Lymphocyte subset pattern in acromegaly

Circulating immune cell profile in patients with acromegaly: results from the PROMISE, a prospective clinical trial

OBJECTIVE

Although GH and IGF-1 have long been proposed to play a role in immune-modulation, the circulating immune cell phenotype in acromegaly (ACRO) is poorly understood.

DESIGN

This observational, prospective, single-site clinical trial (NCT05069324) analyzed peripheral blood mononuclear cell (PBMC) subpopulations in ACRO, investigating the role of disease control, pharmacological treatments, and metabolic profile.

METHODS

Sixty consecutive patients with ACRO (34 males, mean age 54.7 ± 15) attending an outpatient visit between July 2020 and December 2024 were enrolled. Patients were compared with two populations: 40 healthy controls (CTRL) and 40 patients with type 2 diabetes (T2DM), with no significant differences in age or sex. An 8-week follow-up evaluation was performed and compared among patients according to the introduction or changes in their pharmacological treatment.

RESULTS

Compared with CTRL, ACRO patients had lower total monocytes with a decreased percentage of classical and an increased proportion of non-classical subsets. There were fewer NK cells, with higher CD56dim and lower CD56bright subpopulations, and similar T and B lymphocytes. Compared with T2DM, ACRO showed lower total monocytes, with higher classical and lower non-classical subsets, as well as lower NK cells and B lymphocytes. In the short-term, treatment appeared unable to restore immune cell profile but partially affected the distributions of innate immune cells subpopulations.

CONCLUSIONS

This is the first evidence of a distinct immunological pattern in ACRO that is independent of glucose metabolism. The immune signature may contribute to the persistence of cardio-metabolic and oncological risk observed in ACRO, even when the disease is adequately controlled by medical treatment.

Acromegaly and joint pain: is there something more? A cross-sectional study to evaluate rheumatic disorders in growth hormone secreting tumor patients

PURPOSE

The aim of the present study was to evaluate the rheumatic profile in acromegalic patients to better characterize joint pain.

METHODS

The immunological pattern (rheumatoid factor; antinuclear antibodies-ANA, extractable nuclear antigens-ENA-Ab; anti-citrullinated protein antibodies; erythrocyte sedimentation rate) was evaluated in 20 acromegaly subjects (AS) and 20 control subjects (CS). Bilateral joint ultrasound of hands/wrists and nail capillaroscopy were also performed.

RESULTS

Articular pain was more frequent in AS than in CS (p = 0.027). No difference was detected in immunological parameters. ANA and ENA-Ab were positive in only 10% of AS and in 5% of CS, while no difference was found in anti-citrullinated protein antibodies. No difference was detected between rheumatoid factor positivity, but threefold higher IgG were detected in AS compared to CS. The erythrocyte sedimentation rate was significantly higher in AS than CS (p = 0.040), while in AS, there was a trend in increased Power Doppler (PWD) articular uptake. The capillaroscopic evaluation showed a significant difference in almost each parameter (presence and number of tortuous capillaries, capillary enlargements, and hemorrhages), showing a moderate-to-severe microangiopathy in AS.

CONCLUSION

The results of our study suggest that joint damage in acromegaly has not an autoimmune etiology. Increased erythrocyte sedimentation rate levels and PWD alteration in acromegalic population reflect a possible inflammatory nature, while the capillaroscopic findings suggest a moderate-to-severe microangiopathy that could help to identify patients with a greater macroangiopathic risk.

Persistent inflammation and endothelial dysfunction in patients with treated acromegaly

OBJECTIVE

Acromegaly is characterized by an excess of growth hormone (GH) and insulin-like growth factor 1 (IGF1). Cardiovascular disease (CVD) risk factors are common in acromegaly and often persist after treatment. Both acute and long-lasting pro-inflammatory effects have been attributed to IGF1. Therefore, we hypothesized that inflammation persists in treated acromegaly and may contribute to CVD risk.

METHODS

In this cross-sectional study, we assessed cardiovascular structure and function, and inflammatory parameters in treated acromegaly patients. Immune cell populations and inflammatory markers were assessed in peripheral blood from 71 treated acromegaly patients (with controlled or uncontrolled disease) and 41 matched controls. Whole blood (WB) was stimulated with Toll-like receptor ligands. In a subgroup of 21 controls and 33 patients with controlled disease, vascular ultrasound measurements were performed.

