ABSTRACT
The circadian clock regulates multiple aspects of human physiology including immunity. People have a circadian preference termed chronotype. Those with an evening preference may be better suited to shift work, but also carry higher risk of adverse health. Shift work leads to misalignment of circadian rhythms and is associated with increased risk of inflammatory disease such as asthma and cancer. Here, we investigate the association between chronotype, shift work, and rheumatoid arthritis (RA). The associations between exposures of shift work and chronotype on risk of RA were studied in up to 444,210 U.K. Biobank participants. Multivariable logistic regression models were adjusted for covariates: age, sex, ethnicity, alcohol intake, smoking history, Townsend Deprivation Index (TDI), sleep duration, length of working week, and body mass index (BMI). After adjusting for covariates, individuals with a morning chronotype had lower odds of having rheumatoid arthritis (RA; odds ratio [OR]: 0.93, 95% confidence interval [CI]: 0.88-0.99) when compared to intermediate chronotypes. The association between morning chronotype and RA persisted with a more stringent RA case definition (covariate-adjusted OR: 0.89, 95% CI: 0.81-0.97). When adjusted for age, sex, ethnicity, and TDI, shift workers had higher odds of RA (OR: 1.22, 95% CI: 1.1-1.36) compared to day workers that attenuated to the null after further covariate adjustment (OR: 1.1, 95% CI: 0.98-1.22). Morning chronotypes working permanent night shifts had significantly higher odds of RA compared to day workers (OR: 1.89, 95% CI: 1.19-2.99). These data point to a role for circadian rhythms in RA pathogenesis. Further studies are required to determine the mechanisms underlying this association and understand the potential impact of shift work on chronic inflammatory disease and its mediating factors.
Subject(s)
Arthritis, Rheumatoid , Shift Work Schedule , Humans , Circadian Rhythm/physiology , Chronotype , Work Schedule Tolerance/physiology , Arthritis, Rheumatoid/etiology , Sleep/physiology , Surveys and QuestionnairesABSTRACT
Photodermatoses, or photosensitivity conditions, are a group of skin disorders caused by exposure to sunlight, overall affecting a large number of people. They cause a range of distressing symptoms including pain and burn, and can make the skin blister, flake and scar. The conditions themselves and the need for patients to avoid and protect themselves from sunlight may affect quality of life and psychological health. This study, from the U.K., aimed to find out what methods of assessment (tools) have been used to evaluate quality of life and psychological health in photodermatoses, and report what the impact is for patients. The authors reviewed relevant published English-language studies and summarised their findings. 20 studies were included: 19 assessing quality of life and three assessing psychological function. Six different tools had been used to assess quality of life, and four different tools to assess psychological health. It was shown that 31-39% of patients with photodermatoses experienced a very large impact on their quality of life. There was a particular impact on issues related to employment, social/leisure activities and clothing choices. Patients had around double the rates of anxiety and depression found in the general population, although few studies focussed on psychological health. The authors also noted that most available tools were not designed to address the unique impact of intermittent sunlight-induced skin conditions and suggested that development of more specific tools could be beneficial. In conclusion, this study confirmed that patients with photodermatoses experience substantial impact on their quality of life and that more research is needed. This is a summary of the study: Quality of life and psychological impact in the photodermatoses: a systematic review.
