gamma/delta and other unconventional T lymphocytes: what do they see and what do they do?

The foreign body response: emerging cell types and considerations for targeted therapeutics

The foreign body response (FBR) remains a clinical challenge in the field of biomaterials due to its ability to elicit a chronic and sustained immune response. Modulating the immune response to materials is a modern paradigm in tissue engineering to enhance repair while limiting fibrous encapsulation and implant isolation. Though the classical mediators of the FBR are well-characterized, recent studies highlight that our understanding of the cell types that shape the FBR may be incomplete. In this review, we discuss the emerging role of T cells, stromal-immune cell interactions, and senescent cells in the biomaterial response, particularly to synthetic materials. We emphasize future studies that will deepen the field's understanding of these cell types in the FBR, with the goal of identifying therapeutic targets that will improve implant integration. Finally, we briefly review several considerations that may influence our understanding of the FBR in humans, including rodent models, aging, gut microbiota, and sex differences. A better understanding of the heterogeneous host cell response during the FBR can enable the design and development of immunomodulatory materials that favor healing.

Vaccine development against tuberculosis before and after Covid-19

Coronavirus disease (Covid-19) has not only shaped awareness of the impact of infectious diseases on global health. It has also provided instructive lessons for better prevention strategies against new and current infectious diseases of major importance. Tuberculosis (TB) is a major current health threat caused by Mycobacterium tuberculosis (Mtb) which has claimed more lives than any other pathogen over the last few centuries. Hence, better intervention measures, notably novel vaccines, are urgently needed to accomplish the goal of the World Health Organization to end TB by 2030. This article describes how the research and development of TB vaccines can benefit from recent developments in the Covid-19 vaccine pipeline from research to clinical development and outlines how the field of TB research can pursue its own approaches. It begins with a brief discussion of major vaccine platforms in general terms followed by a short description of the most widely applied Covid-19 vaccines. Next, different vaccination regimes and particular hurdles for TB vaccine research and development are described. This specifically considers the complex immune mechanisms underlying protection and pathology in TB which involve innate as well as acquired immune mechanisms and strongly depend on fine tuning the response. A brief description of the TB vaccine candidates that have entered clinical trials follows. Finally, it discusses how experiences from Covid-19 vaccine research, development, and rollout can and have been applied to the TB vaccine pipeline, emphasizing similarities and dissimilarities.

Graft-versus-host disease is associated with skewed γδ T-cell clonality after umbilical cord blood transplantation in children with nonmalignant diseases

BACKGROUND AIMS

The γδ T-cells (GDT) are a subpopulation of lymphocytes expressing a distinct T-cell receptor coded by the TRG and TRD genes. GDTs may have immunoregulatory function after stem cell transplantation (SCT), but the relationship between GDT clonality and acute graft-versus-host disease (aGVHD) is not known.

METHODS

We prospectively studied spectratype complex complexity of TCR Vγ (γ) and TCR Vδ (δ) pre-SCT and at approximately day 100 and day 180 post-SCT in a cohort of immunocompetent children receiving allogeneic umbilical cord blood SCT for nonmalignant diseases, with identical reduced-intensity conditioning and aGVHD prophylaxis.

RESULTS

We studied 13 children undergoing SCT at a median age of 0.9 years (total range 0.4-16.6). In those with grade 0-1 aGVHD (N = 10), the spectratype complexity of most γ and δ genes was not significantly different from baseline at day 100 or day 180 post-SCT, and there was balanced expression of genes at the γ and δ loci. In those with grade 3 aGVHD (N = 3), spectratype complexity was significantly below baseline at day 100 and day 180, and there was relative overexpression of δ2. CD3+ cell counts were also lower in participants with grade 3 aGVHD.

CONCLUSIONS

Recovery of a polyclonal GDT repertoire is an early part of immunological recovery after SCT. γ and δ gene expression is balanced in young children before and after SCT. Severe aGVHD is associated with GDT oligoclonality post-SCT and with skewed expression of δ2, which has not been previously reported. This association may reflect aGVHD therapy or aGVHD-associated immune dysregulation. Further studies of GDT clonality during the early post-SCT period may establish whether abnormal GDT spectratype precedes the clinical manifestations of aGVHD.

MicroRNA in medication related osteonecrosis of the jaw: a review

Medication related osteonecrosis of the jaw (MRONJ) is a condition caused by inhibition of the osteoclast activity by the anti-resorptive and anti-angiogenic drugs. Clinically, there is an exposure of the necrotic bone or a fistula which fails to heal for more than 8 weeks. The adjacent soft tissue is inflamed and pus may be present as a result of the secondary infection. To date, there is no consistent biomarker that could aid in the diagnosis of the disease. The aim of this review was to explore the literature on the microRNAs (miRNAs) related to medication related osteonecrosis of the jaw, and to describe the role of each miRNA as a biomarker for diagnostic purpose and others. Its role in therapeutics was also searched. It was shown that miR-21, miR-23a, and miR-145 were significantly different in a study involving multiple myeloma patients as well as in a human-animal study while miR-23a-3p and miR-23b-3p were 12- to 14-fold upregulated compared to the control group in an animal study. The role of the microRNAs in these studies were for diagnostics, predictor of progress of MRONJ and pathogenesis. Apart from its potential diagnostics role, microRNAs have been shown to be bone resorption regulator through miR-21, miR-23a and miR-145 and this could be utilized therapeutically.

The role of unconventional T cells in COVID-19

COVID-19 is a respiratory disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It was first documented in late 2019, but within months, a worldwide pandemic was declared due to the easily transmissible nature of the virus. Research to date on the immune response to SARS-CoV-2 has focused largely on conventional B and T lymphocytes. This review examines the emerging role of unconventional T cell subsets, including γδ T cells, invariant natural killer T (iNKT) cells and mucosal associated invariant T (MAIT) cells in human SARS-CoV-2 infection.

Some of these T cell subsets have been shown to play protective roles in anti-viral immunity by suppressing viral replication and opsonising virions of SARS-CoV. Here, we explore whether unconventional T cells play a protective role in SARS-CoV-2 infection as well. Unconventional T cells are already under investigation as cell-based immunotherapies for cancer. We discuss the potential use of these cells as therapeutic agents in the COVID-19 setting. Due to the rapidly evolving situation presented by COVID-19, there is an urgent need to understand the pathogenesis of this disease and the mechanisms underlying its immune response. Through this, we may be able to better help those with severe cases and lower the mortality rate by devising more effective vaccines and novel treatment strategies.

The dark side of the spoon - glucose, ketones and COVID-19: a possible role for ketogenic diet?

The novel coronavirus disease (COVID-19) is posing a serious challenge to the health-care systems worldwide, with an enormous impact on health conditions and loss of lives. Notably, obesity and its related comorbidities are strictly related with worse clinical outcomes of COVID-19 disease. Recently, there is a growing interest in the clinical use of ketogenic diets (KDs), particularly in the context of severe obesity with related metabolic complications. KDs have been proven effective for a rapid reduction of fat mass, preserving lean mass and providing an adequate nutritional status. In particular, the physiological increase in plasma levels of ketone bodies exerts important anti-inflammatory and immunomodulating effects, which may reveal as precious tools to prevent infection and potential adverse outcomes of COVID-19 disease. We discuss here the importance of KDs for a rapid reduction of several critical risk factors for COVID-19, such as obesity, type 2 diabetes and hypertension, based on the known effects of ketone bodies on inflammation, immunity, metabolic profile and cardiovascular function. We do believe that a rapid reduction of all modifiable risk factors, especially obesity with its metabolic complications, should be a pillar of public health policies and interventions, in view of future waves of SARS-CoV-2 infection.