RESULTS

Leukocyte counts were lower in patients with controlled acromegaly compared to patients with uncontrolled acromegaly and controls. Circulating IL18 concentrations were lower in patients; concentrations of other inflammatory mediators were comparable with controls. In stimulated WB, cytokine production was skewed toward inflammation in patients, most pronounced in those with uncontrolled disease. Vascular measurements in controlled patients showed endothelial dysfunction as indicated by a lower flow-mediated dilatation/nitroglycerine-mediated dilatation ratio. Surprisingly, pulse wave analysis and pulse wave velocity, both markers of endothelial dysfunction, were lower in patients, whereas intima-media thickness did not differ.

CONCLUSIONS

Despite treatment, acromegaly patients display persistent inflammatory changes and endothelial dysfunction, which may contribute to CVD risk and development of CVD.

Compartment Syndrome of the Temporal Muscle

The authors report a patient with masticator space abscess due to an ascending infection following a wisdom tooth extraction. They administered antibiotics and did an incision and drainage; however, osteomyelitis of the mandible and compartment syndrome of the temporal muscle complicated the course. The authors suggest a physiopathology and discuss the management of this study.

Hypersomatotropism induced secondary polycythaemia leading to spontaneous pituitary apoplexy resulting in cure of acromegaly and remission of polycythaemia: 'The virtuous circle'

A young man with subtle clinical features suggestive of hypersomatotropism presented with acute-onset severe headache. Relevant investigations confirmed polycythaemia and growth hormone (GH)-secreting pituitary macroadenoma with apoplexy. Secondary polycythaemia and myeloproliferative disorders were ruled out. At follow-up after 3 months, resolution of polycythaemia and acromegaly was observed, evident on normal haemoglobin levels, a normocellular marrow, and normal insulin-like growth factor-1 (IGF-1) with glucose-suppressed GH levels. Direct mitogenic properties of GH-IGF-1 axis on bone marrow progenitor cells may very rarely lead to erythroid hyperplasia and subsequent polycythaemia, reversible with successful therapy of acromegaly. In this case, polycythaemia secondary to hypersomatotropism likely resulted in pituitary apoplexy with subsequent remission of both acromegaly and resultant polycythaemia.

Reductions in serum IGF-1 during aging impair health span

In lower or simple species, such as worms and flies, disruption of the insulin-like growth factor (IGF)-1 and the insulin signaling pathways has been shown to increase lifespan. In rodents, however, growth hormone (GH) regulates IGF-1 levels in serum and tissues and can modulate lifespan via/or independent of IGF-1. Rodent models, where the GH/IGF-1 axis was ablated congenitally, show increased lifespan. However, in contrast to rodents where serum IGF-1 levels are high throughout life, in humans, serum IGF-1 peaks during puberty and declines thereafter during aging. Thus, animal models with congenital disruption of the GH/IGF-1 axis are unable to clearly distinguish between developmental and age-related effects of GH/IGF-1 on health. To overcome this caveat, we developed an inducible liver IGF-1-deficient (iLID) mouse that allows temporal control of serum IGF-1. Deletion of liver Igf -1 gene at one year of age reduced serum IGF-1 by 70% and dramatically impaired health span of the iLID mice. Reductions in serum IGF-1 were coupled with increased GH levels and increased basal STAT5B phosphorylation in livers of iLID mice. These changes were associated with increased liver weight, increased liver inflammation, increased oxidative stress in liver and muscle, and increased incidence of hepatic tumors. Lastly, despite elevations in serum GH, low levels of serum IGF-1 from 1 year of age compromised skeletal integrity and accelerated bone loss. We conclude that an intact GH/IGF-1 axis is essential to maintain health span and that elevated GH, even late in life, associates with increased pathology.

