Membrane-based immunotherapy with immune checkpoint blockade antibodies confers protection against metastatic breast cancer

Objective

The 4T1 triple negative breast cancer (TNBC) model resembles many of the hallmarks of advanced TNBC in humans. In this study we investigate if combining a membrane-based immunotherapy with immune checkpoint blockade antibodies in a metastatic tumor model could effectively generate protective immunity. This personalized strategy is applicable to indications such as TNBC that exhibit a high degree of heterogeneity and do not respond to approved cancer therapies.

Methods

4T1 tumor tissue was harvested from BALB/c mice and processed to generate tumor membrane vesicles (TMVs). TMVs were then incorporated with GPI-B7-1 and GPI-IL-12 by protein transfer and used for immunization in conjunction with immune checkpoint inhibitors. Survival was assessed using a Kaplan-Meier survival curve and significance determined using a Log-rank test for comparison analysis. Metastasis was assessed by clonogenic assay. Immune response was assessed by IFN-γ ELISPOT. Cell depletion studies were performed with anti-CD4 and anti-CD8 antibodies. Significance was determined using a student’s t test to compare metastasis and immune responses.

Results

TMV-based immunotherapy in combination with anti-CTLA-4 antibody significantly improved survival, reduced pulmonary metastasis, and increased tumor-specific CD8 T cell responses. Interestingly, either treatment alone failed to have a significant impact on survival, metastasis, or immune response.

Conclusions

These results strongly suggest that a TMV-based immunotherapy in combination with anti-CTLA-4 antibody generates effective antitumor immunity. Such a combinatorial approach could potentially translate into an effective treatment for patients with metastatic TNBC.

HER-2+ breast cancer cells expressing GPI-anchored cytokines induce long lasting antitumor memory response

Breast cancer is the leading cause of death among female cancer patients. Human epidermal growth factor receptor 2 (HER-2) overexpression is associated with poor prognosis in 15–20% of breast cancer patients. Anti-HER-2 antibody (Herceptin) prolongs the survival of the HER-2+ breast cancer patients. However, resistance to Herceptin is a cause for relapse of aggressive metastatic cancer in these patients. Our earlier studies have demonstrated that PD-L1 blockade enhances the efficacy of HER-2+ breast cancer whole cell vaccine by increasing infiltration of T cells into the tumor. The goal of the present study is to determine the duration of protective anti-tumor memory response to HER-2+ breast cancer. Here, we demonstrate the beneficial effect of GPI-anchored cytokine molecules as adjuvants for generating long lasting memory response against HER-2+ as well as HER-2 negative breast cancer in syngeneic tumor models. Female BALB/c mice were challenged with D2F2/E2 (HER-2 transfected D2F2) cells or D2F2/E2 transfected with GPI-IL-12 or GPI-GM-CSF. While the wild-type challenged mice developed tumors, the mice challenged with transfected D2F2/E2 cells were protected. Protected mice were re-challenged with D2F2/E2 cells 3 months later and D2F2 cells 4 months later. All the mice challenged with D2F2 or D2F2/E2 were protected. We have observed strong antibody response against HER-2 and D2F2 cells in these mice. Our results show that long lasting protective anti-tumor memory response against D2F2 and D2F2/E2 is generated by vaccination with D2F2/E2 cells expressing GPI-anchored immunostimulatory molecules.

Imaging colon cancer development in mice: IL-6 deficiency prevents adenoma in azoxymethane-treated Smad3 knockouts