Single-Cell Sequencing of T cell Receptors: A Perspective on the Technological Development and Translational Application

T cells recognize peptides bound to major histocompatibility complex (MHC) class I and class II molecules at the cell surface. This recognition is accomplished by the expression of T cell receptors (TCR) which are required to be diverse and adaptable in order to accommodate the various and vast number of antigens presented on the MHCs. Thus, determining TCR repertoires of effector T cells is necessary to understand the immunological process in responding to cancer progression, infection, and autoimmune development. Furthermore, understanding the TCR repertoires will provide a solid framework to predict and test the antigen which is more critical in autoimmunity. However, it has been a technical challenge to sequence the TCRs and provide a conceptual context in correlation to the vast number of TCR repertoires in the immunological system. The exploding field of single-cell sequencing has changed how the repertoires are being investigated and analyzed. In this review, we focus on the biology of TCRs, TCR signaling and its implication in autoimmunity. We discuss important methods in bulk sequencing of many cells. Lastly, we explore the most pertinent platforms in single-cell sequencing and its application in autoimmunity.

Analysis of the Healthy Subject Response to Prolonged Contact with Tuberculosis Patients

Prolonged contact of healthy subjects with Mycobacterium tuberculosis can change their blood formula and immune status, thus reflecting adaptive reactions to constant antigenic load. The peripheral blood analysis of health care workers in a tuberculosis hospital demonstrates changes in cell populations which prevent development of tuberculosis, in particular, CD⁴⁺ Т cells and CD³⁺ Т cells. It is shown that the number of the memory CD⁴⁺ Т cells specific to M.tuberculosis antigens which produce interferon gamma depends on the duration of work contact with tuberculosis patients. The use of health care workers' blood characteristics as a control for tuberculosis patients is discussed.

The association between adherence with oral bisphosphonates and the risk of breast cancer in post-menopausal women

Background

Several observational studies have suggested a protective effect of oral bisphosphonates (BP) on the risk of breast cancer, but no such association has been seen in randomized control trials. The role of oral BP in breast cancer prevention remains unclear.

Aim

To investigate the association between different levels of BP exposure and breast cancer incidence in a cohort of osteoporotic post-menopausal women.

Subjects and methods

This historical prospective study was conducted using the computerized databases of Maccabi Healthcare Services (MHS) in Israel. Included in the study were osteopenic and osteoporotic women aged 55–75 years who started BP therapy between 1998 and 2012. The subjects were enrolled in MHS for at least 3 years before therapy initiation, and had a minimum follow-up of 5 years in MHS. Women with a previous cancer, and women treated with selective estrogen receptor modulators (SERMs) were excluded. BP exposure was expressed in quintiles of proportion of days covered (PDC) with BP during follow-up period and cancer incidence was ascertained by the Israel National Tumor Registry. Person-years of follow-up began on January 1st, 1998 and ended at the date of cancer diagnosis, death, or December 31st, 2012, whichever occurred first.

Results

A total of 11,717 patients (mean age = 66.87 ± 4.38) were eligible for the analysis. During a total of 130,252 person-years of follow-up, (mean 7.2 years) 173 incident cases of breast cancer were diagnosed. Compared to women with a PDC with BP of 20% or lower, the adjusted hazard ratio for breast cancer were HR = 0.81 (95%CI: 0.48–1.39), HR = 0.82 (95%CI: 0.50–1.33), HR = 0.72 (95%CI:0.45–1.15) and HR = 1.14 (95%CI:0.76–1.70) among women with 20–40%, 40–60%, 60%–80%, and 80% or higher, PDC, respectively.

Conclusion

In this study, we did not find a significant association between oral BP therapy for osteoporosis and the risk of breast cancer in postmenopausal women. The discrepancy between our results and the reports of such an association in observational studies might originate from an indication bias.

Usage of Droplet Digital PCR (ddPCR) Assays for T Cell Quantification in Cancer

T cells fulfill a central role in cell-mediated immunity and can be found in the circulation and lymphoid organs upon maturation. For clinical applications, it can be important to quantify (infiltrated) T cells accurately in a variety of body fluids and tissues of benign, inflammatory, or malignant origin. For decades, flow cytometry and immunohistochemistry have been the accustomed methods to quantify T cells. Although these methods are widely used, they depend on the accessibility of T-cell epitopes and therefore require fresh, frozen, or fixated material of a certain quality. Whenever samples are low in quantity or quality, an accurate quantification can be impeded. By shifting the focus from epitopes to DNA, quantification of T cells remains achievable.Mature T cells differ genetically from other cell types as a result of T-cell receptor (TCR) gene rearrangements. This genetic dissimilarity can be exploited to quantify the T-cell fraction in DNA specimens. Conventionally, multiplex PCR and droplet digital PCR (ddPCR), combined with deep-sequencing techniques, can be applied to determine T-cell content. However, these approaches typically target the whole TCR repertoire, thereby supplying additional information about TCR use. Considering this, a simple T-cell quantification, unwantedly, turns into a complex, expensive, and time-consuming procedure. We have developed two generic single duplex ddPCR assays as alternative methods to quantify T cells in a relatively simple, cheap, and fast manner by targeting sequences located between the Dδ2 and Dδ3 genes (TRD locus) and Dβ1 and Jβ1.1 genes (TRB locus). These specific TCR loci become deleted systematically early during lymphoid differentiation and therefore will serve as biomarkers for the quantification of mature T cells. Here, we describe a simple and sensitive ddPCR-based method to quantify T cells relatively fast, accurately and independently of the cellular context.

IL-17 Production from T Helper 17, Mucosal-Associated Invariant T, and γδ Cells in Tuberculosis Infection and Disease

IL-17-producing cells have been shown to be important in the early stages of Mycobacterium tuberculosis (Mtb) infection in animal models. However, there are very little data on the role of IL-17 in human studies of tuberculosis (TB). We recruited TB patients and their highly exposed contacts who were further categorized based on results from an IFN-γ-release assay (IGRA): (1) IGRA positive (IGRA+) at recruitment (latently TB infected), (2) IGRA negative (IGRA-) at recruitment and 6 months [non-converters (NC)], and (3) IGRA- at recruitment and IGRA+ at 6 months (converters). Whole blood was stimulated with mycobacterial antigens and analyzed using T helper (Th) 17 multiplex cytokine assays. Th17, Vγ9Vδ2+, and CD161++Vα7.2+ mucosal-associated invariant T (MAIT) cells were analyzed by flow cytometry. The majority of IL-17 was produced by CD26+CD4+ Th17 cells (median 71%) followed by γδ T cells (6.4%) and MAIT cells (5.8%). TB patients had a significantly lower proportion of Th17 cells and CD4+CD161+Vα7.2+ cells producing both IL-17 and IFN-γ compared to LTBI subjects. IGRA NC had significantly lower levels of CD26-CD4+ and CD8+ MAIT cells producing IL-17 compared to IGRA C but had significantly higher levels of IL-17A, IL-17F, IL-21, and IL-23 in ESAT-6/CFP-10-stimulated supernatants compared to IGRA C. These data provide new insights into the role of IL-17 and IL-17-producing cells at three key stages of the Mtb infection spectrum.

Tissue adaptation: Implications for gut immunity and tolerance

Faria et al. discuss the concept that immune cells undergo specialized adaptation to tissue-specific conditions and its potential implications for tolerance and immunity.

Tissue adaptation is an intrinsic component of immune cell development, influencing both resistance to pathogens and tolerance. Chronically stimulated surfaces of the body, in particular the gut mucosa, are the major sites where immune cells traffic and reside. Their adaptation to these environments requires constant discrimination between natural stimulation coming from harmless microbiota and food, and pathogens that need to be cleared. This review will focus on the adaptation of lymphocytes to the gut mucosa, a highly specialized environment that can help us understand the plasticity of leukocytes arriving at various tissue sites and how tissue-related factors operate to shape immune cell fate and function.

