Impaired beta-oxidation increases vulnerability to influenza A infection.

Influenza A virus (IAV) infection casts a significant burden on society. It has particularly high morbidity and mortality rates in patients suffering from metabolic disorders. The aim of this study was to relate metabolic changes with IAV susceptibility using well-characterized inbred mouse models. We compared the highly susceptible DBA/2J (D2) mouse strain for which IAV infection is lethal with the C57BL/6J (B6) strain, which exhibits a moderate course of disease and survives IAV infection. Previous studies showed that D2 has higher insulin and glucose levels and is predisposed to develop diet-induced type 2 diabetes. Using high-resolution liquid chromatography-coupled MS, the plasma metabolomes of individual animals were repeatedly measured up to 30 days postinfection. The biggest metabolic difference between these strains in healthy and infected states was in the levels of malonylcarnitine, which was consistently increased 5-fold in D2. Other interstrain and intrastrain differences in healthy and infected animals were observed for acylcarnitines, glucose, branched-chain amino acids, and oxidized fatty acids. By mapping metabolic changes to canonical pathways, we found that mitochondrial beta-oxidation is likely disturbed in D2 animals. In noninfected D2 mice, this leads to increased glycerolipid production and reduced acylcarnitine production, whereas in infected D2 animals, peroxisomal beta-oxidation becomes strongly increased. From these studies, we conclude that metabolic changes caused by a distortion of mitochondrial and peroxisomal metabolism might impact the innate immune response in D2, leading to high viral titers and mortality.

[A special on epidemic prevention and control: analysis on expression of 2019-nCoV related ACE2 and TMPRSS2 in eye tissues].

This article was published ahead of print on the official website of Chinese Journal of Ophthalmolog on Apirl 22,2020. Objective: Angiotensin converting enzyme 2 (ACE2) and Transmembrane serine protease 2 (TMPRSS2) are the key proteins for 2019-nCoV entry into host cells. To evaluate the potential infection risk of 2019-nCoV on ocular surface, we compared ACE2 and TMPRSS2 expression among different eye tissues. Methods: Experimental study. Thirty mice were assigned to male, female, aged, diabetic and non-diabetic groups, with 6 mice in each group. Real-time PCR was performed to quantify ACE2 and TMPRSS2 gene expression in conjunctiva, cornea, lacrimal gland, iris, lens, retina, lung, heart, kidney, and liver from male mice. Immunohistochemistry staining was applied to visualize the distribution of the two proteins in different mice tissues, and in human corneal and conjunctival sections. Published transcriptome datasets were extracted to generate the expression comparasion of ACE2 and TMPRSS2 between human conjunctival and corneal tissues, and results were analyzed using Mann-Whitney U test. Female mice, aged mice, STZ-induced diabetic mice, diabetic group control mice were also subjected to ACE2 expression analysis. Results were analyzed using Student's t-test. Results: The expression of ACE2 and TMPRSS2 genes were the highest in conjunctiva among all the six mice eye tissues explored. The expression of these two genes in conjunctiva were lower than that in kidney and lung. ACE2 and TMPRSS2 shared similar expression pattern with the staining concentrated in corneal epithelium, conjunctival epithelium and lacrimal gland serous cells. The expression levels of ACE2 showed gender difference. Female mice had lower ACE2 in conjunctiva and cornea than male mice, with the expression levels being only 43% (t=3.269, P=0.031) and 63% (t=4.080, P=0.015) of that in the male conjunctiva and cornea, respectively. Diabetic mice expressed more ACE2 in conjunctiva (1.21-fold, P>0.05) and lacrimal gland (1.10-fold, P>0.05) compared with the control group. No significant difference on ACE2 expression was found between the aged and young adult mice. The expression level of human conjunctiva ACE2 and TMPRSS2 were significantly higher than that in the cornea (P=0.007), with 5.74-fold and 12.84-fold higher in the conjunctiva than in the corneal epithelium cells, which resembled the situation in mice. Conclusion: The observation of high-level ACE2 and TMPRSS2 expression in conjunctiva among the 6 eye tissues examined suggests that conjunctiva serves as an infection target tissue of 2019-nCoV. (Chin J Ophthalmol, 2020, 56:438-446).

