Bioassays for ThyroTropin Receptor Autoantibodies

Elsevier

Available online 5 February 2023, 101744

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Bioassays using animal models were essential tools in the discovery of thyrotropin and in enhancing our understanding of the physiology of the pituitary-thyroid axis. These same bioassays were also instrumental in the discovery of autoantibodies to the thyrotropin receptor (TSH-R-Ab) and in identifying their role in the pathophysiology of Graves’ disease. The development of cell-based bioassays led to further advances in our knowledge of the functional activity of TSH-R-Ab and to the discovery that TSH-R-Ab can be either thyroid-stimulating or thyroid blocking, and that they occur in other types of autoimmune thyroid diseases (AITD) besides Graves’ disease. More recently, TSH-R-Ab bioassays have been advanced from research tools to clinical laboratory tests. Whereas TSH-R-Ab can be measured with competitive-binding immunoassays, these assays do not provide information on the functional activity of TSH-R-Ab. Bioassays, in contrast, can differentiate between the stimulatory or blocking activity of TSH-R-Ab which provides clinically useful information that can inform the management of patients with AITD. The clinical use of TSH-R-Ab bioassays, however, has been limited to-date by their inherent complexity and long turn-around-time. Recent advances in biosensors have been applied to the development of TSH-R-Ab bioassays that are rapid and simple to perform. We now are entering an era in which bioassays for TSH-R-Ab can be measured routinely by virtually any clinical laboratory.

Section snippetsINTRODUCTION

A biological assay, or bioassay, is an analytical method used to measure the functional activity of a molecule on living organisms, tissue, or live cells. Bioassays are widely used to screen for potential hazardous chemicals in contaminated soils, wastewater, or foods, and are an important tool in the development of new drugs [1], [2], [3], [4], [5], [6], [*7]. One of the first described bioassays was a bioassay for diphtheria antitoxin developed by Paul Ehrlich ([8]. In medicine, bioassays

THYROTROPIN RECEPTOR

The TSH-R is found on thyrocytes and the cells of other tissues and is a member of the G protein-coupled receptors (GPCRs), the largest known superfamily of cell surface receptors [20]. TSH, produced by the pituitary gland, binds to the TSH-R and activates signal transduction pathways that promote thyrocyte proliferation and production of thyroid hormone. As with all GCPRs, conformation changes in TSH-R occur upon binding of TSH or other agonists, which initiates a signaling cascade in the

AUTOIMMUNE THYROID DISEASE

Autoimmune thyroid diseases (AITD) are common causes of both hyperthyoidism and hypothyroidism and are characterized by the presence of autoantibodies to a number of thyroid antigens such as thyroid peroxidase (TPO) and TSH-R [25]. Although anti-TPO antibodies are highly prevalent in patients with AITD, these antibodies are not thought to be directly involved in the pathogenesis of AITD. In contrast, TSH-R-Ab are uniquely and directly involved in the pathophysiology of certain types of AITD. In

TERMINOLOGY

There are a variety of terms used to describe the different types of TSH-R-Ab. TSH-R antibody (TRAb) refers to any type of autoantibody specific to the TSH-R, but it is commonly used in reference to antibodies detected in an immunoassay. Most immunoassays today use a competitive-binding assay called TSH-R binding inhibitory immunoglobulin (TBII) assay. In contrast, bioassays measure either thyroid stimulatory antibodies (TSAb), also referred to as thyroid stimulating immunoglobulins (TSI), or

ANTI-TSH-R MONOCLONAL ANTIBODIES

Anti-TSH-R monoclonal antibodies have been important in efforts to understand the role of TSH-R-Ab in pathogenesis of AITD. A number of murine anti-TSH-R monoclonal antibodies have been isolated and described, but the most important development in this area is the isolation of human monoclonal antibodies to the TSH-R from AITD patients [35], [36], [37], [38], [39], [40]. Ever since it has been known that TSH-R-Ab exhibit different functional activities, it has been suspected that certain