Function of matrix IGF-1 in coupling bone resorption and formation

Balancing bone resorption and formation is the quintessential component for the prevention of osteoporosis. Signals that determine the recruitment, replication, differentiation, function, and apoptosis of osteoblasts and osteoclasts direct bone remodeling and determine whether bone tissue is gained, lost, or balanced. Therefore, understanding the signaling pathways involved in the coupling process will help develop further targets for osteoporosis therapy, by blocking bone resorption or enhancing bone formation in a space- and time-dependent manner. Insulin-like growth factor type 1 (IGF-1) has long been known to play a role in bone strength. It is one of the most abundant substances in the bone matrix, circulates systemically and is secreted locally, and has a direct relationship with bone mineral density. Recent data has helped further our understanding of the direct role of IGF-1 signaling in coupling bone remodeling which will be discussed in this review. The bone marrow microenvironment plays a critical role in the fate of mesenchymal stem cells and hematopoietic stem cells and thus how IGF-1 interacts with other factors in the microenvironment are equally important. While previous clinical trials with IGF-1 administration have been unsuccessful at enhancing bone formation, advances in basic science studies have provided insight into further mechanisms that should be considered for future trials. Additional basic science studies dissecting the regulation and the function of matrix IGF-1 in modeling and remodeling will continue to provide further insight for future directions for anabolic therapies for osteoporosis.

Growth hormone modulates migration of thymocytes and peripheral T cells

In the context of immunoneuroendocrine cross talk, growth hormone (GH) exerts pleiotropic effects in the immune system. For example, GH-transgenic mice, as well as animals and humans treated with GH, exhibit enhanced cellularity in the thymus. GH also stimulates the thymic microenvironment, augmenting chemokine and extracellular matrix (ECM) production, with consequent increase in ECM- and chemokine-driven thymocyte migratory responses. Peripheral T cell migration triggered by laminin or fibronectin was enhanced in cells from GH-transgenic versus wild-type control adult mice, as seen for CD4(+) and CD8(+) T cells from mesenteric lymph nodes. Migration of these T lymphocytes, triggered by the chemokine CXCL12, in conjunction with laminin or fibronectin, was also enhanced compared with control counterparts. Considering that GH can be used as an adjuvant therapy in immunodeficiencies, including AIDS, the concepts defined herein, that GH enhances developing and peripheral T cell migration, provide new clues for future GH-related immune interventions.

Improving immunity in the elderly: current and future lessons from nonhuman primate models

The immune system must overcome daily challenges from pathogens to protect the body from infection. The success of the immune response to infection relies on the ability to sense and evaluate microbial threats and organize their elimination, while limiting damage to host tissues. This delicate balance is achieved through coordinated action of the innate and adaptive arms of the immune system. Aging results in several structural and functional changes in the immune system, often described under the umbrella term "immune senescence". Age-related changes affect both the innate and adaptive arms of the immune system and are believed to result in increased susceptibility and severity of infectious diseases, which is further exacerbated by reduced vaccine efficacy in the elderly. Therefore, multiple strategies to improve immune function in the aged are being investigated. Traditionally, studies on immune senescence are conducted using inbred specific pathogen free (SPF) rodents. This animal model has provided invaluable insight into the mechanisms of aging. However, the limited genetic heterogeneity and the SPF status of this model restrict the successful transfer of immunological discoveries between murine models and the clinical setting. More recently, nonhuman primates (NHPs) have emerged as a leading translational model to investigate immune senescence and to test interventions aimed at delaying/reversing age-related changes in immune function. In this article, we review and summarize advances in immuno-restorative approaches investigated in the NHP model system and discuss where the NHP model can support the development of novel therapeutics.

Polycythemia as rare secondary direct manifestation of acromegaly: management and single-centre epidemiological data

Polycythemia associated with acromegaly is usually caused by the systemic manifestations of the disease, such as sleep-apnea or concomitant erythropoietin-secreting kidney tumors. The recognition of underlying pathologies requires a thorough diagnostic process. We report a unique case of acromegaly with polycythemia, not caused by commonly described manifestations of the disease, and receding with octreotide therapy. The medical history of 141 acromegalic patients followed by the Endocrinology Unit of the San Martino University Hospital in Genoa has been also reviewed, together with the literature evidence for similar cases. The diagnostic workflow and 2-years follow-up of a 43-years old acromegalic, polycythemic man with a history of past smoking, moderate hypertension, and mental retardation are described. The hematological parameters of our cohort was retrospectively compared with those of a healthy, age/gender-related control group as well. Therapy with octreotide LAR, 20 mg i.m. q28d was begun soon after diagnosis of acromegaly in the polycythemic patient. Haematocrit level, hormonal setting, as well as pituitary tumor size and visual perimetry during treatment were recorded. Octreotide LAR treatment normalized hormonal alterations, as well as hematological parameters. Polycythemia has not recurred after 2 years of therapy. The median hemoglobin and hematocrit levels of the retrospectively analyzed cohort of acromegalic were significantly lower than normal ranges of a healthy, age/sex- related control population. In conclusions, polycythemia can be a direct, albeit rare, secondary manifestation of acromegaly, that must be considered during the diagnostic work-up of acromegalic patients presenting with such disorder.

