An update on the microbiome in vasculitis.

PURPOSE OF REVIEW: To summarize recent evidence regarding the presence and potential role of the microbiome in systemic vasculitides. RECENT FINDINGS: Microbiomic descriptions are now available in patients with small, medium and large vessel vasculitis. The majority of studies have evaluated gastrointestinal inhabitants, with a smaller number of studies describing the nasal, pulmonary or vascular microbiomes. Most published studies are observational and cross-sectional. Dysbiosis is seen frequently in vasculitis patients with reduced microbial diversity observed in nasal, fecal and vascular samples compared with disease and/or healthy controls. Predominant bacteria vary, but overall, patients with vasculitis tend to have more pathogenic and less commensal bacteria in active disease. In the few longitudinal studies available, improvement or resolution of dysbiosis has been observed following vasculitis treatment and improved disease activity. SUMMARY: Dysbiosis and reduced microbial diversity has been identified in patients with small, medium and large vessel vasculitis. Although limited data suggests microbiomes may 'normalize' following immunosuppression, cause or effect cannot be determined. It is hypothesized that microbial disruption in a genetically susceptible individual may trigger excessive host immune activation and vasculitis; however, larger studies with longitudinal and translational design are needed to further our current understanding.

Crucial role of NLRP3 inflammasome in a murine model of Kawasaki disease.

Kawasaki disease (KD) is a systemic febrile syndrome during childhood that is characterized by coronary arteritis. The etiopathogenesis of KD remains to be elucidated. NLRP3 inflammasome is a large multiprotein complex that plays a key role in IL-1ß-driven sterile inflammatory diseases. In the present study, we investigated the role of NLRP3 inflammasome in a murine model of KD induced by Candida albicans water-soluble fraction (CAWS) and found that NLRP3 inflammasome is required for the development of CAWS-induced vasculitis. CAWS administration induced IL-1ß production, caspase-1 activation, leukocyte infiltration, and fibrotic changes in the aortic root and coronary arteries, which were significantly inhibited by a deficiency of IL-1ß, NLRP3, and ASC. In vitro experiments showed that among cardiac resident cells, macrophages, but not endothelial cells or fibroblasts, expressed Dectin-2, but did not produce IL-1ß in response to CAWS. In contrast, CAWS induced caspase-1 activation and IL-1ß production in bone marrow-derived dendritic cells (BMDCs), which were inhibited by a specific caspase-1 inhibitor and a deficiency of NLRP3, ASC, and caspase-1. CAWS induced NLRP3 and pro-IL-1ß expression through a Dectin-2/Syk/JNK/NF-κB pathway, and caspase-1 activation and cleavage of pro-IL-1ß through Dectin-2/Syk/JNK-mediated mitochondrial ROS generation, indicating that CAWS induces the priming and activation of NLRP3 inflammasome in BMDCs. These findings provide new insights into the pathogenesis of KD vasculitis, and suggest that NLRP3 inflammasome may be a potential therapeutic target for KD.

Comparative in vitro activity of bacteriophage endolysin HY-133 against Staphylococcus aureus attached to vascular graft surface.

Novel strategies are needed for combating Staphylococcus aureus biofilm in vascular graft infections. We investigated the in vitro activity of bacteriophage endolysin HY-133, daptomycin and rifampin against S. aureus attached to vascular graft surface. Daptomycin showed rapid bactericidal effect on surface-associated S. aureus, while the activity of HY-133 on graft surface-adherent cells was moderate and rifampin did not achieve bactericidal effect. Even in the highest concentrations, all antimicrobials used failed in a complete eradication of the surface-adherent bacteria.

Equine pastern vasculitis in a horse associated with a multidrug-resistant Pseudomonas aeruginosa isolate.

