Two functionally distinct subsets of IL-17 producing γδ T cells.

The γδ T cells play an important role in both mice and humans as a source of the cytokine IL-17, which is key for immune resistance to certain pathogens. In mice, most of these IL-17 producers, termed γδT-17 cells, actually comprise two distinct types: those expressing an invariant Vγ6Vδ1+ TCR and those expressing a Vγ4+ TCR. Murine γδT-17 cells acquire an inherent bias to produce IL-17 and other "type 17" cytokines during thymic development. The similarities and differences between the two mouse γδT-17 types are reviewed here, and the potential implications of their differences are discussed. There is some evidence that two distinct TCR-defined IL-17-producing γδ T cell subsets also exist in humans, but unlike the mouse γδT-17 cells, these cells are probably not imprinted with an IL-17 bias during thymic development, but rather acquire an IL-17 bias in the periphery.

Thinking inside the box: intracellular roles for complement system proteins come into focus.

Over the last decade, perspectives on the complement system in the context of cancer have shifted, with complement proteins now implicated in many of the hallmarks of cancer. Systemically, the generation of complement anaphylatoxin C5a, the most potent inflammatory mediator of the cascade, occurs following convertase-mediated cleavage of complement component C5. In a recent manuscript, Ding et al., propose that in colorectal cancer cells, C5 cleavage can occur intracellularly and in a convertase-independent manner, identifying cathepsin D as an enzyme capable of cleaving C5 into C5a [1]. Intracellular C5a is functional and promotes ß-catenin stabilisation via the assembly of a KCTD5/cullin3/Roc-1 complex. Importantly, the blockade of C5aR1 prevents tumorigenesis. This study adds to a growing body of evidence indicating that complement proteins, previously thought to primarily have extracellular or membrane-bound functions, also have important intracellular roles.

Filial Cannibalism Leads to Chronic Nest Failure of Eastern Hellbender Salamanders (Cryptobranchus alleganiensis).

AbstractIn species that provide parental care, parents will sometimes cannibalize their own young (i.e., filial cannibalism). Here, we quantified the frequency of whole-clutch filial cannibalism in a species of giant salamander (eastern hellbender; Cryptobranchus alleganiensis) that has experienced precipitous population declines with unknown causes. We used underwater artificial nesting shelters deployed across a gradient of upstream forest cover to assess the fates of 182 nests at 10 sites over 8 years. We found strong evidence that nest failure rates increased at sites with low riparian forest cover in the upstream catchment. At several sites, reproductive failure was 100%, mainly due to cannibalism by the caring male. The high incidence of filial cannibalism at degraded sites was not explained by evolutionary hypotheses for filial cannibalism based on poor adult body condition or low reproductive value of small clutches. Instead, larger clutches at degraded sites were most vulnerable to cannibalism. We hypothesize that high frequencies of filial cannibalism of large clutches in areas with low forest cover could be related to changes in water chemistry or siltation that influence parental physiology or that reduce the viability of eggs. Importantly, our results identify chronic nest failure as a possible mechanism contributing to population declines and observed geriatric age structure in this imperiled species.

Chronic pain in people living with dementia: challenges to recognising and managing pain, and personalising intervention by phenotype.

Pain is common in people with dementia, and pain can exacerbate the behavioural and psychological symptoms of dementia. Effective pain management is challenging, not least in people with dementia. Impairments of cognition, communication and abstract thought can make communicating pain unreliable or impossible. It is unclear which biopsychosocial interventions for pain management are effective in people with dementia, and which interventions for behavioural and psychological symptoms of dementia are effective in people with pain. The result is that drugs, physical therapies and psychological therapies might be either underused or overused. People with dementia and pain could be helped by assessment processes that characterise an individual's pain experience and dementia behaviours in a mechanistic manner, phenotyping. Chronic pain management has moved from a 'one size fits all' approach, towards personalised medicine, where interventions recommended for an individual depend upon the key mechanisms underlying their pain, and the relative values they place on benefits and adverse effects. Mechanistic phenotyping through careful personalised evaluation would define the mechanisms driving pain and dementia behaviours in an individual, enabling the formulation of a personalised intervention strategy. Central pain processing mechanisms are particularly likely to be important in people with pain and dementia, and interventions to accommodate and address these may be particularly helpful, not only to relieve pain but also the symptoms of dementia.