Mouse Models of Virus-Induced Type 1 Diabetes.

Virus infections have been linked to the induction of autoimmunity and disease development in human type 1 diabetes. Experimental models have been instrumental in deciphering processes leading to break of immunological tolerance and type 1 diabetes development. Animal models have also been useful for proof-of-concept studies and for preclinical testing of new therapeutic interventions. This chapter describes two robust and clinically relevant mouse models for virus-induced type 1 diabetes; acceleration of disease onset in prediabetic nonobese diabetic (NOD) mice following Coxsackievirus infection and diabetes induction by lymphocytic choriomeningitis virus (LCMV) infection of transgenic mice expressing viral neo-antigens under control of the rat insulin promoter (RIP).

Rat Models of Virus-Induced Type 1 Diabetes.

Studies performed in humans and animal models have implicated the environment in the etiology of type 1 diabetes (T1D), but the nature and timing of the interactions triggering ß cell autoimmunity are poorly understood. Virus infections have been postulated to be involved in disease mechanisms, but the underlying mechanisms are not known. It is exceedingly difficult to establish a cause-and-effect relationship between viral infection and diabetes in humans. Thus, we have used the BioBreeding Diabetes-Resistant (BBDR) and the LEW1.WR1 rat models of virus-induced disease to elucidate how virus infection leads to T1D. The immunophenotype of these strains is normal, and spontaneous diabetes does not occur in a specific pathogen-free environment. However, ß cell inflammation and diabetes with many similarities to the human disease are induced by infection with the parvovirus Kilham rat virus (KRV). KRV-induced diabetes in the BBDR and LEW1.WR1 rat models is limited to young animals and can be induced in both male and female rats. Thus, these animals provide a powerful experimental tool to identify mechanisms underlying virus-induced T1D development.

Impaired upregulation of Stat2 gene restrictive to pancreatic ß-cells is responsible for virus-induced diabetes in DBA/2 mice.

Viral infection is a putative causal factor for the development of type 1 diabetes, but the exact pathogenic mechanism of virus-induced diabetes (VID) remains unclear. Here, to identify the critical factors that regulate VID, we analyzed encephalomyocarditis D (EMC-D) VID-sensitive DBA/2 mice in comparison with resistant B6 mice. EMC-D virus-induced cell death occurred more frequently in DBA/2 ß-cells than in B6 ß-cells with 100U/ml IFN-ß priming in vitro. We therefore purified ß-cells using flow cytometry from mice two days after EMC-D virus infection and subjected them to microarray analysis. As a results, innate immune response pathway was found to be enriched in B6 ß-cells. The signal transducer and activator of transcription 2 (Stat2) gene interacted with genes in the pathway. Stat2 gene expression levels were lower in DBA/2 mice than in B6 mice, restrictive to ß-cells. Moreover, administration of IFN-ß failed to upregulate Stat2 gene in DBA/2 ß-cells than in those of B6 in vivo. The viral titer significantly increased only in the DBA/2 pancreas. Thus, these provided data suggest that impaired upregulation of Stat2 gene restrictive to ß-cells at the early stage of infection is responsible for VID development in DBA/2 mice.

Study of 2009 H1N1 Pandemic Influenza Virus as a Possible Causative Agent of Diabetes.

Context: Recent studies have suggested that influenza A virus (IAV) might be involved in the etiology of diabetes. Objective and Methods: To address this question, we tested the ability of H1N1 pandemic IAV to infect, replicate, and damage human ß cells/pancreatic islets in vitro and induce pancreatic damage and/or glucose metabolism alterations in chemical and autoimmune models of ß cell damage in vivo. Moreover, we looked for direct and/or indirect evidence of correlation between IAV infection and autoimmunity/diabetes in humans. Results: Human H1N1 A/California/2009-derived viruses infected human pancreatic islets in vitro, inducing a proinflammatory response associated with substantial increases of CXCL9 and CXCL10 release. In vivo, infected mice showed a clear susceptibility to the virus, with its localization also found in extrapulmonary organs, including the pancreas. Infection was able to induce mild modifications of glycemia in C57B6 mice after chemical damage of islets but did not modulate the autoimmune damage of islets in NOD mice. One of 69 nasopharyngeal swabs collected from patients at the onset of type 1 diabetes yielded positive results for IAV. Pancreas sections from 17 organ donors available from the Network for Pancreatic Organ Donors With Diabetes showed the persistence of CXCL10-positive cells in islet autoimmunity-positive subjects; however, extremely rare cells stained for viral RNA and not preferentially in autoimmune subjects. Conclusion: Influenza H1N1 pdm strains are able to infect and replicate in mammalian pancreatic cells both in vitro and in vivo but did not cause any functional impairment consistent with diabetes.