BIOASSAYS FOR TSH-R-AB

A summary of the advances in the development of TSH-R-Ab bioassays is shown in Table 1. The first generation of TSAb bioassays used the same principles that had been used to measure TSH activity. These early TSAb bioassays used cultured dog thyroid cells, human thyroid cells and later a continuous rat thyrocyte cell line (FRTL-5) [49], [50], [51]. Concerns about differences between the human and rat TSH-R lead to the use of cell lines transfected with the gene for human TSH-R. The most common

LATEST GENERATION OF BIOASSAYS

Recently, novel biosensors have been developed that allow for real-time measurement of cAMP dynamics inside live cells and thus can be used to provide a quantitative measurement of GPCR activation [*68], [69], [70], [71]. These biosensors allow for simple, homogeneous, high-throughput screening assays for cAMP and thus are excellent tools in both academic and pharmaceutical laboratories. A live-cell TSAb bioassay that uses a cyclic nucleotide-gated calcium channel and aequorin was recently

BIOASSAYS FOR THYROID-BLOCKING AUTOANTIBODIES (TBAB)

Thyroid-blocking activity is caused by TSH-R-Ab that block the stimulatory action of TSH. Initial bioassays for the measurement of thyroid-blocking activity were based on the same cell-based systems as used for TSAb, but they detected the ability of patient antisera to block TSH or TSAb-stimulated cAMP levels [74], [75], [76], [77], [78], [79]. Other bioassays for detecting TBAb were based on the inhibition of the TSH-mediated proliferation of FRTL-5 cells using tritiated nucleoside

CONCERNS ABOUT TSAB AND TBAB BIOASSAYS

A number of concerns have been raised about the accuracy and relevance of bioassays in general, and TSAb/TBAb bioassays, in particular. The first concern relates to the fact that the original bioassays used thyroid cells and measured thyrocyte proliferation and hormone production. Thus, these bioassays could be thought to more closely reflect the in vivo activity of the antibodies. In order to streamline TSAb bioassays, non-thyroid cells, engineered to express human TSH-R, or mutant forms of

SUMMARY

Methodologies available for bioassays have advanced significantly. The most recent generation of bioassays do not require laboratories to perform cell culture and the protocols are very straightforward and can be easily automated. This raises the possibility of routine use of selective bioassays in clinical laboratories. In the case of TSH-R-Ab bioassays, this is important because these bioassays provide results on the functional activity of TSH-R-Ab which has clinical utility and which can be

Acknowledgements

The author wishes to acknowledge the helpful discussions with my many colleagues

Disclosure

PDO consults for Quidel Corporation, San Diego, USA

PRACTICE POINTS OR TAKE-HOME MESSAGES•

Bioassays continue to play an important role in medicine.

Bioassays for TSHR-Ab have been important tools for understanding the pathogenesis of AITD.

Bioassays for TSHR-Ab can determine the functional activity of TSHR-Ab

Advances in bioassay methodology have improved significantly and TSHR-Ab bioassays are no longer complex, laborious, and slow.

Routine use of TSHR-Ab

References (84)J. SandersTSH receptor monoclonal antibodies with agonist, antagonist, and inverse agonist activities

Methods Enzymol

(2010)

T.W. Rall et al.Formation of a cyclic adenine ribonucleotide by tissue particles

J Biol Chem

(1958)

T. Ando et al.Thyrotropin receptor antibodies: new insights into their actions and clinical relevance

Best Pract Res Clin Endocrinol Metab

(2005)

J. Van NoordwijkBioassays in Whole Animals

J Pharm Biomed Anal

(1989)

C.J. Keddy et al.Review of whole-organism bioassays: soil, freshwater sediment, and freshwater assessment in Canada

Ecotoxicol Environ Saf

(1995)

S.H. HassanToxicity assessment using different bioassays and microbial biosensors

Environ Int

(2016)