Comparative genomic analysis of buffalo (Bubalus bubalis) NOD1 and NOD2 receptors and their functional role in in-vitro cellular immune response

Nucleotide binding and oligomerization domain (NOD)-like receptors (NLRs) are innate immune receptors that recognize bacterial cell wall components and initiate host immune response. Structure and function of NLRs have been well studied in human and mice, but little information exists on genetic composition and role of these receptors in innate immune system of water buffalo—a species known for its exceptional disease resistance. Here, a comparative study on the functional domains of NOD1 and NOD2 was performed across different species. The NOD mediated in-vitro cellular responses were studied in buffalo peripheral blood mononuclear cells, resident macrophages, mammary epithelial, and fibroblast cells. Buffalo NOD1 (buNOD1) and buNOD2 showed conserved domain architectures as found in other mammals. The domains of buNOD1 and buNOD2 showed analogy in secondary and tertiary conformations. Constitutive expressions of NODs were ubiquitous in different tissues. Following treatment with NOD agonists, peripheral lymphocytes showed an IFN-γ response along-with production of pro-inflammatory cytokines. Alveolar macrophages and mammary epithelial cells showed NOD mediated in-vitro immune response through NF-κB dependent pathway. Fibroblasts showed pro-inflammatory cytokine response following agonist treatment. Our study demonstrates that both immune and non-immune cells could generate NOD-mediated responses to pathogens though the type and magnitude of response depend on the cell types. The structural basis of ligand recognition by buffalo NODs and knowledge of immune response by different cell types could be useful for development of non-infective innate immune modulators and next generation anti-inflammatory compounds.

Global characterization of differential gene expression profiles in mouse Vγ1+ and Vγ4+ γδ T cells

Peripheral γδ T cells in mice are classified into two major subpopulations, Vγ1⁺ and Vγ4⁺, based on the composition of T cell receptors. However, their intrinsic differences remain unclear. In this study, we analyzed gene expression profiles of the two subsets using Illumina HiSeq 2000 Sequencer. We identified 1995 transcripts related to the activation of Vγ1⁺ γδ T cells, and 2158 transcripts related to the activation of Vγ4⁺ γδ T cells. We identified 24 transcripts differentially expressed between the two subsets in resting condition, and 20 after PMA/Ionomycin treatment. We found that both cell types maintained phenotypes producing IFN-γ, TNF-α, TGF-β and IL-10. However, Vγ1⁺ γδ T cells produced more Th2 type cytokines, such as IL-4 and IL-5, while Vγ4⁺ γδ T cells preferentially produced IL-17. Our study provides a comprehensive gene expression profile of mouse peripheral Vγ1⁺ and Vγ4⁺ γδ T cells that describes the inherent differences between them.

Pro-inflammatory T-lymphocytes rapidly infiltrate into the brain and contribute to neuronal injury following cardiac arrest and cardiopulmonary resuscitation

Although inflammatory mechanisms have been linked to neuronal injury following global cerebral ischemia, the presence of infiltrating peripheral immune cells remains understudied. We performed flow cytometry of single cell suspensions obtained from the brains of mice at varying time points after global cerebral ischemia induced by cardiac arrest and cardiopulmonary resuscitation (CA/CPR) to characterize the influx of lymphocytes into the injured brain. We observed that CA/CPR caused a large influx of lymphocytes within 3h of resuscitation that was maintained for the 3day duration of our experiments. Using cell staining flow cytometry we observed that the large majority of infiltrating lymphocytes were CD4(+) T cells. Intracellular stains revealed a large proportion of pro-inflammatory T cells expressing either TNFα or INFγ. Importantly, the lack of functional T cells in TCRα knockout mice reduced neuronal injury following CA/CPR, implicating pro-inflammatory T cells in the progression of ischemic neuronal injury. Finally, we made the remarkable observation that the novel CD4(+)CD40(+) (Th40) population of pro-inflammatory T cells that are strongly associated with autoimmunity are present in large numbers in the injured brain. These data indicate that studies investigating the neuro-immune response after global cerebral ischemia should consider the role of infiltrating T cells in orchestrating the acute and sustained immune response.

The immunobiology of the mammalian epididymis: the black box is now open!

Spermatozoa represent an immunologic challenge for the mammalian males. They are produced long after the establishment of the immune library of the individual and harbor specific spermatic antigens that are found nowhere else in other organs, tissues and cells. Consequently, spermatozoa are somehow “foreign” to the male adaptive immune system. In order not to elicit autoimmune responses that would be detrimental for male fertility, spermatozoa should be either physically separated from the adaptive immune response and/or, the immune system challenged by spermatic antigens must be efficiently silenced. Within the mammalian male genital tract it becomes more and more obvious that a range of strategies are at stake to ensure that the immune-stranger spermatozoa do not constitute an immunological issue. In this review the focus will be on the immune status of the epididymis tubule, in which spermatozoa that have left the testes will mature for approximately 2 weeks and may be stored for prolonged period of time. How the epididymal immune environment compares to that of the testis and what are the immune regulatory processes at work in the epididymal compartment will only be briefly described. Instead, this review will focus on recent data that highlight epididymal immune regulatory actors that partly explain/illustrate the rather complicated, fragile but nevertheless robust immune environment of the epididymis.

High-potency sucralfate prevents and rapidly reverses chemo-radiation mucositis in a patient with stage 4b head and neck cancer

AIM: To study usefulness of high-potency sucralfate (HPS) in a patient with chemoradiation mucositis and discuss its mechanism of action.

METHODS: HPS, a non-covalently cross-link of sucralfate, cations and bidentate anionic chelators, has a maintains a surface concentration of sucralfate 3 h following administration that is 7-23 fold that possible with standard-potency sucralfate. The accelerated mucosal healing and pain alleviation of HPS in patients with erosive esophageal reflux, prompted its use in this patient with chemoradiation mucositis of the oropharynx and alimentary tract. A literature-based review of the immuno-modulatory effects of sucralfate is discussed.

RESULTS: Within 48 h of intervention: (1) there was complete disappearance of oral mucositis lesions; tenderness with (2) patient-reported disappearance of pain, nausea and diarrhea; patient required (3) no opiate analgesia and (4) no tube-feeding supplements to regular diet. Dysgeusia and xerostomia persisted. A modified Naranjo Questionnaire score of 10 supported the likelihood that HPS intervention caused the observed clinical effects. No adverse reactions noted.

CONCLUSION: In this patient HPS was useful to treat chemo-radiation mucositis of the oropharynx and alimentary tract. HPS may directly or indirectly facilitate an immunomodulatory mechanism involving accelerated growth factor activation, which may be a new target for therapeutic intervention in such patients.

Epstein-Barr virus-associated lymphoid malignancies: the expanding spectrum of hematopoietic neoplasms

Ubiquitous Epstein-Barr virus (EBV) infects not only B cells but also T and NK cells, and is associated with various lymphoid malignancies. The spectrum of EBV-associated lymphoid malignancies is expanding from Burkitt lymphoma to the newly defined systemic EBV+ T cell lymphoproliferative disease of childhood and hydroa vacciniforme-like lymphoma. However, some EBV-associated malignancies are not defined well and overlap other diseases. Furthermore, the role of EBV in tumorigenesis of lymphoid malignancies is still not clear. Further studies are necessary to clarify the pathogenesis of EBV-associated lymphoid malignancies for a better classification of each disease and for the establishment of effective treatment.