Crucial role of Reg I from acinar-like cell cluster touching with islets (ATLANTIS) on mitogenesis of beta cells in EMC virus-induced diabetic mice.

Recently, we reported the presence of distinct cell clusters named acinar-like cell clusters touching Langerhans islets with thin interstitial surrounding (ATLANTIS) in human pancreas. A morphological study in humans demonstrated that ATLANTIS and islet cell clusters are found together in the microenvironment enclosed by a common basement membrane, and ATLANTIS releases vesicles containing Regenerating gene protein (REG Iα) to islet cell clusters. We examined 1) the presence or absence of ATLANTIS in homozygous Reg I (mouse homologue of human REG Iα) deficient (Reg I-/-) and wild-type mice, and 2) the possible role of ATLANTIS in the regeneration of beta cell clusters after encephalomyocarditis (EMC) virus (D-variant) infection in Reg I-/- and wild-type mice. ATLANTIS was found in both wild-type and Reg I-/- mice. In both groups, mean blood glucose increased transiently to greater than 14.0 mmol/L at 5 days after EMC virus infection and recovered to baseline at 12 days. At 12 days after EMC virus infection, lower BrdU labeling indices were observed in islet beta cells of Reg I-/- mice compared to wild-type mice. Beta cell volume 12 days after EMC virus infection in Reg I-/- mice did not differ from that of wild-type mice. These results suggest that Reg I, which is released from ATLANTIS to islet beta cell clusters, has a crucial role in beta cell regeneration in EMC virus-induced diabetes. The presence of mechanism(s) other than that mediated by Reg I in beta cell restoration after destruction by EMC virus was also suggested.

Up-regulation of 14-3-3ß plays a role in intimal hyperplasia following carotid artery injury in diabetic Sprague Dawley rats by promoting endothelial cell migration and proliferation.

PURPOSE: The objective of this study was to determine whether diabetes mellitus (DM)-induced up-regulation of 14-3-3ß (YWHAB) in endothelial cells enhances intimal hyperplasia in carotid artery-injured DM Sprague-Dawley (SD) rats. METHODS: YWHAB expression and rat aortic endothelial cell (RAOEC) vitality were examined using Cell Counting Kit-8 (CCK-8), quantitative reverse transcription PCR (qRT-PCR), and western blot analysis in cells treated with different glucose concentrations (5.6, 10, 15, 25, or 35 mM). For in vivo experiments, a YWHAB small interfering (si) RNA recombinant lentiviral vector (YWHAB-LV) or Mock siRNA recombinant lentiviral vector (Mock-LV) were injected into streptozotocin-induced DM SD rats via the tail vein. YWHAB expression and carotid artery morphology were assessed 7 days post injury using immunofluorescence (IF) and hematoxylin-eosin (HE) staining. The proliferation and migration of Mock-LV and YWHAB-LV-infected RAOECs treated with 25 mM glucose were examined using cell scratch tests and flow cytometry. BCL2-Associated X (BAX) distribution in RAOECs treated with 25 mM glucose was examined using IF staining and western blot analysis. RESULTS: Western blot, qRT-PCR, and CCK-8 analyses demonstrated that both YWHAB expression and cell vitality increased with increasing glucose concentration (p <0.05). YWHAB IF staining was increased in DM rats compared with the normal group (p <0.05). HE staining showed that intimal hyperplasia is alleviated in YWHAB-silenced DM rats (p <0.05). YWHAB silencing suppressed the proliferation and migration of RAOECs treated with 25 mM glucose (p <0.05). Moreover, western blot analyses and IF staining demonstrated that YWHAB silencing increased the translocation of BAX from the cytoplasm to mitochondria in RAOECs treated with 25 mM glucose (p <0.05). CONCLUSIONS: Our results indicate that hyperglycemia-induced up-regulation of YWHAB in endothelial cell plays a significant role in intimal hyperplasia following carotid artery injury by enhancing endothelial cell proliferation and migration. YWHAB inhibition in hyperglycemic patients may constitute a potential target for therapeutic interventions via restenosis prevention.