Subject(s)
Photosensitivity Disorders , Quality of Life , Anxiety , Anxiety Disorders , Humans , SunlightABSTRACT
BACKGROUND: The photodermatoses affect large proportions of the population but their impact on quality of life (QoL) and psychological health has not been reviewed. Several tools are available to evaluate QoL and psychological impacts. OBJECTIVES: To systematically review current literature to identify tools used to assess QoL and psychological impacts in patients with photodermatoses, and to summarize the reported findings. METHODS: A systematic search of PubMed, OVID Medline, PsycInfo and CINAHL was performed for articles investigating QoL and/or psychological impact in patients with photodermatoses, published between 1960 and September 2018. RESULTS: Twenty studies were included: 19 incorporated QoL assessment while three evaluated psychological morbidity. Six QoL tools were found to be used: Dermatology Life Quality Index (DLQI), Children's DLQI, Family DLQI, Skindex (16- and 29-item versions), Erythropoietic Protoporphyria Quality of Life (EPP-QoL) and EuroQol. Between 31% and 39% of photosensitive patients reported a very large impact on QoL (DLQI > 10). Employment and education, social and leisure activities, and clothing choices were particularly affected. Only one tool was specifically designed for a photodermatosis (EPP-QoL). Four tools were used to evaluate psychological impact: the Hospital Anxiety and Depression Scale, Fear of Negative Evaluation, brief COPE and Illness Perception Questionnaire-Revised. Levels of anxiety and depression were approximately double British population data. Patients with facial involvement, female gender and younger age at onset showed more psychological morbidity. CONCLUSIONS: Several tools have been used to assess QoL in the photodermatoses, and confirm substantial impact on QoL. Development of specific, validated QoL measures would address their unique impacts. Research delineating their psychological comorbidity is sparse and requires further exploration. What's already known about this topic? The photodermatoses negatively impact quality of life (QoL) and cause psychological distress, but no reviews of this area appear in the literature. What does this study add? Few studies have explored the psychological and social impacts of the photodermatoses. There are no fully validated QoL tools specific to the photodermatoses. Around one-third of adult and child patients with photosensitivity experience very or extremely large impact on QoL, with particular effect on clothing choices, employment and social and leisure activities. Studies suggest anxiety and depression levels in these patients are around double those in the U.K. general population. More attention is required on these 'hidden' conditions.
Subject(s)
Photosensitivity Disorders , Quality of Life , Adult , Anxiety , Anxiety Disorders , Child , Female , Humans , Photosensitivity Disorders/epidemiology , Surveys and QuestionnairesABSTRACT
Acute liver failure (ALF) is a rare condition with fatal outcome. Characteristic is rapid onset of liver damage without preexisting liver diseases, including hepatic encephalopathy and coagulopathy. Early and correct diagnosis is essential for further management of patients, since diagnosis impacts therapy choice. Survival of patients with ALF has improved dramatically due to advances in critical care medicine and the use of liver transplantation.
Subject(s)
Hepatic Encephalopathy , Liver Failure, Acute , Liver Transplantation , Critical Care , Humans , Liver Failure, Acute/diagnosis , Liver Failure, Acute/therapyABSTRACT
Interactions between the hepatic portal and cardiovascular systems are frequently found in patients with liver disease. Cirrhotic cardiomyopathy (CCMP) is defined as reduced cardiac function in patients with liver cirrhosis in the absence of other known causes of cardiac disease. The typical hyperdynamic circulatory state by means of increased cardiac output and reduced systemic vascular resistance may mask left ventricular failure. Portopulmonary hypertension (POPH) is defined as increased pulmonary arterial pressure and the presence of portal hypertension, and is associated with increased mortality. Targeted medical therapies include vasodilators such as prostanoids, endothelin receptor antagonists and phosphodiesterase-5 inhibitors. Hypoxic or ischaemic hepatitis (HH) is defined by a sharp increase of serum aminotransferase levels due to liver cell necrosis as result of cardiac, circulatory or respiratory failure. An overview of these diseases is provided in this article.