The facilitators and barriers to improving functional activity and wellbeing in people with dementia: a qualitative study from the process evaluation of Promoting Activity, Independence and Stability in Early Dementia (PrAISED).

BACKGROUND: The PRomoting Activity, Independence and Stability in Early Dementia (PrAISED) study delivered an exercise and functional activity programme to participants living with dementia. A Randomised Controlled Trial showed no measurable benefits in activities of daily living, physical activity or quality of life. OBJECTIVE: To explore participants' responses to PrAISED and explain why an intervention that might be expected to have produced measurable health gains did not do so. METHODS: A process evaluation using qualitative methods, comprising interviews and researcher notes. SETTING: Data were collected in participants' homes or remotely by telephone or videoconferencing. SAMPLE: A total of 88 interviews were conducted with 44 participants living with dementia (n = 32 intervention group; n = 12 control group) and 39 caregivers. A total of 69 interviews were conducted with 26 therapists. RESULTS: Participants valued the intervention as proactively addressing health issues that were of concern to them, and as a source of social contact, interaction, information and advice. Facilitators to achieving positive outcomes included perceiving progress towards desired goals, positive expectations, therapists' skills and rapport with participants, and caregiver support. Barriers included: cognitive impairment, which prevented independent engagement and carry-over between sessions; chronic physical health problems and intercurrent acute illness and injury; 'tapering' (progressively infrequent supervision intended to help develop habits and independent activity); and the COVID-19 pandemic. CONCLUSIONS: Self-directed interventions may not be appropriate in the context of dementia, even in the mild stages of the condition. Dementia-specific factors affected outcomes including caregiver support, rapport with therapists, availability of supervision, motivational factors and the limitations of remote delivery. The effects of cognitive impairment, multimorbidity and frailty overwhelmed any positive impact of the intervention. Maintenance of functional ability is valued, but in the face of inevitable progression of disease, other less tangible outcomes become important, challenging how we frame 'health gain' and trial outcomes.

Conversation Analysis Based Simulation (CABS): A method for improving communication skills training for healthcare practitioners.

BACKGROUND: Actors portraying simulated patients are widely used in communication skills training in healthcare, but debates persist over the authenticity of these interactions. However, healthcare professionals value simulation-based training because of the opportunity to think and react in real time, which alternatives cannot provide. OBJECTIVE: To describe a method for the use of simulation which maximises authenticity by grounding training in real, observed, patterns of patient communication. DESIGN: Naturally occurring care interactions were video recorded and analysed using conversation analysis (CA) to identify communication patterns. We focused on sites of recurring interactional trouble as areas for training, and identified more and less effective ways of dealing with these. We used the CA findings to train actors portraying simulated patients, based on the observed interactional patterns. SETTINGS AND PARTICIPANTS: Patients living with dementia and healthcare practitioners (HCPs) on two acute healthcare of the elderly wards in the English East Midlands. OUTCOME MEASURES: One month later HCPs reported using the skills learned in clinical practice. Masked-ratings of before and after simulated patient encounters confirmed these self-reports in relation to one key area of training. RESULTS: The Conversation Analysis Based Simulation (CABS) method used in this setting showed positive results across a range of quantitative and qualitative outcome measures. What is significant for the transferability of the method is that qualitative feedback from trainees highlighted the ability of the method to not only illuminate their existing effective practices, but to understand why these were effective and be able to articulate them to others. DISCUSSION/CONCLUSION: While the CABS method was piloted in the dementia care setting described here, it has potential applicability across healthcare settings where simulated consultations are used in communication skills training. Grounding simulated interaction in the observed communication patterns of real patients is an important means of maximising authenticity. PATIENT AND PUBLIC CONTRIBUTION: The VideOing to Improve dementia Communication Education (VOICE) intervention which piloted the CABS method was developed by a multidisciplinary team, including three carers of people with dementia. People living with dementia were involved in the rating of the before and after video simulation assessments.