BACKGROUND: Equine pastern vasculitis is an uncommon disorder in horses. Underlying causes are difficult to assess, especially bacterial infections. CLINICAL SUMMARY: A 13-year-old French saddle gelding horse presented for evaluation of a six weeks history of pastern dermatitis. Histopathological examination of skin biopsy samples revealed small vessel vasculitis. A pure growth of a multidrug-resistant Pseudomonas aeruginosa (MRPA) was obtained from a deep skin biopsy. Clinical remission was observed after a six week course of enrofloxacin and lesions did not recur. CONCLUSIONS AND CLINICAL IMPORTANCE: To the best of the authors' knowledge, this is the first report of a pastern vasculitis associated with MRPA and successfully treated with a six week course of enrofloxacin.

Fulminant arterial vasculitis as an unusual complication of disseminated staphylococcal disease due to the emerging CC1 methicillin-susceptible Staphylococcus aureus clone: a case report.

BACKGROUND: Staphylococcus aureus has emerged as a leading cause of invasive severe diseases with a high rate of morbidity and mortality worldwide. The wide spectrum of clinical manifestations and outcome observed in staphylococcal illness may be a consequence of both microbial factors and variability of the host immune response. CASE PRESENTATION: A 14-years old child developed limb ischemia with gangrene following S. aureus bloodstream infection. Histopathology revealed medium-sized arterial vasculitis. The causing strain belonged to the emerging clone CC1-MSSA and numerous pathogenesis-related genes were identified. Patient's genotyping revealed functional variants associated with severe infections. A combination of virulence and host factors might explain this unique severe form of staphylococcal disease. CONCLUSION: A combination of virulence and genetic host factors might explain this unique severe form of staphylococcal disease.

Crescentic poststreptococcal acute glomerulonephritis accompanied by small vessel vasculitis: case report of an elderly male.

BACKGROUND: Poststreptococcal acute glomerulonephritis (PSAGN) in the elderly tends to have a severe clinical course and often presents with crescentic necrotizing glomerulonephritis in the renal biopsy. However, vasculitis lesions are unusual. CASE PRESENTATION: We present a 71-year-old man who was admitted to our hospital for a recurrent gout attack with a rapid decline of renal function. Low C3 levels and a high anti-streptolysin O titer were observed, while myeloperoxidase- and proteinase 3- antineutrophil cytoplasmic antibody (ANCA) were negative. In addition to cellular crescent and necrosis lesions, diffuse peritubular capillaritis and venulitis as well as small arteriole vasculitis in the glomerular hilus were also apparent. Although granular C3c deposits in the capillary wall and hump lesions were not found, immunofluorescent staining for nephritis-associated plasmin receptor (NAPlr) and in situ zymography for plasmin activity were both positive. We thus diagnosed PSAGN accompanied by small vessel vasculitis. Steroid therapy gradually improved the patient's renal function, and hemodialysis was discontinued after 1 month. CONCLUSIONS: In our case, streptococcus infection might have concurrently provoked vasculitis, and NAPlr staining was useful for confirming diagnosis.

Late preterm prelabor rupture of fetal membranes: fetal inflammatory response and neonatal outcome.

BackgroundTo characterize the influence of microbial invasion of the amniotic cavity (MIAC) and/or intra-amniotic inflammation (IAI) on the intensity of the fetal inflammatory response and the association between the presence of the fetal inflammatory response syndrome (FIRS) and short-term neonatal morbidity in the preterm prelabor rupture of membranes (PPROM) between the gestational ages of 34 and 37 weeks.MethodsOne hundred and fifty-nine women were included in the study. The umbilical cord blood interleukin (IL)-6 concentrations were determined using enzyme-linked immunosorbent assay kits. FIRS was defined based on the umbilical cord blood IL-6 concentration and the presence of funisitis and/or chorionic plate vasculitis.ResultsWomen with both MIAC and IAI had the highest median umbilical cord blood IL-6 concentrations and highest rates of FIRS. Women with FIRS had the higher rates of early-onset sepsis and intraventricular hemorrhage grades I and II when FIRS was characterized based on the umbilical cord blood IL-6 concentrations and the histopathological findings.ConclusionThe presence of both MIAC and IAI was associated with a higher fetal inflammatory response and a higher rate of FIRS. Different aspects of short-term neonatal morbidity were related to FIRS when defined by umbilical cord blood IL-6 concentrations and the histopathology of the placenta.