Insulin-sparing and fungible effects of E4orf1 combined with an adipocyte-targeting sequence in mouse models of type 1 and type 2 diabetes.

Obesity impairs glycemic control and causes insulin resistance and type 2 diabetes. Adenovirus 36 (Ad36) infection can increase the uptake of excess glucose from blood into adipocytes by increasing GLUT4 translocation through the Ras-Akt signaling pathway, which bypasses PI3K-Akt-mediated insulin receptor signaling. E4orf1, a viral gene expressed early during Ad36 infection, is responsible for this insulin-sparing effect and may be an alternative target for improving insulin resistance. To deliver the gene to adipocytes only, we connected the adipocyte-targeting sequence (ATS) to the 5' end of E4orf1 (ATS-E4orf1). In vitro transfection of ATS-E4orf1 into preadipocytes activated factors for GLUT4 translocation and adipogenesis to the same extent as did Hemagglutinin (HA)-E4orf1 transfection as positive reference. Moreover, the Transwell migration assay also showed that ATS-E4orf1 secreted by liver cells activated Akt in preadipocytes. We used a hydrodynamic gene delivery technique to deliver ATS-E4orf1 into high-fat diet-fed and streptozotocin-injected mice (disease models of type 2 and type 1 diabetes, respectively). ATS-E4orf1 improved the ability to eliminate excess glucose from the blood and ameliorated liver function in both disease models. These findings suggest that ATS-E4orf1 has insulin-sparing and fungible effects in type 2 and 1 diabetes independent of the presence of insulin.

Rotavirus acceleration of type 1 diabetes in non-obese diabetic mice depends on type I interferon signalling.

Rotavirus infection is associated with childhood progression to type 1 diabetes. Infection by monkey rotavirus RRV accelerates diabetes onset in non-obese diabetic (NOD) mice, which relates to regional lymph node infection and a T helper 1-specific immune response. When stimulated ex vivo with RRV, plasmacytoid dendritic cells (pDCs) from naïve NOD mice secrete type I interferon, which induces the activation of bystander lymphocytes, including islet-autoreactive T cells. This is our proposed mechanism for diabetes acceleration by rotaviruses. Here we demonstrate bystander lymphocyte activation in RRV-infected NOD mice, which showed pDC activation and strong upregulation of interferon-dependent gene expression, particularly within lymph nodes. The requirement for type I interferon signalling was analysed using NOD mice lacking a functional type I interferon receptor (NOD.IFNAR1(-/-) mice). Compared with NOD mice, NOD.IFNAR1(-/-) mice showed 8-fold higher RRV titers in lymph nodes and 3-fold higher titers of total RRV antibody in serum. However, RRV-infected NOD.IFNAR1(-/-) mice exhibited delayed pDC and lymphocyte activation, no T helper 1 bias in RRV-specific antibodies and unaltered diabetes onset when compared with uninfected controls. Thus, the type I interferon signalling induced by RRV infection is required for bystander lymphocyte activation and accelerated type 1 diabetes onset in genetically susceptible mice.

Reduced Tyk2 gene expression in ß-cells due to natural mutation determines susceptibility to virus-induced diabetes.

Accumulating evidence suggests that viruses play an important role in the development of diabetes. Although the diabetogenic encephalomyocarditis strain D virus induces diabetes in restricted lines of inbred mice, the susceptibility genes to virus-induced diabetes have not been identified. We report here that novel Tyrosine kinase 2 (Tyk2) gene mutations are present in virus-induced diabetes-sensitive SJL and SWR mice. Mice carrying the mutant Tyk2 gene on the virus-resistant C57BL/6 background are highly sensitive to virus-induced diabetes. Tyk2 gene expression is strongly reduced in Tyk2-mutant mice, associated with low Tyk2 promoter activity, and leads to decreased expression of interferon-inducible genes, resulting in significantly compromised antiviral response. Tyk2-mutant pancreatic ß-cells are unresponsive even to high dose of Type I interferon. Reversal of virus-induced diabetes could be achieved by ß-cell-specific Tyk2 gene expression. Thus, reduced Tyk2 gene expression in pancreatic ß-cells due to natural mutation is responsible for susceptibility to virus-induced diabetes.

