Efficacy of sustained knowledge translation (KT) interventions in chronic disease management in older adults: systematic review and meta-analysis of complex interventions

BACKGROUND

Chronic disease management (CDM) through sustained knowledge translation (KT) interventions ensures long-term, high-quality care. We assessed implementation of KT interventions for supporting CDM and their efficacy when sustained in older adults.

METHODS

Design: Systematic review with meta-analysis engaging 17 knowledge users using integrated KT.

ELIGIBILITY CRITERIA

Randomized controlled trials (RCTs) including adults (> 65 years old) with chronic disease(s), their caregivers, health and/or policy-decision makers receiving a KT intervention to carry out a CDM intervention for at least 12 months (versus other KT interventions or usual care).

INFORMATION SOURCES

We searched MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials from each database's inception to March 2020.

OUTCOME MEASURES

Sustainability, fidelity, adherence of KT interventions for CDM practice, quality of life (QOL) and quality of care (QOC). Data extraction, risk of bias (ROB) assessment: We screened, abstracted and appraised articles (Effective Practice and Organisation of Care ROB tool) independently and in duplicate.

DATA SYNTHESIS

We performed both random-effects and fixed-effect meta-analyses and estimated mean differences (MDs) for continuous and odds ratios (ORs) for dichotomous data.

RESULTS

We included 158 RCTs (973,074 participants [961,745 patients, 5540 caregivers, 5789 providers]) and 39 companion reports comprising 329 KT interventions, involving patients (43.2%), healthcare providers (20.7%) or both (10.9%). We identified 16 studies described as assessing sustainability in 8.1% interventions, 67 studies as assessing adherence in 35.6% interventions and 20 studies as assessing fidelity in 8.7% of the interventions. Most meta-analyses suggested that KT interventions improved QOL, but imprecisely (36 item Short-Form mental [SF-36 mental]: MD 1.11, 95% confidence interval [CI] [- 1.25, 3.47], 14 RCTs, 5876 participants, I2 = 96%; European QOL-5 dimensions: MD 0.01, 95% CI [- 0.01, 0.02], 15 RCTs, 6628 participants, I2 = 25%; St George's Respiratory Questionnaire: MD - 2.12, 95% CI [- 3.72, - 0.51] 44 12 RCTs, 2893 participants, I2 = 44%). KT interventions improved QOC (OR 1.55, 95% CI [1.29, 1.85], 12 RCTS, 5271 participants, I2 = 21%).

CONCLUSIONS

KT intervention sustainability was infrequently defined and assessed. Sustained KT interventions have the potential to improve QOL and QOC in older adults with CDM. However, their overall efficacy remains uncertain and it varies by effect modifiers, including intervention type, chronic disease number, comorbidities, and participant age.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018084810.

Saving millions of lives but some resources squandered: emerging lessons from health research system pandemic achievements and challenges

During the SARS-CoV-2 pandemic, astonishingly rapid research averted millions of deaths worldwide through new vaccines and repurposed and new drugs. Evidence use informed life-saving national policies including non-pharmaceutical interventions. Simultaneously, there was unprecedented waste, with many underpowered trials on the same drugs. We identified lessons from COVID-19 research responses by applying WHO's framework for research systems. It has four functions-governance, securing finance, capacity-building, and production and use of research-and nine components. Two linked questions focused the analysis. First, to what extent have achievements in knowledge production and evidence use built on existing structures and capacity in national health research systems? Second, did the features of such systems mitigate waste? We collated evidence on seven countries, Australia, Brazil, Canada, Germany, New Zealand, the United Kingdom and the United States, to identify examples of achievements and challenges.We used the data to develop lessons for each framework component. Research coordination, prioritization and expedited ethics approval contributed to rapid identification of new therapies, including dexamethasone in the United Kingdom and Brazil. Accelerated vaccines depended on extensive funding, especially through the Operation Warp Speed initiative in the United States, and new platforms created through long-term biomedical research capacity in the United Kingdom and, for messenger ribonucleic acid (mRNA) vaccines, in Canada, Germany and the United States. Research capacity embedded in the United Kingdom's healthcare system resulted in trial acceleration and waste avoidance. Faster publication of research saved lives, but raised challenges. Public/private collaborations made major contributions to vastly accelerating new products, available worldwide, though unequally. Effective developments of living (i.e. regularly updated) reviews and guidelines, especially in Australia and Canada, extended existing expertise in meeting users' needs. Despite complexities, effective national policy responses (less evident in Brazil, the United Kingdom and the United States) also saved lives by drawing on health research system features, including collaboration among politicians, civil servants and researchers; good communications; and willingness to use evidence. Comprehensive health research strategies contributed to success in research production in the United Kingdom and in evidence use by political leadership in New Zealand. In addition to waste, challenges included equity issues, public involvement and non-COVID research. We developed recommendations, but advocate studies of further countries.