Impact of COVID-19 lockdown on physical exercise among participants receiving the Promoting Activity, Independence and Stability in Early Dementia (PrAISED) intervention: a repeated measure study.

BACKGROUND: The potential decrease in daily physical activity associated with the COVID-19 pandemic lockdowns may have a negative impact on people living with dementia. Given the limited literature around the effects of home confinement in people living with dementia, this study investigated changes in physical exercise levels of participants in the intervention arm of the Promoting Activity, Independence and Stability in Early Dementia (PrAISED) Randomised Controlled Trial during the first COVID-19 national lockdown. It hypothesised that participants would maintain physical exercise levels. METHODS: A repeated measure (three time points) study involving 30 participants (mean age = 78.0 years, 15 male and 15 female, 22 (73.0%) living with their primary caregiver), from four regions in England receiving the PrAISED intervention. PrAISED is an individually tailored intervention of physical exercises and functional activities. Trained therapists deliver therapy sessions over a period of 52 weeks. Study participants received therapy sessions via phone or video calling during the COVID-19 lockdown. This study investigated self-reported minutes of physical exercise recorded on study calendars for the months of February (i.e., baseline - pre-lockdown), May (i.e., T1 - during lockdown), and August (i.e., T2-post-lockdown) 2020. RESULTS: Participants reported a statistically significant increase in activity levels between February and May (Wilcoxon Z = -2.013, p = 0.044) and a statistically significant decrease between May and August (Wilcoxon Z = -2.726, p = 0.004). No significant difference was found in the physical activity levels from pre- to post-lockdown (Wilcoxon Z = 0.485, p = 0.620). CONCLUSION: Despite concerns that the restrictions associated with the COVID-19 pandemic might lead to reductions in physical exercise, participants in receipt of the PrAISED intervention increased their amount of physical exercise during lockdown. Our findings support the potential of remote support for people living with dementia to help them maintain physical exercise levels in circumstances where face-to-face service provision is not possible. TRIAL REGISTRATION: The PrAISED trial and process evaluation have received ethical approval number 18/YH/0059 from the Bradford/Leeds Ethics Committee. The Clinical Trial Identifier for PrAISED is: ISRCTN15320670 ( https://doi.org/10.1186/ISRCTN15320670 ). Registration was made on 04/09/2018.

Clonal Vγ6+Vδ4+ T cells promote IL-17-mediated immunity against Staphylococcus aureus skin infection.

T cell cytokines contribute to immunity against Staphylococcus aureus, but the predominant T cell subsets involved are unclear. In an S. aureus skin infection mouse model, we found that the IL-17 response was mediated by γδ T cells, which trafficked from lymph nodes to the infected skin to induce neutrophil recruitment, proinflammatory cytokines IL-1α, IL-1ß, and TNF, and host defense peptides. RNA-seq for TRG and TRD sequences in lymph nodes and skin revealed a single clonotypic expansion of the encoded complementarity-determining region 3 amino acid sequence, which could be generated by canonical nucleotide sequences of TRGV5 or TRGV6 and TRDV4 However, only TRGV6 and TRDV4 but not TRGV5 sequences expanded. Finally, Vγ6+ T cells were a predominant γδ T cell subset that produced IL-17A as well as IL-22, TNF, and IFNγ, indicating a broad and substantial role for clonal Vγ6+Vδ4+ T cells in immunity against S. aureus skin infections.