Facial nerve palsy after reactivation of herpes simplex virus type 1 in diabetic mice.

OBJECTIVES/HYPOTHESIS: Bell's palsy is highly associated with diabetes mellitus (DM). Either the reactivation of herpes simplex virus type 1 (HSV-1) or diabetic mononeuropathy has been proposed to cause the facial paralysis observed in DM patients. However, distinguishing whether the facial palsy is caused by herpetic neuritis or diabetic mononeuropathy is difficult. We previously reported that facial paralysis was aggravated in DM mice after HSV-1 inoculation of the murine auricle. In the current study, we induced HSV-1 reactivation by an auricular scratch following DM induction with streptozotocin (STZ). STUDY DESIGN: Controlled animal study. METHODS: Diabetes mellitus was induced with streptozotocin injection in only mice that developed transient facial nerve paralysis with HSV-1. Recurrent facial palsy was induced after HSV-1 reactivation by auricular scratch. RESULTS: After DM induction, the number of cluster of differentiation 3 (CD3)(+) T cells decreased by 70% in the DM mice, and facial nerve palsy recurred in 13% of the DM mice. Herpes simplex virus type 1 deoxyribonucleic acid (DNA) was detected in the facial nerve of all of the DM mice with palsy, and HSV-1 capsids were found in the geniculate ganglion using electron microscopy. Herpes simplex virus type 1 DNA was also found in some of the DM mice without palsy, which suggested the subclinical reactivation of HSV-1. CONCLUSIONS: These results suggested that HSV-1 reactivation in the geniculate ganglion may be the main causative factor of the increased incidence of facial paralysis in DM patients.

Ability of bacteriophage in resolving wound infection caused by multidrug-resistant Acinetobacter baumannii in uncontrolled diabetic rats.

Acinetobacter baumannii, a substantial nosocomial pathogen, has developed resistance to almost all available antimicrobial drugs. Bacteriophage therapy is a possible alternative treatment for multidrug-resistant (MDR) bacterial infections. In this study, we have successfully isolated bacteriophage active against clinical strains of A. baumannii by enrichment from hospital sewage sludge using representatives of those strains. The bacteriophage isolated against A. baumannii formed plaques against beta-lactamases producing strains of A. baumannii. The utility of bacteriophage specific for A. baumannii to resolve wound infection in uncontrolled diabetic rats was evaluated. Five groups of uncontrolled diabetic rats were used. Group I was noninfected (Control), Group II was infected with MDR A. baumannii and challenged with bacteriophage, Group III was infected with MDR A. baumannii, Group IV was infected with MDR A. baumannii and challenged with antibiotic colistin, and Group V consisted of noninfected rats and sprayed with phage (Phage control). A significant decrease in infection, period of epithelization, and wound contraction was observed in the phage-challenged group when compared with antibiotic-treated uncontrolled diabetic rats and the control group. To conclude the study, new insights are provided into the biology of the broad host range of A. baumannii phage, demonstrating that A. baumannii phage has prospects for the treatment of infections caused by the MDR A. baumannii.

PTPN22 controls virally-induced autoimmune diabetes by modulating cytotoxic T lymphocyte responses in an epitope-specific manner.

Ptpn22 is one of the most potent autoimmunity predisposing genes and strongly associates with type 1 diabetes (T1D). Previous studies showed that non-obese diabetic mice with reduced expression levels of Ptpn22 are protected from T1D due to increased number of T regulatory (Treg) cells. We report that lack of Ptpn22 exacerbates virally-induced T1D in female rat insulin promoter lymphocytic choriomeningitis virus (RIP-LCMV-GP) mice, while maintaining higher number of Treg cells throughout the antiviral response in the blood and spleen but not in the pancreatic lymph nodes. GP33-41-specific pentamer-positive cytotoxic lymphocytes (CTLs) are numerically reduced in the absence of Ptpn22 at the expansion and contraction phase but reach wild-type levels at the memory phase. However, they show similar effector function and even a subtle increase in the production of IL-2. In contrast, NP396-404-specific CTLs develop normally at all phases but display enhanced effector function. Lack of Ptpn22 also augments the memory proinflammatory response of GP61-80 CD4 T cells. Hence, lack of Ptpn22 largely augments antiviral effector T cell responses, suggesting that caution should be taken when targeting Ptpn22 to treat autoimmune diseases where viral infections are considered environmental triggers.