Location, location, location: tissue-specific regulation of immune responses

Discovery of DCs and PRRs has contributed immensely to our understanding of induction of innate and adaptive immune responses. Activation of PRRs leads to secretion of inflammatory cytokines that regulate priming and differentiation of antigen-specific T and B lymphocytes. Pathogens enter the body via different routes, and although the same set of PRRs is likely to be activated, it is becoming clear that the route of immune challenge determines the nature of outcome of adaptive immunity. In addition to the signaling events initiated following innate-immune receptor activation, the cells of the immune system are influenced by the microenvironments in which they reside, and this has a direct impact on the resulting immune response. Specifically, immune responses could be influenced by specialized DCs, specific factors secreted by stromal cells, and also, by commensal microbiota present in certain organs. Following microbial detection, the complex interactions among DCs, stromal cells, and tissue-specific factors influence outcome of immune responses. In this review, we summarize recent findings on the phenotypic heterogeneity of innate and adaptive immune cells and how tissue-specific factors in the systemic and mucosal immune system influence the outcome of adaptive-immune responses.

Evaluation of the safety and immunogenicity of a candidate tuberculosis vaccine, MVA85A, delivered by aerosol to the lungs of macaques

Tuberculosis (TB) is a reemerging disease. The only available vaccine, Mycobacterium bovis BCG, is delivered intradermally and confers highly variable efficacy against pulmonary disease. There is an urgent need for improved vaccination strategies. Murine studies suggest that immunizations delivered directly to the respiratory mucosa might be a more effective route of vaccination. This study compared the immunogenicity of a leading candidate tuberculosis (TB) vaccine, modified vaccinia virus Ankara expressing antigen 85A (MVA85A), in rhesus macaques, delivered either as an aerosol or as an intradermal boost immunization 12 weeks after an intradermal BCG prime vaccine. Aerosol vaccination was well tolerated. MVA85A delivered by aerosol or by intradermal injection induced antigen-specific immune responses in the periphery and the lung, with a trend toward the highest response when the compartment and route of delivery were matched. The ability of poxvirus-vectored vaccines delivered by the systemic route to induce responses in the mucosal immune compartment in macaques is in contrast to the independent compartmentalization of mucosal and systemic immune systems described in mice. Unlike intradermal vaccination, aerosol vaccination did not induce a detectable serum anti-vector antibody response. The delivery of vaccines to the lungs might provide an immunization strategy that limits the induction of systemic anti-vector immunity, which would be extremely useful in the development of improved vaccine strategies. This is the first study to show a recombinant MVA-vectored vaccine to be highly immunogenic when delivered by the aerosol route to nonhuman primates. These results provide important safety and proof-of-concept data for further evaluation of this route of immunization for use in human clinical trials.

Characterization of avian thymic hormone and chicken parvalbumin 3 target cells

Avian thymic hormone (ATH) is a β-parvalbumin produced by epithelial cells in the thymic cortex and in the eyes of chickens. Chicken parvalbumin 3 (CPV3) is a homologous protein produced in the thymus and in hair cells of the chicken ear. ATH circulates in the blood on a five-day cycle and stimulates cell-mediated immunity when administered to young chickens. We report the identification of target cells for ATH and CPV3 and the immunophenotype of target cells for ATH. Newly hatched chicks were injected intracoelomically with ATH and killed 5, 10, 15 or 20 min later. Naïve chickens also were killed at 1, 7 and 14 days of age. Various tissues were examined by EM for the presence of either ATH or CPV3 using colloidal gold labeling. Gold particles were initially present on plasma membranes of lymphocytes in T cell areas of spleen and cecal tonsils from the chicks injected with ATH, internalized within 10 min, and accumulated in nuclei by 20 min. Immunofluorescence staining also identified the presence of ATH in T cell areas of spleen and cecal tonsils. Target cells labeled for ATH were immunophenotyped by double labeling. They were positive for CD3, CD8 and the lymphocyte receptor TCR-1, a phenotype characteristic of cytotoxic γδ T cells. Some of the target cells in the spleen were TCR-3 positive. Targeting of lymphocytes by CPV3 indicated that it may also be an immunomodulating hormone.

IBS, NERD and functional dyspepsia are immuno-neuronal disorders of mucosal cytokine imbalances clinically reversible with high potency sucralfate

Irritable bowel syndrome (IBS), non-erosive reflux disorder (NERD), and functional dyspepsia (FD) are best classified as immuno-neuronal disorders of the mucosa or functional mucosal syndromes (FMS). Each appears to be clinically reversible using high potency sucralfate (HPS). In FMS of the GI tract, postprandial nausea, altered motility, discordant peristalsis, vomiting, diarrhea, and hyperalgesia are the clinical expressions of a mucosal imbalance between pro-inflammatory cytokines of up-regulated intra-epithelial lymphocytes (IELs) and feedback anti-inflammatory cytokines tasked with moderating the antigenic response of IELs. Normal functioning GI tract requires an operative balance between pro-inflammatory and anti-inflammatrory cytokines, a balance governed by locally expressed growth factors. The surface concentration of sucralfate can be enhanced 7-23-fold by suspending it in a select concentration of cations and multi-dentate cationic chelators. Increased surface concentration of sucralfate facilitates novel dose effects which include efficient activation of growth factors, quiescence of gated-nociceptor firing and resultant restoration of normal GI function.

The role of dendritic cells in Mycobacterium tuberculosis infection

The immune response against Mycobacterium tuberculosis is multifactorial, involving a network of innate and adaptive immune responses. Characterization of the immune response, a clear understanding of the dynamics and interplay of different arms of the immune response are critical to allow the development of better tools for combating tuberculosis. Dendritic cells (DCs) are one of the key cells in bridging innate and adaptive immune response through their significant role in capturing, processing and presenting antigens. The outcome of interaction of M. tuberculosis with DCs is not fully understood and the available reports are contradictory were some findings reported that DCs strengthen the cellular immune response against mycobacterium infection whereas others reported M. tuberculosis impairs the function of DCs were infected DCs are poor stimulators of M. tuberculosis Ag-specific CD4 T cells. Other studies showed that the outcome depends on M. tuberculosis strain type and type of receptor on DCs during recognition. In this review I shall highlight the recent findings in the outcome of interaction of Mycobacterium tuberculosis with DCs.

Human Vdelta1 gamma-delta T cells exert potent specific cytotoxicity against primary multiple myeloma cells

BACKGROUND AIMS

Human gamma-delta (γδ) T cells are potent effector lymphocytes of innate immunity involved in anti-tumor immune surveillance. However, the Vδ1 γδ T-cell subset targeting multiple myeloma (MM) has not previously been investigated.

METHODS

Vδ1 T cells were purified from peripheral blood mononuclear cells of healthy donors and patients with MM by immunomagnetic sorting and expanded with phytohemagglutinin (PHA) together with interleukin (IL)-2 in the presence of allogeneic feeders. Vδ1 T cells were phenotyped by flow cytometry and used in a 4-h flow cytometric cytotoxicity assay. Cytokine release and blocking studies were performed. Primary myeloma cells were purified from MM patients' bone marrow aspirates.

RESULTS

Vδ1 T cells expanded from healthy donors displayed prominent cytotoxicity by specific lysis against patients' CD38 (+) CD138 (+) bone marrow-derived plasma cells. Vδ1 T cells isolated from MM patients showed equally significant killing of myeloma cells as Vδ1 T cells from normal donors. Vδ1 T cells showed similarly potent cytotoxicity against myeloma cell lines U266 and RPMI8226 and plasma cell leukemia ARH77 in a dose-dependent manner. The interferon (IFN)-γ secretion and Vδ1 T-cell cytotoxicity against myeloma cells was mediated in part through the T-cell receptor (TCR) in addition to involvement of Natural killer-G2D molecule (NKG2D), DNAX accessory molecule-1 (DNAM-1), intracellular cell adhesion molecule (ICAM)-1, CD3 and CD2 receptors. In addition, Vδ1 T cells were shown to exert anti-myeloma activity equal to that of Vδ2 T cells.

