A retrospective analysis of antineutrophil cytoplasmic antibody-associated vasculitis aiming for an equation prediction end-stage renal disease.

We provided a predictable method that measures the risk of progression to end-stage renal disease (ESRD) in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) by using a few routine serum markers of kidney functions at diagnosis. In a retrospective cohort study, the medical records of 254 AAV patients were reviewed. We derived a novel equation for the prediction of the progression to ESRD using variables with a P-value < 0.1 in the multivariable Cox hazard model analysis. We assigned a weight to each variable according to the slopes like a coefficient of a linear equation. The median age of the AAV patients was 59 years and 42 AAV patients progressed to ESRD. In the multivariable Cox analysis using variables with significance in the univariable analysis, MPO-ANCA (or P-ANCA) positivity, blood urea nitrogen, serum creatinine, and serum albumin tended to be associated with the progression to ESRD (P-value < 0.1). We develop an Equation for predicting ESRD in AAV (EPEA) using those variables with the slope of each one. When the cut-off of EPEA was set as -0.094, AAV patients with EPEA ≥ -0.094 had a significantly higher risk of progression to ESRD than those with EPEA < -0.094 (RR, 39.622). AAV patients with EPEA ≥ -0.094 exhibited a significantly lower ESRD-free survival rate than those with EPEA < -0.094. We provided a method to obtain EPEA and demonstrated its predictive potential for ESRD in immunosuppressive drug-naïve AAV patients. Key points • A novel equation for the prediction of the progression to ESRD was developed using variables with a P-value < 0.1 in the multivariable Cox hazard model analysis. A weight was assigned to each variable according to the slopes like a coefficient of a linear equation. • An optimal cut-off of EPEA for progression to ESRD was obtained using the receiver operator characteristic (ROC) curve analysis. • AAV patients with EPEA more than the cut-off had a significantly higher risk of progression to ESRD than those without (RR, 39.622). • AAV patients with EPEA more than the cut-off exhibited a significantly lower ESRD-free survival rate than those without.

Antineutrophil Cytoplasmic Antibody Positivity Is Associated with Vascular Involvement in Behçet's Disease.

PURPOSE: We investigated whether antineutrophil cytoplasmic antibody (ANCA) positivity is associated with vascular manifestations at diagnosis of Behçet's disease (BD) and poor outcomes during follow-up. MATERIALS AND METHODS: We retrospectively reviewed the medical records of 1060 patients with BD. Among them, 808 patients could be diagnosed with BD based on the revised version of the International Criteria for Behçet's Disease (ICBD) in 2014 (2014 ICBD criteria) and 588 patients could be diagnosed with BD based on the International Study Group (ISG) criteria proposed in 1990 (1990 ISG criteria). We examined the sites and patterns of vascular involvement in the BD patients at diagnosis and evaluated adverse outcomes during follow up, such as all-cause mortality, acute coronary syndrome, and deep vein thrombosis. RESULTS: Among the 808 patients with BD based on the 2014 ICBD criteria, the rate of ANCA positivity at diagnosis was 2.2%. ANCA-positive BD patients exhibited a higher frequency of overall vascular manifestations (22.2% vs. 6.1%) and higher frequencies of vascular involvement in the upper extremities and visceral arteries than ANCA-negative BD patients (5.6% vs. 0.1% and 5.6% vs. 0.1%). Among the 588 BD patients based on the 1990 ISG criteria, similarly, ANCA-positive BD patients exhibited a higher frequency of vascular manifestations than ANCA-negative BD patients. ANCA positivity, however, did not seem to be associated with poor outcomes in BD patients during follow up. CONCLUSION: ANCA positivity in BD patients was found to be associated with cross-sectional vascular involvement in the upper extremities and visceral arteries at diagnosis but was not predictive of poor outcomes during follow-up.

Rituximab Biosimilar Prevents Poor Outcomes of Microscopic Polyangiitis and Granulomatosis with Polyangiitis as Effectively as Rituximab Originator.