The development of colorectal cancer in the azoxymethane-induced mouse model can be observed by using a miniaturized optical coherence tomography (OCT) imaging system. This system is uniquely capable of tracking disease development over time, allowing for the monitoring of morphological changes in the distal colon due to tumor development and the presence of lymphoid aggregates. By using genetically engineered mouse models deficient in Interleukin 6 (IL-6) and Smad family member 3 (Smad3), the role of inflammation on tumor development and the immune system can be elucidated. Smad3 knockout mice develop inflammatory response, wasting, and colitis associated cancer while deficiency of proinflammatory cytokine IL-6 confers resistance to tumorigenesis. We present pilot data showing that the Smad3 knockout group had the highest tumor burden, highest spleen weight, and lowest thymus weight. The IL-6 deficiency in Smad3 knockout mice prevented tumor development, splenomegaly, and thymic atrophy. This finding suggests that agents that inhibit IL-6 (e.g. anti-IL-6 antibody, non-steroidal anti-inflammatory drugs [NSAIDs], etc.) could be used as novel therapeutic agents to prevent disease progression and increase the efficacy of anti-cancer agents. OCT can also be useful for initiating early therapy and assessing the benefit of combination therapy targeting inflammation.

Time-serial Assessment of Drug Combination Interventions in a Mouse Model of Colorectal Carcinogenesis Using Optical Coherence Tomography

Optical coherence tomography (OCT) is a high-resolution, nondestructive imaging modality that enables time-serial assessment of adenoma development in the mouse model of colorectal cancer. In this study, OCT was utilized to evaluate the effectiveness of interventions with the experimental antitumor agent α-difluoromethylornithine (DFMO) and a nonsteroidal anti-inflammatory drug sulindac during early [chemoprevention (CP)] and late stages [chemotherapy (CT)] of colon tumorigenesis. Biological endpoints for drug interventions included OCT-generated tumor number and tumor burden. Immunochistochemistry was used to evaluate biochemical endpoints [Ki-67, cleaved caspase-3, cyclooxygenase (COX)-2, β-catenin]. K-Ras codon 12 mutations were studied with polymerase chain reaction-based technique. We demonstrated that OCT imaging significantly correlated with histological analysis of both tumor number and tumor burden for all experimental groups (P < 0.0001), but allows more accurate and full characterization of tumor number and burden growth rate because of its time-serial, nondestructive nature. DFMO alone or in combination with sulindac suppressed both the tumor number and tumor burden growth rate in the CP setting because of DFMO-mediated decrease in cell proliferation (Ki-67, P < 0.001) and K-RAS mutations frequency (P = 0.04). In the CT setting, sulindac alone and DFMO/sulindac combination were effective in reducing tumor number, but not tumor burden growth rate. A decrease in COX-2 staining in DFMO/sulindac CT groups (COX-2, P < 0.01) confirmed the treatment effect. Use of nondestructive OCT enabled repeated, quantitative evaluation of tumor number and burden, allowing changes in these parameters to be measured during CP and as a result of CT. In conclusion, OCT is a robust minimally invasive method for monitoring colorectal cancer disease and effectiveness of therapies in mouse models.

Otolaryngological complications of occipitocervical injury

Occipitocervical injuries are rare, accounting for 15% of all fatal spinal trauma. In patients who survive the initial incident, early detection and appropriate management is vital to avoid significant neurological disability and mortality. We present the case of a patient with neck trauma who was initially cleared of spinal injuries in the emergency department but who later developed acute hearing loss. We describe how the investigation of the hearing loss led to the detection of this devastating injury and report its successful management. Patients with persistent neck pain following trauma, particularly in the presence of degenerative spinal disease, should have cervical spine computed tomography to exclude occipitocervical injuries and other occult injuries.

Tertiary syphilis in the cervical spine: a case report and review of the literature

As the prevalence of syphilis rises, an increase in tertiary syphilis with spinal involvement is predicted. We report what we believe to be the first case of compressive cervical spine syphilitic gummata, with central cord compression signs. We also review the relevant literature to date. The diagnosis of syphilis in the spine relies on the physician to be aware of it as part of the differential diagnosis. Treponemal laboratory tests are an important aid in establishing a diagnosis.