Connection between γδ T-cell- and Adenosine- Mediated Immune Regulation in the Pathogenesis of Experimental Autoimmune Uveitis.

Regulatory effects of γδ T-cells on immune responses have been studied for years. We have investigated the regulatory effect of γδ T-cells on Th1 and Th17 autoimmune responses, and have studied molecular and cellular mechanisms by which γδ T-cells enhance or inhibit immune responses, exploiting a well-characterized murine model of experimental autoimmune uveitis (EAU). Our results show that (1) aberrant γδ T-cell activation is an important pathogenic event in EAU; (2) γδ T-cells have a unique regulatory effect on Th17 autoimmune responses, which is shaped by the activation status of γδ T-cells; and (3) γδ-mediated immunoregulation is closely linked with the extracellular adenosine metabolism. Reciprocal interactions between γδ T-cells and extracellular adenosine partially determine the development of EAU.

Microvascular Outcomes in Patients With Diabetes After Bariatric Surgery Versus Usual Care: A Matched Cohort Study.

Background: Bariatric surgery improves glycemic control in patients with type 2 diabetes mellitus (T2DM), but less is known about microvascular outcomes. Objective: To investigate the relationship between bariatric surgery and incident microvascular complications of T2DM. Design: Retrospective matched cohort study from 2005 to 2011 with follow-up through September 2015. Setting: 4 integrated health systems in the United States. Participants: Patients aged 19 to 79 years with T2DM who had bariatric surgery (n = 4024) were matched on age, sex, body mass index, hemoglobin A1c level, insulin use, diabetes duration, and intensity of health care use up to 3 nonsurgical participants (n = 11 059). Intervention: Bariatric procedures (76% gastric bypass, 17% sleeve gastrectomy, and 7% adjustable gastric banding) compared with usual care. Measurements: Adjusted Cox regression analysis investigated time to incident microvascular disease, defined as first occurrence of diabetic retinopathy, neuropathy, or nephropathy. Results: Median follow-up was 4.3 years for both surgical and nonsurgical patients. Bariatric surgery was associated with significantly lower risk for incident microvascular disease at 5 years (16.9% for surgical vs. 34.7% for nonsurgical patients; adjusted hazard ratio [HR], 0.41 [95% CI, 0.34 to 0.48]). Bariatric surgery was associated with lower cumulative incidence at 5 years of diabetic neuropathy (7.2% for surgical vs. 21.4% for nonsurgical patients; HR, 0.37 [CI, 0.30 to 0.47]), nephropathy (4.9% for surgical vs. 10.0% for nonsurgical patients; HR, 0.41 [CI, 0.29 to 0.58]), and retinopathy (7.2% for surgical vs. 11.2% for nonsurgical patients; HR, 0.55 [CI, 0.42 to 0.73]). Limitation: Electronic health record databases could misclassify microvascular disease status for some patients. Conclusion: In this large, multicenter study of adults with T2DM, bariatric surgery was associated with lower overall incidence of microvascular disease (including lower risk for neuropathy, nephropathy, and retinopathy) than usual care. Primary Funding Source: National Institute of Diabetes and Digestive and Kidney Diseases.

Bifidobacterium breve UCC2003 Employs Multiple Transcriptional Regulators To Control Metabolism of Particular Human Milk Oligosaccharides.

