Functional status of immune cells in patients with long-lasting type 2 diabetes mellitus

Although patients with diabetes contract infectious diseases at higher frequencies, and in more severe forms, compared to non-diabetics, the underlying defects of the immune function have not been defined clearly. To address this, we designed an immune monitoring protocol and analysed the functional status of various immune cells. Peripheral blood mononuclear cells (PBMCs) were stimulated with the proper ligands and the functional reactivity of each lineage of cells was subsequently measured. Patients with type 2 diabetes mellitus (T2DM) had PBMC composition ratios comparable to healthy controls, except for a higher frequency of B cell and effector T cell fractions. The capacity of myeloid cells to secrete proinflammatory cytokines was not diminished in terms of the sensitivity and magnitude of the response. Furthermore, cytolytic activity and interferon (IFN)-γ production of natural killer (NK) cells and CD8⁺ T cells were not decreased in T2DM patients. Phenotypical maturation of dendritic cells, indicated by the up-regulation of major histocompatibility complex (MHC) proteins and co-stimulatory molecules in response to lipopolysaccharide (LPS), was slightly enhanced in T2DM patients. Finally, the functional differentiation profiles of CD4⁺ T cells did not differ between T2DM patients and the control group. These data indicate that patients with long-lasting T2DM do not have any gross functional defects in immune cells, at least in circulating monocytes, dendritic cells, NK cells and T lymphocytes.

Long-term control of diabetes in immunosuppressed nonhuman primates (NHP) by the transplantation of adult porcine islets

Pig islets are an alternative source for islet transplantation to treat type 1 diabetes (T1D), but reproducible curative potential in the pig-to-nonhuman primate (NHP) model has not been demonstrated. Here, we report that pig islet grafts survived and maintained normoglycemia for >6 months in four of five consecutive immunosuppressed NHPs. Pig islets were isolated from designated pathogen-free (DPF) miniature pigs and infused intraportally into streptozotocin-induced diabetic rhesus monkeys under pretreatment with cobra venom factor (CVF), anti-thymocyte globulin (ATG) induction and maintenance with anti-CD154 monoclonal antibody and low-dose sirolimus. Ex vivo expanded autologous regulatory T cells were adoptively transferred in three recipients. Blood glucose levels were promptly normalized in all five monkeys and normoglycemia (90-110 mg/dL) was maintained for >6 months in four cases, the longest currently up to 603 days. Intravenous glucose tolerance tests during the follow-up period showed excellent glucose disposal capacity and porcine C-peptide responses. Adoptive transfer of autologous regulatory T cells was likely to be associated with more stable and durable normoglycemia. Importantly, the recipients showed no serious adverse effects. Taken together, our results confirm the clinical feasibility of pig islet transplantation to treat T1D patients without the need for excessive immunosuppressive therapy.

Reactive oxygen species in rats with chronic post-ischemia pain

BACKGROUND

An emerging theme in the study of the pathophysiology of persistent pain is the role of reactive oxygen species (ROS). In the present study, we examined the hypothesis that the exogenous supply of antioxidant drugs during peri-reperfusion would attenuate pain induced by ischemia/reperfusion (IR) injury. We investigated the analgesic effects of three antioxidants administered during peri-reperfusion using an animal model of complex regional pain syndrome-type I consisting of chronic post-ischemia pain (CPIP) of the hind paw.

METHODS

Application of a tight-fitting tourniquet for a period of 3 h produced CPIP in male Sprague-Dawley rats. Low-dose allopurinol (4 mg/kg), high-dose allopurinol (40 mg/kg), superoxide dismutase (SOD, 4000 U/kg), N-nitro-L-arginine methyl ester (L-NAME, 10 mg/kg), or SOD (4000 U/kg)+L-NAME (10 mg/kg) was administered intraperitoneally just after tourniquet application and at 1 and 2 days after reperfusion for 3 days. The effects of antioxidants in rats were investigated using mechanical and cold stimuli. Each group consisted of seven rats.

RESULTS

Allopurinol caused significant alleviation in mechanical and cold allodynia for a period of 4 weeks in rats with CPIP. Both SOD and L-NAME, which were used to investigate the roles of superoxide (O2(-)) and nitric oxide (NO) in pain, also attenuated neuropathic-like pain symptoms in rats for 4 weeks.

CONCLUSIONS

Our findings suggest that O2(-) and NO mediate IR injury-induced chronic pain, and that ROS scavengers administered during the peri-reperfusion period have long-term analgesic effects.

