Ageing of Australian lamb beyond 14 days does not further improve eating quality.

Limited studies are available assessing the impact of extended ageing on lamb eating quality of a wide range of cuts. From lamb (n = 153) and young mutton (n = 40) carcasses, seven cuts (eye of rack, eye of shoulder, knuckle, loin, outside, rump and topside) were collected and aged based on three ageing times (5, 14 or 21 days). Additionally, residual glycogen was determined from the loin at the corresponding ageing time. Untrained consumers assessed samples for tenderness, juiciness, flavour liking and overall liking. Increasing ageing time from 5 to 14 or 21 days significantly improved cut eating quality; however, ageing beyond 14 days showed no additional benefit. The ageing effect reduced when corrected for pH and temperature measurements, confirming ageing can improve eating quality when pH and temperature variation exists. Loin residual glycogen had no impact on eating quality at each ageing time. Our results confirm the importance of establishing optimum ageing times for cuts to ensure the highest consumer acceptability.

Is the Utility of the GLIM Criteria Used to Diagnose Malnutrition Suitable for Bicultural Populations? Findings from Life and Living in Advanced Age Cohort Study in New Zealand (LiLACS NZ).

OBJECTIVES: To investigate associations between nutrition risk (determined by SCREEN-II) and malnutrition (diagnosed by the GLIM criteria) with five-year mortality in Maori and non-Maori of advanced age. DESIGN: A longitudinal cohort study. SETTING: Bay of Plenty and Lakes regions of New Zealand. PARTICIPANTS: 255 Maori; 400 non-Maori octogenarians. MEASUREMENTS: All participants were screened for nutrition risk using the Seniors in the Community: Risk Evaluation for Eating and Nutrition (SCREEN-II). Those at high nutrition risk (SCREEN-II score <49) had the Global Leadership Initiative in Malnutrition (GLIM) criteria applied to diagnose malnutrition or not. Demographic, physical and health characteristics were obtained by trained research nurses using a standardised questionnaire. Five-year mortality was calculated from Government data. The association of nutrition risk (SCREEN-II) and a malnutrition diagnosis (GLIM) with five-year mortality was examined using logistic regression and cox proportional hazard models of increasing complexity. RESULTS: 56% of Maori and 46% of non-Maori participants had low SCREEN-II scores indicative of nutrition risk. The prevalence of GLIM diagnosed malnutrition was lower for both Maori and non-Maori (15% and 19% of all participants). Approximately one-third of participants (37% Maori and 32% non-Maori) died within the five-year follow-up period. The odds of death for both Maori and non-Maori was significantly lower with greater SCREEN II scores (better nutrition status), (OR (95% CI); 0.58 (0.38, 0.88), P < 0.05 and 0.53 (0.38, 0.75), P < 0.001, respectively). GLIM diagnosed malnutrition was not significantly associated with five-year mortality for Maori (OR (95% CI); 0.88 (0.41, 1.91), P >0.05) but was for non-Maori. This association remained significant after adjustment for other predictors of death (OR (95% CI); 0.50 (0.29, 0.86), P< 0.05). Reduced food intake was the only GLIM criterion predictive of five-year mortality for Maori (HR (95% CI); 10.77 (4.76, 24.38), P <0.001). For non-Maori, both aetiologic and phenotypic GLIM criteria were associated with five-year mortality. CONCLUSION: Nutrition risk, but not malnutrition diagnosed by the GLIM criteria was significantly associated with mortality for Maori. Conversely, both nutrition risk and malnutrition were significantly associated with mortality for non-Maori. Appropriate phenotypic criteria for diverse populations are needed within the GLIM framework.

Assessment of Dietary Intake in Three Cohorts of Advanced Age in Two Countries: Methodology Challenges.