CONCLUSIONS

We have shown for the first time that Vδ1 T cells are highly myeloma-reactive and have therefore established Vδ1 γδ T cells as a potential candidate for a novel tumor immunotherapy.

Application of flow cytometric in situ hybridization assay to Epstein-Barr virus-associated T/natural killer cell lymphoproliferative diseases

Epstein-Barr virus (EBV) infects various types of lymphocytes and is associated with not only B cell-origin lymphoma, but also T or natural killer cell lymphoproliferative diseases (T/NK LPD). Recently, we established a novel assay to identify EBV-infected cells using FISH. Using this assay, dual staining with antibodies to both surface antigens and an EBV-encoded small RNA (EBER) probe can be performed. In the present study, we applied this recently developed FISH assay to EBV-associated T/NK LPD to confirm its diagnostic utility. Using FISH, we prospectively analyzed peripheral blood from patients with suspected EBV-associated T/NK LPD. The results were compared with those obtained using immunobead sorting followed by quantitative PCR. In all, 26 patients were included study. Using FISH, 0.15-67.0% of peripheral blood lymphocytes were found to be positive for EBER. Dual staining was used to determine EBER-positive cell phenotypes in 23 of 26 subjects (88.5%). In five of seven patients with hydroa vacciniforme-like lymphoma (an EBV-positive cutaneous T cell lymphoma), EBER-positive cells were identified as CD3(+) CD4(-) CD8(-) TCRγδ(+) T cells. Furthermore, in a 25-year-old male patient with systemic EBV-positive T cell LPD, two lymphocyte lineages were positive for EBER: CD4(+) CD8(-) and CD4(-) CD8(+) T cells. Thus, we confirmed that our newly developed assay is useful for quantifying and characterizing EBV-infected lymphocytes in EBV-associated T/NK LPD and that it can be used not only to complement the pathological diagnosis, but also to clarify the pathogenesis and to expand the spectrum of EBV-associated diseases.

The role of T lymphocytes in cancer patients undergoing immunotherapy with autologous dendritic cells

INTRODUCTION

Cancer stems from mutations in specific genes that induce uncontrolled cell proliferation. Dendritic cells (DCs) are important immunologic cells and play a crucial role in the induction of an antitumour response.

PATIENTS AND METHODS

We examined the immune response mediated by T lymphocytes, helper T cells, cytotoxic T cells, and regulatory T cells, as well as the cytokines [interleukin (IL)-2, IL-12, interferon (IFN)-γ, tumour necrosis factor (TNF)-α and IL-10], produced by these cell populations, in cancer patients (N = 7) undergoing immunotheraphy with autologous DCs.

RESULTS

We observed an initial increase in T helper cells (CD4+) expressing IL-2, IFN-γ, IL-12, TNF-α, and IL-10 after initiation of treatment, with statistically significant for the cytokines IL-2, TNF-α and IL-10. A similar significant effect was observed for IL-2-expressing cytotoxic T cells (CD8+). The percentage of total T cells (CD3+) remained elevated throughout immunotherapy. Regulatory T cells (CD25+/FOXP3+) only showed high percentage of their maximum value when analyzed the pretreatment levels, with statistically significant.

CONCLUSION

Immunotherapy with DCs stimulated the immune response, as evidenced by an increase in percent fluorescence of most cell populations investigated during the specified treatment period.

The role of Vδ2-negative γδ T cells during cytomegalovirus reactivation in recipients of allogeneic stem cell transplantation

Reactivation of cytomegalovirus (CMV) remains a serious complication after allogeneic stem cell transplantation, but the role of γδ T cells is undefined. We have studied the immune reconstitution of Vδ2negative (Vδ2neg) γδ T cells, including Vδ1 and Vδ3 subsets and Vδ2positive (Vδ2pos) γδ T cells in 40 patients during the first 24 months after stem cell transplantation. Significant long-term expansions of Vδ2neg but not Vδ2pos γδ T cells were observed during CMV reactivation early after transplantation, suggesting direct involvement of γδ T cells in anti-CMV immune responses. Similarly, significantly higher numbers of Vδ2neg γδ T cells were detected in CMV-seropositive healthy persons compared with seronegative donors; the absolute numbers of Vδ2pos cells were not significantly different. The expansion of Vδ2neg γδ T cells appeared to be CMV-related because it was absent in CMV-negative/Epstein-Barr virus-positive patients. T-cell receptor-δ chain determining region 3 spectratyping of Vδ2neg γδ T cells in healthy subjects and patients showed restricted clonality. Polyclonal Vδ2neg cell lines generated from CMV-seropositive healthy donors and from a recipient of a graft from a CMV-positive donor lysed CMV-infected targets in all cases. Our study shows new evidence for role of γδ T cells in the immune response to CMV reactivation in transplantation recipients.

Adipose tissue lymphocytes: types and roles

Besides adipocytes, specialized in lipid handling and involved in energy balance regulation, white adipose tissue (WAT) is mainly composed of other cell types among which lymphocytes represent a non-negligible proportion. Different types of lymphocytes (B, alphabetaT, gammadeltaT, NK and NKT) have been detected in WAT of rodents or humans, and vary in their relative proportion according to the fat pad anatomical location. The lymphocytes found in intra-abdominal, visceral fat pads seem representative of innate immunity, while those present in subcutaneous fat depots are part of adaptive immunity, at least in mice. Both the number and the activity of the different lymphocyte classes, except B lymphocytes, are modified in obesity. Several of these modifications in the relative proportions of the lymphocyte classes depend on the degree of obesity, or on leptin concentration, or even fat depot anatomical location. Recent studies suggest that alterations of lymphocyte number and composition precede the macrophage increase and the enhanced inflammatory state of WAT found in obesity. Lymphocytes express receptors to adipokines while several proinflammatory chemokines are produced in WAT, rendering intricate crosstalk between fat and immune cells. However, the evidences and controversies available so far are in favour of an involvement of lymphocytes in the control of the number of other cells in WAT, either adipocytes or immune cells and of their secretory and metabolic activities. Therefore, immunotherapy deserves to be considered as a promising approach to treat the endocrino-metabolic disorders associated to excessive fat mass development.

Microbial colonization drives expansion of IL-1 receptor 1-expressing and IL-17-producing gamma/delta T cells

IL-17 cytokine production by the Th17 T cell subset is regulated by intestinal commmensals. We show that microbial colonization also regulates innate IL-17 production. A population of CD62L(-) gamma/delta T cells, in particular a lineage expressing the IL-1 receptor 1 (IL-1R1), can be quickly activated by microbes to produce IL-17. Antibiotic treatment and monocolonization of mice suggest that specific commensals-but not metronidazole-sensitive anaerobes like Bacteroides species-are required for maintaining IL-1R1(+) gamma/delta T cells. Signaling through the guanine nucleotide exchange factor VAV1, but not through Toll-like receptors or antigen presentation pathways, is essential for inducing IL-1R1(+) gamma/delta T cells. Furthermore, IL-1R1(+) gamma/delta T cells are a potential source of IL-17 that can be activated by IL-23 and IL-1 in both infectious and noninfectious settings in vitro and in vivo. Thus, commensals orchestrate the expansion of phenotypically distinct gammadelta T cells, and innate immunity is a three-way interaction between host, pathogens, and microbiota.

Regulatory T Cells in Autoimmune Diseases: Anti-Ergotypic T Cells

T regulatory cells play an important role in regulating T-cell responses to self-antigens and control autoimmunity and autoimmune disease. Anti-ergotypic T cells are a subset of such regulatory T cells that respond to activation markers, ergotopes, expressed on other activated T cells. Anti-ergotypic T cells do not respond to nonactivated T cells. Ergotopes include the a-chain of the IL-2 receptor (CD25). Anti-ergotypic T cells were found to downregulate experimental diseases such as experimental autoimmune encephalomyelitis (EAE) and adjuvant arthritis (AA). Anti-ergotypic T cells are present in humans and are activated after T-cell vaccination. Here we review anti-ergotypic T cells in animal models and in humans and contrast anti-ergotypic T cells with other regulatory T-cell subsets.