Cervical spondylotic myelopathy: the outcome and potential complications of surgical treatment

PURPOSE OF THE STUDY

Cervical spondylotic myelopathy is the most common cause of spinal cord dysfunction in patients over 60 years old. Symptoms often develop gradually and insidiously and are characterized by neck stiffness, arm pain, numbness and clumsiness of hands, as well as weakness of the hands and legs frequently leading to a change in mobility. Surgery is performed primarily to prevent the progression of symptoms but also with the aim of improving existing symptoms. Aim of our study was to assess the outcomes and potential complications of surgical decompression of cervical spondylotic myelopathy (CSM).

MATERIAL AND METHODS

Prospective data was collected from 71 patients who were treated surgically for CSM over a four-year period (June 2006 to June 2010). Only patients with confirmed spondylotic cervical myelopathy were included in the study; those with an inflammatory, infectious or neoplastic etiology were excluded. The Nurick scale was used as a primary outcome measure, and the improvement in upper limb function as a secondary outcome measure. Statistical significance was assessed using the paired t-test.

RESULTS

34/71 (47.9%) patients had an anterior decompression, 36/71 (50.7%) patients underwent posterior surgery and one patient (1.4%) received a combined approach: The Nurick score: The mean score improved by 0.9 from 2.4 preoperatively to 1.5 postoperatively for the whole series. Three patients were able to return to work. The preoperative Nurick score showed a positive correlation with the postoperative Nurick score at one year (Pearson Coefficient = 0.85). Upper limb symptoms: Postoperatively, 24 patients were free of any upper limb involvement compared with 6 patients preoperatively. The main improvement was in patients who prior to surgery had subjective symptoms with no objective signs of weakness or muscle wasting. 35/48 (72.9%) of this group showed improvement compared to 7/17 (41.2%) of patients who demonstrated objective weakness and/or wasting preoperatively.

COMPLICATIONS

The overall rate of complications was 18.2%. There were two mortalities as a result of pneumonia (2.8%), one patient had to be transferred to the intensive care unit for cardiac failure (1.4%), fixation failure occurred in two patients (2.8%), worsening of myelopathy occurred in two patients (2.8%), C5 temporary radiculopathy presented in two patients (2.8%), superficial wound infection developed in one patient (1.4%) and three patients (4.2%) complained of severe axial pain in the postoperative period. DISCUSSION Our results demonstrate that the greater the preoperative disability the greater the final disability is expected to be. Cord signal change, as an indicator of the pathological severity of the disease, correlates with a worse functional outcome. The degree of improvement postoperatively (i.e. the functional change) does not show a significant correlation with the initial preoperative status. It appears however, that there is a better chance of improvement in patients with no objectively detectable weakness or muscle wasting. The rate of complications encountered in this series is comparable with those in the literature, which renders them valid for quoting when considering surgical treatment for CSM.

CONCLUSION

Surgical decompression offers a real chance of improvement in the functional outcome of CSM, especially during the earlier stages of the disease. The surgical decision needs to be considered carefully due to the advanced age of the patient population and the greater burden of co-morbidities, which increase the surgical risks significantly.

Accuracy of prognostic scores in decision making and predicting outcomes in metastatic spine disease

INTRODUCTION

Management of metastatic spinal disease has changed significantly over the last few years. Different prognostic scores are used in clinical practice for predicting survival. The aim of this study was to assess the accuracy of prognostic scores and the role of delayed presentation in predicting the outcome in patients with metastatic spine disease.

METHODS

Retrospectively, four years of data were collected (2007-2010). Medical records review included type of tumour, duration of symptoms, expected survival and functional status. The Karnofsky performance score was used for functional assessment. Modified Tokuhashi and Tomita scores were used for survival prediction.

RESULTS

A total of 55 patients who underwent surgical stabilisation were reviewed. The mean age was 63 years (range: 32-87 years). The main primary sources of tumours included myeloma, breast cancer, lymphoma, lung cancer, renal cell cancer and prostate cancer. Of the cases studied, 29 patients had posterior instrumented stabilisation alone, 10 patients had an anterior procedure alone and 16 patients (with an expected survival of more than one year) had both anterior and posterior procedures performed. Twenty-three patients presented with spinal cord compression. The mean follow-up duration was 9 months (range: 1-39 months). Patients who were treated within one week of referral survived longer than anticipated. Patients were divided into three groups based on their expected survival. Actual survival was better in all three groups after surgery. Discrepancies in scores were prominent in patients with myeloma, breast and prostate cancers. Functional outcome was better in patients under 65 years of age.

