The mechanism of resistance to parasite infection. (100.14)

The parasite, Toxoplasma gondii (T. gondii) can cause severe disease in immunocompromised humans. Susceptibility to T. gondii is also linked to the MHC haplotype: B10.D2 (H-2d) mice are relatively resistant to T. gondii infection than C57Bl/6 mice (B6, H-2b). CD8 T cells, activated by MHC molecules, are known to be that primary mediators of protection from T. gondii, and it is possible that differences in their responses might determine susceptibility to infection. Indeed, in H-2d mice, we recently identified the key immunodominant peptide, HF10, contained in the GRA6 protein that elicited protective CD8 T cell responses. In contrast, we show here that the CD8 T cell response to T. gondii in susceptible B6 mice is weaker and specific for a distinct peptide derived from the ROP5 protein. Furthermore, unlike the HF10 peptide that generated protective CD8 T cells in H-2d mice, immunization with the ROP5 peptide failed to diminish the parasite burden in chronically infected H-2b mice. Thus, susceptibility to T. gondii correlates with MHC-linked processing of specific parasite proteins that elicit differential CD8 T cell responses in mice.

A novel MHC class Ib-mediated immune surveillance mechanism detects the absence of ERAAP (100.16)

Immune surveillance mechanisms detect failures in vital parts of the host immune system, such as in the antigen processing pathway. The ER aminopeptidase associated with antigen processing, ERAAP, is an essential component of the antigen processing pathway, and is required to generate the final peptides presented by MHC class I molecules. It has been unclear how the immune system detects deficiencies in ERAAP function, and here we describe a potential mechanism to do so. Non-classical MHC class I, or MHC class Ib, molecules present novel peptides in ERAAP-deficient cells, and elicit potent CD8 T cell responses in wild-type mice. Using these CD8 T cells as a probe, we identified a novel peptide presented by Qa-1b. FL9-Qa-1b-specific CD8 T cells can be readily detected in naïve mice and constitute a substantial fraction of the anti-ERAAP-/- immune response in wild-type mice. Additionally, WT CD8 T cells detect and eliminate MHC class Ib-expressing ERAAP-deficient cells. Therefore, we suggest that presentation of the FL9 peptide by Qa-1b molecules is a surveillance mechanism for detecting inhibition of ERAAP function.

Right postoperative pleural effusion following laparoscopic appendicectomies: a case series

Pleural effusion is not a commonly reported complication of appendicectomy. In our experience, we have performed all forms of appendicitis by laparoscopy (n = 217) since August 2006. We report three consecutive cases of right postoperative pleural effusion, all of which occurred during the immediate postoperative course of a laparoscopic appendicectomy. All three patients presented a perforated appendicitis. The right postoperative pleural effusions seem to be linked to the laparoscopic approach, and can be explained by the cumulative effects of peritoneal lavage, pneumoperitoneum and Trendelenburg position. The first two cases were managed medically by intravenous antibiotic therapy. The third patient required a pleural drainage by thoracoscopy. Surgeons should be aware of this complication when operating perforated appendicitis by the laparoscopic method.

Everolimus versus azathioprine in a cyclosporine and ketoconazole-based immunosuppressive therapy in kidney transplant: 3-year follow-up of an open-label, prospective, cohort, comparative clinical trial

In cyclosporine-based protocols, everolimus is more effective than azathioprine to reduce acute rejection. Ketoconazole may reduce cyclosporine and everolimus requirements. We compared kidney transplant patients treated with everolimus or azathioprine in a ketoconazole- and cyclosporine-based immunosuppressive regimen. This open-label, prospective trial of low immunologic risk patients. Included one group (n = 11) who received everolimus (target blood level, 3-8 ng/mL) and the other (n = 11) azathioprine (2.0-2.5 mg/kg/d). Both received steroids, ketoconazole, and cyclosporine with C(0) targets (ng/mL) in the everolimus group of 200-250, 100-125, and 50-65 for months 1 and 2 and thereafter and in the azathioprine group of 250-300 in month 1, 200-250 in month 2, 180-200 until month 6, and 100-125 thereafter. Their baseline characteristics were similar. Two biopsy-proven acute rejections occurred in each group. Three-year graft and patient survival in both groups was 100%. Creatinine clearances at months 6, 12, 24, and 36 were 63.7 +/- 25.4, 58.9 +/- 24.9, 56.0 +/- 22.9, and 57.0 +/- 27.6 in the everolimus group versus 72.6 +/- 20, 68.6 +/- 21.3, 71.4 +/- 23.2, and 68.4 +/- 19.2 in the azathioprine group (NS for every comparison). Major complications were rare and similar in both groups. Five patients in the everolimus group received simvastatin versus 4 in the azathioprine cohort (P = .53). The average cyclosporine doses to achieve targets were 0.8-1.2 mg/kg in the everolimus group and 1.6-2.2 mg/kg in the azathioprine group. The average everolimus dose after month 2 was 0.75-0.9 mg/d. We concluded that with cyclosporine, ketoconazole, and steroids, everolimus was as effective and safe as azathioprine. Cyclosporine reduction with everolimus did not influence graft survival or function at 3 years.

