Ceramide synthesis regulates T cell activity and GVHD development

Allogeneic hematopoietic cell transplantation (allo-HCT) is an effective immunotherapy for a variety of hematologic malignances, yet its efficacy is impeded by the development of graft-versus-host disease (GVHD). GVHD is characterized by activation, expansion, cytokine production, and migration of alloreactive donor T cells. Hence, strategies to limit GVHD are highly desirable. Ceramides are known to contribute to inflammation and autoimmunity. However, their involvement in T-cell responses to alloantigens is undefined. In the current study, we specifically characterized the role of ceramide synthase 6 (CerS6) after allo-HCT using genetic and pharmacologic approaches. We found that CerS6 was required for optimal T cell activation, proliferation, and cytokine production in response to alloantigen and for subsequent induction of GVHD. However, CerS6 was partially dispensable for the T cell-mediated antileukemia effect. At the molecular level, CerS6 was required for efficient TCR signal transduction, including tyrosine phosphorylation, ZAP-70 activation, and PKCθ/TCR colocalization. Impaired generation of C16-ceramide was responsible for diminished allogeneic T cell responses. Furthermore, targeting CerS6 using a specific inhibitor significantly reduced T cell activation in mouse and human T cells in vitro. Our study provides a rationale for targeting CerS6 to control GVHD, which would enhance the efficacy of allo-HCT as an immunotherapy for hematologic malignancies in the clinic.

Regulatory T-Cell Therapy for Graft-versus-host Disease

Graft-versus-host disease (GVHD) is a significant cause of non-relapse mortality after allogeneic hematopoietic cell transplantation (allo-HCT). Existing strategies to prevent and treat GVHD are incomplete, where a significant portion of allo-HCT recipients developed this complication. Despite this, one such therapy has emerged involving the use of regulatory T cells (Tregs) to control GVHD. The use of natural Tregs (nTregs) yielded positive pre-clinical results and are actively under investigation to reduce GVHD. However, broad application of this approach may require standardization of Treg expansion methods and dosing. Inducible Tregs (iTregs) can be seamlessly generated, but controversial pre-clinical findings and phenotype instability have hampered their translation into the clinic. Here, we review the current biological differences between nTregs and iTregs, as well as their effects on GVHD and graft-versus-leukemia (GVL) responses. We conclude by exploring the idea of combinational cellular therapies for the prevention of GVHD and preservation of GVL.

CD8(+) Tregs promote GVHD prevention and overcome the impaired GVL effect mediated by CD4(+) Tregs in mice

Adoptive natural regulatory T cell (nTreg) therapy has improved the outcome for patients suffering from graft-versus-host disease (GVHD) following allogeneic hematopoietic cell transplantation (Allo-HCT). However, fear of broad immune suppression and subsequent dampening of beneficial graft-versus-leukemia (GVL) responses remains a challenge. To address this concern, we generated alloreactive induced Tregs (iTregs) from resting CD4(+) or CD8(+) T cells and tested their ability to suppress GVH and maintain GVL responses. We utilized major mismatched and haploidentical murine models of HCT with host-derived lymphoma or leukemia cell lines to evaluate GVH and GVL responses simultaneously. Alloreactive CD4(+) iTregs were effective in preventing GVHD, but abrogated the GVL effect against aggressive leukemia. Alloreactive CD8(+) iTregs moderately attenuated GVHD while sparing the GVL effect. Hence, we reasoned that using a combination of CD4(+) and CD8(+) iTregs could achieve the optimal goal of Allo-HCT. Indeed, the combinational therapy was superior to CD4(+) or CD8(+) iTreg singular therapy in GVHD control; importantly, the combinational therapy maintained GVL responses. Cellular analysis uncovered potent suppression of both CD4(+) and CD8(+) effector T cells by the combinational therapy that resulted in effective prevention of GVHD, which could not be achieved by either singular therapy. Gene expression profiles revealed alloreactive CD8(+) iTregs possess elevated expression of multiple cytolytic molecules compared to CD4(+) iTregs, which likely contributes to GVL preservation. Our study uncovers unique differences between alloreactive CD4(+) and CD8(+) iTregs that can be harnessed to create an optimal iTreg therapy for GVHD prevention with maintained GVL responses.