The Covid-19 Pandemic Has Exposed Opportunities To Strengthen Our Health Research Systems

Professor Sir Mark Walport, FRS, FMed Sci, FRCP, physicianscientist, academic leader and visionary health research planner, was the recipient of the 2020 Henry G. Friesen International Prize in Health Research. He is a former Chief Executive, UK Research and Innovation (UKRI) and UK government's Chief Scientific Advisor. He continues to be a champion of fundamental science in health research, engineering, technology and innovation, and is a major spokesperson on COVID-19 pandemic trends at the global level.

Can Systems Thinking Become "The Way We Do Things?" Comment on "What Can Policy-Makers Get Out of Systems Thinking? Policy Partners' Experiences of a Systems-Focused Research Collaboration in Preventive Health"

In "What Can Policy-Makers Get Out of Systems Thinking? Policy Partners’ Experiences of a Systems-Focused Research Collaboration in Preventive Health," Haynes et al glean two important insights from the policy-makers they interview. First: active promotion of systems thinking may work against its champions. Haynes and colleagues’ findings support a backgrounding of systems thinking; more important for policy-makers than understanding the finer details of systems thinking is working in situations of mutual learning and shared expertise. Second: coproduction may be getting short shrift in prevention research. Most participant comments were not about systems thinking, but about the benefits of working across sectors. Operationalizing the ‘co’ in co-production is not easy, but it may be where the pay-off will be for prevention researchers, who must understand the critical success factors of co-production and its potential pitfalls, to capitalize on its significant opportunities.

Re-imagining Research: A Bold Call, but Bold Enough? Comment on "Experience of Health Leadership in Partnering with University-Based Researchers in Canada: A Call to 'Re-Imagine' Research"

Many articles over the last two decades have enumerated barriers to and facilitators for evidence use in health systems. Bowen et al’s article "Response to Experience of Health Leadership in Partnering with University-Based Researchers: A Call to ‘Re-imagine Research’" furthers the debate by focusing on an under-explored research area (health system design and health service organization) with an under-studied stakeholder group (health system leaders), by undertaking a broad program of research on partnerships, and, based on participant responses, by calling for re-imagining of research itself. In response to the claim that the research community is not providing expertise to this pressing issue in the health system, I provide four high level reasons: partnerships mean different things to different people, our language does not reflect the reality we want, our health systems have yet to fully embrace evidence use, and complexity is easier to talk about than act within. Bowen et al’s study, and their broader program of research, is well-placed to explore these issues further, helping identify appropriate researcher-health system leader partnership models for various health system change projects. Given the positive shifts identified in this study, and the knowledge that participants demonstrate about what needs to change, the time is right for bold action, re-imagining not only research, but healthcare, such that the production and use of evidence for better health is embraced and supported.

Evaluation of the "Foundations in Knowledge Translation" training initiative: preparing end users to practice KT

BACKGROUND

Current knowledge translation (KT) training initiatives are primarily focused on preparing researchers to conduct KT research rather than on teaching KT practice to end users. Furthermore, training initiatives that focus on KT practice have not been rigorously evaluated and have focused on assessing short-term outcomes and participant satisfaction only. Thus, there is a need for longitudinal training evaluations that assess the sustainability of training outcomes and contextual factors that may influence outcomes.

METHODS

We evaluated the KT training initiative "Foundations in KT" using a mixed-methods longitudinal design. "Foundations in KT" provided training in KT practice and included three tailored in-person workshops, coaching, and an online platform for training materials and knowledge exchange. Two cohorts were included in the study (62 participants, including 46 "Foundations in KT" participants from 16 project teams and 16 decision-maker partners). Participants completed self-report questionnaires, focus groups, and interviews at baseline and at 6, 12, 18, and 24 months after the first workshop.