Identity of Toxoplasma gondii antigens that elicit CD4 T cells and their protective potential (130.13)

Toxoplasma gondii (Toxo) can cause severe disease in immunocompromised individuals. Previous studies in various strains of mice have shown that genetic resistance to disease is linked to the MHC locus and protection is largely mediated by Toxo-specific CD8 T cells. In B10.D2 (H-2d) mice, CD8 T cells recognize an immunodominant peptide derived from the Toxo-protein, GRA6. However, a GRA6-specific response is not detected in C57BL/6 (B6, H-2b) mice. Instead, Toxo immunization of B6 mice elicits primarily a CD4 T cell response to unknown Toxo antigens. To identify the CD4 T cell stimulating antigens, we generated a Toxo-specific, lacZ inducible, CD4 T cell hybridoma and used it as a probe to screen a Toxo-cDNA library in bone marrow derived dendritic cells. The results reveal that CD4 T cells can be elicited by a hypothetical protein in the Toxo sequence database. We have defined the minimal peptide presented by MHC class II molecules and we will discuss the protective potential of this peptide-specific CD4 T cells in Toxo infected mice.

Cognitive modifiability of children with developmental disabilities: a multicentre study using Feuerstein's Instrumental Enrichment--Basic program

The study aimed at exploring the effectiveness of cognitive intervention with the new "Instrumental Enrichment Basic" program (IE-basic), based on Feuerstein's theory of structural cognitive modifiability that contends that a child's cognitive functioning can be significantly modified through mediated learning intervention. The IE-basic progam is aimed at enhancing domain-general cognitive functioning in a number of areas (systematic perception, self-regulation abilities, conceptual vocabulary, planning, decoding emotions and social relations) as well as transferring learnt principles to daily life domains. Participants were children with DCD, CP, intellectual impairment of genetic origin, autistic spectrum disorder, ADHD or other learning disorders, with a mental age of 5-7 years, from Canada, Chile, Belgium, Italy and Israel. Children in the experimental groups (N=104) received 27-90 h of the program during 30-45 weeks; the comparison groups (N=72) received general occupational and sensory-motor therapy. Analysis of the pre- to post-test gain scores demonstrated significant (p<0.05) advantage of experimental over comparison groups in three WISC-R subtests ("Similarities", "Picture Completion", "Picture Arrangement") and Raven Coloured Matrices. Effect sizes ranged from 0.3 to 0.52. Results suggest that it is possible to improve cognitive functioning of children with developmental disability. No advantage was found for children with specific aetiology. Greater cognitive gains were demonstrated by children who received the program in an educational context where all teachers were committed to the principles of mediated learning.

Switching to sirolimus in renal transplant recipients with hepatitis C virus: a safe option

INTRODUCTION

The presence of hepatitis C virus (HCV) in renal transplant recipients is an independent risk factor for death and graft failure. Chronic allograft nephropathy (CAN) favored by the use of calcineurin inhibitors (CNI) is one of the main causes of graft loss, whereas sirolimus (SRL) has proven to maintain better graft function with lower rates of CAN.

OBJECTIVES AND METHODS

We developed a protocol to evaluate the safety of SRL in transplant recipients with respect to HCV. We studied 5 patients (3 men) of mean age 52 +/- 9.2 years with HCV who had not received antiviral treatment. The viral genotypes were 1b in 4 cases and 2a/2c in 1 case. Basic immunosuppression was mycophenolate mofetil (MMF) and corticosteroids in all patients, cyclosporine (CsA) in 4 cases, and tacrolimus (Tac) in 1 case. Before the switch, a renal biopsy was performed and viral replication and cryoglobulins determined.

RESULTS

Biopsy provided a diagnosis of CAN in 1 case, CNI toxicity-associated CAN in 2 cases, CNI toxicity in 1 case, and no renal damage in the remaining case. We observed a nonsignificant decrease in the number (log) of viral copies with a stabilization of renal function but with a slight to moderate increase in proteinuria.

CONCLUSIONS

The switch seemed to be safe with no increase in viral copies. Graft renal function remained stable with increased proteinuria that must be supervised, even though it did not reach statistical significance.

Reconstruction of the right anterior circulation with the Pipeline embolization device to achieve treatment of a progressively symptomatic, large carotid aneurysm

INTRODUCTION

We present the use of the Pipeline embolization device (PED) to achieve reconstruction of the right anterior circulation in a patient with a dolichoectatic internal carotid artery (ICA) and middle cerebral artery (MCA) and an associated symptomatic, large, carotid-ophthalmic segment aneurysm.

