Recombinant guinea pig TNF-alpha enhances antigen-specific type 1 T lymphocyte activation in guinea pig splenocytes

Lead exposure induces structural damage, digestive stress, immune response and microbiota dysbiosis in the intestine of silver carp (Hypophthalmichthys molitrix)

Lead (Pb) is one of the most common trace metals in water, and its high concentration in the environment can cause harm to aquatic animals and humans. In the present study, the effects of Pb exposure (3.84 mg/kg) on the morphology, digestive enzyme activity, immune function and microbiota structure of silver carp (Hypophthalmichthys molitrix) intestines within 96 h were detected. Moreover, the correlation between them was analyzed. The results showed that Pb exposure on the one hand severely impaired the intestinal morphology, including significantly shortening the intestinal villi's length, increasing the goblet cells' number, causing the intestinal leukocyte infiltration, and thickening the intestinal wall abnormally, on the other hand, increasing the activity of intestinal digestive enzyme (trypsin and lipase). In addition, the mRNA expressions of structure-related genes (Claudin-7 and villin-1) were down-regulated, and the immune factors genes (IL-8, IL-10 and TNF-α) were up-regulated after Pb exposure. Furthermore, data of the MiSeq sequencing showed that the abundance of membrane transport, immune system function and digestive system of silver carp intestinal microbiota all decreased, while cellular antigens increased. Finally, the canonical correlation analysis (CCA) showed that there were correlations between silver carp's intestinal microbiota and intestinal morphology and immune factors. In conclusion, it is speculated that the entry of Pb into the intestine leads the microbiota dysbiosis, affects the intestinal immunity and digestive function, and further damages the intestinal barrier of silver carp.

Detection of herpes simplex virus type 2 (HSV-2) -specific cell-mediated immune responses in guinea pigs during latent HSV-2 genital infection

Genital infections with herpes simplex virus type 2 (HSV-2) are a source of considerable morbidity and are a health concern for newborns exposed to virus during vaginal delivery. Additionally, HSV-2 infection diminishes the integrity of the vaginal epithelium resulting in increased susceptibility of individuals to infection with other sexually transmitted pathogens. Understanding immune protection against HSV-2 primary infection and immune modulation of virus shedding events following reactivation of the virus from latency is important for the development of effective prophylactic and therapeutic vaccines. Although the murine model of HSV-2 infection is useful for understanding immunity following immunization, it is limited by the lack of spontaneous reactivation of HSV-2 from latency. Genital infection of guinea pigs with HSV-2 accurately models the disease of humans including the spontaneous reactivation of HSV-2 from latency and provides a unique opportunity to examine virus-host interactions during latency. Although the guinea pig represents an accurate model of many human infections, relatively few reagents are available to study the immunological response to infection. To analyze the cell-mediated immune response of guinea pigs at extended periods of time after establishment of HSV-2 latency, we have modified flow-cytometry based proliferation assays and IFN-γ ELISPOT assays to detect and quantify HSV-specific cell-mediated responses during latent infection of guinea pigs. Here we demonstrate that a combination of proliferation and ELISPOT assays can be used to quantify and characterize effecter function of virus-specific immune memory responses during HSV-latency.

A Novel Non-Replication-Competent Cytomegalovirus Capsid Mutant Vaccine Strategy Is Effective in Reducing Congenital Infection