Bifidobacterial carbohydrate metabolism has been studied in considerable detail for a variety of both plant- and human-derived glycans, particularly involving the bifidobacterial prototype strain Bifidobacterium breve UCC2003. We recently elucidated the metabolic pathways by which the human milk oligosaccharide (HMO) constituents lacto-N-tetraose (LNT), lacto-N-neotetraose (LNnT) and lacto-N-biose (LNB) are utilized by B. breve UCC2003. However, to date, no work has been carried out on the regulatory mechanisms that control the expression of the genetic loci involved in these HMO metabolic pathways. In this study, we describe the characterization of three transcriptional regulators and the corresponding operator and associated (inducible) promoter sequences, with the latter governing the transcription of the genetic elements involved in LN(n)T/LNB metabolism. The activity of these regulators is dependent on the release of specific monosaccharides, which are believed to act as allosteric effectors and which are derived from the corresponding HMOs targeted by the particular locus.IMPORTANCE Human milk oligosaccharides (HMOs) are a key factor in the development of the breastfed-infant microbiota. They function as prebiotics, selecting for a specific range of microbes, including a number of infant-associated species of bifidobacteria, which are thought to provide a range of health benefits to the infant host. While much research has been carried out on elucidating the mechanisms of HMO metabolism in infant-associated bifidobacteria, to date there is very little understanding of the transcriptional regulation of these pathways. This study reveals a multicomponent transcriptional regulation system that controls the recently identified pathways of HMO metabolism in the infant-associated Bifidobacterium breve prototype strain UCC2003. This not only provides insight into the regulatory mechanisms present in other infant-associated bifidobacteria but also provides an example of a network of sequential steps regulating microbial carbohydrate metabolism.

γδ T Cells Shape Preimmune Peripheral B Cell Populations.

We previously reported that selective ablation of certain γδ T cell subsets, rather than removal of all γδ T cells, strongly affects serum Ab levels in nonimmunized mice. This type of manipulation also changed T cells, including residual γδ T cells, revealing some interdependence of γδ T cell populations. For example, in mice lacking Vγ4(+) and Vγ6(+) γδ T cells (B6.TCR-Vγ4(-/-)/6(-/-)), we observed expanded Vγ1(+) cells, which changed in composition and activation and produced more IL-4 upon stimulation in vitro, increased IL-4 production by αß T cells as well as spontaneous germinal center formation in the spleen, and elevated serum Ig and autoantibodies. We therefore examined B cell populations in this and other γδ-deficient mouse strains. Whereas immature bone marrow B cells remained largely unchanged, peripheral B cells underwent several changes. Specifically, transitional and mature B cells in the spleen of B6.TCR-Vγ4(-/-)/6(-/-) mice and other peripheral B cell populations were diminished, most of all splenic marginal zone (MZ) B cells. However, relative frequencies and absolute numbers of Ab-producing cells, as well as serum levels of Abs, IL-4, and BAFF, were increased. Cell transfers confirmed that these changes are directly dependent on the altered γδ T cells in this strain and on their enhanced potential of producing IL-4. Further evidence suggests the possibility of direct interactions between γδ T cells and B cells in the splenic MZ. Taken together, these data demonstrate the capability of γδ T cells of modulating size and productivity of preimmune peripheral B cell populations.

γδ T cells affect IL-4 production and B-cell tolerance.

γδ T cells can influence specific antibody responses. Here, we report that mice deficient in individual γδ T-cell subsets have altered levels of serum antibodies, including all major subclasses, sometimes regardless of the presence of αß T cells. One strain with a partial γδ deficiency that increases IgE antibodies also displayed increases in IL-4-producing T cells (both residual γδ T cells and αß T cells) and in systemic IL-4 levels. Its B cells expressed IL-4-regulated inhibitory receptors (CD5, CD22, and CD32) at diminished levels, whereas IL-4-inducible IL-4 receptor α and MHCII were increased. They also showed signs of activation and spontaneously formed germinal centers. These mice displayed IgE-dependent features found in hyper-IgE syndrome and developed antichromatin, antinuclear, and anticytoplasmic autoantibodies. In contrast, mice deficient in all γδ T cells had nearly unchanged Ig levels and did not develop autoantibodies. Removing IL-4 abrogated the increases in IgE, antichromatin antibodies, and autoantibodies in the partially γδ-deficient mice. Our data suggest that γδ T cells, controlled by their own cross-talk, affect IL-4 production, B-cell activation, and B-cell tolerance.