Improved islet yields after purification following the novel endogenous trypsin inhibitor and histidine-tryptophan-ketoglutarate treatment in pigs

BACKGROUND

Adult porcine islet xenotransplantation into humans is greatly diminished by the difficulty to isolate islets because of their fragility. The goal of this study was to improve the efficacy of islet yields using endogenous trypsin inhibitor and histidine-tryptophan-ketoglutarate (HTK) perfusate.

METHOD

We compared two porcine islet isolation protocols: Eurocollins solution for in situ pancreas perfusion without use of an endogenous trypsin inhibitor versus HTK solution including endogenous trypsin inhibitor for pancreas perfusion.

RESULTS

Endogenous trypsin inhibitor and HTK strategies significantly improved total islet yield, recovery, and islet index after purification (P < .05), whereas unpurified islet yield did not increase. An average of 228,000 +/- 95,000 islet equivalents (IEQ) (n = 20) purified islets were obtained in the first group compared with 115,000 +/- 56,000 IEQ (n = 18) in the second group. The average islet index was significantly increased in the first group compared with the second group before and after purification: before: 0.28 versus 0.49 versus after: 0.25 versus 0.4 (P < .05). At this time, islet purity, viability, and stimulation index did not show a significant difference between groups.

CONCLUSION

Our study showed that endogenous trypsin inhibitor and HTK strategies significantly improved purified islet isolation efficacy because of reduction of islet fragility.

Experimental microencapsulation of porcine and rat pancreatic islet cells with air-driven droplet generator and alginate

Transplantation of microencapsulated islets is proposed as an ideal therapy for the treatment of type 1 diabetes mellitus without immunosuppression. This strategy is based on the principle that foreign cells are protected from the host immune system by an artificial membrane. The aim of this study was to establish an ideal condition of microencapsulation using an air-driven droplet generator and alginate in vitro. The optimal conditions for islet encapsulation were an alginate inflow rate of 10 mL/h, CO2 flow rate of 2.0 L/min in a concentration of 2% alginate. For 2.5% alginate, the alginate inflow rate of 20 mL/h, CO2 flow rate 3.0 L/min was ideal; alginate inflow rate of 40 mL/h, CO2 flow rate of 4.0 L/min showed good microcapsules at 3% alginate. Viability of encapsulated islets was greater than 90%. In terms of insulin secretion, encapsulated islets secreted insulin in response to glucose in static culture medium. However, there was no normal response to low or high glucose challenge with a stimulation index less than 2.0. Microencapsulation of pig islets was successfully performed with air-driven droplet generator and alginate in vitro. Further studies about biocompatibility and glucose control in vivo may provide a useful tool for treatment of patients with diabetes mellitus.

Comparative study on biologic and immunologic characteristics of the pancreas islet cell between 24 degrees C and 37 degrees C culture in the rat

The aim of this study was to investigate the effect of culture at 24 degrees C on cell viability, cellular function, immunogenicity, and cytokine profiles of rat pancreatic islets. Pancreatic islets were isolated from Lewis rats and cultured at either 24 degrees C or 37 degrees C for 14 days. Islet recovery was counted as islet equivalents; islet viability was examined with fluorescent vital staining. Islet function was measured with a glucose stimulation test. Annexin V, and MHC class I and II expression were measured using flow cytometric assay for apoptosis and immunogenicity, respectively. Lymphocyte cell proliferation was examined with WST-1 proliferation assay. Cytokine profiles were analyzed with quantitative real time RT-PCR. All these parameters were measured on 1, 3, 5, 7 and 14 culture days after islet isolation. Islet recovery was higher in islets cultured at 24 degrees C than 37 degrees C without a change in viability. Insulin secretion after glucose stimulation was more effective in 24 degrees C culture conditions. Decreased apoptotic cell death was demonstrated in 24 degrees C cultured islets. Both MHC class I and II expression on islets and lymphocyte proliferation upon coculture with islets were less prominent in 24 degrees C cultured islets. TNF-alpha expression was lower in islets cultured at 24 degrees C than in islets cultured at 37 degrees C. Both IL-1beta and IL-10 cytokine expressions were similar under both culture conditions. This study demonstrated that cell recovery and function are increased in islets cultured at 24 degrees C than those at 37 degrees C with decreased antigenicity and proinflammatory cytokine expression.

