-rater reliability K = 1·00, P = 0·002, K = 0·737, P = 0·001, respectively. There were statistically significant within group differences for pain response following traction for patients with a positive manual unloading test (P<0·001), while patients with a negative manual unloading test did not demonstrate a statistically significant change (P>0·05). There were significant between group differences for proportion of responders to traction based on manual unloading response (P = 0·031), and manual unloading response demonstrated a moderate to strong relationship with traction response Phi = 0·443, P = 0·015. DISCUSSION AND CONCLUSION: The manual unloading test appears to be a reliable test and has a moderate to strong correlation with pain relief that exceeds minimal clinically important difference (MCID) following traction supporting the validity of this test.

Pathogenic Rickettsia species acquire vitronectin from human serum to promote resistance to complement-mediated killing.

Bacteria of the genus Rickettsia are transmitted from arthropod vectors and primarily infect cells of the mammalian endothelial system. Throughout this infectious cycle, the bacteria are exposed to the deleterious effects of serum complement. Using Rickettsia conorii, the etiologic agent of Mediterranean spotted fever (MSF), as a model rickettsial species, we have previously demonstrated that this class of pathogen interacts with human factor H to mediate partial survival in human serum. Herein, we demonstrate that R. conorii also interacts with the terminal complement complex inhibitor vitronectin (Vn). We further demonstrate that an evolutionarily conserved rickettsial antigen, Adr1/RC1281, interacts with human vitronectin and is sufficient to mediate resistance to serum killing when expressed at the outer-membrane of serum sensitive Escherichia coli. Adr1 is an integral outer-membrane protein whose structure is predicted to contain eight membrane-embedded ß-strands and four 'loop' regions that are exposed to extracellular milieu. Site-directed mutagenesis of Adr1 revealed that at least two predicted 'loop' regions are required to mediate resistance to complement-mediatedkilling and vitronectin acquisition. These results demonstrate that rickettsial species have evolved multiple mechanisms to evade complement deposition and that evasion of killing in serum is an evolutionarily conserved virulence attribute for this genus of obligate intracellular pathogens.

Post-dural puncture headaches following spinal drain placement during thoracoabdominal aortic aneurysm repair: incidence, associated risk factors, and treatment.

PURPOSE: Spinal drains are used as a neuroprotective measure during thoracoabdominal aortic aneurysm (TAA) repair. Unfortunately, these drains can cause post-dural puncture headaches (PDPH). While PDPH following spinal anesthesia have been thoroughly evaluated, limited data exists about the incidence and risk factors for PDPH following spinal drains. Additionally, the efficacy of treatment with conservative therapies and epidural blood patches (EBP) for PDPH secondary to spinal drains has not been well documented. METHODS: Data on 235 patients receiving spinal drains for scheduled TAA repair and surviving to discharge between January, 2005 and July, 2012 at the University of Wisconsin Hospitals and Clinics were retrospectively reviewed. The following data were extracted from the patient medical record: patient demographics, pre-existing medical conditions, spinal drain details, PDPH presentation, PDPH treatment methods, and success of treatments used. This data was then analyzed for statistical significance. RESULTS: Of 235 patients, 43 (18.3 %) developed PDPH. Younger age (p < 0.001) and history of preoperative headache (p ≤ 0.001) were found to increase the risk of PDPH. Use of EBP, either as the primary treatment, or following failed conservative therapy, was found to be a more effective treatment for PDPH than conservative therapies alone (p = 0.017). CONCLUSIONS: Spinal drain placement carries a risk of PDPH, as supported by an 18.3 % PDPH incidence in this study. Younger patients and/or patients with a history of chronic headache are at elevated risk for PDPH. Treatment using EBP, either as primary therapy or following unsuccessful conservative therapies, is a significantly more effective treatment than conservative therapies alone.