OBJECTIVES: Dietary intake information is key to understanding nutrition-related outcomes. Intake changes with age and some older people are at increased risk of malnutrition. Application, difficulties, and advantages of the 24-hour multiple pass recall (24hr-MPR) dietary assessment method in three cohorts of advanced age in the United Kingdom (UK) and New Zealand (NZ) is described. PARTICIPANTS: The Newcastle 85+ study (UK) recruited a single year birth cohort of people aged 85 years during 2006-7. LiLACS NZ recruited a 10-year birth cohort of Maori (indigenous New Zealanders) aged 80-90 years and a single year birth cohort of non-Maori aged 85 years in 2010. MEASUREMENTS: Two 24hr-MPR were conducted on non-consecutive days by trained assessors. Pictorial resources and language were adapted for the New Zealand and Maori contexts. Detailed methods are described. RESULTS: In the Newcastle 85+ study, 805 (93%) participants consented to the 24-MPR, 95% of whom completed two 24hr-MPR; in LiLACS NZ, 218 (82%) consented and 203 (76%) Maori and 353 (90%) non-Maori completed two 24hr-MPR. Mean time to complete each 24hr-MPR was 22 minutes in the Newcastle 85+ study, and 45 minutes for Maori and 39 minutes for non-Maori in LiLACS NZ. Dietary assessment of participants residing in residential care and those requiring proxy respondents were successfully included in both studies. Most participants (83-94%) felt that data captured by the 24hr-MPR reflected their usual dietary intake. CONCLUSIONS: Dietary assessment using 24hr-MPR was successful in capturing detailed dietary data including information on portion size and time of eating for over 1300 octogenarians in the UK and New Zealand (Maori and non- Maori). The 24hr-MPR is an acceptable method of dietary assessment in this age group.

Health and Social Factors Associated with Nutrition Risk: Results from Life and Living in Advanced Age: A Cohort Study in New Zealand (LiLACS NZ).

OBJECTIVES: To establish the prevalence of high nutrition risk and associated health and social risk factors for New Zealand Maori and non-Maori in advanced age. DESIGN: A cross sectional analysis of inception cohorts to LiLACS NZ. SETTING: Bay of Plenty and Lakes region of the North Island, New Zealand. PARTICIPANTS: 255 Maori and 400 non- Maori octogenarians. MEASUREMENTS: Nutrition risk was assessed using a validated questionnaire Seniors in the Community: Risk Evaluation for Eating and Nutrition (SCREEN II). Demographic, social, physical and health characteristics were established using an interviewer administered questionnaire. Health related quality of life (HRQOL) was assessed with the SF-12, depressive symptoms using the GDS-15. RESULTS: Half (49%) of Maori and 38% of non-Maori participants were at high nutrition risk (SCREEN II score <49). Independent risk factors were for Maori younger age (p=0.04), lower education (p=0.03), living alone (p<0.001), depressive symptoms (p=0.01). For non- Maori high nutrition risk was associated with female gender (p=0.005), living alone (p=0.002), a lower physical health related quality of life (p=0.02) and depressive symptoms (p=0.002). CONCLUSION: Traditional risk factors apply to both Maori and non-Maori whilst education as indicative of low socioeconomic status is an additional risk factor for Maori. High nutrition risk impacts health related quality of life for non-Maori. Interventions which socially facilitate eating are especially important for women and for Maori to maintain cultural practices and could be initiated by routine screening.

The BRIGHT Trial: what are the factors associated with nutrition risk?