Analysis on Donor and Isolation-Related Factors of Successful Isolation of Human Islet of Langerhans From Human Cadaveric Donors

We analyzed the preexisting donor factors and isolation variables that affected isolation of human islets of Langerhans. Sixty-nine pancreata from cadaveric donors were analyzed for donor factors of age, gender, body mass index, cause of death as well as graft factors of cold ischemia time, pancreas status, distensibility during intraductal collagenase distension and time of collagenase expansion and digestion. Islet isolations that recovered >100,000 IEQ (n = 53) were compared to those generating less than 100,000 IEQ (n = 16) to analyze the factors affecting islet yield during donor harvest and isolation procedures. The mean islet recovery was 216.0 x 10(3) (IEQ) or 2840 (IEQ) per gram of pancreas. Mean purity was 54%. The success rate of islet isolation was 76%. Mean age was 31 years, and mean cold ischemia time was 6.9 hours. In univariate analysis, the status of the pancreas was the only significant factor for successful isolation, and gender, time of collagenase expansion and digestion were marginal factors. In stepwise multivariate logistic regression analysis of donor and isolation-related factors, donor gender, pancreas status and digestion time were significant factors. During the same period we performed three cases of clinical islet allotransplantation and one autotransplantation. This study confirmed that the same donor factors and variables in the isolation process can affect the ability to obtain successful human islet isolation. Enough experience and pertinent review of donor and isolation factors can make islet isolation consistent, supporting clinical islet transplantation without unnecessary cost.

Experimental islet isolation in porcine pancreas with new enzyme Liberase PI

The aim of this study was to investigate the results of 20 consecutive porcine islet isolations using a new enzyme Liberase PI. Twenty pancreata were procured for islet isolation, which was performed using modified Ricordi's method with Liberase PI. Quantitation of islet viability staining, insulin stimulation assay, intracellular insulin content/DNA, and in vivo transplantability into diabetic nude mice were examined for quality control. The results were compared between a high-yield group (>2500 IEQ/g pancreas) and a low-yield group (<2500 IEQ/g pancreas). Sufficient amount of purified islets (3000 IEQ/g pancreas) were obtained using the new brand enzyme Liberase PI. These islets showed good quality in structure and functions, which were demonstrated by in vitro and in vivo standard assays. Isolation index (IEQ/number) of the low-yield group was lower than that of high-yield group (0.75 vs 0.86), which means more fragmentation of islets in the low-yield group. There were no differences in function between the two groups. In conclusion, we obtained sufficient numbers of viable, functional islets from porcine pancreas using a new brand enzyme Liberase PI and low-temperature isolation technique. However, overdigestion of islets during the isolation remains to be overcome. Advance in porcine islet isolation technique will in the future make the porcine islet xenotransplantation a reality for the cure of diabetes mellitus.

Conserved CDR3 regions in T-cell receptor (TCR) CD8(+) T cells that recognize the Tax11-19/HLA-A*0201 complex in a subject infected with human T-cell leukemia virus type 1: relationship of T-cell fine specificity and major histocompatibility complex/peptide/TCR crystal structure

We investigated the T-cell receptor (TCR) repertoire of CD8(+) T cells that recognize the Tax11-19 immunodominant epitope of Tax protein expressed by human T-cell leukemia virus (HTLV-1) that is implicated in the disease HTLV-1-associated myelopathy (HAM/TSP). A panel of Tax11-19-reactive CD8(+) T-cell clones was generated by single-cell cloning of Tax11-19/HLA-A*0201 tetramer-positive peripheral blood lymphocytes from an HTLV-1-infected individual. The analyses of TCR usage revealed that the combination of diverse TCR alpha and beta chains could be used for the recognition of Tax11-19 but the major population of T-cell clones (15 of 24 clones) expressed the TCR V beta 13S1 and V alpha 17 chain. We found striking similarities in CDR3 regions of TCR alpha and beta chains between our major group of CD8(+) T-cell clones and those originating from different subjects as previously reported, including TCRs with resolved crystal structures. A 3-amino-acid sequence (PG-G) in the CDR3 region of the V beta chain was conserved among all the Tax11-19-reactive T-cell clones expressing V beta 13S1 and V alpha 17 chains. Conserved amino acids in the CDR3 region do not directly contact the Tax11-19 peptide, as corroborated by the crystal structure of B7-TCR, a TCR that is almost identical to VB13S1 clones isolated in this study. Analysis of fine peptide specificity using altered peptide ligands (APL) of Tax11-19 revealed a similar recognition pattern among this panel of T-cell clones. These data suggest that the PG-G amino acids in the CDR3 beta loop provide a structural framework necessary for the maintenance of the tertiary TCR structure.

