Trans heterodimer between two non-arthritis-associated HLA alleles can predispose to arthritis in humanized mice

Asian-type DEL (RHD*DEL1) with an allo-anti-D: A paradoxical observation in a healthy multiparous woman

BACKGROUND

The DEL phenotype is the D variant expressing the least amounts of D antigen per red cell. Asian-type DEL (RHD:c:1227G > A) is the most prevalent DEL in East Asia without any anti-D alloimmunization reported before. We investigated the first observation of an anti-D in any DEL phenotype, reported in the Japanese language at a 1987 conference, only 3 years after the discovery of DEL.

METHODS

We contacted the proband 35 years after the initial report. Standard hemagglutination, adsorption/elution, and flow cytometry tests were performed, as was nucleotide sequencing for the RHD, RHCE, and HLA class I and class II genes.

RESULTS

The healthy multiparous Japanese woman, a regular blood donor, still had the anti-D of titer 8 representing an alloantibody by standard serologic methods. Unexpectedly, she carried an Asian-type DEL without any additional RHD gene variation. All 12 HLA alleles identified were known in the Japanese population. Interestingly, one of her HLA-DRB1 and a variant of her HLA-DQB1 alleles had previously been associated with anti-D immunization.

CONCLUSION

We described an allo-anti-D, maintained for more than three decades, in an Asian-type DEL. The combination of two implicated HLA alleles were rare and could have contributed to the anti-D immunization. Continued monitoring of anti-D immunization events in patients with DEL is warranted, and we discuss possible mechanisms for further study. As only this single observation has been recognized in the last 35 years, the current recommendation is affirmed: Individuals with Asian-type DEL should be treated as Rh D-positive for transfusion and Rh immune prophylaxis purposes.

Transcriptomic profiling reveals gene expression in human peripheral blood after exposure to low-dose ionizing radiation

Although the health effects of exposure to low-dose ionizing radiation have been the focus of many studies, the affected biological functions and underlying regulatory mechanisms are not well-understood. In particular, the influence of radiation exposure at doses of less than 200 mGy on the regulation of genes and pathways remains unclear. To investigate the molecular alterations induced by varying doses of low-dose radiation (LDR), transcriptomic analysis was conducted based on ribonucleic acid (RNA) sequencing following exposure to 50 and 150 mGy doses. Human peripheral blood was collected, and the samples were divided into three groups, including two treatments and one control (no radiation). A total of 876 (318 upregulated and 558 downregulated) and 486 (202 upregulated and 284 downregulated) differentially expressed genes (DEGs) were identified after exposure to 50 mGy and 150 mGy, respectively. Most upregulated genes in both the 50 mGy and 150 mGy groups were associated with 'antigen processing and presentation,' which appeared to be the major targets affected by LDR exposure. Several interacting genes, including HLA-DQA1, HLA-DQA2, HLA-DQB2, HLA-DRB1, and HLA-DRB5 were mapped to 'antigen processing and presentation,' 'immune system-related diseases' and the 'cytokine-mediated signaling pathway,' suggesting that these genes might drive the downstream transmission of these signal transduction pathways. Our results suggest that exposure to LDR may elicit changes in key genes and associated pathways, probably helping further explore the biological processes and molecular mechanism responsible for low-dose occupational or environmental exposures in humans.

HLA transgenic mice: application in reproducing idiosyncratic drug toxicity

Various types of transgenic mice carrying either class I or II human leukocyte antigen (HLA) molecules are readily available, and reports describing their use in a variety of studies have been published for more than 30 years. Examples of their use include the discovery of HLA-specific antigens against viral infection as well as the reproduction of HLA-mediated autoimmune diseases for the development of therapeutic strategies. Recently, HLA transgenic mice have been used to reproduce HLA-mediated idiosyncratic drug toxicity (IDT), a rare and unpredictable adverse drug reaction that can result in death. For example, abacavir-induced IDT has successfully been reproduced in HLA-B*57:01 transgenic mice. Several reports using HLA transgenic mice for IDT have proven the utility of this concept for the evaluation of IDT using various HLA allele combinations and drugs. It has become apparent that such models may be a valuable tool to investigate the mechanisms underlying HLA-mediated IDT. This review summarizes the latest findings in the area of HLA transgenic mouse models and discusses the current challenges that must be overcome to maximize the potential of this unique animal model.

CD74/DQA1 dimers predispose to the development of arthritis in humanized mice

Rheumatoid arthritis (RA) is associated with the presence of certain HLA class II genes. However, why some individuals carrying RA non-associated alleles develop arthritis is still unexplained. The trans-heterodimer between two RA non-associated HLA genes can render susceptibility to develop arthritis in humanized mice, DQA1*0103/DQB1*0604, suggesting a role for DQ α chains in pathogenesis. In this study we determined the role of DQA1 in arthritis by using mice expressing DQA1*0103 and lacking endogenous class II molecules. Proximity ligation assay showed that DQA1*0103 is expressed on the cell surface as a dimer with CD74. Upon immunization with type II collagen, DQA1*0103 mice generated an antigen-specific cellular and humoral response and developed severe arthritis. Structural modelling suggests that DQA1*0103/CD74 form a pocket with similarity to the antigen binding pocket. DQA1*0103 mice present type II collagen-derived peptides that are not presented by an arthritis-resistant DQA1*0103/DQB1*0601 allele, suggesting that the DQA1*0103/CD74 dimer may result in presentation of unique antigens and susceptibility to develop arthritis. The present data provide a possible explanation by which the DQA1 molecule contributes to susceptibility to develop arthritis.

Application of Humanized Mice in Immunological Research

During the past decade, the development of humanized mouse models and their general applications in biomedical research greatly accelerated the translation of outcomes obtained from basic research into potential diagnostic and therapeutic strategies in clinic. In this chapter, we firstly present an overview on the history and current progress of diverse humanized mouse models and then focus on those equipped with reconstituted human immune system. The update advancement in the establishment of humanized immune system mice and their applications in the studies of the development of human immune system and the pathogenesis of multiple human immune-related diseases are intensively reviewed here, while the shortcoming and perspective of these potent tools are discussed as well. As a valuable bridge across the gap between bench work and clinical trial, progressive humanized mouse models will undoubtedly continue to play an indispensable role in the wide area of biomedical research.

[Phase IV non-interventional studies in the treatment of rheumatoid arthritis with biologicals in Germany : real-life clinical practice data]

BACKGROUND

In contrast to the restrictive nature of randomised controlled trials (RCT), non-interventional studies (NIS) investigate the features of a therapy in daily clinical practice. The observational plan of NIS does not dictate a treatment strategy, but is based on the product label. Unlike RCT, NIS therefore have no actual inclusion and exclusion criteria, allowing the study of broad heterogeneous patient populations.

METHODS

NIS carried out in Germany with support from the pharmaceutical industry and investigating the use of biologics for the treatment of rheumatoid arthritis were identified and their findings were compared with those from the RCT of the respective biologic.

RESULTS

Analysis of the identified NIS revealed the following: (1) populations in NIS were on average more than twice as large as in RCT, (2) patient characteristics in NIS and RCT were different, (3) the effectiveness of biologics in NIS was comparable to the efficacy observed in RCT, and (4) NIS collected supplementary data, e.g. on usage and dosing in clinical practice.

CONCLUSION

NIS represent an important tool for the assessment of daily clinical practice. Despite methodological drawbacks, NIS provide valuable data that contribute to a more complete picture of the value of treatment with biologics. The English version of this article is available at SpringerLink (under "Supplemental").