PURPOSE: There has been no extensive study to compare the efficacy between rituximab originator (Mabthera®) and its biosimilar (Truxima®) for microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA). Here, we investigated the clinical effects of rituximab on poor outcomes of MPA and GPA in Korean patients, and compared those between Mabthera® and Truxima®. MATERIALS AND METHODS: We retrospectively reviewed the medical records of a total of 139 patients, including 97 MPA patients and 42 GPA patients. At diagnosis, antineutrophil cytoplasmic antibody positivity and comorbidities were assessed. During follow-up, all-cause mortality, relapse, end-stage renal disease, cerebrovascular accident and acute coronary syndrome were evaluated as poor outcomes. In this study, rituximab was used as either Mabthera® or Truxima®. RESULTS: The median age at diagnosis was 60.1 years and 46 patients were men (97 MPA and 42 GPA patients). Among poor outcomes, patients receiving rituximab exhibited a significantly lower cumulative relapse-free survival rate compared to those not receiving rituximab (p=0.002). Nevertheless, rituximab use did not make any difference in other poor outcomes of MPA and GPA except for relapse, which might be a rebuttal to the fact that rituximab use after relapse eventually led to better prognosis. There were no significant differences in variables at diagnosis and during follow-up between patients receiving Mabthera® and those receiving Truxima®. Patients receiving Truxima® exhibited a similar pattern of the cumulative survival rates of each poor outcome to those receiving Mabthera®. CONCLUSION: Truxima® prevents poor outcomes of MPA and GPA as effectively as does Mabthera®.

Multivariable index for assessing the activity and predicting all-cause mortality in antineutrophil cytoplasmic antibody-associated vasculitis.

BACKGROUND: So far, there has been no tool to estimate activity at diagnosis and predict all-cause mortality in patients with ANCA-associated vasculitis (AAV). Hence, we determined the initial predictors of them in patients with AAV. METHODS: We retrospectively reviewed the medical records of 182 patients with AAV. Severe AAV was defined as Birmingham Vasculitis Activity Score (BVAS) ≥ 16. The cutoffs were extrapolated by the receiver operator characteristic (ROC) curve. The odds ratio (OR) and the relative risk (RR) were assessed using the multivariable logistic regression analysis and the chi-square test, respectively. RESULTS: In the comparison analysis, patients with severe AAV exhibited the higher neutrophil and platelet counts, creatinine, erythrocyte sedimentation rate and C-reactive protein, and the lower lymphocyte count, hemoglobin, and serum albumin than those without. In the multivariable logistic regression analysis, creatinine ≥ 0.9 mg/dL (OR 2.264), lymphocyte count ≤ 1430.0/mm3 (OR 1.856), and hemoglobin ≤ 10.8 g/dL (OR 2.085) were associated with severe AAV. We developed a new equation of a multivariable index for AAV (MVIA) = 0.6 × (Lymphocyte count ≤ 1430.0/mm3 ) + 0.7 × (Hemoglobin ≤ 10.8 g/dL) + 0.8 × (Creatinine ≥ 0.9 mg/dL). The optimal cutoff of MVIA for severe AAV was set as 1.35. Severe AAV was identified more frequently in patients with MVIA at diagnosis ≥1.35 than those without (RR 4.432). Patients with MVIA at diagnosis ≥1.35 exhibited the lower cumulative patient survival rate than those without. CONCLUSION: Multivariable index for AAV could assess the cross-sectional activity and predict all-cause mortality in patients with AAV.

Can antineutrophil cytoplasmic antibody positivity at diagnosis predict the poor outcomes of Sjögren's syndrome?