Subject(s)
Cardiomyopathies/complications , Cardiomyopathies/physiopathology , Liver Cirrhosis/complications , Liver Cirrhosis/physiopathology , Cardiac Output/physiology , Cardiomyopathies/diagnosis , Cardiomyopathies/therapy , Combined Modality Therapy , Diagnosis, Differential , Humans , Hypertension, Portal/complications , Hypertension, Portal/diagnosis , Hypertension, Portal/physiopathology , Hypertension, Portal/therapy , Hypertension, Pulmonary/complications , Hypertension, Pulmonary/diagnosis , Hypertension, Pulmonary/physiopathology , Hypertension, Pulmonary/therapy , Intensive Care Units , Liver Cirrhosis/diagnosis , Liver Cirrhosis/therapy , Prognosis , Vascular Resistance/physiology , Ventricular Dysfunction, Left/complications , Ventricular Dysfunction, Left/diagnosis , Ventricular Dysfunction, Left/physiopathology , Ventricular Dysfunction, Left/therapyABSTRACT
BACKGROUND: Long-term outcome of chronic hepatitis C patients with successful viral eradication seems to be promising. AIM: To evaluate mortality, incidence of hepatocellular carcinoma (HCC), liver failure and liver transplantation in sustained virological responders (SVR) and non-SVR patients with different stages of fibrosis. METHODS: Seven hundred and fourteen patients with a follow-up of 7.2 (1-21.1) years (age: 51.4 ± 12.0 years, 276 female, IFN-monotherapy: n = 19, IFN/RBV: n = 122, peg-IFN/RBV: n = 573, SVR: 551, non-SVR: 163) were studied. Two hundred and ten of 540 patients with a liver biopsy prior to treatment had advanced stages of fibrosis (Metavir F3/F4). RESULTS: Forty-eight patients died during follow-up, 15 with SVR and 33 without (P < 0.001). Five- and 10-year mortality rates were 1.8% (10/551) and 2.7% (15/551) in the SVR group and 8.6% (14/163) and 19.1% (31/163) in the non-SVR patients (P < 0.001). In 29 patients, decompensation of liver disease [SVR: 9 (1.6%) vs. non-SVR: 20 (12.3%); P < 0.001] occurred and in 29 patients, HCC developed during follow-up [SVR: 10 (1.8%) vs. non-SVR: 19 (11.7%); P < 0.001]. Non-SVR was an independent predictor for developing (i) HCC [HR: 2.36 (95% CI: 1.07-5.23; P = 0.034], (ii) liver-related complications [HR: 2.62; (95% CI: 1.18-5.81; P = 0.018] and (iii) mortality (HR: 3.46; 95% CI: 1.91-6.29; P < 0.001). For patients with early stages of fibrosis (F0-F2), a survival benefit of SVR patients could not be demonstrated. CONCLUSIONS: Successful anti-viral therapy decreases mortality, incidence of hepatocellular carcinoma and liver failure in patients with advanced fibrosis. However, hepatocellular carcinoma development or liver failure are not prevented completely, and further follow-up of patients is advisable.
Subject(s)
Antiviral Agents/therapeutic use , Carcinoma, Hepatocellular/epidemiology , Hepatitis C, Chronic/drug therapy , Liver Neoplasms/epidemiology , Adult , Aged , Carcinoma, Hepatocellular/virology , Female , Follow-Up Studies , Hepatitis C, Chronic/complications , Humans , Liver Failure/epidemiology , Liver Failure/virology , Liver Neoplasms/virology , Liver Transplantation/statistics & numerical data , Male , Middle Aged , Retrospective StudiesABSTRACT
Acute and acute-on-chronic liver failure are often associated with development of organ failure. Its occurrence is associated with high morbidity and mortality. Extracorporeal replacement therapies are frequently necessary in these patient populations. Replacement therapies can be divided into renal replacement therapies and liver support therapies. These therapies consist of artificial liver support systems (i.e., MARS(®) system, Prometheus(®)), which are able to remove water-soluble and albumin-bound toxins, and of bioartifical liver support systems. This manuscript provides a review of current practice in the extracorporeal support of patients with liver diseases in the intensive care unit.
Subject(s)
Critical Care/methods , Intensive Care Units , Liver Failure/therapy , Liver, Artificial , Multiple Organ Failure/therapy , Renal Replacement Therapy , Humans , Liver Cirrhosis/complications , Liver Cirrhosis/diagnosis , Liver Cirrhosis/therapy , Liver Failure/diagnosis , Liver Failure/etiology , Multiple Organ Failure/diagnosis , Multiple Organ Failure/etiologyABSTRACT
Pulmonary-hepatic vascular disorders are frequent complications in patients with portal hypertension and cirrhosis. Hepatopulmonary syndrome (HPS), portopulmonary hypertension (POPH), and hepatic hydrothorax are relevant disease entities in these patients. HPS occurs in up to 30 % of patients with cirrhosis and is associated with a more than 2-fold increased mortality. The diagnosis of HPS should be established early by arterial blood gas analysis and contrast-enhanced echocardiography, whereas POPH is diagnosed by the presence of pulmonary arterial hypertension evaluated via right heart catheterization and the presence of portal hypertension. Therapeutic options include initiation of long-term oxygen therapy and liver transplantation in patients with severe HPS. Patients with POPH should receive targeted medical therapies with endothelin receptor antagonists, phosphodiesterase-5 inhibitors and/or prostanoids. In contrast, ß-blockers should be avoided. This review summarizes current knowledge regarding pulmonary-hepatic vascular disorders, with a focus on HPS.