OBJECTIVES: To determine the nutrition risk status and factors associated with nutrition risk among older adults enrolled in the Brief Risk Identification Geriatric Health Tool (BRIGHT Trial). DESIGN: A cluster randomised controlled trial. SETTING: Three main centres in New Zealand. PARTICIPANTS: A total of 3,893 older adults were recruited from 60 general practices in three of the District Health Board (DHB) regions aged 75 years and older (or 65 years and older if Maori). MEASUREMENTS: Nutrition risk was assessed using the Australian Nutrition Screening Initiative (ANSI). Validated questionnaires were used to establish quality of life (WHOQOL-BREF), physical function (the Nottingham Extended Activities of Daily Living) and depressive symptoms (15 item Geriatric Depression Scale). Demographic, standard of living and health data were established. RESULTS: Sixty two percent of participants were identified to be at moderate or high nutrition risk. The mean ANSI score was 4.9 (range 0-21, maximum 29). Factors which independently predicted moderate or high nutrition risk were female gender, being Maori and other ethnicities versus European, not being married, taking multiple medications, having more depressive symptoms, cardiovascular disease and diabetes. Protective factors independently related to low nutrition risk were living with others, higher physical and social health related QOL and higher functional status. WHOQOL environmental and psychological factors were not associated with nutrition risk when other predictive factors were taken into account. CONCLUSION: Nearly two thirds of participants were identified to be at higher nutrition risk. Women, living alone, taking multiple medications, with depressive symptoms, cardiovascular disease and ndiabetes were factors associated with higher nutrition risk. Those at low nutrition risk had a better functional status and physical and social health related QOL.

The Diabetes Excess Weight Loss (DEWL) Trial: a randomised controlled trial of high-protein versus high-carbohydrate diets over 2 years in type 2 diabetes.

AIMS/HYPOTHESIS: To compare the effectiveness of low-fat high-protein and low-fat high-carbohydrate dietary advice on weight loss, using group-based interventions, among overweight people with type 2 diabetes. Study design Multicentre parallel (1:1) design, blinded randomised controlled trial. METHODS: Individuals with type 2 diabetes aged 30­75 years and a BMI >27 kg/m2 were randomised, by an independent statistician using sequentially numbered sealed envelopes, to be prescribed either a low-fat high-protein (30% of energy as protein, 40% as carbohydrate, 30% as fat) or a low-fat high carbohydrate(15% of energy as protein, 55%as carbohydrate,30% as fat) diet. Participants attended 18 group sessions over 12 months. Primary outcomes were change in weight and waist circumference assessed at baseline, 6 and 12 months.Secondary outcomes were body fatness, glycaemic control,lipid profile, blood pressure and renal function. A further assessment was undertaken 12 months after the intervention.Research assessors remained blinded to group allocation throughout. Intention-to-treat analysis was performed. RESULTS: A total of 419 participants were enrolled (mean±SDage 58±9.5 years,BMI 36.6±6.5 kg/m2 and HbA1c 8.1±1.2%(65 mmol/mol)). The study was completed by 70%(294/419).No differences between groups were found in change in weight or waist circumference during the intervention phase or the 12-month follow-up. Both groups had lost weight (2­3 kg, p<0.001) and reduced their waist circumference (2­3 cm, p<0.001) by 12 months and largely maintained this weight loss for the following 12 months. By 6 months, the difference in self-reported dietary protein between groups was small (1.1%total energy; p<0.001). No significant differences between groups were found in secondary outcomes: body fatness, HbA1c, lipids, blood pressure and renal function.There were no important adverse effects. CONCLUSIONS/INTERPRETATION: In a 'real-world' setting, prescription of an energy-reduced low-fat diet, with either increased protein or carbohydrate, results in similar modest losses in weight and waist circumference over 2 years

Roles of pre-treatment time and junctional proteins in Caco-2 cell microparticle uptake.

Microparticle uptake in the small intestine is relevant to both the delivery of pharmaceutics and exposure to environmental pollutants. The Caco-2 enterocyte model is a useful tool to study the parameters that affect epithelial microparticle permeability and the mechanisms controlling them. The current study used this model to explore further the different effects of 10% ethanol v/v or ice on transepithelial resistance (TER), microparticle uptake and immunofluorescent labelling of intercellular junctions. The same exposure times for both treatments were used, rather than those shown in the literature to produce demonstrable changes induced by each. The effects of both pre-treatments were greater after 60 min than after 15 min. Ethanol pre-treatment for 60 min decreased TER, increased particle uptake and was associated with a disorganisation of tight and adhering junctional proteins. Pre-treatment with ice for 60 min however, increased TER, decreased particle uptake and was associated with concentration of intercellular junctional proteins in a more constrained manner. These findings on the effects of pre-treatment with ethanol or ice for 60 min suggest that the extent of uptake is influenced by changes in the distribution of intercellular junctional proteins.