We investigated the clinical implication of ANCA positivity at diagnosis on the poor outcomes in patients with Sjögren's syndrome. The medical records of 606 Korean patients with Sjögren's syndrome were retrospectively reviewed. The results of perinuclear (P)-ANCA, myeloperoxidase (MPO)-ANCA, cytoplasmic (C)-ANCA, and proteinase 3 (PR3)-ANCA were collected and the frequencies of all-cause mortality, interstitial lung disease (ILD), end-stage renal disease (ESRD), and lymphoma were assessed as the poor outcomes of Sjögren's syndrome. Comparison of the cumulative patient survivals between the two groups was analysed by the Kaplan-Meier survival analysis. Of the 606 patients, ANCA was detected in 10.2% of Sjögren's syndrome patients without AAV. Twenty-one patients (3.5%) died, 99 patients (16.3%) suffered from ILD, and 8 patients had ESRD. Lymphoma occurred in 5 patients (0.8%) during 37.5 months. Sjögren's syndrome patients with ANCA positivity exhibited a lower cumulative ILD-free survival rate than those with ANCA negativity (P = 0.001). Sjögren's syndrome patients with P-ANCA positivity and those with MPO-ANCA (or P-ANCA) positivity showed a lower cumulative ILD-free survival rate than those without (P = 0.012 and P < 0.001). Also, Sjögren's syndrome patients with P-ANCA positivity exhibited a lower cumulative ESRD-free survival rate than those without (P = 0.043). ANCA positivity was associated with neither all-cause mortality nor lymphoma in Sjögren's syndrome patients. ANCA positivity and MPO-ANCA (or P-ANCA) positivity at diagnosis was associated with the development of ILD during follow-up in patients with Sjögren's syndrome.

Clinical significance of ANCA positivity in patients with IgA vasculitis: a retrospective monocentric study.

We assessed the detection rate of antineutrophil cytoplasmic antibody (ANCA) and investigated the clinical significance of ANCA positivity at diagnosis in patients with IgA vasculitis (Henoch-Schönlein purpura). We retrospectively reviewed their medical records of 86 IgA vasculitis patients. We divided IgA vasculitis patients based on ANCA positivity and compared variables at diagnosis and poor outcomes and medication during follow-up between the two groups. All-cause mortality, relapse, chronic kidney disease (CKD) (stage 3-5) and end-stage renal disease (ESRD) were defined as poor outcomes. We assessed the renal histological features based on the International Study of Kidney Disease in Children (ISKDC) classification and Oxford classification. Comparison of cumulative survivals was analysed by the Kaplan-Meier survival analysis. Five of 86 IgA vasculitis patients (5.8%) had ANCA and all ANCA-positive patients had myeloperoxidase (MPO)-ANCA. IgA vasculitis patients with ANCA exhibited pulmonary and nervous involvement of IgA vasculitis more frequently than those without. There was no significant difference in renal involvement between the two groups. There were no significant differences in renal histological features and poor outcomes related to renal function between IgA vasculitis patients with and without ANCA. In addition, 5 IgA vasculitis patients did not meet the classification criteria for ANCA-associated vasculitis (AAV). Particularly, there were no significant differences in CKD and ESRD-free survival rates between IgA vasculitis patients with and without ANCA. 5.8% of IgA vasculitis patients had MPO-ANCA and poor outcomes of IgA vasculitis were not affected by the presence of ANCA.

Identification of a Molecular Latch that Regulates Staphylococcal Virulence.

Virulence induction in the Staphylococcus aureus is under the control of a quorum sensing (QS) circuit encoded by the accessory gene regulator (agr) locus. Allelic variation within agr produces four QS specificity groups, each producing a unique secreted autoinducer peptide (AIP) and receptor histidine kinase (RHK), AgrC. Cognate AIP-AgrC interactions activate virulence through a two-component signaling cascade, whereas non-cognate pairs are generally inhibitory. Here we pinpoint a key hydrogen-bonding interaction within AgrC that acts as a switch to convert helical motions propagating from the receptor sensor domain into changes in inter-domain association within the kinase module. AgrC mutants lacking this interaction are constitutively active in vitro and in vivo, the latter leading to a pronounced attenuation of S. aureus biofilm formation. Thus, our work sheds light on the regulation of this biomedically important RHK.

Dynamic switching enables efficient bacterial colonization in flow.