The adherens junctions control susceptibility to Staphylococcus aureus α-toxin.

Staphylococcus aureus is both a transient skin colonizer and a formidable human pathogen, ranking among the leading causes of skin and soft tissue infections as well as severe pneumonia. The secreted bacterial α-toxin is essential for S. aureus virulence in these epithelial diseases. To discover host cellular factors required for α-toxin cytotoxicity, we conducted a genetic screen using mutagenized haploid human cells. Our screen identified a cytoplasmic member of the adherens junctions, plekstrin-homology domain containing protein 7 (PLEKHA7), as the second most significantly enriched gene after the known α-toxin receptor, a disintegrin and metalloprotease 10 (ADAM10). Here we report a new, unexpected role for PLEKHA7 and several components of cellular adherens junctions in controlling susceptibility to S. aureus α-toxin. We find that despite being injured by α-toxin pore formation, PLEKHA7 knockout cells recover after intoxication. By infecting PLEKHA7(-/-) mice with methicillin-resistant S. aureus USA300 LAC strain, we demonstrate that this junctional protein controls disease severity in both skin infection and lethal S. aureus pneumonia. Our results suggest that adherens junctions actively control cellular responses to a potent pore-forming bacterial toxin and identify PLEKHA7 as a potential nonessential host target to reduce S. aureus virulence during epithelial infections.

Antinuclear antibodies in scrub typhus: Transient occurrence during acute illness.

BACKGROUND & OBJECTIVES: The pathological hallmark of scrub typhus infection is focal or disseminated vasculitis. As with other infections, antinuclear antibodies (ANA) have been previously described in scrub typhus. However, the underlying mechanisms and implications of this immunological phenomenon is not well understood. In the present work it was assessed whether ANA is associated with illness severity and outcomes. METHODS: In this prospective study spanning one year, patients fulfilling the diagnostic criteria for scrub typhus were recruited. Patients with other acute infective febrile illnesses were taken as controls. ANA positivity was compared between the cases and controls. ANA in scrub typhus was assessed for correlation with disease severity, organ dysfunction and outcomes. RESULTS: The cohort comprised of 149 patients (scrub 89; controls 60) with mean age 46.5 (SD=16.9) yr; 48.3% were female. ANA was detected in 48 (53.9%) patients with scrub typhus and 9(15%) controls (p < 0.001). The ANA pattern was predominantly speckled (93.8%) in both scrub typhus patients and controls. In patients with scrub typhus, ANA positivity was associated with increasing APACHE-III score [Odds ratio (OR) 1.01; 95% CI 0.99-1.03; p = 0.09]. On bivariate analysis, ANA tended to be correlated with acute respiratory distress syndrome (OR 2.32; 95% CI 0.98-5.46; p = 0.06), hepatic dysfunction (OR 2.25; 95% CI 0.94-5.39, p = 0.06) and aseptic meningitis (OR 6.83; 95% CI 0.80-58.05, p = 0.08). The presence of these antibodies did not correlate with duration of hospitalization or mortality. Convalescent sera on 31 ANA positive scrub typhus patients demonstrated persistence of ANA in only 5 (16.1%) patients. INTERPRETATION & CONCLUSION: The disappearance of ANA during the convalescent phase suggests that ANA is expressed during the acute phase of scrub typhus infection. Its association with organ dysfunction warrants further study of the mechanisms and impact of autoantibody formation in scrub typhus.

Infections and vasculitis.

PURPOSE OF REVIEW: To review recent evidence for infection rates in patients with systemic vasculitides, the role of specific infectious agents in the pathogenesis of vasculitis and recent breakthroughs in the treatment of virus-associated vasculitides. RECENT FINDINGS: In well designed recent studies, infections were found to be common during the first 6-12 months in patients with anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitides (AAV) and giant cell arteritis (GCA) and to contribute significantly to increased mortality during this period. New therapeutic schemes with lower cyclophosphamide doses and shorter corticosteroid courses were associated with decreased infectious rates in elderly patients with AAV whereas a prednisone dose greater than 10 mg/day at the end of the first year were associated with increased infectious-related mortality in patients with GCA. Recently, a potential role for varicella zoster virus in GCA pathogenesis has been proposed but more data are needed in order to establish a causal relationship. Finally, preliminary data show excellent short-term efficacy and safety of the new, interferon-free, oral antiviral agents in the treatment of hepatitis C virus-associated cryoglobulinemic vasculitis. SUMMARY: Infections continue to be one of the main causes of mortality in patients with systemic vasculitides, emphasizing the need for safer immunosuppressive therapies and appropriate prophylaxis.

