Dynamic shear analysis: a novel method to determine mechanical integrity of normal and torn human acetabular labra: Implications for prediction of outcome of repair

Objectives

The aim of this study was to investigate the structural integrity of torn and non-torn human acetabular labral tissue.

Methods

A total of 47 human labral specimens were obtained from a biobank. These included 22 torn specimens and 25 control specimens from patients undergoing total hip arthroplasty with macroscopically normal labra. The specimens underwent dynamic shear analysis using a rheometer to measure storage modulus, as an indicator of structural integrity.

Results

There was a significant difference in the storage modulus between torn (mean modulus = 2144.08 Pa) and non-torn (3178.1 Pa) labra (p = 0.0001).

Conclusion

The acetabular labrum of young patients with a tear has significantly reduced structural integrity compared with a non-torn labrum in older patients with end-stage osteoarthritis. This study contributes to the understanding of the biomechanics of labral tears, and the observation of reduced structural integrity in torn labra may explain why some repairs fail. Our data demonstrate that labral tears probably have a relatively narrow phenotype, presenting a basis for further investigations that will provide quantifiable data to support their classification and a means to develop a standardized surgical technique for their repair. This study also demonstrates the value of novel biomechanical testing methods in investigating pathological tissues of orthopaedic interest.Cite this article: A. K. Woods, J. Broomfield, P. Monk, F. Vollrath, S. Glyn-Jones. Dynamic shear analysis: a novel method to determine mechanical integrity of normal and torn human acetabular labra: Implications for prediction of outcome of repair. Bone Joint Res 2018;7:440-446. DOI: 10.1302/2046-3758.77.BJR-2017-0282.R2.

T helper 1 immunity requires complement-driven NLRP3 inflammasome activity in CD4⁺ T cells

The NLRP3 inflammasome controls interleukin-1β maturation in antigen-presenting cells, but a direct role for NLRP3 in human adaptive immune cells has not been described. We found that the NLRP3 inflammasome assembles in human CD4(+) T cells and initiates caspase-1-dependent interleukin-1β secretion, thereby promoting interferon-γ production and T helper 1 (T(H)1) differentiation in an autocrine fashion. NLRP3 assembly requires intracellular C5 activation and stimulation of C5a receptor 1 (C5aR1), which is negatively regulated by surface-expressed C5aR2. Aberrant NLRP3 activity in T cells affects inflammatory responses in human autoinflammatory disease and in mouse models of inflammation and infection. Our results demonstrate that NLRP3 inflammasome activity is not confined to "innate immune cells" but is an integral component of normal adaptive T(H)1 responses.

Autocrine NLPR3 inflammasome activity is critical to normal adaptive immunity via regulation of IFN-γ in CD4+ T cells

The NLRP3 inflammasome controls IL-1β maturation in antigen presenting cells but a direct role in human adaptive immune cells has not been described. Here we show that the NLRP3 inflammasome assembles in human CD4+ T cells and initiates caspase-1-dependent IL-1b secretion, thereby promoting IFN-γ production and Th1 differentiation in an autocrine fashion. Importantly, NLRP3 assembly requires intracellular C5 activation and stimulation of C5a receptor 1 (C5aR1), which drive reactive oxygen species (ROS) production. The alternative cell surface expressed C5a receptor 2 (C5aR2) negatively regulates this process. Dysregulation of NLRP3 activity in T cells affects inflammatory responses in autoimmune disease or infection. Firstly, CD4+ T cells from patients with cryopyrin-associated periodic syndromes (CAPS), who have constitutively-active NLRP3, exhibit overactive Th1 responses that are normalized by NLRP3 inhibitor treatment. Secondly, IFN-γ production is impaired in T cells from Nlpr3−/− or Il1a/Il1b−/− mice upon viral infection. Our results demonstrate that NLRP3 inflammasome activity is not confined to ‘innate immune cells’ but is an integral component of normal adaptive Th1 responses.

Protein engineering and preclinical development of a GM-CSF receptor antibody for the treatment of rheumatoid arthritis

BACKGROUND AND PURPOSE

For antibody therapies against receptor targets, in vivo outcomes can be difficult to predict because of target-mediated clearance or antigen 'sink' effects. The purpose of this work was to engineer an antibody to the GM-CSF receptor α (GM-CSFRα) with pharmacological properties optimized for chronic, s.c. treatment of rheumatoid arthritis (RA) patients.

EXPERIMENTAL APPROACH

We used an in silico model of receptor occupancy to guide the target affinity and a combinatorial phage display approach for affinity maturation. Mechanism of action and internalization assays were performed on the optimized antibody in vitro before refining the modelling predictions of the eventual dosing in man. Finally, in vivo pharmacology studies in cynomolgus monkeys were carried out to inform the predictions and support future clinical development.