Culture conditions and treatments affect Caco-2 characteristics and particle uptake.

Small intestinal microparticle uptake via a paracellular route is relevant to oral drug delivery and environmental pollution. In vitro investigation uses latex microparticle passage across a confluent Caco-2 cell epithelium. This paper examines the influence of culture conditions on transepithelial resistance (TER); cell dimensions from confocal microscopy; and number of particles below the epithelium. Variables investigated include level of initial TER; multiple TER measurements; involvement of medium; cell source; and pretreatment with ethanol or a range of temperatures. Data were collected after exposure to 2 microm latex particles for 5-120 min: sham groups were exposed to pretreatment but not particles. The results highlight the importance of very precise control of the experimental environment; confirm the pattern of sequential-TER increase/decrease in groups exposed only to particles and show accompanying increases in cell dimensions. Greater particle uptake was associated with ethanol-induced decreased TER, decreased cell height and increased intercellular spaces, similar to previous findings for external irradiation. Low temperatures raised TER but, despite this, cooling did not alter particle uptake. In conclusion, culture microenvironment and sham treatment are crucial considerations in studies of epithelial microparticle uptake in vitro.

An association between ethnicity and cardiovascular outcomes for people with Type 2 diabetes in New Zealand.

AIMS: To investigate the association between ethnicity and risk of first cardiovascular (CV) event for people with Type 2 diabetes in New Zealand. METHODS: A prospective cohort study using routinely collected data from a national primary health care diabetes annual review programme linked to national hospital admission and mortality data. Ethnicity was recorded as European, Maori, Pacific, Indo-Asian, East-Asian or Other. A Cox proportional hazards model was used to investigate factors associated with first CV event. Data was collected from 48,444 patients with Type 2 diabetes, with first data collected between 1 January 2000 and 20 December 2005, no previous cardiovascular event at entry and with complete measurements. Risk factors included ethnicity, gender, socio-economic status, body mass index, smoking, age at diagnosis, duration of diabetes, systolic blood pressure, serum lipids, glycated haemoglobin and urine albumin : creatinine ratio. The main outcome measures were time to first fatal or non-fatal CV event. RESULTS: Median follow-up was 2.4 years. Using combined European and Other ethnicities as a reference, hazard ratios for first CV event were 1.30 for Maori (95% confidence interval 1.19-1.41), 1.04 for Pacific (0.95-1.13), 1.06 for Indo-Asian (0.91-1.24) and 0.73 for East-Asian (0.62-0.85) after controlling for all other risk factors. CONCLUSIONS: Ethnicity was independently associated with time to first CV event in people with Type 2 diabetes. Maori were at 30% higher risk of first CV event and East-Asian 27% lower risk compared with European/Other, with no significant difference in risk for Pacific and Indo-Asian peoples.

Parameters influencing intestinal epithelial permeability and microparticle uptake in vitro.

The hypothesis that, in vivo in situ, villous uptake of 2 microm latex microparticles involves changes at enterocyte tight junctions (TJs) was tested using Caco-2 cells on porous membranes. Epithelial permeability was measured by transepithelial resistance (TER) and particle numbers in surface, intraepithelial and sub-epithelial compartments by microscopy. Apical particle or medium addition initially closed TJs, but this was subsequently reversed in particle-treated groups. Peristaltic onward movement of a bolus was simulated by removing apical particles after an exposure period and leaving the remaining particles to interact with the epithelium: this produced marked TJ loosening during the interaction period. For particle exposure groups, the early similarity with particle numbers in vivo taken up in young adult rats became less marked with time, although bolus removal counteracted this tendency. The TJ response to vasoactive intestinal polypeptide (VIP) was time-dependent. Adsorbed and intraepithelial particle numbers increased with particle exposure time; epithelial-associated microparticle aggregation varied with treatment and submembranous particles were seen in all groups. Correlation between TER changes and particle numbers suggests TJ loosening may be important in microparticle uptake. This Caco-2 model gives epithelial particle numbers that approximate well to published figures for microparticle uptake in vivo and allows effective microenvironmental manipulation.