Using conversation analysis to inform role play and simulated interaction in communications skills training for healthcare professionals: identifying avenues for further development through a scoping review.

BACKGROUND: This paper responds to previously published debate in this journal around the use of sociolinguistic methods in communication skills training (CST), which has raised the significant question of how far consultations with simulated patients reflect real clinical encounters. This debate concluded with a suggestion that sociolinguistic methods offer an alternative analytic lens for evaluating CST. We demonstrate here that the utility of sociolinguistic methods in CST is not limited to critique, but also presents an important tool for development and delivery. METHODS: Following a scoping review of the use of role play and simulated interaction in CST for healthcare professionals, we consider the use of the specific sociolinguistic approach of conversation analysis (CA), which has been applied to the study of health communication in a wide range of settings, as well as to the development of training. DISCUSSION: Role play and simulated interaction have been criticised by both clinicians and sociolinguists for a lack of authenticity as compared to real life interactions. However they contain a number of aspects which healthcare professionals report finding particularly useful: the need to think on one's feet in real time, as in actual interaction with patients; the ability to receive feedback on the simulation; and the ability to watch and reflect on how others approach the same simulation task in real time. Since sociolinguistic approaches can help to identify inauthenticity in role play and simulation, they can also be used to improve authenticity. Analysis of real-life interactions using sociolinguistic methods, and CA in particular, can identify actual interactional practices that are used by particular patient groups. These practices can then be used to inform the training of actors simulating patients. In addition, the emphasis of CA on talk as joint activity means that proper account can be taken of the way in which simulated interaction is co-constructed between simulator and trainee. We suggest that as well as identifying potential weaknesses in current role play and simulation practice, conversation analysis offers the potential to enhance and develop the authenticity of these training methods.

Association Between Bariatric Surgery and Macrovascular Disease Outcomes in Patients With Type 2 Diabetes and Severe Obesity.

Importance: Macrovascular disease is a leading cause of morbidity and mortality for patients with type 2 diabetes, and medical management, including lifestyle changes, may not be successful at lowering risk. Objective: To investigate the relationship between bariatric surgery and incident macrovascular (coronary artery disease and cerebrovascular diseases) events in patients with severe obesity and type 2 diabetes. Design, Setting, and Participants: In this retrospective, matched cohort study, patients with severe obesity (body mass index ≥35) aged 19 to 79 years with diabetes who underwent bariatric surgery from 2005 to 2011 in 4 integrated health systems in the United States (n = 5301) were matched to 14 934 control patients on site, age, sex, body mass index, hemoglobin A1c, insulin use, observed diabetes duration, and prior health care utilization, with follow-up through September 2015. Exposures: Bariatric procedures (76% Roux-en-Y gastric bypass, 17% sleeve gastrectomy, and 7% adjustable gastric banding) were compared with usual care for diabetes. Main Outcomes and Measures: Multivariable-adjusted Cox regression analysis investigated time to incident macrovascular disease (defined as first occurrence of coronary artery disease [acute myocardial infarction, unstable angina, percutaneous coronary intervention, or coronary artery bypass grafting] or cerebrovascular events [ischemic stroke, hemorrhagic stroke, carotid stenting, or carotid endarterectomy]). Secondary outcomes included coronary artery disease and cerebrovascular outcomes separately. Results: Among a combined 20 235 surgical and nonsurgical patients, the mean (SD) age was 50 (10) years; 76% of the surgical and 75% of the nonsurgical patients were female; and the baseline mean (SD) body mass index was 44.7 (6.9) and 43.8 (6.7) in the surgical and nonsurgical groups, respectively. At the end of the study period, there were 106 macrovascular events in surgical patients (including 37 cerebrovascular and 78 coronary artery events over a median of 4.7 years; interquartile range, 3.2-6.2 years) and 596 events in the matched control patients (including 227 cerebrovascular and 398 coronary artery events over a median of 4.6 years; interquartile range, 3.1-6.1 years). Bariatric surgery was associated with a lower composite incidence of macrovascular events at 5 years (2.1% in the surgical group vs 4.3% in the nonsurgical group; hazard ratio, 0.60 [95% CI, 0.42-0.86]), as well as a lower incidence of coronary artery disease (1.6% in the surgical group vs 2.8% in the nonsurgical group; hazard ratio, 0.64 [95% CI, 0.42-0.99]). The incidence of cerebrovascular disease was not significantly different between groups at 5 years (0.7% in the surgical group vs 1.7% in the nonsurgical group; hazard ratio, 0.69 [95% CI, 0.38-1.25]). Conclusions and Relevance: In this observational study of patients with type 2 diabetes and severe obesity who underwent surgery, compared with those who did not undergo surgery, bariatric surgery was associated with a lower risk of macrovascular outcomes. The findings require confirmation in randomized clinical trials. Health care professionals should engage patients with severe obesity and type 2 diabetes in a shared decision making conversation about the potential role of bariatric surgery in the prevention of macrovascular events.