Metabolic reprogramming of alloantigen-activated T cells after hematopoietic cell transplantation

Alloreactive donor T cells are the driving force in the induction of graft-versus-host disease (GVHD), yet little is known about T cell metabolism in response to alloantigens after hematopoietic cell transplantation (HCT). Here, we have demonstrated that donor T cells undergo metabolic reprograming after allogeneic HCT. Specifically, we employed a murine allogeneic BM transplant model and determined that T cells switch from fatty acid β-oxidation (FAO) and pyruvate oxidation via the tricarboxylic (TCA) cycle to aerobic glycolysis, thereby increasing dependence upon glutaminolysis and the pentose phosphate pathway. Glycolysis was required for optimal function of alloantigen-activated T cells and induction of GVHD, as inhibition of glycolysis by targeting mTORC1 or 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) ameliorated GVHD mortality and morbidity. Together, our results indicate that donor T cells use glycolysis as the predominant metabolic process after allogeneic HCT and suggest that glycolysis has potential as a therapeutic target for the control of GVHD.

Inhibition of BTK and ITK with Ibrutinib Is Effective in the Prevention of Chronic Graft-versus-Host Disease in Mice

Bruton’s Tyrosine Kinase (BTK) and IL-2 Inducible T-cell Kinase (ITK) are enzymes responsible for the phosphorylation and activation of downstream effectors in the B-cell receptor (BCR) signaling and T cell receptor (TCR) signaling pathways, respectively. Ibrutinib is an FDA-approved potent inhibitor of both BTK and ITK that impairs B-cell and T-cell function. CD4 T cells and B cells are essential for the induction of chronic graft-versus-host disease (cGVHD). We evaluated these targets by testing the ability of Ibrutinib to prevent or ameliorate cGVHD, which is one of the major complications for patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). We found that Ibrutinib significantly alleviated cGVHD across four different mouse models, accompanied by increased long-term survival and reduced clinical score. The clinical improvements in Ibrutinib-treated recipients were associated with decreased serum-autoantibodies, costimulatory molecule activation, B-cell proliferation, and glomerulonephritis compared to vehicle controls. Ibrutinib was also able to alleviate the clinical manifestations in acute GVHD (aGVHD), where the recipients were given grafts with or without B cells, suggesting that an inhibitory effect of Ibrutinib on T cells contributes to a reduction in both aGVHD and cGVHD pathogenesis. An effective prophylactic regimen is still lacking to both reduce the incidence and severity of human cGVHD following allo-HSCT. Our study shows that Ibrutinib is an effective prophylaxis against several mouse models of cGVHD with minimal toxicity and could be a promising strategy to combat human cGVHD clinically.

Essential Role of Interleukin-12/23p40 in the Development of Graft-versus-Host Disease in Mice

Graft-versus-host disease (GVHD), in both its acute (aGVHD) and chronic (cGVHD) forms, remains a major obstacle impeding successful allogeneic hematopoietic stem cell transplantation (allo-HSCT). T cells, in particular pathogenic T helper (Th) 1 and Th17 subsets, are a driving force for the induction of GVHD. IL-12 and IL-23 cytokines share a common p40 subunit and play a critical role in driving Th1 differentiation and in stabilizing the Th17 phenotype, respectively. In our current study, we hypothesized that p40 is an essential cytokine in the development of GVHD. By using p40-deficient mice, we found that both donor- and host-derived p40 contribute to the development of aGVHD. Neutralization of p40 with an anti-p40 mAb inhibited Th1- and Th17-polarization in vitro. Furthermore, anti-p40 treatment reduced aGVHD severity while preserving the graft-versus-leukemia (GVL) activity. Alleviation of aGVHD was associated with an increase of Th2 differentiation and a decrease of Th1 and Th17 effector T cells in the GVHD target organs. In addition, anti-p40 treatment attenuated the severity of sclerodermatous cGVHD. These results provide a strong rationale that blockade of p40 may represent a promising therapeutic strategy in preventing and treating aGVHD and cGVHD while sparing the GVL effect after allo-HSCT.