KEY RESULTS

Antibody potency was improved 8600-fold, and the target affinity was reached. The refined model predicted pharmacodynamic effects at doses as low as 1 mg kg(-1) and a study in cynomolgus monkeys confirmed in vivo efficacy at 1 mg kg(-1) dosing.

CONCLUSIONS AND IMPLICATIONS

This rational approach to antibody drug discovery enabled the isolation of a potent molecule compatible with chronic, s.c. self-administration by RA patients. We believe this general approach enables the development of optimal biopharmaceuticals.

Contact investigations for outbreaks of Mycobacterium tuberculosis: advances through whole genome sequencing

The control of tuberculosis depends on the identification and treatment of infectious patients and their contacts, who are currently identified through a combined approach of genotyping and epidemiological investigation. However, epidemiological data are often challenging to obtain, and genotyping data are difficult to interpret without them. Whole genome sequencing (WGS) technology is increasingly affordable, and offers the prospect of identifying plausible transmission events between patients without prior recourse to epidemiological data. We discuss the current approaches to tuberculosis control, and how WGS might advance public health efforts in the future.

In vivo evaluation of edge-loading in metal-on-metal hip resurfacing patients with pseudotumours

Objectives

Pseudotumours (abnormal peri-prosthetic soft-tissue reactions) following metal-on-metal hip resurfacing arthroplasty (MoMHRA) have been associated with elevated metal ion levels, suggesting that excessive wear may occur due to edge-loading of these MoM implants. This study aimed to quantify in vivo edge-loading in MoMHRA patients with and without pseudotumours during functional activities.

Methods

The duration and magnitude of edge-loading in vivo was quantified during functional activities by combining the dynamic hip joint segment contact force calculated from the three-dimensional (3D) motion analysis system with the 3D reconstruction of orientation of the acetabular component and each patient’s specific hip joint centre, based on CT scans.

Results

Edge-loading in the hips with pseudotumours occurred with a four-fold increase in duration and magnitude of force compared with the hips without pseudotumours (p = 0.02).

Conclusions

The study provides the first in vivo evidence to support that edge-loading is an important mechanism that leads to localised excessive wear (edge-wear), with subsequent elevation of metal ion levels in MoMHRA patients with pseudotumours.

Regulation of zebrafish hatching by tetraspanin cd63

Tetraspanins cause the clustering of membrane proteins into a level of organisation essential for cellular function. Given the importance and complicated nature of this mechanism, we attempted a novel approach to identify the function of a single component in a biologically relevant context. A morpholino knockdown strategy was used to investigate the role of cd63, a membrane protein associated with intracellular transport and a melanoma marker, in embryonic zebrafish. By using three separate morpholinos targeting cd63, we were able to identify a specific phenotype. Strikingly, morphant fish failed to hatch due to the lack of secreted proteolytic enzymes required for chorion-softening. The morphology of the hatching gland at both the cellular and intracellular levels was disorganised, suggesting a role for cd63 in the functioning of this organ. This work identifies a specific role for cd63 in the zebrafish embryo and provides evidence for the suitability of zebrafish as a model system for the investigation of tetraspanin enriched microdomains.

Mast cells express IL-13R alpha 1: IL-13 promotes human lung mast cell proliferation and Fc epsilon RI expression

BACKGROUND

The Th2 cytokine interleukin (IL)-13 is implicated in the development of various allergic diseases including asthma. The IL-13 receptor, IL-13Ralpha1, is expressed on most leukocytes, except T-cells. Evidence to support IL-13Ralpha1 expression on mast cells is limited.

METHODS

We investigated: (i) IL-13Ralpha1 expression by human lung mast cells (HLMC); (ii) the number of IL-13Ralpha1+ bronchial submucosal mast cells in subjects with asthma and normal controls and (iii) the effect of IL-13 priming on HLMC expression of high-affinity IgE receptor (FcepsilonRI), stem cell factor receptor (CD117), histamine release, proliferation, and survival.

RESULTS

Human lung mast cell expressed IL-13Ralpha1 mRNA. IL-13Ralpha1 was highly expressed on the surface HLMC (82+/-9%). Bronchial submucosal mast cell IL-13Ralpha1 expression was higher in asthmatics (86+/-2%) than normal controls (78+/-2%; P=0.015). IL-13 priming for 30 min did not increase HLMC histamine release, in the presence or absence of SCF or in response to IgE/anti-IgE activation. IL-13 priming for 5 days upregulated HLMC FcepsilonRI expression (22% increase in fluorescent intensity; P=0.003), increased histamine release following IgE/anti-IgE activation by 56% (P=0.03) and increased proliferation by 50% (P=0.003) without affecting cell survival or CD117 expression. The IL-13 specific neutralizing antibody CAT-354 inhibited all IL-13 mediated effects.