Uncoupling p70(s6) kinase activation and proliferation: rapamycin-resistant proliferation of human CD8(+) T lymphocytes

Rapamycin is a fungal macrolide that inhibits the proliferation of T cells. Studies in both animals and humans have found that rapamycin significantly reduces graft rejection. However, though CD8(+) T cells are involved in graft infiltration and rejection, little is known regarding the effects of rapamycin on CD8(+) human T cell responses. In this study, we examined the mechanism of rapamycin-induced inhibition of Ag-driven activation of CD8(+) T cells. Surprisingly, a heterogeneous proliferative response in the presence of rapamycin was observed among different Ag-specific CD8(+) T cell clones; this was also observed in CD8(+) peripheral blood T cells activated with TCR cross-linking ex vivo. Inhibition of T cell proliferation by rapamycin was controlled by both the strength of signal delivered through the Ag receptor as well as the specific costimulatory signals received by the T cell. Rapamycin-resistant proliferation occurred despite inhibition of p70(s6) kinase activity. Moreover, rapamycin-resistant proliferation of the CD8(+) T cell clones was blocked by anti-IL-2 Abs, suggesting that while some of the parallel pathways triggered by IL-2R signaling are sensitive to the effects of rapamycin, others account for the Ag-driven rapamycin resistance. These data provide a new framework for examining the specific mechanism of action of rapamycin in human disease.

Examination of CD8+ T cell function in humans using MHC class I tetramers: similar cytotoxicity but variable proliferation and cytokine production among different clonal CD8+ T cells specific to a single viral epitope

Following infection by human T cell lymphotrophic virus-I (HTLV-I), high frequencies of polyclonal Tax11-19-reactive CD8(+) T cells can be detected in the peripheral blood. To investigate whether there are differences in the effector functions of these cells, we generated a panel of Tax11-19-reactive T cell clones by single cell sorting of HLA-A2/Tax11-19 tetramer binding CD8(+) T cells followed by repeated stimulation with PHA and IL-2. Examination of the TCRs revealed 17 different T cell clones with unique clonal origins. Nine representative CD8(+) T cell clones showed a similar cytotoxic dose-response activity against Ag-pulsed target cells, even though they express different TCRs. This cytotoxic effector function was not influenced by the engagement of either CD28 or CD2 costimulatory molecules. In contrast to the cytotoxic activity, qualitatively different degrees of proliferative response and cytokine secretion were observed among T cell clones of different clonal origin. The induction of proliferation and cytokine secretion required the engagement of costimulatory molecules, particularly CD2-LFA-3 interaction. These results indicate that functionally diverse, polyclonal CTL populations can be activated specific to a single immunodominant viral epitope; they can manifest virtually identical cytotoxic effector function but have marked differences in proliferation and cytokine secretion.

Direct analysis of viral-specific CD8+ T cells with soluble HLA-A2/Tax11-19 tetramer complexes in patients with human T cell lymphotropic virus-associated myelopathy

Human T cell lymphotropic virus-I (HTLV-I)-associated myelopathy is a slowly progressive neurologic disease characterized by inflammatory infiltrates in the central nervous system accompanied by clonal expansion of HTLV-I-reactive CD8+ T-cells. In patients carrying the HLA-A2 allele, the immune response is primarily directed to the Tax11-19 peptide. The frequency, activation state, and TCR usage of HLA-A2/Tax11-19 binding T cells in patients with HTLV-I-associated myelopathy was determined using MHC class I tetramers loaded with the Tax11-19 peptide. Circulating Tax11-19-reactive T cells were found at very high frequencies, approaching 1:10 circulating CD8+ T cells. T cells binding HLA-A2/Tax11-19 consisted of heterogeneous populations expressing different chemokine receptors and the IL-2R beta-chain but not the IL-2R alpha-chain. Additionally, Tax11-19-reactive CD8+ T cells used one predominant TCR Vbeta-chain for the recognition of the HLA-A2/Tax11-19 complex. These data provide direct evidence for high frequencies of circulating Tax11-19-reactive CD8+ T cells in patients with HTLV-I-associated myelopathy.

Gene cloning of the human cytomegalovirus (HCMV) antigen reactive with the serum from a HCMV-infected patient

The human cytomegalovirus(HCMV) gene encoding the protein reactive with the sera of HCMV-infected patient was cloned and characterized. A reactive phage clone was screened from a lambda gt11 expression library of cDNA of HCMV AD169 strain using HCMV-infected patient sera. The recombinant protein was expressed as 138 kDa-fusion protein with beta-galactosidase, which was reactive with IgM or IgG HCMV antibody-positive sera, but not with anti-HCMV antibody-negative sera. A homology search of the DNA sequence of the cloned gene with HCMV AD169 sequences revealed that it was composed of 709 base pairs spanning between 0.174 and 0.177 map units of the UL32 region of the HCMV AD169 strain genome. This position corresponded to a part of the gene encoding 150 kDa phosphoprotein-(pp150), a major tegument protein, which was reported as an immunogenic protein which evoked strong and longstanding antibody response and had no sequence homology with the proteins of other herpesviruses. These results suggested that pp150 was an immunogenic protein in natural HCMV infection and therefore this clone was regarded as a useful candidate for developing an antigen for the serodiagnosis of HCMV.