L.A. Beyer et al.Historical perspective on the use of animal bioassays to predict carcinogenicity: evolution in design and recognition of utility

Crit Rev Toxicol

(2011)

S. Kohler et al.Reporter gene bioassays in environmental analysis

Fresenius J Anal Chem

(2000)

A. NajmiModern Approaches in the Discovery and Development of Plant-Based Natural Products and Their Analogues as Potential Therapeutic Agents

Molecules

(2022)

A.A. Stromstedt et al.Bioassays in natural product research - strategies and methods in the search for anti-inflammatory and antimicrobial activity

Phytochem Anal

(2014)

K. Svobodova et al.New in vitro reporter gene bioassays for screening of hormonal active compounds in the environment

Appl Microbiol Biotechnol

(2010)

J. Bretram et al.[Rabbit test for diagnosis of pregnancy; modification of the classical technique, communication and preliminary statistical study].

Ginecol Obstet Mex

(1951)

J. MagnerHistorical note: many steps led to the 'discovery' of thyroid-stimulating hormone

Eur Thyroid J

(2014)

J. McKenzieThe bioassay of thyrotropin in serum

Endocrinology

(1958)

L. LoebStudies on Compensatory Hypertrophy of the Thyroid Gland: VII. A Comparison between the Effect of Administration of Thyroxin, Thyroid and Anterior Pituitary Substance on the Compensatory Hypertrophy of the Thyroid Gland in the Guinea Pig

Am J Pathol

(1929)

D.D. Adams et al.The assessment of thyroid function by tracer tests with radioactive iodine

N Z Med J

(1956)

R. BrimblecombeStudies on the biological assay of thyrotrophic hormone

J Endocrinol

(1952)

M.V. Mussett et al.The international standard for thyrotrophin

Bull World Health Organ

(1955)

J. McKenzieDelayed thyroid response to serum from thyrotoxic patients

Endocrinology

(1958)

T. DianaPrevalence and clinical relevance of thyroid stimulating hormone receptor-blocking antibodies in autoimmune thyroid disease

Clin Exp Immunol

(2017)

T. Diana et al.Thyrotropin receptor antibodies and Graves' orbitopathy

J Endocrinol Invest

(2021)

R. FredrikssonThe G-protein-coupled receptors in the human genome form five main families. Phylogenetic analysis, paralogon groups, and fingerprints

Mol Pharmacol

(2003)

T. Davies et al.The TSH receptor reveals itself

J Clin Invest

(2002)

R.H. Strasser et al.A novel catecholamine-activated adenosine cyclic 3',5'-phosphate independent pathway for beta-adrenergic receptor phosphorylation in wild-type and mutant S49 lymphoma cells: mechanism of homologous desensitization of adenylate cyclase

Biochemistry

(1986)

J. Van SandeThyroid stimulating immunoglobulins, like thyrotropin activate both the cyclic AMP and the PIP2 cascades in CHO cells expressing the TSH receptor

Mol Cell Endocrinol

(1992)

D. SinclairAnalytical aspects of thyroid antibodies estimation

Autoimmunity

(2008)

G.A. BrentClinical practice. Graves' disease

N Engl J Med

(2008)

T. Diana et al.Thyrotropin Receptor Blocking Antibodies

Horm Metab Res

(2018)

S.A. Morshed et al.Characterization of thyrotropin receptor antibody-induced signaling cascades

Endocrinology

(2009)

T. DianaAnalytical Performance and Validation of a Bioassay for Thyroid-Blocking Antibodies

Thyroid

(2016)

S.D. LyttonNovel chimeric thyroid-stimulating hormone-receptor bioassay for thyroid-stimulating immunoglobulins

Clin Exp Immunol

(2010)

S.D. Lytton et al.Functional diagnostics for thyrotropin hormone receptor autoantibodies: bioassays prevail over binding assays

Front Biosci (Landmark Ed)

(2018)

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