RESULTS

Participant-level outcomes include survey results which indicated that participants' self-efficacy in evidence-based practice (F(1,8.9) = 23.7, p = 0.001, n = 45), KT activities (F(1,23.9) = 43.2, p < 0.001, n = 45), and using evidence to inform practice increased over time (F(1,11.0) = 6.0, p = 0.03, n = 45). Interviews and focus groups illustrated that participants' understanding of and confidence in using KT increased from baseline to 24 months after the workshop. Interviews and focus groups suggested that the training initiative helped participants achieve their KT project objectives, plan their projects, and solve problems over time. Contextual factors include teams with high self-reported organizational capacity and commitment to implement at the start of their project had buy-in from upper management that resulted in secured funding and resources for their project. Training initiative outcomes include participants who applied the KT knowledge and skills they learned to other projects by sharing their knowledge informally with coworkers. Sustained spread of KT practice was observed with five teams at 24 months.

CONCLUSIONS

We completed a longitudinal evaluation of a KT training initiative. Positive participant outcomes were sustained until 24 months after the initial workshop. Given the emphasis on implementing evidence and the need to train implementers, these findings are promising for future KT training.

Engaging patients as partners in health research: Lessons from BC, Canada

Canada is seeing increased interest in engaging patients in health research, recognizing the potential to improve its relevance and quality. The momentum is promising, but there may be a tendency to ignore the challenges inherent when lay people and professionals collaborate. We address some of these challenges as they relate to recruitment, training, and support for patients at the British Columbia (BC) Support for People and Patient-Oriented Research Unit, part of Canada's Strategy for Patient-Oriented Research. A retrospective review of a telehealth project demonstrates that, as well as the practical elements of recruitment, training, and support, attention must be paid to issues of credibility, legitimacy, and power when engaging patients. We propose that all patient-oriented research projects would benefit from using a similar framework to guide patient engagement planning and implementation, helping to anticipate and mitigate challenges from the outset. Projects would ideally also include the study of patient engagement methods, to add to this important body of knowledge.

Reviewer training to assess knowledge translation in funding applications is long overdue

Background

Health research funding agencies are placing a growing focus on knowledge translation (KT) plans, also known as dissemination and implementation (D&I) plans, in grant applications to decrease the gap between what we know from research and what we do in practice, policy, and further research. Historically, review panels have focused on the scientific excellence of applications to determine which should be funded; however, relevance to societal health priorities, the facilitation of evidence-informed practice and policy, or realizing commercialization opportunities all require a different lens.

Discussion

While experts in their respective fields, grant reviewers may lack the competencies to rigorously assess the KT components of applications. Funders of health research—including health charities, non-profit agencies, governments, and foundations—have an obligation to ensure that these components of funding applications are as rigorously evaluated as the scientific components. In this paper, we discuss the need for a more rigorous evaluation of knowledge translation potential by review panels and propose how this may be addressed.

Conclusion

We propose that reviewer training supported in various ways including guidelines and KT expertise on review panels and modalities such as online and face-to-face training will result in the rigorous assessment of all components of funding applications, thus increasing the relevance and use of funded research evidence. An unintended but highly welcome consequence of such training could be higher quality D&I or KT plans in subsequent funding applications from trained reviewers.

Extracting DNA from 'jaws': high yield and quality from archived tiger shark (Galeocerdo cuvier) skeletal material

Archived specimens are highly valuable sources of DNA for retrospective genetic/genomic analysis. However, often limited effort has been made to evaluate and optimize extraction methods, which may be crucial for downstream applications. Here, we assessed and optimized the usefulness of abundant archived skeletal material from sharks as a source of DNA for temporal genomic studies. Six different methods for DNA extraction, encompassing two different commercial kits and three different protocols, were applied to material, so-called bio-swarf, from contemporary and archived jaws and vertebrae of tiger sharks (Galeocerdo cuvier). Protocols were compared for DNA yield and quality using a qPCR approach. For jaw swarf, all methods provided relatively high DNA yield and quality, while large differences in yield between protocols were observed for vertebrae. Similar results were obtained from samples of white shark (Carcharodon carcharias). Application of the optimized methods to 38 museum and private angler trophy specimens dating back to 1912 yielded sufficient DNA for downstream genomic analysis for 68% of the samples. No clear relationships between age of samples, DNA quality and quantity were observed, likely reflecting different preparation and storage methods for the trophies. Trial sequencing of DNA capture genomic libraries using 20 000 baits revealed that a significant proportion of captured sequences were derived from tiger sharks. This study demonstrates that archived shark jaws and vertebrae are potential high-yield sources of DNA for genomic-scale analysis. It also highlights that even for similar tissue types, a careful evaluation of extraction protocols can vastly improve DNA yield.