Localized populations of CD8 MHC class I tetramer SIV-specific T cells in lymphoid follicles and genital epithelium

CD8 T cells play an important role in controlling viral infections. We investigated the in situ localization of simian immunodeficiency virus (SIV)-specific T cells in lymph and genital tissues from SIV-infected macaques using MHC-class I tetramers. The majority of tetramer-binding cells localized in T cell zones and were CD8⁺. Curiously, small subpopulations of tetramer-binding cells that had little to no surface CD8 were detected in situ both early and late post-infection, and in both vaginally and rectally inoculated macaques. These tetramer⁺CD8^low/− cells were more often localized in apparent B cell follicles relative to T cell zones and more often found near or within the genital epithelium than the submucosa. Cells analyzed by flow cytometry showed similar populations of cells. Further immunohistological characterization revealed small populations of tetramer⁺CD20⁻ cells inside B cell follicles and that tetramer⁺ cells did not stain with γδ-TCR nor CD4 antibodies. Negative control tetramer staining indicated that tetramer⁺CD8^low/− cells were not likely NK cells non-specifically binding to MHC tetramers. These findings have important implications for SIV-specific and other antigen-specific T cell function in these specific tissue locations, and suggest a model in which antigen-specific CD8+ T cells down modulate CD8 upon entering B cell follicles or the epithelial layer of tissues, or alternatively a model in which only antigen-specific CD8 T cells that down-modulate CD8 can enter B cell follicles or the epithelium.

Pathogenesis of Mycobacterium avium subsp. paratuberculosis in neonatal calves after oral or intraperitoneal experimental infection

Understanding the host response to Mycobacterium avium subsp. paratuberculosis is critical to the development of effective vaccines and therapeutics for the control of this disease in the field. The current study compared the effectiveness of oral and intraperitoneal (IP) methods of experimental inoculation and two strains of M. avium subsp. paratuberculosis (strain K-10 and clinical isolate 509) on the level of infection and lesion development. Calves were inoculated with 4x10(11) to 8x10(12)cfu live bacteria, depending upon treatment group. Fecal shedding of M. avium subsp. paratuberculosis was minimal and infrequent over the course of the study for calves that received strain K-10 (oral and IP), however, calves orally inoculated with the clinical isolate shed high numbers of bacteria in their feces up to 4 months post-inoculation. Colonization was present in a number of intestinal tissues and lymph nodes with the lowest number of affected tissues in the IP calves and the highest for calves receiving the clinical isolate via oral inoculation. Microscopic lesions were predominantly found in the ileal and jejunal sections of small intestine and their associated lymph nodes, as well as the ileocecal valve and node. These data suggest that a variety of experimental infection regimes can be effective but oral inoculation with a clinical isolate may result in greater colonization of tissues and fecal shedding of M. avium subsp. paratuberculosis.

Association between Vgamma2Vdelta2 T cells and disease progression after infection with closely related strains of HIV in China

BACKGROUND

Human immunodeficiency virus (HIV) infection and disease are accompanied by decreases in the absolute number and function of Vgamma2Vdelta2 T cells, suggesting that this subset of cells may play an important role in controlling disease. We performed a cross-sectional study involving HIV-infected former blood donors and assessed the association between Vgamma2Vdelta2 T cells and markers of disease progression.

METHODS

Changes in Vgamma2Vdelta2 T cell count and function were compared between HIV-infected individuals and healthy blood donors using the Mann-Whitney U test. The relationships between Vgamma2Vdelta2 T cell count, plasma viral load, and CD4 T cell count were analyzed using the Spearman correlation.

RESULTS

We found significant positive correlations between CD4 T cell count and both total Vgamma2Vdelta2 T cell count (P<.001) and functional (isopentenyl pyrophosphate-responsive) Vgamma2Vdelta2 T cell count (P<.001). We found significant reverse correlations between viral load and both total Vgamma2Vdelta2 T cell count (P<.05) and functional Vgamma2Vdelta2 T cell count (P<.05).

CONCLUSIONS

The association of Vgamma2Vdelta2 T cells with disease progression in 146 HIV-infected participants supports the view that intact Vgamma2Vdelta2 T cell populations are important for controlling HIV disease.

Enhanced secretion of interferon-gamma by bovine gammadelta T cells induced by coculture with Mycobacterium bovis-infected dendritic cells: evidence for reciprocal activating signals

Evidence suggests that gammadelta T cells form part of the innate immune response to Mycobacterium bovis infection. Dendritic cells (DCs) are capable of secreting high levels of interleukin-12 (IL-12) following infection with mycobacteria and can induce interferon-gamma (IFN-gamma) secretion by natural killer and gammadelta T cells We investigated the innate interactions occurring between WC1(+)gammadelta T cells and M. bovis-infected DCs. Following coculture with M. bovis-infected DCs, secretion of IFN-gamma and expression of CD25 and major histocompatibility complex class II on WC1(+)gammadelta T cells were significantly enhanced. Reciprocal enhancement of IL-12 secretion by the DCs was also observed and this interaction was found to be contact dependent. We hypothesize that there is an early, transient signal between the WC1(+)gammadelta T cells and the DCs, which promotes the synthesis of biologically active IL-12, and which is dependent upon cell-cell contact. Reciprocal signals including IL-12 are then delivered to WC1(+)gammadelta cells, which leads to the enhanced secretion of IFN-gamma, and the up-regulation of activation markers and antigen presentation molecules by the WC1(+)gammadelta T cells. These interactions are likely to form a critical part of the T helper type 1-conditioning response of DCs to M. bovis.

Rational design of vaccines against tuberculosis directed by basic immunology

Tuberculosis represents a serious problem for public health worldwide, and effective vaccines are urgently required. This represents a significant challenge as the causative bacterial agent, Mycobacterium tuberculosis, has developed strategies to persist in infected hosts despite the presence of potent T-cell-mediated immune responses. New advances in basic immunology are giving us improved understanding of what constitutes a protective immune response and ways this response is manipulated by the bacillus. Such insights should inform us how to design more effective vaccination strategies against intracellular pathogens.

Immunisation with BCG and recombinant MVA85A induces long-lasting, polyfunctional Mycobacterium tuberculosis-specific CD4+ memory T lymphocyte populations

In the search for effective vaccines against intracellular pathogens such as HIV, tuberculosis and malaria, recombinant viral vectors are increasingly being used to boost previously primed T cell responses. Published data have shown prime-boost vaccination with BCG-MVA85A (modified vaccinia virus Ankara expressing antigen 85A) to be highly immunogenic in humans as measured by ex vivo IFN-gamma ELISPOT. Here, we used polychromatic flow cytometry to investigate the phenotypic and functional profile of these vaccine-induced Mycobacterium tuberculosis (M.tb) antigen 85A-specific responses in greater detail. Promisingly, antigen 85A-specific CD4(+) T cells were found to be highly polyfunctional, producing IFN-gamma, TNF-alpha, IL-2 and MIP-1beta. Surface staining showed the responding CD4(+) T cells to be relatively immature (CD45RO(+) CD27(int)CD57(-)); this observation was supported by the robust proliferative responses observed following antigenic stimulation. Furthermore, these phenotypic and functional properties were independent of clonotypic composition and epitope specificity, which was maintained through the different phases of the vaccine-induced immune response. Overall, these data strongly support the use of MVA85A in humans as a boosting agent to expand polyfunctional M.tb-specific CD4(+) T cells capable of significant secondary responses.