Congenital cytomegalovirus (CMV) infection is a leading cause of mental retardation and deafness in newborns. The guinea pig is the only small animal model for congenital CMV infection. A novel CMV vaccine was investigated as an intervention strategy against congenital guinea pig cytomegalovirus (GPCMV) infection. In this disabled infectious single-cycle (DISC) vaccine strategy, a GPCMV mutant virus was used that lacked the ability to express an essential capsid gene (the UL85 homolog GP85) except when grown on a complementing cell line. In vaccinated animals, the GP85 mutant virus (GP85 DISC) induced an antibody response to important glycoprotein complexes considered neutralizing target antigens (gB, gH/gL/gO, and gM/gN). The vaccine also generated a T cell response to the pp65 homolog (GP83), determined via a newly established guinea pig gamma interferon enzyme-linked immunosorbent spot assay. In a congenital infection protection study, GP85 DISC-vaccinated animals and a nonvaccinated control group were challenged during pregnancy with wild-type GPCMV (10(5) PFU). The pregnant animals carried the pups to term, and viral loads in target organs of pups were analyzed. Based on live pup births in the vaccinated and control groups (94.1% versus 63.6%), the vaccine was successful in reducing mortality (P = 0.0002). Additionally, pups from the vaccinated group had reduced CMV transmission, with 23.5% infected target organs versus 75.9% in the control group. Overall, these preliminary studies indicate that a DISC CMV vaccine strategy has the ability to induce an immune response similar to that of natural virus infection but has the increased safety of a non-replication-competent virus, which makes this approach attractive as a CMV vaccine strategy.

IMPORTANCE

Congenital CMV infection is a leading cause of mental retardation and deafness in newborns. An effective vaccine against CMV remains an elusive goal despite over 50 years of CMV research. The guinea pig, with a placenta structure similar to that in humans, is the only small animal model for congenital CMV infection and recapitulates disease symptoms (e.g., deafness) in newborn pups. In this report, a novel vaccine strategy against congenital guinea pig cytomegalovirus (GPCMV) infection was developed, characterized, and tested for efficacy. This disabled infectious single-cycle (DISC) vaccine strategy induced a neutralizing antibody or a T cell response to important target antigens. In a congenital infection protection study, animals were protected against CMV in comparison to the nonvaccinated group (52% reduction of transmission). This novel vaccine was more effective than previously tested gB-based vaccines and most other strategies involving live virus vaccines. Overall, the DISC vaccine is a safe and promising approach against congenital CMV infection.

Increased severity of tuberculosis in Guinea pigs with type 2 diabetes: a model of diabetes-tuberculosis comorbidity

Impaired glucose tolerance and type 2 diabetes were induced in guinea pigs to model the emerging comorbidity of Mycobacterium tuberculosis infection in diabetic patients. Type 2 diabetes mellitus was induced by low-dose streptozotocin in guinea pigs rendered glucose intolerant by first feeding a high-fat, high-carbohydrate diet before M. tuberculosis exposure. M. tuberculosis infection of diabetic guinea pigs resulted in severe and rapidly progressive tuberculosis (TB) with a shortened survival interval, more severe pulmonary and extrapulmonary pathology, and a higher bacterial burden compared with glucose-intolerant and nondiabetic controls. Compared with nondiabetics, diabetic guinea pigs with TB had an exacerbated proinflammatory response with more severe granulocytic inflammation and higher gene expression for the cytokines/chemokines interferon-γ, IL-17A, IL-8, and IL-10 in the lung and for interferon-γ, tumor necrosis factor-α, IL-8, and monocyte chemoattractant protein-1 in the spleen. TB disease progression in guinea pigs with impaired glucose tolerance was similar to that of nondiabetic controls in the early stages of infection but was more severe by day 90. The guinea pig model of type 2 diabetes-TB comorbidity mimics important features of the naturally occurring disease in humans. This model will be beneficial in understanding the complex pathogenesis of TB in diabetic patients and to test new strategies to improve TB and diabetes control when the two diseases occur together.

Diverse cytokine profile from mesenteric lymph node cells of cull cows severely affected with Johne's disease