Age and growth of the tiger shark Galeocerdo cuvier off the east coast of Australia

Total lengths (L(T)) at age and growth rates for south-west Pacific Galeocerdo cuvier were estimated from vertebral growth-band counts of 202 sagitally sectioned centra from 112 females (71-430 cm L(T)), 79 males (72-351 cm L(T)) and 11 of unknown sex. Captive growth data were also examined to complement vertebral age estimations. The sexes combined modelled growth coefficient (k = 0.08) was smaller than previously reported for G. cuvier populations elsewhere. Split-band and narrow banding patterns were identified as potential sources of age underestimation in this species.

Evidence-informed healthcare through integration of health research

A foundational element of modern healthcare is an evidence-based practice. However, the conduct of research to generate evidence and the subsequent application of research findings are viewed by many Canadian healthcare organizations as separate from healthcare delivery. This mindset impedes effective translation of knowledge into practice. In this article, underlying issues that enable this disintegrated model to persist are described, and strategies to help healthcare organizations achieve integration of research are summarized.

Time to shift from systems thinking-talking to systems thinking-action: Comment on "Constraints to applying systems thinking concepts in health systems: A regional perspective from surveying stakeholders in Eastern Mediterranean countries"

A recent International Journal of Health Policy and Management (IJHPM) article by Fadi El-Jardali and colleagues makes an important contribution to the literature on health system strengthening by reporting on a survey of healthcare stakeholders in Low- and Middle-Income Countries (LMICs) about Systems Thinking (ST). The study's main contributions are its confirmation that healthcare stakeholders understand the importance of ST but do not know how to act on that understanding, and the call for collective action by the global community of systems thinkers committed to healthcare improvement. We offer three basic considerations for next steps by this community, derived from our recent work in ST and the related field of Knowledge Translation (KT): resist the temptation to adopt a reductionist approach; recognize not everyone needs to understand ST; and do not wait for everything to be in place before getting started.

How funding agencies can support research use in healthcare: an online province-wide survey to determine knowledge translation training needs

Background

Health research funding agencies are increasingly promoting evidence use in health practice and policy. Building on work suggesting how agencies can support such knowledge translation (KT), this paper discusses an online survey to assess KT training needs of researchers and research users as part of a Canadian provincial capacity-building effort.

Methods

The survey comprised 24 multiple choice and open-ended questions including demographics, interest in learning KT skills, likelihood of participating in training, and barriers and facilitators to doing KT at work. More than 1,200 people completed the survey. The high number of responses is attributed to an engagement strategy involving partner organizations (health authorities, research institutes, universities) in survey development and distribution. SPSS was used to analyze quantitative results according to respondents’ primary role, geographic region, and work setting. Qualitative results were analyzed in NVivo.

Results

Over 85 percent of respondents are interested in learning more about the top KT skills identified. Research producers have higher interest in disseminating research results; research users are more interested in the application of research results. About one-half of respondents require beginner-level training in KT skills; one-quarter need advanced training. Time and cost constraints are the biggest barriers to participating in KT training. More than one-half of respondents have no financial support for travel and almost one-half lack support for registration fees. Time is the biggest challenge to integrating KT into work.

Conclusions

Online surveys are useful for determining knowledge translation training needs of researchers, research users and ultimately organizations. In this case, findings suggest the importance of considering all aspects of KT in training opportunities, while taking into account different stakeholder interests. Funders can play a role in developing new training opportunities as part of a broad effort, with partners, to build capacity for the use of health research evidence. Survey results would ideally be complemented with an objective needs assessment based on core competencies, and should be acted on in a way that acknowledges the complexity of knowledge translation in healthcare, existing training activities, and the expertise stakeholders already have but may not refer to as knowledge translation.