CONCLUSIONS

The prognostic scoring systems are not uniformly effective in all types of primary tumours. However, they are useful in decision making for surgical intervention, taking other factors into account, in particular the age of the patient, the type and stage of the primary tumour and general health.

Characterization of a novel mouse model for human B-cell lymphomas (127.31)

The risk of developing lymphoma is markedly increased after solid organ transplantation. Up to 20% of people who receive a solid organ transplant develop a lymphoma. Calcineurin (CN) A beta knockout (Cnab-/-) mice do not reject allogeneic tumors suggesting an immunosuppressive state, is also a unique model for reverse immunosurveillance. Currently, there is no mouse model for low grade lymphomas based on immune dysregulation. Since we observed a spontaneous activation of T cells, and B-cell lymphomas in CNAβ deficient mice, we hypothesize that CN is involved in T-cell regulation, the lack of regulation causes smoldering inflammation which in turn activates B cells and results in lymphomagenesis. The lymphomas in Cnab-/- mice are positive for B cell surface marker (CD21) but negative for T cell (TCRβ) markers and they are clonal in origin and exhibit malignant (destroying the normal architecture of adjoining area) phenotype. In addition, we do see spontaneous activation of T cells in Cnab-/- mice early in life and continue to accumulate, and B cells later when they are old with mild inflammatory lesions in the gut and liver in Helicobacter-free (clean) colony. Since inflammation is considered to be one of the hallmarks of cancer and also the root cause of cancer, this is a novel mouse model for understanding a slow growing, difficult to cure form of lymphomas.

Accuracy of prognostic scores in decision making and predicting outcomes in metastatic spine disease

INTRODUCTION

Management of metastatic spinal disease has changed significantly over the last few years. Different prognostic scores are used in clinical practice for predicting survival. The aim of this study was to assess the accuracy of prognostic scores and the role of delayed presentation in predicting the outcome in patients with metastatic spine disease.

METHODS

Retrospectively, four years of data were collected (2007-2010). Medical records review included type of tumour, duration of symptoms, expected survival and functional status. The Karnofsky performance score was used for functional assessment. Modified Tokuhashi and Tomita scores were used for survival prediction.

RESULTS

A total of 55 patients who underwent surgical stabilisation were reviewed. The mean age was 63 years (range: 32-87 years). The main primary sources of tumours included myeloma, breast cancer, lymphoma, lung cancer, renal cell cancer and prostate cancer. Of the cases studied, 29 patients had posterior instrumented stabilisation alone, 10 patients had an anterior procedure alone and 16 patients (with an expected survival of more than one year) had both anterior and posterior procedures performed. Twenty-three patients presented with spinal cord compression. The mean follow-up duration was 9 months (range: 1-39 months). Patients who were treated within one week of referral survived longer than anticipated. Patients were divided into three groups based on their expected survival. Actual survival was better in all three groups after surgery. Discrepancies in scores were prominent in patients with myeloma, breast and prostate cancers. Functional outcome was better in patients under 65 years of age.

CONCLUSIONS

The prognostic scoring systems are not uniformly effective in all types of primary tumours. However, they are useful in decision making for surgical intervention, taking other factors into account, in particular the age of the patient, the type and stage of the primary tumour and general health.