Mycobacterium avium subsp. paratuberculosis, the causative agent of Johne's disease, is able to dampen or distort immune responses at the mucosal sites and coexist with a massive infiltration of immune cells in the gastrointestinal tract. Knowledge of the mechanism by which M. avium subsp. paratuberculosis subverts the immune response at the mucosal level in cattle is important for the development of improved disease control strategies, including new vaccines and diagnostic tests. In this study, 38 cull cows from herds infected with M. avium subsp. paratuberculosis were divided into four groups, based on M. avium subsp. paratuberculosis culture from gut tissues and histopathological lesion scores. Cytokine gene expression and secretion from M. avium subsp. paratuberculosis sonicate-stimulated peripheral blood mononuclear cell (PBMC) and mesenteric lymph node (MLN) cultures of the animals were compared. Antigen stimulation of MLN cells from the severely lesioned group resulted in significant upregulation of the mRNA expression of five cytokines, gamma interferon (IFN-γ), interleukin-10 (IL-10), IL-13, IL-17A, and tumor necrosis factor alpha (TNF-α), which have a diverse range of functions, while there was no significant upregulation of these cytokines by the other groups. There were major differences between the responses of the PBMC and MLN cultures, with higher levels of secreted IFN-γ released from the MLN cultures and, conversely, higher levels of IL-10 released from the PBMC cultures. The upregulation of all five cytokines from cells at the site of infection in the severely lesioned animals suggested a dysregulated immune response, contributing to a failure to clear infection in this group of animals.

The in vivo immunomodulatory effect of recombinant tumour necrosis factor-alpha in guinea pigs vaccinated with Mycobacterium bovis bacille Calmette-Guérin

Previous studies from our laboratory demonstrated that treatment in vitro with recombinant guinea pig tumour necrosis factor TNF (rgpTNF)-α-enhanced T cell and macrophage functions. Similarly, injection of Mycobacterium tuberculosis-infected guinea pigs with anti-TNF-α altered splenic granuloma organization and caused inflammatory changes and reduced the cell-associated mycobacteria in the tuberculous pluritis model. In this study, rgpTNF-α was injected into bacille Calmette-Guérin (BCG)-vaccinated guinea pigs to modulate immune functions in vivo. Guinea pigs were vaccinated intradermally with BCG, 2 × 10(3) colony-forming units (CFU) and injected intraperitoneally with either rgpTNF-α (25 µg/animal) or 1% bovine serum albumin (BSA) for a total of 12 injections given every other day. Treatment with rgpTNF-α significantly enhanced the skin test response to purified protein derivative (PPD), reduced the number of CFUs and increased the PPD-induced proliferation in the lymph nodes at 6 weeks after vaccination. The levels of interleukin (IL)-12 mRNA were increased in the lymph node and spleen cells stimulated with PPD. TNF-α treatment induced a decrease in TNF-α, IL-12p40 and IL-10 mRNA levels in peritoneal cells following PPD stimulation while live M. tuberculosis caused an increase in TNF-α mRNA and a decrease in the IL-10 mRNA expression. TNF-α injection also induced an increase in the infiltration of mononuclear cells and in the proportions of CD3(+) T cells in the lymph nodes. These results indicate that rgpTNF-α enhances some aspects of T cell immunity and promotes control of mycobacteria in the tissues. Future studies will address the role of TNF-α in BCG-vaccinated guinea pigs following low-dose pulmonary challenge with virulent M. tuberculosis.

Neutralization of TNFalpha alters inflammation in guinea pig tuberculous pleuritis

Previously, treatment with anti-gpTNFalpha antibody enhanced TNFalpha mRNA expression in pulmonary granulomas microdissected from non-vaccinated guinea pigs, and modified splenic granuloma architecture. In this study, pleural fluid, cells, and granulomatous tissues were collected 3, 5, and 8 days post-pleurisy induction in guinea pigs treated with anti-gpTNFalpha or normal serum control. Neutralizing TNFalpha reduced the percentage of macrophages in the pleural exudate while increasing the proportions of neutrophils and lymphocytes. Cell-associated mycobacterial loads were increased in guinea pigs treated with anti-gpTNFalpha antibody. Cells from the pleural exudate in both treatment groups at day 3 expressed predominantly TNFalpha and IFNgamma mRNA. By day 5, treatment with anti-gpTNFalpha antibody significantly reduced TNFalpha mRNA and increased TGFbeta and iNOS mRNA expression, a transition which did not occur in the control group until day 8. TNFalpha mRNA overwhelmed the cytokine milieu of microdissected pleural granulomas in the control group at day 3 whereas TNFalpha, IFNgamma, and TGFbeta mRNA dominated the anti-gpTNFalpha-treated group. At day 8, granulomas from the control group began shifting towards an anti-inflammatory profile with increased levels of TGFbeta mRNA. Neutralization of TNFalpha hastened the transition to an anti-inflammatory cytokine response in guinea pig pleural granulomas and exudate cells.