A review of the application of molecular genetics for fisheries management and conservation of sharks and rays

Since the first investigation 25 years ago, the application of genetic tools to address ecological and evolutionary questions in elasmobranch studies has greatly expanded. Major developments in genetic theory as well as in the availability, cost effectiveness and resolution of genetic markers were instrumental for particularly rapid progress over the last 10 years. Genetic studies of elasmobranchs are of direct importance and have application to fisheries management and conservation issues such as the definition of management units and identification of species from fins. In the future, increased application of the most recent and emerging technologies will enable accelerated genetic data production and the development of new markers at reduced costs, paving the way for a paradigm shift from gene to genome-scale research, and more focus on adaptive rather than just neutral variation. Current literature is reviewed in six fields of elasmobranch molecular genetics relevant to fisheries and conservation management (species identification, phylogeography, philopatry, genetic effective population size, molecular evolutionary rate and emerging methods). Where possible, examples from the Indo-Pacific region, which has been underrepresented in previous reviews, are emphasized within a global perspective.

Nonatopic wheezy children have reduced interferon-gamma

Viruses cause asthmatic exacerbations in schoolchildren. We tested the hypothesis that children who wheezed with viral respiratory tract infections secrete higher levels of the type 1 cytokine interferon-gamma (IFN-gamma) in the peripheral circulation than children who had never wheezed. Blood was taken from 13 children (eight atopic) with episodic wheeze and 11 controls. CD4 and CD8 cells were separated from peripheral blood mononuclear cells and stimulated with phorbol 12-myrisate 13-acetate (PMA) and ionomycin for 24 h. IFN-gamma, IL-4, and IL-5 were measured in the supernatant by ELISA. IFN-gamma production by CD4 and CD8 cells was lower in children with a history of wheeze (CD4, P = 0.046; CD8, P = 0.037). These children were then analysed according to atopic status. CD4 and CD8 IFN-gamma production in nonatopic wheezy children was reduced (CD4, P=0.009; CD8, P=0.003). IFN-gamma production by atopic wheezy children was lower than by controls, but the differences were not significant (CD4, P = 0.2831; CD8, P = 0.1372). CD8 IL-5 was lower in children who wheezed (P=0.012). Release of IL-4 and IL-5 by CD4 cells did not differ between the three groups. We propose that defective IFN-gamma secretion by CD4 and CD8 cells may contribute to viral-induced wheeze in nonatopic children.

Ovalbumin-specific, MHC class I-restricted, alpha beta-positive, Tc1 and Tc0 CD8+ T cell clones mediate the in vivo inhibition of rat IgE

In the following study, we demonstrate that medium responder PVG rats immunized i.p. with OVA complexed to the adjuvant aluminum hydroxide exhibit a moderate IgE response (400-1000 ng/ml). In these rats, we demonstrate that underlying the MHC class II-restricted CD4+ T cell response, there is an MHC class I-restricted CD8+ T cell component that plays an important role in restricting the magnitude and duration of the IgE response. We show that in vivo depletion of CD8+ T cells effects a massive increase in IgE (20-fold), and that they are MHC class I-restricted, OVA-specific, cytolytic cells that universally produce IFN-gamma (25-69 ng/ml) and IL-2 (7.6-22 U/ml), and occasionally secrete IL-4 (68-81 U/ml IL-4), and when adoptively transferred into CD8-depleted recipients, can effect a significant reduction in IgE (3- to 50-fold). We also demonstrate that this in vivo inhibition of IgE is dependent on the Ag-specific activation of the CD8+ T cells, and that the activated CD8+ T cells will suppress total/bystander IgE in an Ag-nonspecific manner. These data are consistent with a growing literature demonstrating sensitization of MHC class I-restricted CD8+ T cells by exogenous protein Ags delivered to mucosal sites, and may represent a mechanism whereby a selective pressure can be applied on the functional outcome of an immunoglobulin response to environmental allergens.

Antigen-specific CD8+ T cells inhibit IgE responses and interleukin-4 production by CD4+ T cells