Bacteria colonize environments that contain networks of moving fluids, including digestive pathways, blood vasculature in animals, and the xylem and phloem networks in plants. In these flow networks, bacteria form distinct biofilm structures that have an important role in pathogenesis. The physical mechanisms that determine the spatial organization of bacteria in flow are not understood. Here, we show that the bacterium P. aeruginosa colonizes flow networks using a cyclical process that consists of surface attachment, upstream movement, detachment, movement with the bulk flow, and surface reattachment. This process, which we have termed dynamic switching, distributes bacterial subpopulations upstream and downstream in flow through two phases: movement on surfaces and cellular movement via the bulk. The model equations that describe dynamic switching are identical to those that describe dynamic instability, a process that enables microtubules in eukaryotic cells to search space efficiently to capture chromosomes. Our results show that dynamic switching enables bacteria to explore flow networks efficiently, which maximizes dispersal and colonization and establishes the organizational structure of biofilms. A number of eukaryotic and mammalian cells also exhibit movement in two phases in flow, which suggests that dynamic switching is a modality that enables efficient dispersal for a broad range of cell types.

Surface-attached molecules control Staphylococcus aureus quorum sensing and biofilm development.

Bacteria use a process called quorum sensing to communicate and orchestrate collective behaviours, including virulence factor secretion and biofilm formation. Quorum sensing relies on the production, release, accumulation and population-wide detection of signal molecules called autoinducers. Here, we develop concepts to coat surfaces with quorum-sensing-manipulation molecules as a method to control collective behaviours. We probe this strategy using Staphylococcus aureus. Pro- and anti-quorum-sensing molecules can be covalently attached to surfaces using click chemistry, where they retain their abilities to influence bacterial behaviours. We investigate key features of the compounds, linkers and surfaces necessary to appropriately position molecules to interact with cognate receptors and the ability of modified surfaces to resist long-term storage, repeated infections, host plasma components and flow-generated stresses. Our studies highlight how this surface approach can be used to make colonization-resistant materials against S. aureus and other pathogens and how the approach can be adapted to promote beneficial behaviours of bacteria on surfaces.

Bubble-Driven Detachment of Bacteria from Confined Microgeometries.

Moving air-liquid interfaces, for example, bubbles, play a significant role in the detachment and transport of colloids and microorganisms in confined systems as well as unsaturated porous media. Moreover, they can effectively prevent and/or postpone the development of mature biofilms on surfaces that are colonized by bacteria. Here we demonstrate the dynamics and quantify the effectiveness of this bubble-driven detachment process for the bacterial strain Staphylococcus aureus. We investigate the effects of interface velocity and geometrical factors through microfluidic experiments that mimic some of the confinement features of pore-scale geometries. Depending on the bubble velocity U, at least three different flow regimes are found. These operating flow regimes not only affect the efficiency of the detachment process but also modify the final distribution of the bacteria on the surface. We organize our results according to the capillary number, [Formula: see text], where µ and γ are the viscosity and the surface tension, respectively. Bubbles at very low velocities, corresponding to capillary numbers Ca < 5 × 10-5, exhibit detachment efficiencies of up to 80% at the early stage of bacterial adhesion. In contrast, faster bubbles at capillary numbers Ca > 10-3, have lower detachment efficiencies and cause significant nonuniformities in the final distribution of the cells on the substrate. This effect is associated with the formation of a thin liquid film around the bubble at higher Ca. In general, at higher bubble velocities bacterial cells in the corners of the geometry are less influenced by the bubble passage compared to the central region.

Local and global consequences of flow on bacterial quorum sensing.