Experimental protection of diabetic mice against Lethal P. aeruginosa infection by bacteriophage.

The emergence of antibiotic-resistant bacterial strains has become a global crisis and is vulnerable for the exploration of alternative antibacterial therapies. The present study emphasizes the use of bacteriophage for the treatment of multidrug resistant P. aeruginosa. P. aeruginosa was used to induce septicemia in streptozotocin (STZ) induced diabetic and nondiabetic mice by intraperitoneal (i.p.) injection of 3 × 10(8) CFU, resulting in a fatal bacteremia within 48 hrs. A single i.p. injection of 3 × 10(9) PFU phage GNCP showed efficient protection in both diabetic (90%) and nondiabetic (100%) bacteremic mice. It was further noted that the protection rate was reduced in diabetic mice when phage GNCP was administered after 4 h and 6 h of lethal bacterial challenge. In contrast, nondiabetic bacteremic mice were rescued even when treatment was delayed up to 20 h after lethal bacterial challenge. Evaluation of results confirmed that a single intraperitoneal injection of the phage dose (3 × 10(9) PFU/mL) was more effective than the multiple doses of imipenem. These results uphold the efficacy of phage therapy against pernicious P. aeruginosa infections, especially in cases of immunocompromised host.

Combination therapy with an anti-IL-1ß antibody and GAD65 DNA vaccine can reverse recent-onset diabetes in the RIP-GP mouse model.

Type 1 diabetes is thought to be an autoimmune condition in which self-reactive T cells attack insulin-secreting pancreatic ß-cells. As a proinflammatory cytokine produced by ß-cells or macrophages, interleukin-1ß (IL-1ß) represents a potential therapeutic target in diabetes. We reasoned IL-1ß blockade could be combined with islet antigen-specific approaches involving GAD of 65 kDa (GAD65)-expressing plasmids, as previously shown in combination therapies (CTs) with anti-CD3. Thus, we investigated whether anti-IL-1ß antibody alone or combined with GAD65 vaccine could reverse diabetes development in a virus-induced mouse model. Given alone, anti-IL-1ß had no effect on diabetes, while GAD65 plasmid resulted in 33% disease reversal after a 5-week observation. However, CTs cured 53% of animals and prevented worsening of glycemic control in nonprotected individuals for up to 12 weeks. While the GAD65 vaccine arm of the CT was associated with increased forkhead box p3(+) regulatory T-cell frequency in pancreatic lymph nodes, islet infiltration by CD11b(+/high) cells was less frequent upon CT, and its extent correlated with treatment success or failure. Altogether, our CTs provided prolonged improvement of clinical and immunological features. Despite unsuccessful clinical trials using anti-IL-1ß monotherapy, these data hold promise for treatment of type 1 diabetic patients with IL-1ß blockade combined with antigen-specific vaccines.

Functional redundancy of CXCR3/CXCL10 signaling in the recruitment of diabetogenic cytotoxic T lymphocytes to pancreatic islets in a virally induced autoimmune diabetes model.

Cytotoxic T lymphocytes (CTLs) constitute a major effector population in pancreatic islets from patients suffering from type 1 diabetes (T1D) and thus represent attractive targets for intervention. Some studies have suggested that blocking the interaction between the chemokine CXCL10 and its receptor CXCR3 on activated CTLs potently inhibits their recruitment and prevents ß-cell death. Since recent studies on human pancreata from T1D patients have indicated that both ligand and receptor are abundantly present, we reevaluated whether their interaction constitutes a pivotal node within the chemokine network associated with T1D. Our present data in a viral mouse model challenge the notion that specific blockade of the CXCL10/CXCR3 chemokine axis halts T1D onset and progression.

The role of the intestinal microbiota in type 1 diabetes.