There is a growing body of evidence which suggests that CD8+ T cells play an important part in regulating the IgE response to non-replicating antigens. In this study we have systematically investigated their role in the regulation of IgE and of CD4+ T cell responses to ovalbumin (OVA) by CD8+ T cell depletion in vivo. Following intraperitoneal immunization with alum-precipitated OVA, OVA-specific T cell responses were detected in the spleen and depletion of CD8+ T cells in vitro significantly enhanced the proliferative response to OVA. Depletion of CD8+ T cells in vivo 7 days after immunization failed to enhance IgE production, while depletion of CD8+ T cells on days 12-18 greatly enhanced the IgE response, which rose to 26 micrograms/ml following a second injection of anti-CD8 on day 35 and remained in excess of 1 microgram/ml over 300 days afterwards. Reconstitution on day 21 of rats CD8-depleted on day 12 with purified CD8+ T cells from animals immunized on day 12 completely inhibited the IgE response. This effect was antigen specific; CD8+ T cells from OVA-primed animals had little effect on the IgE response of bovine serum albumin immunized rats. In vivo, CD8+ T cell depletion decreased interferon (IFN)-gamma production but enhanced interleukin (IL)-4 production by OVA-stimulated splenic CD4+ T cells. Furthermore, CD8+ T cell depletion and addition of anti-IFN-gamma antibody enhanced IgE production in vitro in an IL-4-supplemented mixed lymphocyte reaction. These data clearly show that antigen-specific CD8+ T cells inhibit IgE in the immune response to non-replicating antigens. The data indicate two possible mechanisms: first, CD8+ T cells have direct inhibitory effects on switching to IgE in B cells and second, they inhibit OVA-specific IL-4 production but enhance IFN-gamma production by CD4+ T cells.

Generation of rat MHC class-I-restricted ovalbumin-specific IgE inhibitory CD8+ T cell clones

Allergic disease presents an increasing health problem in industrialised countries. Despite improved diagnosis and drug therapy, the number of fatalities from asthma and anaphylaxis continues to rise. A key element in the aetiology of the allergic response to inert protein antigens is an inherent imbalance in the atopic allergen specific CD4+ T cells, resulting in a dominance of the pathological, IL-4 producing, T helper 2 phenotype which favours B cell IgE production. Previous work from our laboratory, and elsewhere, has established that CD8+ T cells play an important role in regulating the magnitude and duration of IgE responses and may be vital for the restoration of IgE immunologic homoeostasis in 'normal' non-atopic humans and low/medium responder rodents. We have found that CD8+ T cell depletion during a critical period after immunization produces a high and persistent IgE response in otherwise IgE hyporesponsive animals. We and others have demonstrated that small, but important, quantities of soluble antigen can enter the MHC class I pathway and, using ovalbumin (OVA)-transfected antigen-presenting cells, have succeeded in cloning OVA-specific, MHC class I-restricted rat alpha/beta T cell receptor (TcR) positive CD8+ T cells. These cells universally secrete IFN-gamma (5-69 ng/ml) and IL-2 (7.6-37.0 U/ml) and occasionally IL-4 (16.0-8/1.0 IU). When adoptively transferred, 1 x 10(6) of these cloned cells inhibit IgE production in vivo by as much as 50-fold and this effect can be titrated down to 1 x 10(3) cells. The IgE regulatory activity of the clones appears unrelated to their cytolytic potential or to their capacity to make IFN-gamma.

Depletion of CD8+ T cells following primary immunization with ovalbumin results in a high and persistent IgE response

The role of CD8+ T cells in the regulation of IgE was investigated by in vivo CD8+ T-cell depletion. Following intraperitoneal immunization with ovalbumin (OVA), OVA-specific T cell responses were first detected in the draining lymph nodes (LN) and subsequently in the spleen. In vitro depletion of LN CD8+ cells reduced the OVA-specific LN CD4+ T cell response; while depletion of splenic CD8+ cells enhanced the OVA-specific splenic CD4+ T cell response, suggesting an early helper and later suppressor function. CD8+ cell depletion in vivo up to 7 days after immunization failed to enhance IgE production, but depletion of CD8+ T cells between day 12 and day 18 increased IgE levels to over 10 microg/ml. Adoptive transfer of 1 x 10(7) purified CD8+ T cells (> 95% CD8+ > 98% CD3+ < 1% NK, < 1% CD4+) from parallel immunized rats or of 1 x 106 cells of an OVA-specific, MHC class I restricted CD8+ T cell line suppressed the IgE, but not IgG, response by > 95%. These results provide further evidence that CD8+ T cells inhibit IgE production, possibly by preventing the generation of adequate amounts of appropriate CD4+ T cell help.

