Autoimmunity as a possible cause of growth hormone deficiency

Identifying Growth Hormone Deficiency in Brain-Injured Patients: The Quality of Life Scale-99

Traumatic brain injury (TBI) is frequently associated with hypopituitarism. The hypothalamic-pituitary axis appears to be susceptible to the same forces that cause injury to the parenchyma of the brain. Following even a mild TBI (mTBI), patients may suffer transient or permanent decreases in anterior pituitary hormones, including somatotropin (growth hormone [GH]), gonadotropins (luteinizing hormone and follicle-stimulating hormone), thyrotropin, and adrenocorticotropic hormone, with the most frequent long-term deficiency being GH deficiency (GHD). GHD is common after mTBI and is often the cause of persistent post-concussive symptoms a year or more post-injury. GHD is known to cause physical and cognitive fatigue, cognitive inefficiency, metabolic changes, and a range of psychological symptoms. Confusing the picture is that some symptoms of GHD are also common to brain injury itself. To facilitate the detection of GHD when comorbid with TBI, we utilized a new symptom inventory, the Quality-of-Life Scale-99 (QoLS-99), and administered it to a cohort of chronic TBI subjects with and without GHD, distinguished using the insulin tolerance test (ITT). Between 2018 and 2023, 371 patients completed the QoLS-99, of which 263 underwent GH testing with the ITT. Of these 263 patients, 136 (52%) were diagnosed with GHD. A retrospective comparison of QoLS-99 scores found that loss of libido (p < 0.006), a reliance on sleep aids (p < 0.011), and feeling overweight (p < 0.015) were the strongest univariate predictors of GHD. Most survey items did not elicit a significant difference in response between the GHD groups, and for those that did, effect sizes were mild to moderate. Still, initial findings demonstrate strong predictive value in a subset of survey items (i.e., GHD symptoms) that are most discriminating in the sample of patients with TBI. A multivariate prediction model using this subset of questions was able to differentiate GHD status in patients with TBI, correctly identifying 88% of GHD cases with a 37% false positive rate. Based on these findings, we recommend that clinicians inquire about libido, insomnia, and body image as potential markers for GHD. Furthermore, given the amenability of patients with GHD to growth hormone replacement therapy, we strongly encourage clinicians and basic scientists to develop interventions for the large and underserved population of patients with TBI with comorbid GHD.

Autoimmune Pituitary Disease: New Concepts With Clinical Implications

Some endocrine disorders, including hypophysitis and isolated adrenocorticotropic hormone (ACTH) deficiency, are caused by an autoimmune response to endocrine organs. Although the pathogenesis of some autoimmune endocrine diseases has been elucidated, it remains obscure for most. Anti-PIT-1 hypophysitis (anti-PIT-1 antibody syndrome) is a newly described pituitary autoimmune disease characterized by acquired and specific growth hormone (GH), prolactin (PRL), and thyroid-stimulating hormone (TSH) deficiencies. This disorder is associated with a thymoma or neoplasm that ectopically expresses pituitary-specific transcription factor 1 (PIT-1) protein. Circulating anti-PIT-1 antibody is a disease marker, and PIT-1-reactive cytotoxic T cells (CTLs) play a pivotal role in disease development. In addition, isolated ACTH deficiency appears to be caused by autoimmunity to corticotrophs; however, the pathogenesis remains unclear. A recently described case of isolated ACTH deficiency with large cell neuroendocrine carcinoma (LCNEC) showed ectopically expressed proopiomelanocortin (POMC), and circulating anti-POMC antibody and POMC-reactive CTLs were also detected. As CTL infiltrations around corticotrophs were also observed, isolated ACTH deficiency may be associated at least in part with a paraneoplastic syndrome. Although several underlying mechanisms for pituitary autoimmunity have been proposed, these observations highlight the importance of paraneoplastic syndrome as a cause of pituitary autoimmune disease. In this review, we focus on the pathophysiology and connection of anti-PIT-1 hypophysitis and isolated ACTH deficiency and discuss the state-of-art knowledge for understanding pituitary autoimmunity.