Spondylodiscitis in children: a retrospective series

We retrospectively reviewed the records of 16 children treated for spondylodiscitis at our hospital between 2000 and 2007. The mean follow-up was 24 months (12 to 38). There was a mean delay in diagnosis in hospital of 25 days in the ten children aged less than 24 months. At presentation only five of the 16 children presented with localising signs and symptoms. Common presenting symptoms were a refusal to walk or sit in nine children, unexplained fever in six, irritability in five, and limping in four. Plain radiography showed changes in only seven children. The ESR was the most useful investigation when following the clinical course of the disease. Positive blood cultures were obtained in seven children with Staphylococcus aureus being isolated in five. Antibiotics were used in 14 children and spinal bracing in six. Children with spondylodiscitis often present with a confusing clinical picture leading to late diagnosis. The early use of MRI in the investigation of children with an atypical picture may avoid unnecessary delay in starting treatment and possibly prevent long-term problems. All except one of our children had made a complete clinical recovery at final follow-up. However, all six children in the > 24-month age group showed radiological evidence of degenerative changes which might cause problems in the future.

SMAD3 deficiency causes immune dysregulation, colitis and colon tumorigenesis (66.13)

Introduction: TGFβ plays important role in T cell development, differentiation, tolerance and autoimmune diseases. However, recent studies have shown an important role for TGF-β1 and β3 in pathogenic helper T-cell (Th17) differentiation in the presence of IL-1β, IL-6 and IL-23. SMAD3 is mediates TGFβ signaling in many cell types including lymphocytes. Smad3 /- mice develop inflammation-induced colon cancer upon Helicobacter hepaticus infection suggesting that TGFβ1 signaling through SMAD3 is essential to prevent inflammation and progression to colon cancer. In this study we investigated the role of SMAD3 in inflammation using mice deficient in Smad3. Methods: Splenocytes are cultured in the presence of anti-CD3/CD28 beads, TGFβ1 and IL-2 for 3 days. Cytokines are determined by ELISA, CBA and MSD methods. Cells are stained with antibodies for CD4, CD25, CD62L and intracellular FOXP3 and Helios. Results: Smad3-/- mice exhibit inflammatory response upon infection with commensal bacterium H. hepaticus. We find that while SMAD3 signaling is important for inducible Treg cell generation and for their maintenance, deficiency of SMAD3 increases IL-6 and IL-17 levels suggesting a regulatory role for SMAD3 in Th17 cell differentiation. Conclusions: While SMAD3 signaling is important for iTreg cell generation and maintenance, it is not required for Th17 cell differentiation. In addition, we find that SMAD3 signaling negatively regulates Th17 differentiation through induction of FOXP3.

Divergent effects of calcineurin Aβ on regulatory and conventional T-cell homeostasis

Calcineurin (CN) is a phosphatase that activates nuclear factor of activated T cells (NFAT). While the CN inhibitors cyclosporine A (CsA) and tacrolimus (FK506) can prevent graft rejection, they also cause inflammatory diseases. We investigated the role of calcineurin using mice deficient in the CN catalytic subunit Aβ (CNAβ). Cnab(-/-) mice exhibit defective thymocyte maturation, splenomegaly and hepatomegaly. Further, as Cnab(-/-) mice age, they exhibit spontaneous T-cell activation and enhanced production of proinflammatory cytokines (IL-4, IL-6, and IFNγ). FOXP3(+) T(reg) cells were significantly decreased in Cnab(-/-) mice likely contributing to increased T-cell activation. Interestingly, we found that CNAβ is critical for promotion of BCL-2 expression in FOXP3(+) T(reg) and for permitting TGFβ signaling, as TGFβ induces FOXP3 in control but not in Cnab(-/-) T-cells. Together, these data suggest that CNAβ is important for the production and maintenance of T(reg) cells and to ensure mature T-cell quiescence.

Impact of kyphoplasty treatment for vertebral compression fractures on pain and function in 105 patients

PURPOSE OF THE STUDY

Vertebral compression fractures are very common. Symptomatic relief with conservative therapy is often difficult to achieve. Balloon kyphoplasty is a relatively new technique which stabilises the vertebral body and restores spinal alignment in recent fractures, it achieves significant pain relief and improved functional outcome is reported. The aim of this prospective study was to determine the level of pain relief and functional outcome in patients who were initially treated conservatively for 4-6 weeks and if symptoms did not have tendency to resolve, then had kyphoplasty surgery.