Factors influencing intestinal microparticle uptake in vivo.

The aim of this study is to compare microparticle uptake in animals of different ages, gender and species and at different time points. The 2mum latex/in vivo in situ model uses the observation of animal responses or post-mortem changes and also particle identification by fluorescence microscopy in nine sequential intestinal segments and secondary sites. The wide size range of animals studied requires particle numbers in tissue compartments to be related to intestinal tissue section area through a circumference measurement. Area under the curve (AUC) data for particles in intestinal tissue are plotted against measurements of intestinal length, allowing comparisons to be made across different ages and species and between males and females. The percentage uptake of administered dose and particle numbers in macerated tissue are also reported. Some parameters, in particular species, do not appear to affect the extent of microparticle uptake, which ranges from 0.12 to 0.32% of the administered dose. Particle uptake does, however, vary with age, being significantly greater in young adult males (7 weeks) than in younger (3 weeks) and older (17 and 52 weeks) age groups. It is concluded that age is more important in determining the extent of uptake than gender or species.

Polymorphism in the immunoglobulin VH gene V1-69 affects susceptibility to rheumatoid arthritis in subjects lacking the HLA-DRB1 shared epitope.

OBJECTIVE: To investigate the contribution of polymorphism in the immunoglobulin heavy chain variable region V1-69 gene set to genetic susceptibility to rheumatoid arthritis (RA) in Czech and British patients. METHODS: We used V1-69 gene sequence-specific polymerase chain reaction (PCR) and restriction enzyme digestion to study polymorphism in the V1-69 gene set in germline DNA of 109 Czech and 159 British RA patients and 164 ethnically matched controls. Polymorphism was further studied by nucleotide sequencing of the V1-69 gene locus in germline DNA. RESULTS: We found that all patients and controls had at least one V1-69 gene copy. In the Czech RA cohort, the dimorphic nucleotide in codon 73 of V1-69 (GAA or AAA) was present in the homozygous form 73(A/A) in 31 of 109 (28.4%) RA patients vs 12 of 79 (15.2%) controls [odds ratio (OR)=2.22, P<0.001]. When the RA patients and controls were classified according to HLA shared epitope (SE) status, 73(A/A) was found in 18 of 76 (23.7%) SE(+) patients compared with 13 of 38 (34.2%) SE(-) patients, four of 12 (18.2) SE(+) controls and eight of 57 (14%) SE(-) controls. This suggests that homozygosity for the dimorphic sequence 73(A) contributed to susceptibility to RA in SE(-) Czech individuals (OR=3.2, P<0.001). The most striking observation was that none of the 38 SE(-) Czech patients, compared with 11 of 76 (14.5%) SE(+) RA patients, three of 22 (13.6%) SE(+) and 11 of 57 (19.3%) SE(-) ethnically matched controls, were homozygous for the alternative dimorphic sequence 73(G/G) (OR=9.1, P<0.05). These data, however, were not replicated in a Caucasoid British RA population. CONCLUSION: The dimorphic sequence at codon 73 (73(A/A)) of the V1-69 gene contributes to genetic susceptibility in SE(-) Czech RA patients.

Rearrangement of the human heavy chain variable region gene V3-23 in transgenic mice generates antibodies reactive with a range of antigens on the basis of VHCDR3 and residues intrinsic to the heavy chain variable region.