Intraepithelial gammadelta+ lymphocytes: a comparative study between celiac disease, small intestinal bacterial overgrowth, and irritable bowel syndrome

BACKGROUND

Intraepithelial lymphocytes (IELs) phenotyping has emerged as a useful test in intestinal pathology. In celiac disease (CD), a permanent and marked increase of gammadelta+ IELs has been described. However, there is a lack of knowledge about this peculiar IELs population in other intestinal pathologies.

AIM

To analyze the percentage of IELs, specifically gammadelta+ IELs subset, present in duodenal mucosa biopsies from patients with CD and compare it with those obtained from patients with small intestinal bacterial overgrowth (SIBO) or irritable bowel syndrome (IBS).

METHODS

Twelve patients with untreated CD, 8 patients with SIBO, and 10 patients with diarrhea-predominant IBS were evaluated. All subjects underwent upper endoscopy for mucosal biopsy and jejunal aspirate. From 2 small bowel biopsies, intraepithelial cells were isolated and labeled with the following monoclonal antibodies CD103-PE (phycoerythrin), CD3-FITC (fluoresecein isothio-cynate), CD-7R-PE, CD45RO-APC (allophycocyanin), and TcR gammadelta-FITC. Flow cytometry analysis was performed on a standard FACScan. Total and IELs subset counts were expressed as percentage.

RESULTS

Mean total IELs percentage was 16.7+/-6% in IBS, 25.4+/-17% in SIBO, and 26+/-13% in CD patients (P=0.2). CD and SIBO patients, had significantly higher percentages of gammadelta+ IELs (15.7+/-13% and 14.6+/-8%) than IBS subjects (4.1+/-2.5%, P<0.05). There was no difference between CD and SIBO (P=0.6).

CONCLUSIONS

An increased density of gammadelta+ IELs is typical, but not specific for CD. A similar increase was observed in subjects with SIBO. Our findings suggest that this unique T-cell population might have a key role against intestinal bacterial infections.

Molecular genetic analysis of haematological malignancies II: mature lymphoid neoplasms

Molecular genetic techniques have become an integral part of the diagnostic assessment for many lymphomas and other chronic lymphoid neoplasms. The demonstration of a clonal immunoglobulin or T cell receptor gene rearrangement offers a useful diagnostic tool in cases where the diagnosis is equivocal. Molecular genetic detection of other genomic rearrangements may not only assist with the diagnosis but can also provide important prognostic information. Many of these rearrangements can act as molecular markers for the detection of low levels of residual disease. In this review, we discuss the applications of molecular genetic analysis to the chronic lymphoid malignancies. The review concentrates on those disorders for which molecular genetic analysis can offer diagnostic and/or prognostic information.

Role of alpha/beta and gamma/delta T cells in renal ischemia-reperfusion injury

T cells have been implicated in the pathogenesis of renal ischemia-reperfusion injury (IRI). To date existing data about the role of the T cell receptor (Tcr) are contradictory. We hypothesize that the Tcr plays a prominent role in the late phase of renal IRI. Therefore, renal IRI was induced in alpha/beta, gamma/delta T cell-deficient and wild-type mice by clamping renal pedicles for 30 min and reperfusing for 24, 48, 72, and 120 h. Serum creatinine increased equally in all three groups 24 h after ischemia but significantly improved in Tcr-deficient animals compared with wild-type controls after 72 h. A significant reduction in renal tubular injury and infiltration of CD4+ T-cells in both Tcr-deficient mice compared with wild-type controls was detected. Infiltration of alpha/beta T cells into the kidney was reduced in gamma/delta T cell-deficient mice until 72 h after ischemia. In contrast, gamma/delta T cell infiltration was equal in wild-type and alpha/beta T cell-deficient mice, suggesting an interaction between alpha/beta and gamma/delta T cells. Data from gamma/delta T cell-deficient mice were confirmed by in vivo depletion of gamma/delta T cells in C57BL/6 mice. Whereas alpha/beta T cell-deficient mice were still protected after 120 h, gamma/delta T cell-deficient mice showed a "delayed wild-type phenotype" with a dramatic increase in kidney-infiltrating alpha/beta, Tcr-expressing CD4+ T-cells. This report provides further evidence that alpha/beta T cells are major effector cells in renal IRI, whereas gamma/delta T cells play a role as mediator cells in the first 72 h of renal IRI.

Migratory Pathways of T Cells and Response to CXCR3 and CXCR4 Ligands: Adhesion Molecules Involved and Implications for Multiple Sclerosis Pathogenesis

Gammadelta T lymphocytes are thought to be involved in multiple sclerosis (MS) pathogenesis. In this work, we discuss the characteristics of these cells and possible implications in the pathogenesis of MS, focusing on the mechanism(s) underlying extravasation and tissue localization. Phenotype and transendothelial migration of gammadelta T cells from healthy donors and patients with relapsing-remitting MS were studied. In MS patients the V delta 2 T cell subset, expressing NKRP1A/CD161 adhesion molecule, is expanded and capable of transendothelial migration. V delta 1/V delta 2 subsets use distinct signal transduction pathways: V delta 1 cells lack NKRP1A and express PECAM-1/CD31, which drives transmigration, while V delta 2 cells are PECAM-1 negative and use NKRP1A. V delta 2 migration is coupled with CAMKII, whereas V delta 1 depend on PI-3K. NKRP1A and PECAM-1 selectively activate the two pathways: indeed, oligomerization of NKRP1A on V delta 2 T cells leads to CAMKII activation, occupancy of PECAM-1 on V delta 1 cells triggers the PI-3K-dependent Akt/PKB pathway. Moreover, V delta 2 T cells are CXCR3(bright)CXCR4(dull), while V delta 1 are mostly CXCR4(+). V delta 1 and V delta 2 cells transmigrate in response to IP-10/CXCL10 and SDF-1/CXCL12 according to the expression of their specific receptors. In a fraction of V delta 1 T cells coexpressing CXCR3 and CXCR4, the homeostatic chemokine 6Ckine/SLC/CCL21 is more effective. IP-10/CXCL10 or 6Ckine/SLC/CCL21 and SDF-1/CXCL12-induced transmigration is coupled to PI-3K/Akt/PKB, but only CXCR3 is capable of inducing CAMKII activation. We suggest that both subsets of gammadelta T lymphocytes may migrate to the site of lesion in MS using two different signaling pathways to extravasate and responding to different chemokines.

Is a new tuberculosis vaccine necessary and feasible? A Cuban opinion

Mycobacterium tuberculosis kills more human beings worldwide than any other pathogen. An estimated two billion people are already infected with the bacterium. In 2006, tuberculosis (TB) will kill nearly one million more people than in 1992. In Cuba, TB is not a serious health problem any more and we are striving to eliminate it in the near future. The most widely applied human vaccine in the world is BCG. It is also a safe vaccine except when it is applied to immunocompromised persons. Its protective efficacy is a controversial topic. In spite of this, more than 80 years of experience with this vaccine has demonstrated that BCG is effective, at least in significantly preventing childhood TB, including the meningeal and disseminated forms of the disease, but does not protect against the predominant pulmonary form of the disease in adults, which means that our best TB vaccine now is inadequate; we therefore need a new vaccine. The following facts, apart from the experience with BCG, support discussion about the feasibility of a new and better TB vaccine: Less than 10% of the 2 billion TB infected persons develop active disease. It has been demonstrated that HIV + TB co-infection increases 30 times the risk of contracting active TB and it increases the risk of being killed by the bacterium. Some new vaccine candidates, now under development and evaluation, are showing promising results in preclinical studies, and a few of them have entered clinical trials. There seems to be a consensus that a new TB vaccine will be feasible, but some challenging issues must be positively solved, such as, the lack of universally accepted correlates for protection, improved diagnostics, and final vaccine efficacy evaluation conducted on large phase III clinical trials in underdeveloped countries. The ethical, economical, organizational and scientific questions involved in this global task are enormous, but feasible.