MATERIAL AND METHODS

105 patients underwent balloon kyphoplasty between April 2006 and August 2010 and had 1 year follow up. Total 170 levels were augmented, 65% (n=68) of patients were female and the average age was 74 years. Pain relief was assessed using visual analogue score (VAS) and functional outcome using Oswestry Disability Index (ODI).

RESULTS

Results showed decrease of the average pre-operative VAS from 8.2 to 4.4 in the immediate postoperative period (p=0.000). This dramatic improvement remained and was 4.1 at 6 weeks, 3.3 at 6 months and 3.6 at 1 year. The average pre-operative ODI was 58. This improved to 47 in the immediate post-operative period (p=0.002). At 6 weeks this had improved further to 40 and further improvements were seen at 6 months (ODI 37) and 1 year (ODI 38). The average screening time was 2 minutes and 20 seconds. The average volume of cement used per level was 5.5 cm3. Radiographic measurements were performed by independent radiologist. The average pre-operative vertebral angle was 11.6° and 10.9° postoperatively. This was maintained throughout the follow up. This represented a negligible 6% improvement in vertebral body angle. We did not experience any clinically significant complications, we have encountered 11 minor complications which did not require any additional measures (cement leaks, penetration of the vertebral body margins by balloons or K wires and rib fractures).

DISCUSSION

Pain relief and improvement of functional outcome was sustained after one year. Limited number of patients who had 2 year follow up showed trend of minimal deterioration of both parameters (VAS and ODI). This can be explained by incidence of few adjacent segment fractures and progressive overall osteoarthritic changes in this aging population. Radiological evaluation showed maintenance of achieved alignment which did not deteriorate over time. Complication rate was low and did not require any further surgical interventions and did not have any effect on final good clinical outcome.

CONCLUSION

Balloon kyphoplasty proved to be safe surgical technique and should be considered in patients with ongoing pain following an acute vertebral compression fracture that does not improve with initial conservative treatment. It significantly improves pain and functional status in elderly patients.

Calcineurin Aβ signalling is required for Treg-cell generation and prevention of T-cell activation and B-cell lymphomagenesis (100.13)

Introduction: Calcineurin (CN), a protein phosphatase activated by Ca2+-calmodulin, is involved in activation of NFAT. CN inhibitors such as cyclosporine A (CsA) and FK506 are potent inhibitors of T-cell responses and are commonly used to prevent graft rejection. Consistently, CNAβ-deficient mice exhibit defective thymocyte maturation in young mice. However, T cells undergo spontaneous activation in older Cnab-/- mice, and succumb to B-cell lymphomas. Methods: Splenocytes are cultured in the presence of anti-CD3/CD28 beads, TGFβ1 and IL-2 for 3 days. Cytokines in culture supernatants are determined by ELISA, CBA and MSD methods. Cells are stained with CD4, CD25, CD62L and intracellular FOXP3. Results: We observed that FOXP3+ Treg cells are decreased while mature activated T cells (CD62L-CD44+) are increased in KO mice compared to control mice. While TGFβ1 induced the expression of FOXP3 in WT cultures, it failed to induce FOXP3 in KO cultures. Cytokine profiles revealed that CNAβ is required to inhibit IL-4, IL-6, IL-10, IL-17 and IFNγ by TGFβ1. IHC analyses of lymphomas revealed that the lymphomas are of B cell origin and they do not express FOXP1, a marker for activated B cells (ABCs). Discussion: These data show that CNAβ is important for the development and homeostasis of mature T cells and Treg cells. The data also suggest that in the absence of CNAβ, a defective T-cell regulation results in activation of T cells, production of inflammatory cytokines and cause cancer.