CLINICAL PRESENTATION

A 36-year-old man presented with progressive right eye vision loss followed by sudden severe headache. Subsequent neuroimaging revealed a large right carotid-ophthalmic segment aneurysm and diffuse ectasia of the supraclinoid ICA and proximal MCA. A coil embolization of the aneurysm was performed without stent support. Over the next year, the patient experienced increasing headache and progressive bitemporal vision loss. Serial MRI showed progressive coil compaction and recanalization of the aneurysm.

TREATMENT

The right anterior circulation was reconstructed with a total of six PEDs that extended from the distal M1 segment of the MCA proximally into the distal cavernous segment of the ICA. Follow-up angiography at 1 and 4 months demonstrated progressive complete occlusion of the aneurysm and a reorganization of blood flow to the anterior cerebral and anterior choroidal arteries. MRI and radiographic imaging provided evidence of progressive contraction of the intra-aneurysmal thrombus. The patient's headaches resolved and serial visual field examinations have demonstrated gradual improvement after treatment.

CONCLUSION

Extensive cerebrovascular reconstructions that are not possible using commercially available endovascular devices can be achieved with Pipeline. The safety, efficacy and long term implications of such reconstructions are currently being defined.

Contrast responses to bright slits of visual cells in the superior colliculus of the albino rat

Contrast is the most effective stimulus in the visual system. The response of single cells to changes in stimulus contrast has been studied in a large variety of animals and the contrast response function determined. In the rat, studies on responses to contrast have been focused primarily in the geniculocortical pathway and there are relatively few in subcortical structures. We report here for the first time the contrast response function of single units located in the superior colliculus (SC) of the albino rat to several stimulus contrast. Cells in the SC require a relatively high contrast to elicit a reliable response and the dynamic response range is restricted to a short contrast interval.

The absence of ER trimming alters peptides presented by non-classical MHC class I molecules (78.8)

The nature, function and pathways used to produce peptides for presentation by non-classical MHC class I molecules is poorly understood. Here we show that cells from mice lacking the ER aminopeptidase associated with antigen processing (ERAAP) present an immunologically distinct peptide-MHC class I repertoire. Wild-type mice immunized with ERAAP-deficient cells mount robust CD8 T cell responses specific for peptides presented by classical as well as non-classical MHC I molecules. These CD8 T cells produce pro-inflammatory cytokines and effectively kill ERAAP-deficient target cells in vitro as well as in vivo. Further, peptides presented by non-classical MHC class I molecules are expressed in a tissue-specific manner and elicit CD8 T cell responses both by direct and cross-priming. Thus, ERAAP trims the final peptides presented by classical as well as non-classical MHC class I molecules, and may be involved in trimming peptides for cross-presentation.

This research was supported by grants from the NIH (AI060040) to N.S.; N.A.N. is supported by the Irvington Institute Fellowship Program of the Cancer Research Institute.

Immunodominant, protective response to the parasite Toxoplasma gondii requires antigen processing in the endoplasmic reticulum

The parasite Toxoplasma gondii replicates in a specialized intracellular vacuole and causes disease in many species. Protection from toxoplasmosis is mediated by CD8(+) T cells, but the T. gondii antigens and host genes required for eliciting protective immunity are poorly defined. Here we identified GRA6, a polymorphic protein secreted in the parasitophorous vacuole, as the source of the immunodominant and protective decapeptide HF10 presented by the H-2L(d) major histocompatibility complex class I molecule. Presentation of the HF10-H-2L(d) ligand required proteolysis by ERAAP, the endoplasmic reticulum aminopeptidase associated with antigen processing. Consequently, expansion of protective CD8(+) T cell populations was impaired in T. gondii-infected ERAAP-deficient mice, which were more susceptible to toxoplasmosis. Thus, endoplasmic reticulum proteolysis is critical for eliciting protective immunity to a vacuolar parasite.

Synchronous multiple small bowel intussusceptions in an adult with blue rubber bleb naevus syndrome: Report of a case and review of literature

Background

Blue rubber bleb naevus syndrome (BRBNS), is an uncommon condition characterised by cavernous haemangiomas of skin and gastrointestinal tract. The most common complication of this syndrome is gastrointestinal bleeding. Intussusception of bowel, although a known complication, has rarely been reported.

Case presentation

We report the case of a 37-year-old man who presented with multiple intussusceptions of small bowel. He required an urgent laparotomy and bowel resections. He suffered from BRBNS. This is the first reported case of multiple synchronous intussusceptions affecting both jejunum and ileum, secondary to haemangiomas occurring in an adult with BRBNS. The underlying conditions of acute abdomen in patients with BRBNS may include intramural haemorrhage, infarction, volvulus or intussusception of bowel. Treatment options include pharmacological manipulation, bowel resection, and interventions such as sclerotherapy, angiographic embolisation, endoscopic ligation, electrocautery and laser photocoagulation for visceral lesions.

Conclusion

A high index of suspicion is required whilst dealing with acute abdomen in patients with BRBNS. Clinical trials may provide some answers as to the preference of treatment in individual cases, as the current level of evidence does not offer a clear choice of optimal treatment.