Impact of Pituitary Autoimmunity and Genetic Disorders on Growth Hormone Deficiency in Children and Adults

Growth hormone (GH), mostly through its peripheral mediator, the insulin-like growth factor 1(IGF1), in addition to carrying out its fundamental action to promote linear bone growth, plays an important role throughout life in the regulation of intermediate metabolism, trophism and function of various organs, especially the cardiovascular, muscular and skeletal systems. Therefore, if a prepubertal GH secretory deficiency (GHD) is responsible for short stature, then a deficiency in adulthood identifies a nosographic picture classified as adult GHD syndrome, which is characterized by heart, muscle, bone, metabolic and psychic abnormalities. A GHD may occur in patients with pituitary autoimmunity; moreover, GHD may also be one of the features of some genetic syndromes in association with other neurological, somatic and immune alterations. This review will discuss the impact of pituitary autoimmunity on GHD and the occurrence of GHD in the context of some genetic disorders. Moreover, we will discuss some genetic alterations that cause GH and IGF-1 insensitivity and the arguments in favor and against the influence of GH/IGF-1 on longevity and cancer in the light of the papers on these issues that so far appear in the literature.

Why were Sardinians the shortest Europeans? A journey through genes, infections, nutrition, and sex

Since ancient times the Mediterranean island of Sardinia has been known for harboring a population with an average body height shorter than almost every other ethnic group in Europe. After over a century of investigations, the cause(s) at the origin of this uniqueness are not yet clear. The shorter stature of Sardinians appears to have been documented since prehistoric times, as revealed by the analysis of skeletal remains discovered in archaeological sites on the island. Recently, a number of genetic, hormonal, environmental, infective and nutritional factors have been put forward to explain this unique anthropometric feature, which persisted for a long time, even when environmental and living conditions improved around 1960. Although some of the putative factors are supported by sound empirical evidence, weaker support is available for others. The recent advent of whole genome analysis techniques shed new light on specific variants at the origin of this short stature. However, the marked geographical variability of stature across time and space within the island, and the well-known presence of pockets of short height in the population of the southern districts, are still puzzling findings that have attracted the interest of anthropologists and geneticists. The purpose of this review is to focus on the state-of-the-art research on stature, as well as the factors that made Sardinians the shortest among Europeans.

Involvement of endocrine system in a patient affected by glycogen storage disease 1b: speculation on the role of autoimmunity

Glycogen storage disease type 1b (GSD1b) is an inherited metabolic defect of glycogenolysis and gluconeogenesis due to mutations of the SLC37A4 gene and to defective transport of glucose-6-phosphate. The clinical presentation of GSD1b is characterized by hepatomegaly, failure to thrive, fasting hypoglycemia, and dyslipidemia. Patients affected by GSD1b also show neutropenia and/or neutrophil dysfunction that cause increased susceptibility to recurrent bacterial infections. GSD1b patients are also at risk for inflammatory bowel disease. Occasional reports suggesting an increased risk of autoimmune disorders in GSD1b patients, have been published. These complications affect the clinical outcome of the patients. Here we describe the occurrence of autoimmune endocrine disorders including thyroiditis and growth hormone deficiency, in a patient affected by GSD1b. This case further supports the association between GSD1b and autoimmune diseases.

Endocrine autoimmune diseases and female infertility

An increasing body of evidence suggests that immune-mediated processes affect female reproductive success at multiple levels. Crosstalk between endocrine and immune systems regulates a large number of biological processes that affect target tissues, and this crosstalk involves gene expression, cytokine and/or lymphokine release and hormone action. In addition, endocrine-immune interactions have a major role in the implantation process of the fetal (paternally derived) semi-allograft, which requires a reprogramming process of the maternal immune system from rejection to temporary tolerance for the length of gestation. Usually, the female immune system is supportive of all of these processes and, therefore, facilitates reproductive success. Abnormalities of the female immune system, including autoimmunity, potentially interfere at multiple levels. The relevance of the immune system to female infertility is increasingly recognized by investigators, but clinically is often not adequately considered and is, therefore, underestimated. This Review summarizes the effect of individual autoimmune endocrine diseases on female fertility, and points towards selected developments expected in the near future.

Influence of adult height on rheumatoid arthritis: association with disease activity, impairment of joint function and overall disability

Objectives

To investigate whether normal variation of adult height is associated with clinical characteristics in rheumatoid arthritis (RA), including disease activity (DAS28), impairment of joint function (mechanical joint score, MJS) and overall disability (health assessment questionnaire, HAQ).

Methods

A cohort (134 males, 287 females) of consecutively recruited RA patients of Northern European origin was studied. Height, weight and demographic information were obtained. A core set of disease measurements, including DAS28, MJS and HAQ, were recorded at baseline, 12 and 24 months. Other clinical variables (e.g. disease duration, IgM rheumatoid factor, antibodies to cyclic citrullinated peptide, C-reactive protein, erythrocyte sedimentation rate) were recorded at baseline. Socioeconomic status, smoking status, comorbid condition, other autoimmune conditions and drug therapy were also recorded. Associations were analyzed using univariate statistics and multivariate linear regression models. Mediation tests were also carried out for evaluating the relationship between gender, height and disease measures.