T-bet is critical for the development of acute graft-versus-host disease through controlling T cell differentiation and function

T-bet is a master regulator for IFN-γ production and Th1 differentiation. We evaluated the roles of T-bet and IFN-γ in T cell responses in acute graft-versus-host disease (GVHD) and found that T-bet(-/-) T cells induced significantly less GVHD compared with wild-type or IFN-γ(-/-) counterparts in both MHC-mismatched and MHC-matched but minor histocompatibility Ag-mismatched models driven by CD4 T cells. T-bet(-/-), but not IFN-γ(-/-), CD4 T cells had a markedly reduced ability to cause tissue damage in liver and gut. This distinct outcome is reflected by the differential gene expression on donor CD4 T cells deficient for T-bet or IFN-γ. At mRNA and protein levels, we defined several T-bet-dependent molecules that may account for the impaired ability of T-bet(-/-) T cells to migrate into target organs and to produce Th1-related cytokines. Moreover, these molecules were independent of either endogenous IFN-γ, such as CXCR3 and programmed death-1, or systematic IFN-γ, such as NKG2D, I-A(b), and granzyme B. Although both T-bet(-/-) and IFN-γ(-/-) CD4 T cells are prone to differentiate into Th17 cells, polarized Th17 cells deficient for T-bet but not for IFN-γ had a significantly reduced ability to cause GVHD. Finally, T-bet(-/-) T cells had a compromised graft-versus-leukemia effect, which could be essentially reversed by neutralization of IL-17 in the recipients. We conclude that T-bet is required for Th1 differentiation and migration, as well as for optimal function of Th17 cells. Thus, targeting T-bet or regulating its downstream effectors independent of IFN-γ may be a promising strategy to control GVHD in the clinic.

[Complex pacemaker dysfunction. Sometimes a problem does not come alone...]

The electrocardiogram of a multimorbid patient with a pacemaker is discussed. At first sight, it clearly shows dysfunction of an implanted pacemaker. However, this case illustrates that sometimes a second careful look is essential to reveal further hidden problems.

Immune Modulation after Total Hip Surgery

BACKGROUND

Major trauma affects the immune system, and immunosuppression may render the patients susceptible to septic complications. The purpose of this study was to investigate lipopolysaccharide (LPS)-induced releases of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) in whole blood in patients undergoing total hip replacement.

METHODS

Seven patients (6 females) who underwent elective total hip replacement were included. Ex vivo LPS-induced releases of TNF-alpha and IL-6 were measured in a whole blood assay at days 1, 6, 9 and 12 postoperatively, using low- and high-dose LPS incubation. At the same time, white blood cell counts were analyzed.

RESULTS

The amount of TNF-alpha release was significantly reduced at days 6 and 12. Compared to monocyte counts, TNF-alpha release was significantly decreased also at day 9 in low- and high-dose LPS stimulation. IL-6 in plasma was significantly increased at day 1 and normalized thereafter. There were no differences in LPS-induced IL-6 levels compared to the levels before surgery.

CONCLUSION

This in vivo/ex vivo study shows a reduced capacity of whole blood to release LPS-induced TNF-alpha at day 6 through to day 12 after major orthopedic surgery. Attenuated TNF-alpha release may contribute to an increased postoperative susceptibility to gram-negative sepsis.

[Cemented versus cementless revision femoral stems using morselized allograft--a prospective, randomized study with 5 years follow-up]

BACKGROUND

There are only few studies on hip revision using the impaction grafting technique. Furthermore, data on cementless femoral stems as compared to cemented and polished femoral stems are lacking. We wanted to determine whether cementless femoral stems were equally good in preserving bone mineral density around the femoral stem and in functional outcome.

