Mouse models of inflammatory bowel disease are critical for basic and translational research that is advancing the understanding and treatment of this disease. Assessment of these mouse models frequently relies on histologic endpoints. In recent years, whole slide imaging and digital pathology-based image analysis platforms have become increasingly available for implementation into the pathology workflow. These automated image analysis approaches allow for nonbiased quantitative assessment of histologic endpoints. In this study, the authors sought to develop an image analysis workflow using a commercially available image analysis platform that requires minimal training in image analysis or programming, and this workflow was used to score 2 mouse models of colitis that are primarily characterized by immune cell infiltrates in the lamina propria. Although the software was unable to accurately and consistently segment hematoxylin and eosin-stained sections, automated quantification of CD3 immunolabeling resulted in strong correlations with the pathologist's score in all studies and allowed for the identification of 8 of the 9 differences among treatment groups that were identified by the pathologist. These results demonstrate not only the ability to incorporate solutions based on image analysis into the pathologist's workflow but also the importance of immunohistochemical or histochemical surrogates for the incorporation of image analysis in histologic assessments.
This study evaluated the hypothesis that the disease status of Saanen goats infected with caprine arthritis-encephalitis lentivirus (CAEV) is associated with the focus of immune responses to viral antigens, particularly the surface envelope glycoprotein (SU). Specifically, we have proposed that Th2 responses promote progressive immune-mediated arthritis, whereas Th1 responses restrict virus replication and development of clinical disease. The present study determined the isotype of SU antibodies associated with progressor and long-term nonprogressor (LTNP) status. We show that chronically infected goats that develop clinical arthritis have predominantly IgG1 antibodies to SU during both preclinical and clinical stages of disease, whereas SU antibodies of LTNP goats are relatively biased toward IgG2. Additional studies determined the isotype of SU antibodies induced initially by CAEV infection. These experiments show that initial IgG1-dominated responses to SU are associated with subsequent development of preclinical inflammatory joint lesions, whereas lack of joint pathology is associated with an IgG2 bias of initial responses to SU. Our results using the CAEV model suggest that isotype bias of SU antibodies is a reliable indicator of clinical disease caused by lentiviruses. Isotype analysis may be a useful method to screen candidate lentiviral vaccines intended to prevent disease progression.
Important research goals in lentivirus vaccine development include defining immune mechanisms and epitopes on viral antigens involved in the control of virus replication and developing immunogens and vaccination strategies to elicit relevant immune responses. Numerous reports indicate that neutralizing antibodies are involved in preventing infection or controlling lentivirus replication (2,3,33,41,60). Therefore, the induction of neutralizing antibodies by immunization is an important consideration in the development of vaccine strategies.The identification of human monoclonal antibodies (MAbs) that neutralize primary human immunodeficiency virus type 1 (HIV-1) isolates demonstrates the presence of conserved neutralization epitopes on the gp120 surface envelope (SU) (31, 55). Immunization with soluble gp120 generally elicits antibodies directed primarily to linear epitopes (8,32,35,44,57), with limited responses to neutralization epitopes (9,16,32,37,61). The difficulty in eliciting broadly cross-reactive neutralizing antibodies by protein immunization has been attributed to the immunodominance of linear nonneutralizing or weakly neutralizing linear epitopes and the relatively poor immunogenicity or exposure of discontinuous neutralization epitopes (7,9,32,42,47). This concept is supported by observations that cross-reactive neutralizing antibodies to primary HIV isolates are induced by immunization with either oligomeric HIV SU or monomeric gp120 under conditions that preserve the conformation of SU together with adjuvants that potentiate the immunogenicity of conformational epitopes (15,31,36,46,51,53,54,58).Our laboratory is utilizing the caprine arthritis-encephalitis lentivirus (CAEV) model to evaluate immunization strategies to induce cross-reactive neutralizing antibodies by using monomeric SU (10). SU is a primary target of humoral immune responses to CAEV, and infected goats develop high titers of binding antibodies directed to immunodominant nonneutralization epitopes (21,26). Initial antibody responses to SU are predominately directed to linear epitopes, and maturation of the immune response results in increased reactivity to conformational epitopes (unpublished data), resulting in low titers of generally type-specific neutralizing antibodies in some infected animals (11,29,34). A previous study of epitope exposure on CAEV SU suggested that cross-reactive neutralizing antibodies could be induced by immunization with monomeric SU (29). This study showed that recombinant CAEV gp135 SU adsorbs homologous and heterologous neutralizing antibodies in goat sera, indicating that covert cross-reactive neutralization epitopes on virion-associated SU are exposed on soluble monomeric SU. A preliminary immunization trial demonstrated
Optimization and standardization of immunohistochemistry (IHC) protocols within and between laboratories requires reproducible positive and negative control samples. In many situations, suitable tissue or cell line controls are not available. We demonstrate here a method to incorporate target antigens into synthetic protein gels that can serve as IHC controls. The method can use peptides, protein domains, or whole proteins as antigens, and is compatible with a variety of fixation protocols. The resulting gels can be used to create tissue microarrays (TMAs) with a range of antigen concentrations that can be used to objectively quantify and calibrate chromogenic, fluorescent, or mass spectrometry-based IHC protocols. The method offers an opportunity to objectively quantify IHC staining results, and to optimize and standardize IHC protocols within and between laboratories.
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