Subject(s)
Critical Care/methods , Hepatopulmonary Syndrome/therapy , Liver Failure/therapy , Multiple Organ Failure/therapy , Combined Modality Therapy , Hepatopulmonary Syndrome/diagnosis , Hepatopulmonary Syndrome/physiopathology , Humans , Liver/physiopathology , Liver Cirrhosis/complications , Liver Cirrhosis/physiopathology , Liver Cirrhosis/therapy , Liver Failure/diagnosis , Liver Failure/physiopathology , Lung/physiopathology , Multiple Organ Failure/diagnosis , Multiple Organ Failure/physiopathologyABSTRACT
BACKGROUND: Genetic factors can play an important role for treatment response and disease progression in chronic viral hepatitis. AIM: To review the influence of host genetic factors on the clinical course as well as on treatment response in patients with viral hepatitis. METHODS: Review of the literature. RESULTS: A landmark genome-wide association study (GWAS) identified polymorphisms in the IL28B gene on chromosome 19 (19q13.13) associated with response to therapy with pegylated interferon-α (PEG-IFN) and ribavirin (RBV) and spontaneous viral clearance in acute hepatitis C. Furthermore, IL28B genotype is associated with changes of lipid metabolism and insulin resistance. A further GWAS demonstrated that ITPA genetic variants protect HCV genotype 1 patients from RBV-induced anaemia. Another polymorphism in the patatin-like phospholipase domain containing 3 (PNPLA3) is associated with hepatic steatosis. Difficult-to-treat hepatitis C patients homozygous for GG had an up to five-fold lower chance of viral clearance on PEG/RBV than non-GG patients. In chronic hepatitis B patients treated with PEG-IFN several retrospective analyses of IL28B rs12980275 and rs12979860 genotypes yielded conflicting results which can be explained by the heterogeneity between the study populations. Some variants of the HLA-DP locus (HLA-DPA1 A allele and HLA-DPB1) protect against progression of chronic hepatitis B infection. CONCLUSIONS: The determination of IL28B polymorphisms may be useful to individualise treatment options when using PEG/RBV based therapies for chronic hepatitis C infection. In contrast, so far identified genetic factors play only a minor role in chronic hepatitis B infection.
Subject(s)
Antiviral Agents/therapeutic use , Hepatitis B, Chronic/drug therapy , Hepatitis C, Chronic/drug therapy , Drug Therapy, Combination , Genotype , HLA-DP alpha-Chains , HLA-DP beta-Chains , Hepatitis B, Chronic/genetics , Hepatitis C, Chronic/genetics , Humans , Interferon alpha-2 , Interferon-alpha/therapeutic use , Interferons , Interleukins/genetics , Polyethylene Glycols/therapeutic use , Polymorphism, Genetic , Recombinant Proteins/therapeutic use , Ribavirin/therapeutic use , Treatment OutcomeABSTRACT
BACKGROUND: The IL28B genotype in rs12979860 predicts success of peginterferon/ribavirin (PEG/RBV) therapy in patients with chronic hepatitis C (CHC). Recently, a dinucleotide frame shift variant in ss469415590 (TT or ΔG) was described, which generates the novel interferon lambda 4 protein (IFNL4). IFNL4 ss469415590 (ΔG) allele carriers have an impaired clearance of HCV infection and response to IFN-α therapy. In this study, we compared the role of IFNL4 polymorphism with the two commonly used IL28B SNPs rs12979860 and rs8099917 on response to PEG/RBV in patients with CHC. AIM: To compare the role of IFNL4 polymorphism with the two commonly used IL28B SNPs rs12979860 and rs8099917 on response to PEG/RBV in patients with CHC. METHODS: A total of 754 PEG/RBV patients treated (male/female = 484/270; Caucasians: 98.8%; mean age: 42.8 [CI 95%: 42.0-43.6] y; genotype (GT)1: n = 435, GT2: n = 23, GT3: n = 185, GT4: n = 114) were investigated. Liver fibrosis was assessed by liver biopsy in 456 patients. Single nucleotide polymorphisms (SNPs) in ss469415590, rs12979860 and rs8099917 were analysed by RT-PCR system. RESULTS: Of the patients, 12.9% (n = 97) had the ss469415590 ΔG/ΔG genotype (IFNL4), 51.3% (n = 387) were heterozygous (TT/ΔG) and 35.8% (n = 270) had TT/TT. IFNL4 polymorphism was independently associated with SVR in GT1 (OR: 2.539, CI 95%: 1.629-3.021, P < 0.001) and GT4 (OR: 12.573, CI 95%: 3.427-46.133, P < 0.001), but not in GT3 (OR: 1.514, CI 95%: 0.933-2.458, P = 0.093). IFNL4 correlated strongly with rs12979860 (ρ = 0.988, P < 0.001), but only moderately with rs8099917 (ρ = 0.598, P < 0.001). CONCLUSIONS: These findings underscore the role of IFNL4 for treatment response in patients with CHC genotypes 1 and 4. However, due to its strong correlation with rs12979860 in IL28B, there is no benefit in additional testing for IFNL4 for treatment prediction in Caucasian patients. By contrast, IFNL4 improves prediction of response to interferon-based therapies, if SNP rs8099917 is used.