Results

In males, height was inversely associated with DAS28, MJS and HAQ (at baseline and over 24 months) independent of other factors (e.g. weight, body mass index, age, disease duration, osteoporosis, autoantibodies, erosive disease, joint replacement, steroid use, smoking status, socioeconomic status and comorbid disease). In females, a similar trend was seen but the relationships were non significant. In the whole population, the association of female gender with more active disease and poor function disappeared after adjustment for height. Mediation analysis indicated that height served as a full mediator in the relationship of gender with disease activity and overall disability. Confirmation of these findings was demonstrated in a second RA population (n = 288).

Conclusion

Adult height is inversely associated with disease activity, impairment of joint function and overall disability in RA, particularly in males. The association of female sex with more severe disease activity and disability appears to be mediated by smaller stature.

Involvement of genes related to inflammation and cell cycle in idiopathic short stature

Idiopathic Short Stature (ISS) defines a condition in which height is <-2SD compared to the mean of a reference population where systemic, endocrinological, nutritional or chromosomal disorders have not been identified and diagnosis is based on exclusion of any known causes of short stature. JAK/STAT pathway is triggered by GH binding to the GH receptor and promotes cellular growth through transcription of GH-responsive genes. In order to identify "candidate genes" differently expressed in ISS subjects with respect to control ones, we analyzed the expression of 84 genes related to JAK/STAT pathway by RT(2) Profiler PCR array approach in a total of 10 subjects. Then, we validated the observed data by Real Time PCR and ELISA assays in a major number of subjects. We found two genes that were differently expressed in ISS subjects with respect to the control group: CXCL9 and FCGR1A/CD64, both significantly up-regulated (fold change 2.17 and 1.70, respectively) and belonging to family of IFN-γ-inducible factors. Further, ISS subjects showed an increased gene expression of IFN-γ and IFI16, higher serum levels of IFN-γ but similar levels of CXCL9 when compared to healthy subjects. In addition, we showed a pubertal modulation of CXCL9 levels. These data suggest that inflammatory and regulatory factors of the cell cycle may be involved in the ISS condition, introducing a new perspective to its etiology.

Diagnosis and treatment of autoimmune hypophysitis: a short review

Medical therapy of autoimmune hypophysitis with immunosuppressive drugs can be effective to induce remission of the disease by treating both pituitary dysfunction and compression symptoms. We describe the case of a 41-yr-old man with autoimmune hypophysitis in whom prednisone therapy induced remission of the disease but was followed by a sudden relapse after withdrawal. A second trial of corticosteroid was started and succeeded in inducing remission of the disease. Eight months after the second withdrawal pituitary function was restored, pituitary mass had disappeared, only partial diabetes insipidus remained unchanged. Review of the literature identified 30 articles, among case reports and case series, reporting a total of 44 cases of autoimmune hypophysitis treated with glucocorticoids and/or azathioprine. Combining all the cases, medical therapy resulted to be effective in reducing the pituitary mass in 84%, in improving anterior pituitary function in 45%, and in restoring posterior pituitary function in 41%. Clinical aspects of autoimmune hypophysitis are discussed and a possible algorithm for the diagnosis and treatment of the disease is proposed.

Growth hormone deficiency: diagnosis and therapy in children

Growth hormone (GH) deficiency (GHD) represents a condition characterized by reduced GH secretion, isolated or associated with other pituitary hormone deficiencies. Diagnosis of GHD in childhood is achieved by secretagogs testing in combination with auxological parameters, such as height and growth velocity and biochemical and radiological findings. Only after excluding other causes of growth failure should a careful assessment of the pituitary-IGF-1 axis be undertaken, using GH-provocative tests and basal serum IGF-I values. As recommended by the GH Research Society, patients with GHD should be treated with recombinant human GH in order to normalize height during childhood and, ultimately, attain a normal adult height.

The molecular basis of hypopituitarism

Hypopituitarism is defined as the deficiency of one or more of the hormones secreted by the pituitary gland. Several developmental factors necessary for pituitary embryogenesis and hormone secretion have been described, and mutations of these genes in humans provide a molecular understanding of hypopituitarism. Genetic studies of affected patients and their families provide insights into possible mechanisms of abnormal pituitary development; however, mutations are rare. This review characterizes several of these developmental proteins and their role in the pathogenesis of hypopituitarism. Continuing research is required to better understand the complexities and interplay between these pituitary factors and to make improvements in genetic diagnosis that can lead to early detection and provide a future cure.