To formulate a 'logic' for how a single immunoglobulin variable region gene generates antibodies with different antigen specificity and polyreactivity, we analysed chimeric antibodies produced in transgenic mice carrying the germ-line human V3-23 gene, multiple diversity (D) and joining (J) gene segments. Hybridomas producing antibodies encoded by the V3-23 gene in combination with different mouse Vkappa genes were obtained by fusion of splenocytes from transgenic mice. All antibodies had human mu-chains and mouse light chains, were multimeric in structure and expressed the human V3-23 gene. Nucleotide sequence analyses of genes encoding the heavy and light chains of 12 antibodies in relation to antigen specificity highlighted the importance of heavy chain variable region CDR3 in determining reactivity with different antigens. However, the results also suggest that non-CDR3 sequences intrinsic to the V3-23 gene itself may be involved in, or determine, the binding of the chimeric antibodies to some of the antigens tested in the current study.

Diurnal variation in orexin A immunoreactivity and prepro-orexin mRNA in the rat central nervous system.

Orexins are a family of neuropeptides originally believed to be important mediators of food intake. The wide distribution of orexins and their receptors, however, has suggested other regulatory functions for these peptides including involvement in sleep and arousal mechanisms. In this study, we have demonstrated diurnal variation in orexin A immunoreactivity in the pons, from where locus coeruleus noradrenergic neurones innervate other brain areas to stimulate arousal, and in the preoptic/anterior hypothalamic region, an area implicated in the regulation of sleep and circadian rhythms. Orexin A immunoreactivity decreased by 50% in the preoptic/anterior hypothalamus from 09:00 to 21:00 h (P < 0.0001), whilst in the pons, it increased by over 30% from 09:00 to 01:00 h (P = 0.02). Prepro-orexin mRNA also displayed diurnal variation. This further suggests that orexins are involved in the regulation of the sleep/wake cycle.

Rheumatoid factor isotype switch and somatic mutation variants within rheumatoid arthritis synovium.

The presence of clonally-related B-lymphocyte aggregates within synovial lining tisue of rheumatoid arthritis (RA) patients suggests a germinal centre-like reaction, which may hold implications for disease pathogenesis and the causes of chronic inflammation. We studied 250 rheumatoid factor (RF) heavy-chain sequences cloned from the synovium of three patients with RA, to determine whether they undergo both somatic mutation and isotype switching consistent with this hypothesis. Size analysis of immunoglobulin heavy-chain cDNAs from synovial RF+ B cells revealed oligoclonal RF+ populations and identically-sized VH-D-JH transcripts of different immunoglobulin isotypes. Sequencing of individual inserts selected from cloned immunoglobulin heavy-chain cDNAs demonstrated a clonal relationship between immunoglobulin M (IgM) RF and IgA RF, suggesting that this isotype switch occurred in synovium. Furthermore, most somatic mutations were found to have occurred after this isotype switch. This finding suggests that the RA synovial microenvironment sustains somatic mutation and isotype switching in RF-specific B lymphocytes akin to secondary lymphoid organs.

Loss of original antigenic specificity in T cell hybridomas transduced with a chimeric receptor containing single-chain Fv of an anti-collagen antibody and Fc epsilonRI-signaling gamma subunit.

T cell hybridomas HCQ6 and MD.45 acquired Ab-type specificity to collagen type II, when engrafted with a chimeric cell surface receptor, scC2Fv/gamma, which includes the single-chain Fv domain (scFv) of the anti-collagen type II mAb C2 and the signaling gamma subunit of the Fc epsilonRI. When transduced into MD.45 cells, scC2Fv/gamma or its mutated form lacking immunoreceptor tyrosine-based activation motif (ITAM), scC2Fv/gammaIC-, formed mainly homodimers. A small proportion of these molecules formed heterodimers with endogenous CD3zeta in these hybridoma cells. By contrast, in HCQ6 cells, the majority of scC2Fv/gamma and scC2Fv/gammaIC- molecules formed heterodimers with CD3zeta, and only a small proportion of them was expressed as homodimers. Stimulation with plastic-immobilized collagen induced IL-2 production in scC2Fv/gamma-transduced MD.45 cells, but not in MD.45 cells transduced with the ITAM-less chimera scC2Fv/gammaIC-. HCQ6 cells transduced with scC2Fv/gamma responded to plastic-bound collagen. Due to the high content of CD3zeta-associated chimeras, HCQ6 cells transduced with the ITAM-less scC2Fv/gammaIC- chimera were also responsive to plastic-bound collagen. When cells were stimulated with collagen in solution, MD.45 cells transduced with scC2Fv/gamma produced IL-2, whereas transduced HCQ6 cells were unresponsive, hence suggesting that the ability of cells transduced with scC2Fv chimeras to respond to soluble collagen correlated with predominant expression of divalent scC2Fv/gamma homodimers, but not monovalent scC2Fv/gamma-CD3zeta or scC2Fv/gammaIC(-)-CD3zeta heterodimers. Of interest, expression of CD3 subunits in hybridomas transduced with scC2Fv chimeras was reduced, resulting in decreased response to cognate Ags.