Differential activation of alveolar and peritoneal macrophages from BCG-vaccinated guinea pigs

We compared the effect of BCG vaccination on the mRNA expression of two prototypic cytokines, IL-12 (Type 1) and IL-10 (Type 2), in guinea pig resident alveolar macrophages (AM) or resident peritoneal macrophages (PM). Cells were stimulated with live or heat-killed Mycobacterium tuberculosis, and/or with recombinant guinea pig (rgp) TNF-alpha and/or rgp IFN-gamma. AM from BCG-vaccinated guinea pigs expressed significantly less IL-10 mRNA and more IL-12p40 mRNA compared to AM from naive animals following stimulation with heat-killed mycobacteria. In PM from BCG-vaccinated guinea pigs, IL-12p40 mRNA was significantly up-regulated; however, the level of IL-10 mRNA was not affected by prior vaccination. rgp TNF-alpha or rgp IFN-gamma, both alone and together, induced a significant increase of H(2)O(2) production in PM from BCG-vaccinated animals. MHC class II expression was dramatically up-regulated in PM from BCG-vaccinated animals stimulated with both rgp TNF-alpha and rgp IFN-gamma. The levels of IL-10 and IL-12p40 mRNA were significantly enhanced in PM stimulated with combinations of rgp TNF-alpha and rgp IFN-gamma, and those cells suppressed the intracellular accumulation of viable, virulent M. tuberculosis. BCG vaccination results in the differential activation of guinea pig AM and PM to promote a Type 1 cytokine milieu and control intracellular mycobacteria.

Guinea pig neutrophils infected with Mycobacterium tuberculosis produce cytokines which activate alveolar macrophages in noncontact cultures

The early influx of neutrophils to the site of infection may be an important step in host resistance against Mycobacterium tuberculosis. In this study, we investigated the effect of M. tuberculosis infection on the ability of guinea pig neutrophils to produce interleukin-8 (IL-8; CXCL8) and tumor necrosis factor alpha (TNF-alpha) and to activate alveolar macrophages. Neutrophils and alveolar macrophages were isolated from naïve guinea pigs, cultured together or alone, and infected with virulent M. tuberculosis for 3, 12, and 24 h. IL-8 protein production in cocultures, as measured by using an enzyme-linked immunosorbent assay, was found to be additive at 24 h and significantly greater in M. tuberculosis-infected cocultures than in uninfected cocultures and in cultures of the infected neutrophils or macrophages alone. The IL-8 mRNA levels, determined by real-time reverse transcription-PCR, were elevated at 24 h in infected cocultures and infected cells cultured alone. In order to elucidate the contributions of neutrophils and their soluble mediators to the activation of alveolar macrophages, neutrophils and alveolar macrophages were cultured in a contact-independent manner by using a Transwell insert system. Neutrophils were infected with virulent M. tuberculosis in the upper wells, and alveolar macrophages were cultured in the lower wells. The release of hydrogen peroxide from alveolar macrophages exposed to soluble products from infected neutrophils was significantly increased compared to that from unexposed alveolar macrophages. Significant up-regulation of IL-1beta and TNF-alpha mRNA levels in alveolar macrophages was observed at 24 and 30 h, respectively, compared to those in cells not exposed to soluble neutrophil products. Treatment with anti-guinea pig TNF-alpha polyclonal antibody completely abolished the response of alveolar macrophages to neutrophil products. This finding suggests that TNF-alpha produced by infected neutrophils may be involved in the activation of alveolar macrophages and hence may contribute to the containment of M. tuberculosis infection during the early period of infection.