γδ T Cell-Dependent Regulatory T Cells Prevent the Development of Autoimmune Keratitis.

To prevent potentially damaging inflammatory responses, the eye actively promotes local immune tolerance via a variety of mechanisms. Owing to trauma, infection, or other ongoing autoimmunity, these mechanisms sometimes fail, and an autoimmune disorder may develop in the eye. In mice of the C57BL/10 (B10) background, autoimmune keratitis often develops spontaneously, particularly in the females. Its incidence is greatly elevated in the absence of γδ T cells, such that ∼80% of female B10.TCRδ(-/-) mice develop keratitis by 18 wk of age. In this article, we show that CD8(+) αß T cells are the drivers of this disease, because adoptive transfer of CD8(+), but not CD4(+), T cells to keratitis-resistant B10.TCRß/δ(-/-) hosts induced a high incidence of keratitis. This finding was unexpected because in other autoimmune diseases, more often CD4(+) αß T cells, or both CD4(+) and CD8(+) αß T cells, mediate the disease. Compared with wild-type B10 mice, B10.TCRδ(-/-) mice also show increased percentages of peripheral memory phenotype CD8(+) αß T cells, along with an elevated frequency of CD8(+) αß T cells biased to produce inflammatory cytokines. In addition, B10.TCRδ-/- mice have fewer peripheral CD4(+) CD25(+) Foxp3(+) αß regulatory T cells (Tregs), which express lower levels of receptors needed for Treg development and function. Together, these observations suggest that in B10 background mice, γδ T cells are required to generate adequate numbers of CD4(+) CD25(+) Foxp3(+) Tregs, and that in B10.TCRδ(-/-) mice a Treg deficiency allows dysregulated effector or memory CD8(+) αß T cells to infiltrate the cornea and provoke an autoimmune attack.

Leptin modifies the prosecretory and prokinetic effects of the inflammatory cytokine interleukin-6 on colonic function in Sprague-Dawley rats.