Subject(s)
Antiviral Agents/therapeutic use , Hepatitis C, Chronic/drug therapy , Interferons/therapeutic use , Interleukins/genetics , Ribavirin/therapeutic use , Adult , Female , Genotype , Hepatitis C, Chronic/genetics , Humans , Male , Middle Aged , Polymorphism, Single Nucleotide , Treatment OutcomeABSTRACT
BACKGROUND: The introduction of direct-acting anti-virals has increased sustained virological response (SVR) rates in chronic hepatitis C genotype 1 infection. At present, data on long-term durability of viral eradication after successful triple therapy are lacking. AIM: To evaluate the long-term durability of viral eradication in patients treated with triple therapy, including direct-acting anti-virals. METHODS: Patients who participated in randomised, controlled trials or an extended access programme of treatment with peginterferon-α2a/ribavirin in combination with a direct-acting anti-viral (telaprevir, danoprevir, faldaprevir, simeprevir, mericitabine, balapiravir) were followed after achieving SVR. The median follow-up after the patients was 21 (range: 7-64) months. RESULTS: One hundred and three patients with chronic hepatitis C genotype 1 infection [f/m: 34/69; GT-1b: 67 GT-1a: 34, GT-4: 2; mean age: 47.6 years (45.5-49.7; 95% CI)] achieving a SVR triple therapy were followed. Two cases of late relapses (2/103, 1.9%; 95% CI: 0.24-6.8) were observed. One patient was cirrhotic, both carried the genotype 1b and completed the prescribed treatment. The relapses occurred 8 and 12 months after cessation of anti-viral treatment. Cloning sequencing revealed identical sequence in both patients. Resistance analysis revealed no presence of viral resistance. CONCLUSION: Like the SVR after peginterferon-α2/ribavirin combination treatment, HCV eradication after triple therapy remains durable after long-term follow-up.
Subject(s)
Antiviral Agents/therapeutic use , Hepatitis C, Chronic/drug therapy , Interferon-alpha/therapeutic use , Polyethylene Glycols/therapeutic use , Ribavirin/therapeutic use , Drug Therapy, Combination , Female , Follow-Up Studies , Hepacivirus/physiology , Hepatitis C, Chronic/genetics , Hepatitis C, Chronic/virology , Humans , Male , Middle Aged , Randomized Controlled Trials as Topic , Recombinant Proteins/therapeutic use , Time Factors , Treatment Outcome , Viral LoadABSTRACT
INTRODUCTION: The efficacy of antiviral therapy with pegylated interferon (PEGIFN) plus ribavirin (RBV) in patients with HIV and hepatitis C virus (HCV) coinfection is limited. Intravenous silibinin (ivSIL), a milk thistle extract with proven antiviral effects represents a novel therapeutic strategy for virological nonresponders. METHODS: We report a case of an HIV-HCV coinfected patient, who has not responded to a prior course of PEGIFN-α2a (180 µg/week/s.c.) and RBV (1000 mg/day/p.o.). Testing for IL-28ß small nucleotid polymorphism revealed the nonfavourable genotype T/T. Antiretroviral therapy was not prescribed because the patients presented with well-preserved CD4+ cell counts and low HIV-RNA levels. She received retreatment with ivSIL for two weeks followed by PEGIFN/RBV combination therapy starting at week 1. RESULTS: After 2 weeks of ivSIL therapy both HCV-RNA and HIV-RNA become undetectable. On ivSIL monotherapy we noticed a trend towards an increase of CD4+ cell counts and a decrease of HIV-RNA. After 16 weeks PEGIFN+RBV was discontinued due to patients wish because of adverse events. HCV-RNA was still negative 24 weeks after cessation of therapy, while HIV-RNA returned to baseline levels. CONCLUSION: ivSIL may represent a potential treatment option for retreatment of HIV-HCV coinfected patients nonresponding to PEGIFN+RBV combination therapy. Further investigations on the possible beneficial effects of ivSIL on CD4+ cell counts and HIV-RNA levels are necessary.