Distinct lipid a moieties contribute to pathogen-induced site-specific vascular inflammation.

Several successful pathogens have evolved mechanisms to evade host defense, resulting in the establishment of persistent and chronic infections. One such pathogen, Porphyromonas gingivalis, induces chronic low-grade inflammation associated with local inflammatory bone loss and systemic inflammation manifested as atherosclerosis. P. gingivalis expresses an atypical lipopolysaccharide (LPS) structure containing heterogeneous lipid A species, that exhibit Toll-like receptor-4 (TLR4) agonist or antagonist activity, or are non-activating at TLR4. In this study, we utilized a series of P. gingivalis lipid A mutants to demonstrate that antagonistic lipid A structures enable the pathogen to evade TLR4-mediated bactericidal activity in macrophages resulting in systemic inflammation. Production of antagonistic lipid A was associated with the induction of low levels of TLR4-dependent proinflammatory mediators, failed activation of the inflammasome and increased bacterial survival in macrophages. Oral infection of ApoE(-/-) mice with the P. gingivalis strain expressing antagonistic lipid A resulted in vascular inflammation, macrophage accumulation and atherosclerosis progression. In contrast, a P. gingivalis strain producing exclusively agonistic lipid A augmented levels of proinflammatory mediators and activated the inflammasome in a caspase-11-dependent manner, resulting in host cell lysis and decreased bacterial survival. ApoE(-/-) mice infected with this strain exhibited diminished vascular inflammation, macrophage accumulation, and atherosclerosis progression. Notably, the ability of P. gingivalis to induce local inflammatory bone loss was independent of lipid A expression, indicative of distinct mechanisms for induction of local versus systemic inflammation by this pathogen. Collectively, our results point to a pivotal role for activation of the non-canonical inflammasome in P. gingivalis infection and demonstrate that P. gingivalis evades immune detection at TLR4 facilitating chronic inflammation in the vasculature. These studies support the emerging concept that pathogen-mediated chronic inflammatory disorders result from specific pathogen-mediated evasion strategies resulting in low-grade chronic inflammation.

Successful treatment of Bordetella bronchiseptica pneumonia by minocycline in anti-neutrophil cytoplasmic antibodies-associated vasculitis patient.

Bordetella bronchiseptica is a bacterial pathogen usually isolated from animals and rarely causes human infections. There are, however, some reports that B. bronchiseptica causes human respiratory infections in immunocompromised patients or those with underlying respiratory diseases, although there is a lack of treatment guidelines. An 80-year-old woman was admitted to our hospital to treat anti-neutrophil cytoplasmic antibodies-associated vasculitis. On the 16th day after admission, she complained of a productive cough with right pleuritic pain and had low-grade fever. After chest CT scans, we diagnosed pneumonia. Gram stain of her sputum revealed moderate levels of gram-negative coccobacilli, which was later identified as B. bronchiseptica by mass spectrometry. According to the result of minimum inhibitory concentration, we successfully treated the pneumonia with minocycline. This case suggests that B. bronchiseptica pneumonia can be treated by minocycline if the minimum inhibitory concentration is less than 0.25 µg/mL.

Contamination during production of heater-cooler units by Mycobacterium chimaera potential cause for invasive cardiovascular infections: results of an outbreak investigation in Germany, April 2015 to February 2016.