The digestive tract hosts trillions of bacteria that interact with the immune system and can influence the balance between pro-inflammatory and regulatory immune responses. Recent studies suggest that alterations in the composition of the intestinal microbiota may be linked with the development of type 1 diabetes (T1D). Data from the biobreeding diabetes prone (BBDP) and the LEW1.WR1 models of T1D support the hypothesis that intestinal bacteria may be involved in early disease mechanisms. The data indicate that cross-talk between the gut microbiota and the innate immune system may be involved in islet destruction. Whether a causal link between intestinal microbiota and T1D exists, the identity of the bacteria and the mechanism whereby they promote the disease remain to be examined. A better understanding of the interplay between microbes and innate immune pathways in early disease stages holds promise for the design of immune interventions and disease prevention in genetically susceptible individuals.

Gene transfer of active Akt1 by an infectivity-enhanced adenovirus impacts ß-cell survival and proliferation differentially in vitro and in vivo.

Type 1 Diabetes is characterized by an absolute insulin deficiency due to the autoimmune destruction of insulin producing ß-cells in the pancreatic islets. Akt1/Protein Kinase B is the direct downstream target of PI3 Kinase activation, and has shown potent anti-apoptotic and proliferation-inducing activities. This study was designed to explore whether gene transfer of constitutively active Akt1 (CA-Akt1) would promote ß-cell survival and proliferation, thus be protective against experimental diabetes. In the study, a fiber-modified infectivity-enhanced adenoviral vector, Ad5RGDpK7, was used to deliver rat insulin promoter (RIP)-driven CA-Akt1 into ß-cells. Our data showed this vector efficiently delivered CA-Akt1 into freshly isolated pancreatic islets, and promoted islet cell survival and ß-cell proliferation in vitro. The therapeutic effect of the vector in vivo was assessed using streptozotocin (STZ)-induced diabetes mice. Two means of vector administration were explored: intravenous and intra-bile ductal injections. While direct vector administration into pancreas via bile-ductal injection resulted in local adverse effect, intravenous injection of the vectors offered therapeutic benefits. Further analysis suggests systemic vector administration caused endogenous Akt expression and activation in islets, which may be responsible, at least in part, for the protective effect of the infectivity-enhanced CA-Akt1 gene delivery vector. Taken together, our data suggest CA-Akt1 is effective in promoting ß-cell survival and proliferation in vitro, but direct in vivo use is compromised by the efficacy of transgene delivery into ß-cells. Nonetheless, the vector evoked the expression and activation of endogenous Akt in the islets, thus offering beneficial bystander effect against STZ-induced diabetes.

Prevention of virus-induced type 1 diabetes with antibiotic therapy.

Microbes were hypothesized to play a key role in the progression of type 1 diabetes (T1D). We used the LEW1.WR1 rat model of Kilham rat virus (KRV)-induced T1D to test the hypothesis that the intestinal microbiota is involved in the mechanism leading to islet destruction. Treating LEW1.WR1 rats with KRV and a combination of trimethoprim and sulfamethoxazole (Sulfatrim) beginning on the day of infection protected the rats from insulitis and T1D. Pyrosequencing of bacterial 16S rRNA and quantitative RT-PCR indicated that KRV infection resulted in a transient increase in the abundance of Bifidobacterium spp. and Clostridium spp. in fecal samples from day 5- but not day 12-infected versus uninfected animals. Similar alterations in the gut microbiome were observed in the jejunum of infected animals on day 5. Treatment with Sulfatrim restored the level of intestinal Bifidobacterium spp. and Clostridium spp. We also observed that virus infection induced the expression of KRV transcripts and the rapid upregulation of innate immune responses in Peyer's patches and pancreatic lymph nodes. However, antibiotic therapy reduced the virus-induced inflammation as reflected by the presence of lower amounts of proinflammatory molecules in both the Peyer's patches and pancreatic lymph nodes. Finally, Sulfatrim treatment reduced the number of B cells in Peyer's patches and downmodulated adaptive immune responses to KRV, but did not interfere with antiviral Ab responses or viral clearance from the spleen, pancreatic lymph nodes, and serum. The data suggest that gut microbiota may be involved in promoting virus-induced T1D in the LEW1.WR1 rat model.