Subject(s)
Antiviral Agents/administration & dosage , HIV Infections/complications , HIV Infections/drug therapy , Hepatitis C, Chronic/complications , Hepatitis C, Chronic/drug therapy , Silymarin/administration & dosage , Adult , CD4 Lymphocyte Count , Female , HIV/isolation & purification , Hepacivirus/isolation & purification , Humans , Interferon alpha-2 , Interferon-alpha/administration & dosage , Polyethylene Glycols/administration & dosage , RNA, Viral/blood , Recombinant Proteins , Ribavirin/administration & dosage , Silybin , Treatment Outcome , Viral LoadSubject(s)
Allergens/adverse effects , Coloring Agents/adverse effects , Dermatitis, Allergic Contact/epidemiology , Phenylenediamines/adverse effects , Allergens/immunology , Azides/adverse effects , Azides/immunology , Cross Reactions , Dermatitis, Allergic Contact/diagnosis , Dermatitis, Allergic Contact/etiology , Dermatitis, Allergic Contact/immunology , England/epidemiology , Humans , Patch Tests/statistics & numerical data , Phenylenediamines/immunology , Risk FactorsABSTRACT
BACKGROUND: Some patients with psoriasis may require hospital admission to stabilize their condition, although the role of inpatient management is changing given recent advances in therapeutic options, emphasis on community-based care for chronic conditions and limited healthcare resources. There is a need for evidence-based national standards for inpatient management of psoriasis taking account of factors that predict length of stay. OBJECTIVES: To determine which factors predict length of stay for patients with psoriasis requiring inpatient hospital care with a view to setting evidence-based standards for inpatient psoriasis management. METHODS: A multicentre service review was conducted on all psoriasis admissions over a 9-month period in four dermatology centres in the U.K. We collected data on admission, at discharge and, where possible, at 3 months following discharge. Psoriasis severity was assessed using four validated scoring systems, including Psoriasis Area and Severity Index (PASI) and Dermatology Life Quality Index. We also recorded length of stay and treatment details. RESULTS: Length of stay varied widely between the four centres, but was similar in the two centres which received a high proportion of tertiary referrals for severe psoriasis (mean 19.7 days, range 1-78, analysis of variance P=0.002). Disease severity, measured by PASI, on admission (mean 15.7, interquartile range 8.3-20.8) was significantly higher in the tertiary centres (P<0.0001). However, there was no significant difference in PASI between centres on discharge. The admission PASI was significantly associated with length of stay (r=0.2, P=0.02). There was no significant correlation between other measures of disease severity and length of stay. CONCLUSIONS: Disease severity on admission for patients with psoriasis is greater in tertiary referral centres for psoriasis and is directly associated with length of stay. Length of stay should be used in conjunction with clinical measures such as PASI improvement to set national standards for quality in secondary care.
Subject(s)
Length of Stay/statistics & numerical data , Psoriasis/therapy , Analysis of Variance , Humans , Medical Records , Quality of Life , Risk Factors , Severity of Illness Index , United KingdomABSTRACT
The Neisseria gonorrhoeae pglA gene has two alleles, one of which is phase variable. A previous study reported that all disseminated gonococcal infection (DGI) isolates contained the phase-variable allele and proposed a causal link. In the present study of 81 strains no absolute correlation between DGI and the phase-variable pglA allele was observed.