Invasive infections with Mycobacterium chimaera were reported in patients with previous open chest surgery and exposure to contaminated heater-cooler units (HCUs). We present results of the surveillance of clinical cases and of contaminated HCUs as well as environmental investigations in Germany up until February 2016. Clinical infections occurred in five male German cases over 50 years of age (range 53-80). Cases had been exposed to HCUs from one single manufacturer during open chest surgery up to five years prior to onset of symptoms. During environmental investigations, M. chimaera was detected in samples from used HCUs from three different countries and samples from new HCUs as well as in the environment at the manufacturing site of one manufacturer in Germany. Our investigation suggests that at least some of the M. chimaera infections may have been caused by contamination of HCUs at manufacturing site. We recommend that until sustainable measures for safe use of HCUs in operation theatres are implemented, users continue to adhere to instructions for use of HCUs and Field Safety Notices issued by the manufacturer, implement local monitoring for bacterial contamination and continuously check the websites of national and European authorities for current recommendations for the safe operation of HCUs.

Peculiarities of the Inflammatory Process in the Reproductive Organs of C57Bl/6 Female Mice with Experimental Tuberculosis.

Intravenous infection of C57Bl/6 female mice with M. tuberculosis H37Rv led to involvement of the lungs and dissemination of the tuberculous infection to the abdominal and pelvic organs. M. tuberculosis were detected in the lungs and spleen in 14, 35, and 90 days and in the uterine horns in 90 days after infection. Morphological analysis of organs showed successive development of exudative necrotic tuberculosis of the lungs, acute and chronic nonspecific inflammation in the reproductive organs (vagina, uterus, and uterine horns). The inflammatory process in the reproductive organs was associated with the development of anaerobic dysbiosis, that was most pronounced in 35 days after infection. Antituberculous therapy was followed by reduction of M. tuberculosis count in the lungs and spleen in 60 and 90 days after infection, eliminatation of M. tuberculosis in the uterine horns, arrest of nonspecific inflammation in female reproductive organs, recovery of the balance between aerobic and anaerobic microflora, and development of candidiasis of the urogenital mucosa.

Evidence for a vascular microbiome and its role in vessel health and disease.

PURPOSE OF REVIEW: We have summarized available evidence for and against the presence of a vascular microbiome. Studies that have attempted to detect bacteria and viruses in blood vessels in both health and disease are critiqued in an attempt to explain contrary results that may be due to variations in methodology. RECENT FINDINGS: Many studies have demonstrated the presence of both bacteria and viruses within diseased blood vessels. Evidence is most compelling in atherosclerosis; however, recent reports have raised questions about the potential role of microbes in nonatherosclerotic aortic aneurysms and vasculitis. Preliminary evidence also suggests that apparently normal vessels may harbor microbes. With the exception of certain viral infections (e.g. hepatitis C virus, HIV, Epstein-Barr virus, and cytomegalovirus) and infectious endocarditis, systemic vasculitides have not been convincingly associated with infectious agents. However, emerging data suggest that different communities of microbes may be present in noninflammatory and inflammatory large-vessel diseases. Whether variations in vascular microbial communities are the cause or a secondary result (epiphenomena) of vessel injury remains to be determined. SUMMARY: Blood vessels may not be sterile. Future studies of microbes in vessel health and disease may provide important insights into disease pathogenesis and suggest new therapies for diseases now considered to be idiopathic and refractory.

Vasculitis and infectious diseases.

