A Comprehensive Approach to Identification of Surface-Exposed, Outer Membrane-Spanning Proteins of Leptospira interrogans

Leptospirosis is a zoonosis with worldwide distribution caused by pathogenic spirochetes belonging to the genus Leptospira. The leptospiral life cycle involves transmission via fresh water and colonization of the renal tubules of their reservoir hosts or infection of accidental hosts, including humans. Bacterial outer membrane proteins (OMPs), particularly those with surface-exposed regions, play crucial roles in virulence mechanisms of pathogens and the adaptation to various environmental conditions, including those of the mammalian host. Little is known about the surface-exposed OMPs in Leptospira, particularly those with outer membrane-spanning domains. Herein, we describe a comprehensive strategy for identification and characterization of leptospiral transmembrane OMPs. The genomic sequence of L. interrogans serovar Copenhageni strain Fiocruz L1–130 allowed us to employ the β-barrel prediction programs, PRED-TMBB and TMBETA-NET, to identify potential transmembrane OMPs. Several complementary methods were used to characterize four novel OMPs, designated OmpL36, OmpL37, OmpL47 and OmpL54. In addition to surface immunofluorescence and surface biotinylation, we describe surface proteolysis of intact leptospires as an improved method for determining the surface exposure of leptospiral proteins. Membrane integration was confirmed using techniques for removal of peripheral membrane proteins. We also demonstrate deficiencies in the Triton X-114 fractionation method for assessing the outer membrane localization of transmembrane OMPs. Our results establish a broadly applicable strategy for the elucidation of novel surface-exposed outer membrane-spanning proteins of Leptospira, an essential step in the discovery of potential virulence factors, diagnostic antigens and vaccine candidates

The OmpL37 Surface-Exposed Protein Is Expressed by Pathogenic Leptospira during Infection and Binds Skin and Vascular Elastin

Pathogenic Leptospira spp. shed in the urine of reservoir hosts into freshwater can be transmitted to a susceptible host through skin abrasions or mucous membranes causing leptospirosis. The infection process involves the ability of leptospires to adhere to cell surface and extracellular matrix components, a crucial step for dissemination and colonization of host tissues. Therefore, the elucidation of novel mediators of host-pathogen interaction is important in the discovery of virulence factors involved in the pathogenesis of leptospirosis. In this study, we assess the functional roles of transmembrane outer membrane proteins OmpL36 (LIC13166), OmpL37 (LIC12263), and OmpL47 (LIC13050), which we recently identified on the leptospiral surface. We determine the capacity of these proteins to bind to host tissue components by enzyme-linked immunosorbent assay. OmpL37 binds elastin preferentially, exhibiting dose-dependent, saturating binding to human skin (Kd, 104±19 nM) and aortic elastin (Kd, 152±27 nM). It also binds fibrinogen (Kd, 244±15 nM), fibrinogen fragment D (Kd, 132±30 nM), plasma fibronectin (Kd, 359±68 nM), and murine laminin (Kd, 410±81 nM). The binding to human skin elastin by both recombinant OmpL37 and live Leptospira interrogans is specifically enhanced by rabbit antiserum for OmpL37, suggesting the involvement of OmpL37 in leptospiral binding to elastin and also the possibility that host-generated antibodies may promote rather than inhibit the adherence of leptospires to elastin-rich tissues. Further, we demonstrate that OmpL37 is recognized by acute and convalescent leptospirosis patient sera and also by Leptospira-infected hamster sera. Finally, OmpL37 protein is detected in pathogenic Leptospira serovars and not in saprophytic Leptospira. Thus, OmpL37 is a novel elastin-binding protein of pathogenic Leptospira that may be promoting attachment of Leptospira to host tissues

Päihteitä käyttävä nuori

Vertaisarvioitu. Näin tutkin.Päihteiden käyttö voi vaikuttaa nuoren psyykkisen ja fyysisen terveyden lisäksi tulevaisuudensuunnitelmiin, kuten ajokortin saamiseen, varusmiespalveluun tai opiskelupaikkaan. Nuoren kohtaamisessa ja päihteiden käytön selvittelyssä tärkeää on neutraali, kiinnostunut ja holhoamaton asenne. Anamneesi on käytön arvioinnin sekä päihdediagnostiikan kulmakivi. Haastattelussa ja tilanteen kartoituksessa kannattaa käyttää tukena erilaisia strukturoituja päihdekyselyjä. Laboratoriotutkimuksilla voi täydentää anamneesin tietoja. Päihteiden käytön lisäksi selvitetään muut nuoren elämän osa-alueet, päihteiltä suojaavat tekijät, riskit ja voimavarat sekä muu psyykkinen oireisto. Päihteiden käyttöä tutkittaessa myös motivoidaan nuorta käytön, seurausten ja syiden ajankohtaiseen tarkasteluun ja tarvittaessa hoitoon. Hoitojärjestelmän kehittämisessä on panostettava yhtenäisiin hoitokäytäntöihin sekä nuorten motivoimiseen ja sitouttamiseen hoitoon

Cervical Myelopathy Associated with Deep Neck Muscle Rhabdomyolysis after Polysubstance Abuse: A Case Report