Generation of mice with a conditional allele for transforming growth factor beta 1 gene

Transforming growth factor beta1 (TGFbeta1) is a multifunctional growth factor involved in wound healing, tissue fibrosis, and in the pathogenesis of many syndromic diseases (e.g., Marfan syndrome, Camurati-Engelmann disease) and muscular, neurological, ophthalmic, cardiovascular and immunological disorders, and cancer. Since the generation of Tgfb1 knockout mice, there has been extraordinary progress in understanding its physiological and pathophysiological function. Here, we report the generation of a conditional knockout allele for Tgfb1 in which its exon 6 is flanked with LoxP sites. As proof of principle, we crossed these mice to LckCre transgenic mice and specifically disrupted Tgfb1 in T cells. The results indicate that T-cell-produced TGFbeta1 is required for normal in vivo regulation of peripheral T-cell activation, maintenance of T-cell homeostasis, and suppression of autoimmunity.

Calcineurin deficiency decreases inflammatory lesions in transforming growth factor beta1-deficient mice

Transforming growth factor (TGF) beta1) is an immunoregulatory cytokine involved in self-tolerance and lymphocyte homeostasis. Tgfb1 knock-out (KO) mice develop severe multi-focal autoimmune inflammatory lesions due to [Ca(2+)]i deregulation in T cells, and die within 3 weeks after birth. Because the calcineurin inhibitor FK506 inhibits the hyperresponsiveness of Tgfb1(-/-) thymocytes, and because calcineurin Abeta (CNAbeta)-deficient mice do not reject allogenic tumours, we have generated Tgfb1(-/-) Cnab(-/-) mice to address whether CNAbeta deficiency prevents T cell activation and inflammation in Tgfb1(-/-) mice. Here we show that in Tgfb1(-/-) Cnab(-/-) mice inflammation is reduced significantly relative to that in Tgfb1(-/-) mice. However, both CD4(+) and CD8(+) T cells in double knock-out (DKO) mice are activated, as revealed by up-regulation of CD11a lymphocyte function-associated antigen-1 (LFA-1), CD44 and CD69 and down-regulation of CD62L. These data suggest that deficiency of CNAbeta decreases inflammatory lesions but does not prevent activation of autoreactive T cells. Also Tgfb1(-/-) T cells can undergo activation in the absence of CNAbeta, probably by using the other isoform of calcineurin (CNAalpha) in a compensatory manner. CNAbeta-deficient T cells undergo spontaneous activation in vivo and are activated upon anti-T cell receptor stimulation in vitro. Understanding the role of calcineurin in T cell regulation should open up new therapeutic opportunities for inflammation and cancer.

Calcineurin Ab deficiency causes defective Treg-cell generation and enhanced effector T-cell differentiation (89.13)

Calcineurin (CN), a protein phosphatase activated by Ca2+-calmodulin, is involved in activation of NFAT by its dephosphorylation. CN inhibitors such as cyclosporine A (CsA) and FK506 are potent inhibitors of T-cell responses and are commonly used to prevent graft rejection. Consistently, CNAβ-deficient mice exhibit defective thymocyte maturation in young mice. However, T cells undergo spontaneous activation in older Cnab-/- mice, which develop splenomegaly, thymomegaly, hepatomegaly and succumb to metastatic B-cell lymphomas. We have also observed that FOXP3+ Treg cells are decreased while mature activated CD4+ and CD8+ T cells (CD62L-CD44+) are increased in Cnab-/- mice compared to age-matched control mice. These data show that CNAβ is important for the development and homeostasis of mature T cells and Treg cells. Cytokine profile analysis revealed that CNAβ signaling is required to inhibit proinflammatory cytokines (IL-4, IL-10, IL-17 and IFNγ) by TGFβ1 and TGFβ1 induced FOXP3 expression in T cells, suggesting that CNAβ signaling is required for Treg-cell generation. The data suggest that in the absence of CNAβ, a defective T-cell regulatory environment leads to accumulation of activated T cells which produce proinflammatory cytokines and cause inflammation and cancer.

Grant support: This study was supported by NIH AI067903 and CA84291 to TD, and IRG7400128 to RB.