Tuberculosis subunit vaccine development: Impact of physicochemical properties of mycobacterial test antigens

Tuberculosis caused by Mycobacterium tuberculosis continues to be one of the major public health problems in the world. The eventual control of this disease will require the development of a safe and effective vaccine. One of the approaches receiving a great deal of attention recently is subunit vaccination. An efficacious antituberculous subunit vaccine requires the identification and isolation of key components of the pathogen that are capable of inducing a protective immune response. Clues to identify promising subunit vaccine candidates may be found in their physicochemical and immunobiological properties. In this article, we review the evidence that the physicochemical properties of mycobacterial components can greatly impact the induction of either protective or deleterious immune response and consequently influence the potential utility as an antituberculous subunit vaccine.

Histidine decarboxylase-stimulating and inflammatory effects of alendronate in mice: Involvement of mevalonate pathway, TNFα, macrophages, and T-cells

Nitrogen-containing bisphosphonates (NBPs) are powerful anti-bone-resorptive drugs, but they frequently induce various inflammatory side effects. Recent clinical applications have disclosed an unexpected new side effect, jaw-bone necrosis and exposure. In vitro studies suggest that the inflammatory effects of NBPs are due to Vgamma2Vdelta2 T-cells, stimulated directly and/or indirectly [the latter via isopentenylpyrophosphate (IPP) in the mevalonate pathway]. Rats and mice, however, lack Vgamma2Vdelta2 T-cells, yet NBPs still induce necrotic and inflammatory reactions. In mice, NBPs induce IL-1-dependent inflammatory reactions, such as inductions of histidine decarboxylase (HDC, the histamine-forming enzyme) in the liver, lung, spleen, and bone marrow, an increase in granulocytic cells in the peritoneal cavity, pleural exudation, and splenomegaly. Here, we examined the involvement of IPP, TNF, macrophages, and T-cells in the inflammatory actions of alendronate (a typical NBP) in mice. Various statins (mevalonate-synthesis inhibitors) suppressed the alendronate-induced HDC inductions, while mevalonate itself augmented such inductions. IPP injection also induced HDC. Like IL-1-deficient mice, TNF-deficient mice were resistant to alendronate-stimulated HDC induction. Alendronate-stimulated HDC inductions were significantly weaker in macrophage-depleted mice and in nude mice than in control mice. Similar, though generally less clear-cut, results were obtained when other alendronate-induced inflammatory reactions were examined. These results suggest that (i) inhibition of the mevalonate pathway causes and/or modifies at least some inflammatory actions of alendronate in mice, (ii) in addition to IL-1, TNF is also involved in the inflammatory actions of alendronate, and (iii) alendronate may act on a variety of cells, including macrophages and T-cells.

Regulation of gammadelta versus alphabeta T lymphocyte differentiation by the transcription factor SOX13

alphabeta and gammadelta T cells originate from a common, multipotential precursor population in the thymus, but the molecular mechanisms regulating this lineage-fate decision are unknown. We have identified Sox13 as a gammadelta-specific gene in the immune system. Using Sox13 transgenic mice, we showed that this transcription factor promotes gammadelta T cell development while opposing alphabeta T cell differentiation. Conversely, mice deficient in Sox13 expression exhibited impaired development of gammadelta T cells but not alphabeta T cells. One mechanism of SOX13 function is the inhibition of signaling by the developmentally important Wnt/T cell factor (TCF) pathway. Our data thus reveal a dominant pathway regulating the developmental fate of these two lineages of T lymphocytes.

Vaccinia virus inhibits T cell receptor-dependent responses by human gammadelta T cells

Vaccinia virus (VV) is an effective vaccine and vector but has evolved multiple mechanisms for evading host immunity. We characterized the interactions of VV (TianTan and New York City Board of Health strains) with human gammadelta T cells because of the role they play in immune control of this virus. Exposure to VV failed to trigger proliferative responses in gammadelta T cells from unprimed individuals, but it was an unexpected finding that VV blocked responses to model antigens by the Vgamma2Vdelta2 T cell subset. Infectious or ultraviolet light-inactivated VV inhibited proliferative Vgamma2Vdelta2 T cell responses to phosphoantigens and tumor cells, prevented cytolysis of Daudi B cells, and reduced cytokine production. Inhibiting Vgamma2Vdelta2 T cells may be a mechanism for evading host immunity and increasing VV virulence. Increased VV replication or expression in the absence of gammadelta T cell responses might contribute to its potency as a vaccine against poxvirus and recombinant antigens.

Aggravation of intestinal inflammation by depletion/deficiency of gammadelta T cells in different types of IBD animal models

The role of gammadelta T cells in inflammatory bowel disease (IBD) is still controversial. Although gammadelta T cells induce IBD in immunodeficient animals, others suggest a protective role of gammadelta T cells. Therefore, this study was conducted in order to elucidate the effect of gammadelta T cell depletion/deficiency on different IBD animal models. Mice depleted of or deficient in gammadelta T cells were exposed to dextran sodium sulfate (DSS) in order to induce colitis. In addition, gammadelta T cells were depleted in mice with terminal ileitis (TNFDeltaARE) or colitis due to interleukin 2 deficiency (IL-2 ko). Finally, DSS-induced colitis was studied in mice deficient in interferon gamma (IFN-gamma ko) upon gammadelta T cell depletion. Depletion of gammadelta T cells aggravated DSS-induced colitis and terminal ileitis of TNFDeltaARE mice. Exacerbated DSS-induced colitis was also found in gammadelta T cell-deficient mice. IL-2 ko mice showed increased mortality upon early (starting at 4 wk of age) but not late depletion (starting at 8 wk of age). Early gammadelta T cell depletion or deficiency resulted in increased IFN-gamma production by both lamina propria lymphocytes and splenocytes in every model investigated herein. In IFN-gamma ko mice, gammadelta T cell depletion did not affect the development and course of DSS-induced colitis. The protective effect of gammadelta T cells in IBD was confirmed in various IBD animal models. Particularly, during the early phase of intestinal inflammation, gammadelta T cells appear to be important. The mechanism seems to involve the control of IFN-gamma production and epithelial regeneration.

Workshop cluster 1+ gammadelta T-cell receptor T cells from calves express high levels of interferon-gamma in response to stimulation with interleukin-12 and -18

Gammadelta T-cell receptor(+) T lymphocytes are an important element of the innate immune system. Early production of interferon (IFN)-gamma by gammadelta T cells may have a role in linking innate and adaptive immune responses and contribute to T helper-1 bias. We investigated the role of cytokines in the activation and induction of IFN-gamma secretion by bovine workshop cluster 1(+) (WC1(+)) gammadelta T cells. The effects of culture with interleukin (IL)-12, IL-18, IL-15 and IL-2 were investigated; these cytokines are known to influence murine and human gammadelta T cells. We report that bovine WC1(+)gammadelta T cells are synergistically stimulated by IL-12 and IL-18 to secrete large quantities of IFN-gamma. Neonatal calves were shown to have significantly higher numbers of circulating WC1(+)gammadelta T cells than adult animals. In addition, the response of peripheral blood WC1(+)gammadelta T cells was significantly higher in neonatal calves compared with adult animals. However, in adult animals the response of lymph node WC1(+)gammadelta T cells to IL-12/IL-18 was more pronounced than that of peripheral blood WC1(+)gammadelta T cells. We hypothesize that the induction of IFN-gamma secretion from WC1(+)gammadelta T cells by IL-12 and IL-18 is likely to be an important element of the innate response to pathogens such as Mycobacterium bovis. The high numbers of WC1(+)gammadelta T cells in neonatal calves, and their inherent ability to respond to inflammatory cytokines, could be a key factor in the enhanced responses seen in calves to BCG vaccination.