When used appropriately, buprenorphine and oxycodone are safe drugs. They are, however, widely abused in combination with other drugs. Here we describe a case series of 8 patients with cervical myelopathy and rhabdomyolysis of the adjacent deep neck muscles after using an opioid in combination with other drugs. All patients were young males who had a previous history of polysubstance abuse. Six of the patients had used buprenorphine in combination with pregabalin and/or benzodiazepines, and one patient had used oxycodone with pregabalin and/or benzodiazepines. One patient used buprenorphine with amphetamine. After taking the drugs, they all reported feeling drowsy and then falling asleep. On waking, they noticed weakness in their extremities. However, only one patient woke with his head in a flexed position. A varying degree of tetraparesis was observed. Cerebrospinal fluid analysis revealed elevated protein levels and white blood cell count. Blood creatine kinase was elevated in 7 patients. Spinal cord MRI showed a hyperintense spinal lesion at the level of C1 – Th3 vertebrae associated with rhabdomyolysis in the adjacent, paravertebral deep neck muscles. We suggest that polysubstance abuse, especially the combination of an opioid with another drug with GABA-agonistic properties, caused a compartment syndrome of the deep paravertebral muscles without excessive head flexion. This subsequently led to compression of the external vascular structures, resulting in venous congestive myelopathy. </p

Cervical Myelopathy Associated with Deep Neck Muscle Rhabdomyolysis after Polysubstance Abuse : A Case Report

When used appropriately, buprenorphine and oxycodone are safe drugs. They are, however, widely abused in combination with other drugs. Here we describe a case series of 8 patients with cervical myelopathy and rhabdomyolysis of the adjacent deep neck muscles after using an opioid in combination with other drugs. All patients were young males who had a previous history of polysubstance abuse. Six of the patients had used buprenorphine in combination with pregabalin and/or benzodiazepines, and one patient had used oxycodone with pregabalin and/or benzodiazepines. One patient used buprenorphine with amphetamine. After taking the drugs, they all reported feeling drowsy and then falling asleep. On waking, they noticed weakness in their extremities. However, only one patient woke with his head in a flexed position. A varying degree of tetraparesis was observed. Cerebrospinal fluid analysis revealed elevated protein levels and white blood cell count. Blood creatine kinase was elevated in 7 patients. Spinal cord MRI showed a hyperintense spinal lesion at the level of C1-Th3 vertebrae associated with rhabdomyolysis in the adjacent, paravertebral deep neck muscles. We suggest that polysubstance abuse, especially the combination of an opioid with another drug with GABA-agonistic properties, caused a compartment syndrome of the deep paravertebral muscles without excessive head flexion. This subsequently led to compression of the external vascular structures, resulting in venous congestive myelopathy.publishedVersionPeer reviewe

Leptospira interrogans Endostatin-Like Outer Membrane Proteins Bind Host Fibronectin, Laminin and Regulators of Complement

The pathogenic spirochete Leptospira interrogans disseminates throughout its hosts via the bloodstream, then invades and colonizes a variety of host tissues. Infectious leptospires are resistant to killing by their hosts' alternative pathway of complement-mediated killing, and interact with various host extracellular matrix (ECM) components. The LenA outer surface protein (formerly called LfhA and Lsa24) was previously shown to bind the host ECM component laminin and the complement regulators factor H and factor H-related protein-1. We now demonstrate that infectious L. interrogans contain five additional paralogs of lenA, which we designated lenB, lenC, lenD, lenE and lenF. All six genes encode domains predicted to bear structural and functional similarities with mammalian endostatins. Sequence analyses of genes from seven infectious L. interrogans serovars indicated development of sequence diversity through recombination and intragenic duplication. LenB was found to bind human factor H, and all of the newly-described Len proteins bound laminin. In addition, LenB, LenC, LenD, LenE and LenF all exhibited affinities for fibronectin, a distinct host extracellular matrix protein. These characteristics suggest that Len proteins together facilitate invasion and colonization of host tissues, and protect against host immune responses during mammalian infection

A LigA Three-Domain Region Protects Hamsters from Lethal Infection by Leptospira interrogans

The leptospiral LigA protein consists of 13 bacterial immunoglobulin-like (Big) domains and is the only purified recombinant subunit vaccine that has been demonstrated to protect against lethal challenge by a clinical isolate of Leptospira interrogans in the hamster model of leptospirosis. We determined the minimum number and location of LigA domains required for immunoprotection. Immunization with domains 11 and 12 was found to be required but insufficient for protection. Inclusion of a third domain, either 10 or 13, was required for 100% survival after intraperitoneal challenge with Leptospira interrogans serovar Copenhageni strain Fiocruz L1-130. As in previous studies, survivors had renal colonization; here, we quantitated the leptospiral burden by qPCR to be 1.2×103 to 8×105 copies of leptospiral DNA per microgram of kidney DNA. Although renal histopathology in survivors revealed tubulointerstitial changes indicating an inflammatory response to the infection, blood chemistry analysis indicated that renal function was normal. These studies define the Big domains of LigA that account for its vaccine efficacy and highlight the need for additional strategies to achieve sterilizing immunity to protect the mammalian host from leptospiral infection and its consequences

An RND-Type Efflux System in Borrelia burgdorferi Is Involved in Virulence and Resistance to Antimicrobial Compounds

Borrelia burgdorferi is remarkable for its ability to thrive in widely different environments due to its ability to infect various organisms. In comparison to enteric Gram-negative bacteria, these spirochetes have only a few transmembrane proteins some of which are thought to play a role in solute and nutrient uptake and excretion of toxic substances. Here, we have identified an outer membrane protein, BesC, which is part of a putative export system comprising the components BesA, BesB and BesC. We show that BesC, a TolC homolog, forms channels in planar lipid bilayers and is involved in antibiotic resistance. A besC knockout was unable to establish infection in mice, signifying the importance of this outer membrane channel in the mammalian host. The biophysical properties of BesC could be explained by a model based on the channel-tunnel structure. We have also generated a structural model of the efflux apparatus showing the putative spatial orientation of BesC with respect to the AcrAB homologs BesAB. We believe that our findings will be helpful in unraveling the pathogenic mechanisms of borreliae as well as in developing novel therapeutic agents aiming to block the function of this secretion apparatus