METHOD

Consecutively 14 patients needing hip revisions for aseptic loosening in the stem with bone stock deficiency Paparowsky grade II were randomized into two groups intraoperatively. Morselized fresh-frozen bone allografts were impacted in both groups. The cemented group received polished Landos Fjord-CrCo stems and the uncemented group received the hydroxyapatite-coated Landos Corail-Titan stems. The dual energy X-ray absorptiometry was used to measure bone mineral density around the femoral stem according to Gruen zones. Function was measured by Merle d'Aubigné score. Patients were controlled at 0.5, 3, 6, 9, 12, 18, 24, 36 and 60 months postoperatively.

RESULTS

There was no statistical difference between the BMD loss in the cemented vs. the uncemented group. The BMD loss was between 0-10 % in distal Gruen zones and was between 10-20 % in proximal Gruen zones. Functional scores were similar and reached a plateau of 16 in the Merle d'Aubigné score after 6 months.

CONCLUSIONS

Cemented technique in hip revisions using morselized bone allograft is as good as uncemented technique in preserving BMD measured by the DEXA method and restoring function in a 5 years follow-up.

[Recurrent hemoptysis as initial symptom of a thoracic angiomatosis in an adult patient]

HISTORY

A 24-year-old man presented with recurrent hemoptysis and decreased exercise capacity. DIAGNOSTIC FINDINGS: The chest radiograph demonstrated multiple disseminated pulmonary nodules. In addition the patient developed a hematopericardium with tamponade. The further diagnostic approach revealed an extensive thoracic angiomatosis affecting the lung and the heart.

TREATMENT AND COURSE

Tumor resection could not be performed. A therapy with Interferon alpha-2a was initiated. After 3 month a significant regression of the pulmonary angiomatosis was documented. On the other hand the cardiac tumor showed no therapeutic response.

CONCLUSION

Thoracic angiomatosis should be considered in the differential diagnosis of otherwise unclear hemoptysis or hematopericardium. Diagnosis intra vitamin requires an aggressive and invasive approach. Interferon alpha-2a is effective in palliative treatment of diffuse angiomatous diseases. But not all angiomatous processes respond to that therapy.

Analysis of beta-catenin gene mutations in pancreatic tumors

BACKGROUND/AIM

Mutations of the adenomatous polyposis coli (APC) tumor suppressor gene have been described in a subset of pancreatic carcinomas. The APC gene modulates the beta-catenin-Tcf pathway. The major player in this pathway is the beta-catenin protein encoded by the beta-catenin gene. A variety of different tumors, including colon, prostate, endometrial, and hepatocellular carcinomas, carry mutations in exon 3 of the beta-catenin gene. The aim of this study was to determine the role of the beta-catenin gene in the genesis of exocrine and endocrine tumors of the pancreas.

METHODS

78 ductal pancreatic adenocarcinomas, 14 ductal pancreatic cancer cell lines, and 33 endocrine pancreatic tumors were evaluated for mutations in exon 3 of the beta-catenin gene by single-strand conformation polymorphism analysis and direct DNA sequencing. In addition, 40 ductal pancreatic adenocarcinomas were analyzed for intracellular beta-catenin accumulation by immunohistochemistry, indicating alterations of the beta-catenin gene.

RESULTS

Neither the 111 exocrine and endocrine pancreatic tumors nor the 14 pancreatic cancer cell lines carried mutations in exon 3 of the beta-catenin gene. Intracellular beta-catenin accumulation was not identified in any of the 40 pancreatic adenocarcinomas.

CONCLUSION

These data suggest that the beta-catenin gene as the major player of the beta-catenin-Tcf pathway does not play an important role in the genesis of pancreatic tumors.

Malignant fibrous histiocytoma of the pancreas: a case report with genetic analysis

BACKGROUND

Malignant fibrous histiocytoma (MFH) is the most common type of soft tissue sarcoma in adults; it occurs frequently in the extremities, the trunk, or retroperitoneal tissues. MFH rarely is detected in digestive organs, such as the liver or stomach.