Subject(s)
Alleles , Antimicrobial Cationic Peptides/genetics , Fimbriae, Bacterial/metabolism , Gonorrhea/microbiology , Neisseria gonorrhoeae/genetics , Genes, Bacterial/physiology , Glycosylation , Gonorrhea/transmission , Humans , Neisseria gonorrhoeae/metabolismABSTRACT
Pili of Neisseria meningitidis are a key virulence factor, being the major adhesin of this capsulate organism and contributing to specificity for the human host. Pili are post-translationally modified by addition of either an O-linked trisaccharide, Gal (beta1-4) Gal (alpha1-3) 2,4-diacetamido-2,4,6-trideoxyhexose or an O-linked disaccharide Gal (alpha1,3) GlcNAc. The role of these structures in meningococcal pathogenesis has not been resolved. In previous studies we identified two separate genetic loci, pglA and pglBCD, involved in pilin glycosylation. Putative functions have been allocated to these genes; however, there are not enough genes to account for the complete biosynthesis of the described structures, suggesting additional genes remain to be identified. In addition, it is not known why some strains express the trisaccharide structure and some the disaccharide structure. In order to find additional genes involved in the biosynthesis of these structures, we used the recently published group A strain Z2491 and group B strain MC58 Neisseria meningitidis genomes and the unfinished Neisseria meningitidis group C strain FAM18 and Neisseria gonorrhoeae strain FA1090 genomes to identify novel genes involved in pilin glycosylation, based on homology to known oligosaccharide biosynthetic genes. We identified a new gene involved in pilin glycosylation designated pglE and examined four additional genes pglB/B2, pglF, pglG and pglH. A strain survey revealed that pglE and pglF were present in each strain examined. The pglG, pglH and pglB2 polymorphisms were not found in strain C311 musical sharp 3 but were present in a large number of clinical isolates. Insertional mutations were constructed in pglE and pglF in N. meningitidis strain C311 musical sharp 3, a strain with well-defined lipopolysaccharide (LPS) and pilin-linked glycan structures. Increased gel migration of the pilin subunit molecules of pglE and pglF mutants was observed by Western analysis, indicating truncation of the trisaccharide structure. Antisera specific for the C311 musical sharp 3 trisaccharide failed to react with pilin from these pglE and pglF mutants. GC-MS analysis of the sugar composition of the pglE mutant showed a reduction in galactose compared with C311 musical sharp 3 wild type. Analysis of amino acid sequence homologies has suggested specific roles for pglE and pglF in the biosynthesis of the trisaccharide structure. Further, we present evidence that pglE, which contains heptanucleotide repeats, is responsible for the phase variation between trisaccharide and disaccharide structures in strain C311 musical sharp 3 and other strains. We also present evidence that pglG, pglH and pglB2 are potentially phase variable.
Subject(s)
Bacterial Proteins/genetics , Fimbriae Proteins/metabolism , Fimbriae, Bacterial/metabolism , Genes, Bacterial , Neisseria meningitidis/genetics , Protein Processing, Post-Translational , Amino Acid Sequence , Bacterial Proteins/physiology , Base Sequence , Carbohydrate Sequence , Molecular Sequence Data , Neisseria meningitidis/metabolism , Neisseria meningitidis/pathogenicity , Oligosaccharides/metabolism , Open Reading Frames/genetics , Phosphorylation , Polymorphism, Genetic , Sequence Alignment , Sequence Homology , VirulenceABSTRACT
Mycobacterium tuberculosis is an important pathogen of mammals that relies on 2-hydroxyphenyloxazoline-containing siderophore molecules called mycobactins for the acquisition of iron in the restrictive environment of the mammalian macrophage. These compounds have been proposed to be biosynthesized through the action of a cluster of genes that include both nonribosomal peptide synthase and polyketide synthase components. One of these genes encodes a protein, MbtB, that putatively couples activated salicylic acid with serine or threonine and then cyclizes this precursor to the phenyloxazoline ring system. We have used gene replacement through homologous recombination to delete the mbtB gene and replace this with a hygromycin-resistance cassette in the virulent strain of M. tuberculosis H37Rv. The resulting mutant is restricted for growth in iron-limited media but grows normally in iron-replete media. Analysis of siderophore production by this organism revealed that the biosynthesis of all salicylate-derived siderophores was interrupted. The mutant was found to be impaired for growth in macrophage-like THP-1 cells, suggesting that siderophore production is required for virulence of M. tuberculosis. These results provide conclusive evidence linking this genetic locus to siderophore production.