CONCLUSION

Human lung mast cell express IL-13Ralpha1 and activation by IL-13 for 5 days increased FcepsilonRI expression and proliferation. Histamine release was not affected by short-term priming with IL-13, but was upregulated by priming for 5 days suggesting that this effect was mediated by the increased FcepsilonRI expression. These data support the view that targeting IL-13 may be beneficial in the treatment of asthma.

Outbreak of low pathogenicity H7N3 avian influenza in UK, including associated case of human conjunctivitis

On 26 April 2006, the veterinary authorities in the United Kingdom reported that there had been an outbreak of avian influenza type A/H7 among a 35 000-bird housed poultry flock in eastern England, United Kingdom.

Inhibition of human interleukin-13-induced respiratory and oesophageal inflammation by anti-human-interleukin-13 antibody (CAT-354)

BACKGROUND

Allergic asthma is a complex disorder characterized by local and systemic T helper type 2 -cell responses such as the production of IL-13, a cytokine associated with the induction of airway hyper-responsiveness (AHR), chronic pulmonary eosinophilia, airway mucus overproduction and eosinophilic oesophagitis.

OBJECTIVE

Our study aimed to address the therapeutic potential of a human anti-human IL-13 IgG4 monoclonal antibody (CAT-354) in a murine model of respiratory and oesophageal inflammation induced by intratracheal human IL-13.

METHODS

BALB/c mice were treated on days 1 and 3 with CAT-354 (intraperitoneal injection), and human IL-13 was injected intratracheally on days 2 and 4. AHR to methacholine, airway eosinophilia in bronchoalveolar lavage fluid, histologic analysis of goblet cell metaplasia and oesophageal eosinophilia were evaluated.

RESULTS

Human IL-13 induced airway eosinophilia and goblet cell metaplasia in mice in a dose-dependent manner. Moreover, intratracheal dosing with 25 microg of human IL-13 was sufficient to induce AHR, goblet cell metaplasia and oesophageal eosinophilia. Pretreatment with CAT-354 significantly reduced AHR, airway eosinophilia and oesophageal eosinophilia.

CONCLUSION

These results demonstrate that anti-human IL-13 (CAT-354) is a potential therapeutic treatment for allergic airway and oesophageal diseases.

Preventing secondary meningococcal disease in health care workers: recommendations of a working group of the PHLS meningococcus forum

Based on new data on the risk of secondary meningococcal disease in health care workers, a review of published cases and an assessment of the available evidence, a change to the recommendations for giving chemoprophylaxis to health care workers in England and Wales is proposed. Previous guidance recommended prophylaxis only for those who had given mouth to mouth resuscitation. Chemoprophylaxis is now recommended for health care workers whose mouth or nose has been directly and heavily exposed to respiratory droplets/secretions from a case of meningococcal disease around the time of hospital admission. Wearing surgical face masks is encouraged to reduce risk of exposure.

Limitations of national guidelines in the management of an outbreak of tuberculosis

National guidelines offer no clear definition of a close (non-household) contact of tuberculosis. The resulting lack of distinction between close and casual contacts may lead to excessive screening in outbreaks of pulmonary tuberculosis in the United Kingdom. Poor compliance with chemoprophylaxis suggests that priority should be given to the follow up of high risk contacts, who should be more clearly defined. A review of the management of a family outbreak of tuberculosis illustrates the problem. Fifty-nine out of 213 non-household contacts screened for infection had grade 3 and 4 Heaf reactions and none developed clinical tuberculosis within one year. Three of the 59 did not attend for chest radiography and a further 11 patients did not attend the outpatients appointment offered. Twenty-three took chemoprophylaxis for three months, 14 did not complete chemoprophylaxis, six (11%) declined it and two were offered x-ray follow up.

Survey of how public health doctors in the United Kingdom and Republic of Ireland investigate the effects of long-term exposure to point sources of chemicals

Public health departments may need to investigate the health effects of long term exposures to chemicals from sources such as landfill sites and factories. Public health consultants responsible for communicable disease and environmental health and directors of public health in all health authorities and health boards in the United Kingdom and the Republic of Ireland were surveyed on behalf of a Faculty of Public Health Medicine guideline development group. The survey achieved a response rate of over 80%. Most public health doctors had investigated the health effects of long term exposure to chemicals, but many found it difficult to conduct effective and appropriate investigations in the face of community and political pressure. Most doctors acknowledged that they were responsible for investigating these problems, but wanted more epidemiological support, training, and guidance.