METHODS

The authors report a patient with MFH of the pancreas who was treated with surgery alone. The tumor was studied for genetic alterations in the p53, p16ink4a, and DPC4 tumor suppressor genes as well as the K-ras oncogene by immunohistochemistry, single strand conformation variant (SSCV) analysis, and direct DNA sequencing.

RESULTS

The authors believe that this is the 13th report of primary pancreatic MFH in the world literature and the first genetic analysis of this rare tumor. The patient is alive with no evidence of recurrence 34 months after surgery. Immunohistochemistry revealed no abnormal accumulation of the p53 protein and normal nuclear p16 expression. Mutation analysis of the p53, p16, DPC4, and K-ras genes showed only a polymorphism at codon 72 of the p53 gene and no mutations in any of the genes.

CONCLUSIONS

Genotypically, MFH of the pancreas is clearly different from other malignant pancreatic tumors, which further supports the hypothesis that this tumor is a rare but distinct entity.

Higher frequency of DPC4/Smad4 alterations in pancreatic cancer cell lines than in primary pancreatic adenocarcinomas

The tumor suppressor gene DPC4/Smad4 at 18q21.1 is inactive in about 50% of pancreatic carcinoma xenografts and cell lines. However, the role of DPC4 in the multistep carcinogenesis of primary pancreatic adenocarcinomas remains uncertain. Therefore, we examined 45 primary human pancreatic adenocarcinomas and 12 pancreatic cancer cell lines for DPC4 alterations by single-strand conformational variant (SSCV) analysis and a PCR-based deletion assay. DPC4 was inactivated by either homozygous deletion or point mutation in 6 of 12 cell lines (50%). None of the primary pancreatic carcinomas carried a DPC4 mutation, although 66% revealed LOH of 18q21 sequences. These findings suggest that inactivation of DPC4 occurs more frequently in tumor-derived cell lines than in primary pancreatic adenocarcinomas. In addition, another, yet unidentified, tumor suppressor gene(s) may be linked with the frequent LOH of 18q21 in primary pancreatic adenocarcinomas.

Mutations of the DPC4/Smad4 gene in neuroendocrine pancreatic tumors

Tumors of the endocrine pancreas are extremely rare, and molecular mechanisms leading to their development are not well understood. A candidate tumor suppressor gene, DPC4, located at 18q21, has recently been shown to be inactivated in half of pancreatic adenocarcinoma xenografts. The close anatomical relationship of the exocrine and endocrine pancreas prompted us to determine the role of DPC4 in the tumorigenesis of 25 pancreatic islet cell tumors (11 insulinomas, nine non-functioning endocrine carcinomas, three gastrinomas, two vipomas). A mutation screening of the highly conserved COOH-terminal domain of DPC4 (exons 8-11) was performed by single-strand conformational variant (SSCP) analysis and a PCR-based deletion assay. Five of nine (55%) non-functioning endocrine pancreatic carcinomas revealed either point mutations, small intragenic deletions or homozygous deletion of DPC4 sequences compared to none of the insulinomas, gastrinomas or vipomas. These results suggest that DPC4 is an important target gene promoting tumorigenesis of non-functioning neuroendocrine pancreatic carcinomas.