Bacteria use a chemical communication process called quorum sensing (QS) to control collective behaviours such as pathogenesis and biofilm formation(1,2). QS relies on the production, release and group-wide detection of signal molecules called autoinducers. To date, studies of bacterial pathogenesis in well-mixed cultures have revealed virulence factors and the regulatory circuits controlling them, including the overarching role of QS(3). Although flow is ubiquitous to nearly all living systems(4), much less explored is how QS influences pathogenic traits in scenarios that mimic host environments, for example, under fluid flow and in complex geometries. Previous studies(5-7) have shown that sufficiently strong flow represses QS. Nonetheless, it is not known how QS functions under constant or intermittent flow, how it varies within biofilms or as a function of position along a confined flow, or how surface topography (grooves, crevices, pores) influence QS-mediated communication. We explore these questions using two common pathogens, Staphylococcus aureus and Vibrio cholerae. We identify conditions where flow represses QS and other conditions where QS is activated despite flow, including characterizing geometric and topographic features that influence the QS response. Our studies highlight that, under flow, genetically identical cells do not exhibit phenotypic uniformity with respect to QS in space and time, leading to complex patterns of pathogenesis and colonization. Understanding the ramifications of spatially and temporally non-uniform QS responses in realistic environments will be crucial for successful deployment of synthetic pro- and anti-QS strategies.

The mechanical world of bacteria.

In the wild, bacteria are predominantly associated with surfaces as opposed to existing as free-swimming, isolated organisms. They are thus subject to surface-specific mechanics, including hydrodynamic forces, adhesive forces, the rheology of their surroundings, and transport rules that define their encounters with nutrients and signaling molecules. Here, we highlight the effects of mechanics on bacterial behaviors on surfaces at multiple length scales, from single bacteria to the development of multicellular bacterial communities such as biofilms.

Colonization, competition, and dispersal of pathogens in fluid flow networks.

The colonization of bacteria in complex fluid flow networks, such as those found in host vasculature, remains poorly understood. Recently, it was reported that many bacteria, including Bacillus subtilis [1], Escherichia coli [2], and Pseudomonas aeruginosa [3, 4], can move in the opposite direction of fluid flow. Upstream movement results from the interplay between fluid shear stress and bacterial motility structures, and such rheotactic-like behavior is predicted to occur for a wide range of conditions [1]. Given the potential ubiquity of upstream movement, its impact on population-level behaviors within hosts could be significant. Here, we find that P. aeruginosa communities use a diverse set of motility strategies, including a novel surface-motility mechanism characterized by counter-advection and transverse diffusion, to rapidly disperse throughout vasculature-like flow networks. These motility modalities give P. aeruginosa a selective growth advantage, enabling it to self-segregate from other human pathogens such as Proteus mirabilis and Staphylococcus aureus that outcompete P. aeruginosa in well-mixed non-flow environments. We develop a quantitative model of bacterial colonization in flow networks, confirm our model in vivo in plant vasculature, and validate a key prediction that colonization and dispersal can be inhibited by modifying surface chemistry. Our results show that the interaction between flow mechanics and motility structures shapes the formation of mixed-species communities and suggest a general mechanism by which bacteria could colonize hosts. Furthermore, our results suggest novel strategies for tuning the composition of multi-species bacterial communities in hosts, preventing inappropriate colonization in medical devices, and combatting bacterial infections.

Filaments in curved streamlines: Rapid formation of Staphylococcus aureus biofilm streamers.

Biofilms are surface-associated conglomerates of bacteria that are highly resistant to antibiotics. These bacterial communities can cause chronic infections in humans by colonizing, for example, medical implants, heart valves, or lungs. Staphylococcus aureus, a notorious human pathogen, causes some of the most common biofilm-related infections. Despite the clinical importance of S. aureus biofilms, it remains mostly unknown how physical effects, in particular flow, and surface structure influence biofilm dynamics. Here we use model microfluidic systems to investigate how environmental factors, such as surface geometry, surface chemistry, and fluid flow affect biofilm development in S. aureus. We discovered that S. aureus rapidly forms flow-induced, filamentous biofilm streamers, and furthermore if surfaces are coated with human blood plasma, streamers appear within minutes and clog the channels more rapidly than if the channels are uncoated. To understand how biofilm streamer filaments reorient in flows with curved streamlines to bridge the distances between corners, we developed a mathematical model based on resistive force theory of slender filaments. Understanding physical aspects of biofilm formation in S. aureus may lead to new approaches for interrupting biofilm formation of this pathogen.