Dual roles of immunoregulatory cytokine TGF-beta in the pathogenesis of autoimmunity-mediated organ damage

Ample evidence suggests a role of TGF-beta in preventing autoimmunity. Multiorgan inflammatory disease, spontaneous activation of self-reactive T cells, and autoantibody production are hallmarks of autoimmune diseases, such as lupus. These features are reminiscent of the immunopathology manifest in TGF-beta1-deficient mice. In this study, we show that lupus-prone (New Zealand Black and White)F(1) mice have reduced expression of TGF-beta1 in lymphoid tissues, and TGF-beta1 or TGF-beta1-producing T cells suppress autoantibody production. In contrast, the expression of TGF-beta1 protein and mRNA and TGF-beta signaling proteins (TGF-beta receptor type II and phosphorylated SMAD3) increases in the target organs, i.e., kidneys, of these mice as they age and develop progressive organ damage. In fact, the levels of TGF-beta1 in kidney tissue and urine correlate with the extent of chronic lesions that represent local tissue fibrosis. In vivo TGF-beta blockade by treatment of these mice with an anti-TGF-beta Ab selectively inhibits chronic fibrotic lesions without affecting autoantibody production and the inflammatory component of tissue injury. Thus, TGF-beta plays a dual, seemingly paradoxical, role in the development of organ damage in multiorgan autoimmune diseases. According to our working model, reduced TGF-beta in immune cells predisposes to immune dysregulation and autoantibody production, which causes tissue inflammation that triggers the production of anti-inflammatory cytokines such as TGF-beta in target organs to counter inflammation. Enhanced TGF-beta in target organs, in turn, can lead to dysregulated tissue repair, progressive fibrogenesis, and eventual end-organ damage.

TGFbeta1 deficiency does not affect the generation and maintenance of CD4+CD25+FOXP3+ putative Treg cells, but causes their numerical inadequacy and loss of regulatory function

TGFbeta1 is considered to be required for peripheral maintenance of CD4(+)CD25(+)FOXP3(+) T(reg) cells. However, we demonstrate no reduction in the percentage of such T cells in the spleens and thymi of Tgfb1(-/-) mice. Although putative T(reg) cells, characterized as CD4(+)CD25(+)FOXP3(+)CD62L(+) T cells, are increased in Tgfb1(-/-) mice, they may be inadequate to control activated T cells since the ratio of activated T cells:putative T(reg) cells is several-fold higher in Tgfb1(-/-) mice than in control mice. We further show that whereas Tgfb1(-/-) mice that express a chicken OVA-specific TCR transgene (DO11.10) have an increase in putative T(reg) cells, there are no detectable CD4(+)CD25(+) T cells in the spleens of DO11.10 Rag1(-/-) mice suggesting that T(reg)-cell generation is self-antigen dependent regardless of whether they express Tgfb1. Finally, we demonstrate that Tgfb1(-/-) T cells remain responsive to the suppressive effect of TGFbeta1 in vitro. These data suggest that TGFbeta1 is required for the regulatory function of T(reg) cells to prevent activation of T cells and autoimmunity.

TGFbeta1 and Treg cells: alliance for tolerance

Transforming growth factor beta1 (TGFbeta1), an important pleiotropic, immunoregulatory cytokine, uses distinct signaling mechanisms in lymphocytes to affect T-cell homeostasis, regulatory T (Treg)-cell and effector-cell function and tumorigenesis. Defects in TGFbeta1 expression or its signaling in T cells correlate with the onset of several autoimmune diseases. TGFbeta1 prevents abnormal T-cell activation through the modulation of Ca2+-calcineurin signaling in a Caenorhabditis elegans Sma and Drosophila Mad proteins (SMAD)3 and SMAD4-independent manner; however, in Treg cells, its effects are mediated, at least in part, through SMAD signaling. TGFbeta1 also acts as a pro-inflammatory cytokine and induces interleukin (IL)-17-producing pathogenic T-helper cells (Th IL-17 cells) synergistically during an inflammatory response in which IL-6 is produced. Here, we will review TGFbeta1 and its signaling in T cells with an emphasis on the regulatory arm of immune tolerance.