Localization, malignant potential, and surgical management of gastrinomas

Between 1987 and 1996 a total of 25 patients with proved Zollinger-Ellison syndrome (ZES) have been treated in our department. If preoperative imaging studies did not show diffuse metastatic disease, patients were scheduled for operation with a standardized surgical approach including thorough exploration and intraoperative ultrasonography (IOUS) of the pancreas and a longitudinal duodenotomy, with separate palpation of the anterior and posterior walls. Postoperatively, patients were followed up by physical examination, fasting gastrin levels, and the secretin stimulation test. Altogether 10 patients had duodenal wall gastrinoma, 14 patients pancreatic gastrinoma, and the tumor was not found in 1 patient. Only 15 tumors (60%) (2 duodenal wall and 13 pancreatic gastrinomas) could be visualized preoperatively. Intraoperatively, 24 of 25 primary gastrinomas were localized. The mean size of duodenal wall gastrinomas (9.6 mm) was significantly smaller than that of pancreatic gastrinomas (28.7 mm) (p < 0.05). At the time of surgical exploration, five duodenal and seven pancreatic gastrinomas had metastasized. The incidence of lymph node metastases was similar for both tumor sites, whereas patients with pancreatic gastrinomas more frequently had liver metastases. The presence of liver metastases was the most important determinant for survival. Four patients (40%) with duodenal and seven with pancreatic (50%) gastrinomas (mean follow-up 5.2 years) were biochemically cured by operation. Of the remaining patients, eight are still alive with recurrent disease. Our results suggest that preoperative localization of gastrinomas often fails despite all modern imaging methods. Therefore a standardized surgical exploration of the pancreas including IOUS and a duodenal exploration should be performed to achieve optimal results. Preoperative diagnostic imaging tests should include computed tomography, ultrasonography, and somatostatin receptor scintigraphy to exclude diffuse metastases. In contrast to liver metastases, lymph node metastases do not have a significant influence on survival.

K-ras oncogene mutations indicate malignancy in cystic tumors of the pancreas

OBJECTIVE

To evaluate clinical parameters, presurgical diagnostic tests, histologic findings, and the presence of K-ras oncogene mutations in cystic tumors of the pancreas to determine which best predict malignancy.

SUMMARY BACKGROUND DATA

Because presurgical, intraoperative, and final pathologic differentiation is difficult in cystic tumors of the pancreas, it would be a major benefit to identify markers that accurately predict malignancy in these rare tumors. The role of K-ras oncogene mutations as an indicator of malignancy has not been determined in these tumors.

METHODS

Nineteen patients with cystic tumors of the pancreas were evaluated, including K-ras mutation analysis based on polymerase chain reaction and restriction digestion assays and direct DNA sequencing, to screen for parameters that accurately predict malignancy.

RESULTS

All malignant cystic pancreatic tumors (five cystadenocarcinomas and three mucin-producing adenocarcinomas) harbored K-ras mutations at codon 12 or 13. K-ras mutations were also detected in the percutaneous fine-needle aspirates of two of these patients. In contrast, none of nine benign cystadenomas or the solid-papillary neoplasm had K-ras mutations. None of the patients with a benign tumor carrying K-ras wild-type sequences developed recurrent disease after a mean follow-up of 50 months. Seven of the 8 malignant cystic pancreatic tumors, but none of the 11 benign tumors, showed dilatation of the main pancreatic duct on computed tomography or endoscopic retrograde cholangiopancreatography.

CONCLUSIONS

K-ras mutation analysis seems to be a powerful tool to determine the malignant potential of cystic pancreatic tumors before and after surgery. Dilatation of the main pancreatic duct on computed tomography or endoscopic retrograde cholangiopancreatography is highly suggestive for malignancy in these rare tumors.

[Detection of hepatic micrometastasis in ductal pancreatic carcinoma by K-ras mutation analysis and determination of clinical relevance]

In this prospective study we evaluated the presence and importance of hepatic micrometastases at the time of operation in patients with resectable pancreatic carcinoma. In 13 patients with pancreatic carcinoma and 5 patients with chronic pancreatitis Truecut-Needle biopsies of the liver were obtained during operation. K-ras mutation analysis was done by the PCR/restriction digestion assay with HphI, followed by an ultrasound of the liver in 3 monthly intervals. Four of 13 (30%) pancreatic cancer patients had K-ras gene mutations in the liver and had a mean survival of 6 months after resection. All chronic pancreatitis patients and 8 of the 9 remaining pancreatic cancer patients without K-ras mutations in the liver biopsies are alive without evidence of liver metastases after a mean follow-up of 9 months. Detection of micrometastases in the liver by K-ras mutation analysis might be a powerful tool to identify occult clinical relevant liver metastases.