NEW FINDINGS: What is the central question of this study? Does crosstalk exist between leptin and interleukin-6 in colonic enteric neurons, and is this a contributory factor in gastrointestinal dysfunction associated with irritable bowel syndrome? What is the main finding and its importance? Leptin ameliorates the prosecretory and prokinetic effects of the pro-inflammatory cytokine interleukin-6 on rat colon. Leptin also suppresses the neurostimulatory effects of irritable bowel syndrome plasma, which has elevated concentrations of interleukin-6, on enteric neurons. This may indicate a regulatory role for leptin in immune-mediated bowel dysfunction. In addition to its role in regulating energy homeostasis, the adipokine leptin modifies gastrointestinal (GI) function. Indeed, leptin-resistant obese humans and leptin-deficient obese mice exhibit altered GI motility. In the functional GI disorder irritable bowel syndrome (IBS), circulating leptin concentrations are reported to differ from those of healthy control subjects. Additionally, IBS patients display altered cytokine profiles, including elevated circulating concentrations of the pro-inflammatory cytokine interleukin-6 (IL-6), which bears structural homology and similarities in intracellular signalling to leptin. This study aimed to investigate interactions between leptin and IL-6 in colonic neurons and their possible contribution to IBS pathophysiology. The functional effects of leptin and IL-6 on colonic contractility and absorptosecretory function were assessed in organ baths and Ussing chambers in Sprague-Dawley rat colon. Calcium imaging and immunohistochemical techniques were used to investigate the neural regulation of GI function by these signalling molecules. Our findings provide a neuromodulatory role for leptin in submucosal neurons, where it inhibited the stimulatory effects of IL-6. Functionally, this translated to suppression of IL-6-evoked potentiation of veratridine-induced secretory currents. Leptin also attenuated IL-6-induced colonic contractions, although it had little direct effect on myenteric neurons. Calcium responses evoked by IBS plasma in both myenteric and submucosal neurons were also suppressed by leptin, possibly through interactions with IL-6, which is elevated in IBS plasma. As leptin has the capacity to ameliorate the neurostimulatory effects of soluble mediators in IBS plasma and modulated IL-6-evoked changes in bowel function, leptin may have a role in immune-mediated bowel dysfunction in IBS patients.

Dermal γδ T cells--What have we learned?

Over the last several years, a number of papers have called attention to a distinct population of γδ T cells preferentially found in the dermis of the skin of normal mice. These cells appear to play an important role in promoting the development of psoriasis, but also are critical for host resistance to particular pathogens. They are characterized by the expression of a limited subset of γδ T cell receptors and a strong propensity to secrete IL-17. Perhaps most importantly, humans appear to carry an equivalent dermal γδ T cell population, likewise biased to secrete IL-17 and also implicated as playing a pathogenic role in psoriasis. This review will attempt to summarize and reconcile recent findings concerning the dermal γδ T cells.

Regulation of IgE Responses by γδ T Cells.

Immunoglobulin E (IgE) antibodies play a crucial role in host defense against parasite infections. However, inappropriate IgE responses are also involved in the pathogenesis of allergic diseases. The generation of IgE antibodies is a tightly controlled process regulated by multiple transcription factors, cytokines, and immune cells including γδ T cells. Accumulating evidence demonstrates that γδ T cells play a critical role in regulating IgE responses; however, both IgE-enhancing and IgE-suppressive effects are suggested for these cells in different experimental systems. In this review, we examine the available evidence and discuss the role of γδ T cells in IgE regulation both in the context of antigen-induced immune responses and in the state of partial immunodeficiency.

IL-23 receptor expression on γδ T cells correlates with their enhancing or suppressive effects on autoreactive T cells in experimental autoimmune uveitis.

We have previously reported that, depending on their activation status, mouse γδ T cells can either enhance or inhibit the activity of IL-17(+) autoreactive T cells in experimental autoimmune uveitis. In this study, we showed that γδ T cells in naive C57BL/6 (B6) mouse do not express the IL-23R, whereas in immunized mice, it is expressed on >50% of γδ T cells. In vitro studies showed that IL-23R expression on γδ T cells is modulated by their state of activation, as weakly activated γδ T cells expressed the IL-23R, but highly activated γδ T cells did not. Functional studies showed that IL-23R(+) γδ T cells had the strongest suppressive effect on IL-17(+) autoreactive T cells, and that this effect was inhibited when the IL-23R was blocked by anti-IL-23R Ab or in the presence of excessive amounts of exogenous IL-23. We conclude that the balance between the enhancing and inhibitory effects of γδ T cells is regulated by their level of IL-23R expression. The expression of variable IL-23R levels allows γδ T cells to have different regulatory effects on adaptive immune responses, conceivably as a result of αß and γδ T cells competing for IL-23.