Differential use of immunoglobulin light chain genes and B lymphocyte expansion at sites of disease in rheumatoid arthritis (RA) compared with circulating B lymphocytes.

The presence of germinal centre-like structures and clonotypic expansion of lymphocytes in RA synovia may indicate a site-specific immune response to local antigens, rather than passively entrapped immune cells, that sustains synovial inflammation. In this study we compare the nature of immunoglobulin light chain variable region gene use in the synovium of RA patients with peripheral B cells to determine the nature of the synovial immune response. Using Vlambda and Vkappa gene fingerprinting, which relies on differences in CDR3 length, we demonstrate differences in the pattern of Vlambda and Vkappa use and clonotypic expansion of B cells between the synovium and peripheral blood of RA patients. Further, we show that some synovial rearrangements with long CDR3 are selectively expanded. These longer than usual CDR3 were generated by a number of mechanisms including N-additions. However, the observed differences were not uniform in different patients. These observations suggest that local synovial antigens drive significant numbers of T and B lymphocytes selected from an existing repertoire shaped by genetic and environmental factors. Further, the data argue against passive retention of most B cells in the synovium of RA patients.

Gene therapy for rheumatoid arthritis. Theoretical considerations.

Current understanding of the pathogenesis of rheumatoid arthritis has provided evidence that therapeutic benefit can be achieved by using antagonists targeted to the inflammatory cytokines involved, mainly tumour necrosis factor-alpha and interleukin-1. Gene delivery of antagonists, which can inhibit the production or action of these cytokines and other mediators, has been achieved in experimental animal models. This new method of delivery can produce therapeutic effects at lower concentrations and in a local environment, overcoming the adverse effects that often accompany protein therapy. However, several technological and biological restraints preclude the immediate adaptation of this method to human treatment. Based on the experimental evidence, possible target therapeutic genes, cell types and vector systems that could be used are discussed in this article.

Rheumatoid factor autoantibodies in health and disease.

Recent advances in molecular biological and human cell hybridization technology have significantly advanced the knowledge of mechanisms that underlie human rheumatoid factor (RF) production. These advances have provided insight into the etiopathogenesis of synovial inflammation and lymphocyte recruitment in rheumatoid arthritis (RA) joints. We have examined the mechanisms that lead to RF production in RA patients and those that regulate RF production in normals. The studies revealed structural features that distinguish RF produced in normals from those produced in RA synovial tissue. There are significant differences in the use of VL and VH genes between the two RF populations. Furthermore, IgV genes encoding synovial RF in RA have extensive evidence for nucleotide changes, leading to amino acid replacement in the complementarity determining regions (CDRs). In addition, RF produced in RA synovia show evidence for affinity maturation, isotype switch to IgG RF, and repertoire shift indicative of a continued recruitment of B cells. Together with computer modeling and crystallographic studies, our data suggest that the mechanisms that operate on RF selection in RA synovia are similar to immune responses to exogenous antigens. In contrast, RF established from human immunized donors (HID) are characterized by a very low ratio of replacement to silent (R:S) nucleotide changes in the CDR1+2. In addition, there is little increase in affinity with increasing numbers of mutations. There is thus evidence for regulatory mechanisms that limit affinity maturation of RF in normals.