The contrasting effects of CD8+ T cells on primary, established and Nippostrongylus brasiliensis-induced IgE responses

Recent data have indicated that CD8+ T cells suppress rodent IgE responses. In this study we investigated the effect of CD8+ T cells on primary and established IgE responses in euthymic and athymic nude rats. Euthymic PVG rats were depleted of CD8+ T cells by intraperitoneal injection of a CD8-specific monoclonal antibody (OX8), which resulted in an apparent loss of 92% of splenic and 98% of peripheral blood CD8+ T cells. The CD8+ T-cell depleted animals failed to mount a significant IgE response compared with control animals given an irrelevant monoclonal antibody (OX21). Furthermore, PVG nude rats reconstituted with purified CD4+ thoracic duct lymphocytes (TDL) alone failed to mount a significant IgE response, while animals given unfractionated TDL (containing CD4+ and CD8+ T cells) did. Depletion of CD8+ T cells 7 days prior to immunization and subsequent reconstitution at the time of immunization restored the IgE response. In contrast, removal of CD8+ T cells 1 month after induction of IgE by immunization with ovalbumin (OVA) and ricin prolonged the IgE response. In all cases IgG antibody responses were unaffected by the presence or absence of CD8+ T cells. This study shows that some CD8+ T cells are required for IgE, but not IgG, production to soluble antigen in a primary immune response. However, later in the immune response CD8+ T cells were shown to inhibit IgE production. These effects were apparently restricted to the immune response to soluble antigen, as Hooded Lister rats infected with 9000 larvae of the nematode Nippostrongylus brasiliensis produced high sustained levels of circulating IgE, in excess of 10 micrograms/ml, regardless of whether CD8+ T cells were depleted before or 1 month after infection.

The role of CD8+ T cells in immunoglobulin E regulation

The link between immunoglobulin E (IgE) antibodies and environmental allergens, allergic sensitization and atopic diseases such as asthma, rhinitis and eczema is well established, yet treatment of these diseases is largely symptomatic and fails to correct the underlying immune disorder. B-cell production of IgE depends on interleukin 4 (IL-4) and is inhibited by interferon (IFN-gamma). These cytokines are produced by T-helper 2 (Th2) and T-helper 1 (Th1) CD4+ T cells respectively. In atopic dermatitis skin and asthmatic lung, Th2 cells predominate but antigen-specific CD4+ T-cell clones derived from peripheral blood are a mixture of Th1, Th2, and Th0. Circulating allergen-specific CD4+ T cells differentiate into Th1- and Th2-like clones in the presence of IL-12 and IL-4 respectively. In rats, CD8+ T cells are potent regulators of IgE responses in vivo, although the mechanism for this is still unclear. CD8+ T-cell depletion in immunized animals prolonged the IgE response but prior depletion did not. Indeed, prior depletion of CD8+ T cells actually inhibited IgE production, suggesting that there may be more than one type of IgE regulatory CD8+ T cell. This was supported by the observation that CD8+ T cells inhibited the differentiation of both Th1 and Th2 CD4+ T cells in vitro as well as IL-4- but not IL-2-induced Th2 CD4+ T-cell growth. The existence of distinct CD8+ T-cell subsets is supported by the observation that IL-4 and IFN-gamma regulate the growth and differentiation of CD8+ T cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Immune regulation: a new role for the CD8+ T cell

During an immune response, peripheral T cells develop into functionally distinct subpopulations that effect cell-mediated immunity and regulate humoral immune responses through the secretion of specific cytokines. Recent data suggest that CD8+ T cells, which have long been regarded simply as cytotoxic cells, play a more active role in the regulation of the immune response. In this article, Mike Kemeny and colleagues suggest that there are functionally distinct subsets of CD8+ T cells that produce different combinations of cytokines and appear to play an important part in determining the pattern of cytokines produced by CD4+ T cells and the isotype of immunoglobulins expressed by B cells.

Moxalactam therapy of difficult infections in patients with serious underlying conditions

Moxalactam was the single therapeutic agent used to treat a variety of infections in sixty-three patients, most of whom had serious concomitant illnesses. Fifty-three patient case reports qualified for evaluation, including those with pneumonia (8), urinary tract infections (18), superficial infections (6), orthopaedic infections (7), osteomyelitis (8), septicaemia (4), pansinusitis (1), and meningitis (1). Preliminary in vitro studies had indicated that most organisms, including those resistant to other antibacterial agents, would respond to moxalactam. Infecting bacteria from the fifty-three evaluable patients included a wide variety of Gram-positive and Gram-negative organisms. Doses of moxalactam ranged from 1 to 16 g/day administered intravenously or intramuscularly for 5 to 41 days. With few explainable exceptions, clinical and bacteriologic responses were adequate and satisfactory. Adverse effects were inconsequential. Allergic reactions were not observed, even in patients with a past history of reactions to penicillin.