Characterization of hepatitis C virus E2 glycoprotein interaction with a putative cellular receptor, CD81

A truncated soluble form of the hepatitis C virus E2 glycoprotein, E2661, binds specifically to the surface of cells expressing human CD81 (hCD81) but not other members of the tetraspanin family (CD9, CD63, and CD151). No differences were noted between the level of E2661 binding to hCD81 expressed on the surface of rat RBL or KM3 cells compared to Daudi and Molt-4 cells, suggesting that additional human-cell-specific factors are not required for the primary interaction of E2 with the cell surface. E2 did not interact with African green monkey (AGM) CD81 on the surface of COS cells, which differs from the hCD81 sequence at four residues within the second extracellular region (EC2) (amino acids [aa] 163, 186, 188, and 196), suggesting that one or more of these residues defines the site of interaction with E2. Various recombinant forms of CD81 EC2 show differences in the ability to bind E2, suggesting that CD81 conformation is important for E2 recognition. Regions of E2 involved in the CD81 interaction were analyzed, and our data suggest that the binding site is of a conformational nature involving aa 480 to 493 and 544 to 551 within the E2 glycoprotein. Finally, we demonstrate that ligation of CD81 by E2661 induced aggregation of lymphoid cells and inhibited B-cell proliferation, demonstrating that E2 interaction with CD81 can modulate cell function.

Invasive meningococcal disease among university undergraduates: association with universities providing relatively large amounts of catered hall accommodation

The incidence of invasive meningococcal disease (IMD) among UK university students and non-students of similar age was investigated. In addition, we sought to identify structural risk factors associated with high rates of IMD in individual universities. Cases were ascertained via Consultants in Communicable Disease Control (or equivalent officers) between September 1994 and March 1997. Data on individual universities were obtained from university accommodation officers. University students had an increased annual rate of invasive meningococcal disease (13.2/10(5), 95% CI 11.2-15.2) compared with non-students of similar age in the same health districts (5.5/10(5), CI 4.7-6.4) and in those health districts without universities (3.7/10(5), CI 2.9-4.4). This trend was highly significant. Regression analysis demonstrated catered hall accommodation to be the main structural risk factor. Higher rates of disease were observed at universities providing catered hall places for > 10% of their student population (15.3/10(5), CI 11.8-18;8) compared with those providing places for < 10% of students (5.9/10(5), CI 4.1-7.7). The majority of IMD amongst students was caused by serogroup B organisms. University students in the UK are at increased risk of IMD compared with non-students of a similar age. The incidence of IMD tends to be greatest at universities with a high provision of catered hall accommodation.

Use of the 1 tuberculin unit (TU) Mantoux test in the assessment of tuberculous infection in children following neonatal BCG vaccination

BACKGROUND

BCG vaccination alters the response to tuberculin testing and influences the potential validity of the Heaf test in the diagnosis of tuberculosis. This study used a purified protein derivative 1 tuberculin unit (TU) Mantoux test with a cut off of 5 mm induration as an indicator of tuberculous infection in high risk children to determine whether this would distinguish infection from previous neonatal BCG vaccination.

METHODS

Children at high risk of tuberculosis on chest radiography, Heaf test, or contact history who had been screened in the contact tracing clinic and referred for further assessment were included in the study. After clinical examination, chest radiography, and Mantoux testing they were assigned to three groups (tuberculous disease, chemoprophylaxis, or no treatment) and followed up for 6-24 months in the outpatient clinic and subsequently by postal questionnaire.

RESULTS

Comparison of the Heaf and Mantoux tests showed a difference in the results with 82% of cases positive by the Heaf test and 59% positive by the Mantoux test. Using the Mantoux test result in combination with clinical and radiographic findings 194 children were allocated to the three groups as follows: primary tuberculosis (5), chemoprophylaxis (101), no treatment (88). During follow up for a mean (range) time of 46 (11-102) months four additional cases received treatment for primary tuberculosis, two in the chemoprophylaxis group and two in the untreated group.

CONCLUSIONS

The use of the 1 TU Mantoux test after neonatal BCG vaccination reduced the number of children receiving treatment from 129 to 93-that is, by 36%. Although the numbers are small, there was no increase in the later development of tuberculosis.

Demineralized bone powder. Clinical applications for bone defects of the hand

The results of 20 consecutive cases of bone defects of the hand treated by curettage and implantation of demineralized bone powder compare well with a similarly matched retrospective group managed with autogenous grafts and curettage alone. Results revealed "excellent" (16 patients) or "good" bone healing (4 patients) in the bone powder group on independent radiographic evaluation. Bone bridging was noted at an average of 9.9 weeks. All defects healed without recurrence, resorption or refracture, with follow-up of 4 to 36 months. In the conventionally managed retrospective group there was a 25% failure rate necessitating re-operation. Demineralized bone powder provides a rapid, safe and effective method of management of bone defects of the hand.