Vasculitis usually presents without a well-known underline cause (idiopathic vasculitis), nevertheless, it is sometimes possible to find out one or more causative agents (secondary vasculitis). Nowadays, thanks to the increasing amount of precise diagnostic tools, a piece of idiopathic vasculitis is reclassified as associated with probable etiology, which can be set off by several factors, such as infections. Infections are considered to be the most common cause of secondary vasculitis. Virtually, every infectious agent can trigger a vasculitis by different mechanisms which can be divided in two main categories: direct and indirect. In the former, infectious agents destroy directly the vascular wall leading, eventually, to a subsequent inflammatory response. In the latter, indirect form, they stimulate an immune response against blood vessels. Different infectious agents are able to directly damage the vascular wall. Among these, it is possible to recognize Staphylococcus spp, Streptococcus spp, Salmonella spp, Treponema spp, Rickettsia spp, Cytomegalovirus, Herpes Simplex Virus 1 and 2, and many others which have a peculiar tropism for endothelial cells. Conversely, another group of microbial agents, such as Mycobacterium tuberculosis, Mycobacterium leprae, Hepatits B Virus, Human Immunodeficiency Virus and others, trigger vasculitis in the indirect way. This is due to the fact that they can share epitopes with the host or modify self-antigens, thus leading to a cross-self reaction of the immune system. These mechanism, in turn, leads to immunological responses classified as type I-IV by Gell-Coombs. Nevertheless, it is difficult to strictly separate the direct and indirect forms, because most infectious agents can cause vasculitis in both ways (mixed forms). This paper will analyze the link between infectious agents and vasculitis, focusing on direct and indirect secondary vasculitis, and on a group of probable infection-related idiopathic vasculitis, and finally on a group of idiopathic vasculitis with microbiological triggers. Furthermore, a diagnostic and therapeutic approach to vasculitis when an underline infection has been suspected is suggested.

Septic vasculitis and vasculopathy in some infectious emergencies: the perspective of the histopathologist.

Sepsis is a potentially life-threatening complication of an infection where cutaneous lesions often represent one of the early signs. A myriad of microorganisms including bacteria, fungi, yeasts, viruses, protozoas, helminths and algae can be implicated. A broad spectrum of clinical and histopathologic findings can be observed in the skin and the common denominator is a thrombotic vasculopathy. The pathogenesis of cutaneous septic vasculitis (SV)/vasculopathy is complex and includes five main mechanisms: disseminated intravascular coagulation, direct invasion and occlusion of blood vessel walls by microorganisms, hypersensitivity reaction with immune complex deposition into blood vessel walls, embolism from a distant infectious site and vascular effects of toxins. Herein we describe the clinicopathologic findings of some selected cases of SV recently observed in our hospital, including purpura fulminans, necrotizing fasciitis, cutaneous meningococcemia, malignant syphilis and disseminated alternaria infection. Histopathologically, a wide spectrum of histopathologic changes was observed in skin specimens from the various entities, involving the intensity and composition of the inflammatory infiltrate, the degree of vascular changes and the presence of microorganisms, that ranged from a predominant not inflammatory, thrombotic-occlusive vasculopathy in purpura fulminans to leukocytoclastic vasculitis like changes in cutaneous meningococcemia to a dermal angiomatosis-like pattern in disseminated Alternaria infection. The different pathologic presentations may be related to the microorganism involved, the main pathogenetic mechanism that induced the vascular injury and the individual immunologic burden. Early skin biopsy for histopathologic examination and microbiologic culture is a cornerstone in the diagnosis of life-threatening diseases that present with cutaneous septic vasculitis. Ancillary techniques, such as immunohistochemistry and polymerase chain reaction are additional novel and helpful tools to identify pathogens, leading to definite diagnosis in cases with challenging or ambiguous clinical and/or pathologic findings.

First report of Westerdykella dispersa as a cause of an angioinvasive fungal infection in a neutropenic host.

Angioinvasive fungal infections (AFIs) are an important cause of morbidity and mortality among immunocompromised patients. However, clinicomicrobiological characteristics and treatment of many AFI agents remain poorly defined. We report the first human case of infection with Westerdykella dispersa, an emergent cause of AFI, which was successfully treated in a neutropenic pediatric patient.

Mycoplasma pneumoniae: an aetiological agent of acute haemorrhagic oedema of infancy.

Acute haemorrhagic oedema of infancy (AHEI) is considered a separate clinical entity among cutaneous small vessel vasculitis of childhood. It usually occurs in children younger than 2 years of age, with spontaneous recovery occurring within a few weeks. A history of recent upper respiratory or urinary tract infections or immunisation is found in most patients. Although Mycoplasma pneumoniae has been linked to a wide array of skin eruptions or diseases, it is not recognised as a possible cause of acute haemorrhagic oedema of infancy. The authors report a child with AHEI and a concurrent M. pneumoniae infection.