Growth hormone is a modulator of lymphocyte migration

Cell migration is crucial for intrathymic T cell differentiation and export of mature T lymphocytes to the peripheral lymphoid organs. The intrinsic regulation of T cell migration, mediated by adhesion molecules and chemokines, can be influenced by a number of endogenous factors, such as hormones, as for instance growth hormone (GH). Laminin deposition was enhanced in GH-treated mice and in GH-transgenic animals, compared with corresponding controls, and thymocyte adhesion to laminin was increased by in vivo GH treatment. An enhancing effect was also observed ex vivo in relation to the number of migrating cells in laminin-coated transwell chambers. Additionally, we found that the chemokine CXCL12, in conjunction with laminin, further enhanced the migration of thymocytes previously exposed to high concentrations of GH in vivo. Moreover, an increase in CXCL12 production has been detected in the thymus of GH-transgenic mice as well as in primary thymic epithelial cell cultures derived from these animals, as compared to age-matched wild-type counterparts. In keeping with these data, in vivo experiments showed that GH favors the trafficking of naive CD4+CD8- recent thymic emigrants to the peripheral lymph nodes. In addition, we found that migration of lymphocytes from mesenteric lymph nodes of GH-transgenic mice, triggered by the chemokine CXCL12, in conjunction with laminin or fibronectin, was enhanced, when compared to lymphocytes from control mice. Since GH-based therapy has been used in human and experimental infectious diseases, this hormone can be envisioned as an additional therapeutic tool in situations in which increasing lymphocyte numbers and migration are required for correcting a given pathological state.

Immune function in hypopituitarism: time to reconsider?

Hypopituitarism is not currently considered as a potential cause of immune disruption in humans. Accumulating data from in vitro and animal models support a role for the pituitary gland in immune regulation. Furthermore, the increased mortality risk noted in patients with adult hypopituitarism remains poorly explained and immune dysfunction could conceivably contribute to this observation. In a recent issue of Clinical & Experimental Immunology, we presented new data relating to immune status in adults with treated, severe hypopituitarism. We observed humoral immune deficiency in a significant proportion, despite stable pituitary replacement, including growth hormone (GH). This was especially evident in those with low pretreatment IGF-I levels and appeared independent of anticonvulsant use or corticosteroid replacement. These observations require substantiation with future studies. In this short review, we summarize existing data relating to the effects of pituitary hormones on immune function and discuss potential clinical implications surrounding the hypothesis of immune dysregulation in severe hypopituitarism.

Combined role of extracellular matrix and chemokines on peripheral lymphocyte migration in growth hormone transgenic mice

Previous evidence indicated that growth hormone (GH) modulates cell migration in the thymus, and that extracellular matrix and chemokines are involved. Herein, we studied migration of peripheral lymphocytes derived from spleen and lymph nodes of GH-transgenic (GH-Tg) mice. We initially found that the relative cell numbers (normalized per gram of body weight) in lymph nodes and spleens from GH-Tg were higher at all ages tested (2-3, 7 and 12 months), as compared to wild type age-matched controls. Functionally, we found that lymphocyte migration triggered by laminin or fibronectin was enhanced in cells from GH-Tg versus control mice, independent of the organ from which the cells were derived (as ascertained in young adult animals). However, such an enhancement in migration was statistically significant only for CD4+ and CD8+ T cells from mesenteric lymph nodes. Migration of lymphocytes from mesenteric lymph nodes of GH-Tg mice, triggered by the chemokine CXCL12, in conjunction with laminin or fibronectin, was enhanced compared to lymphocytes from control mice. Rather surprisingly, the membrane levels of the corresponding extracellular matrix or chemokine receptors in peripheral lymphoid organs of GH-Tg mice did not necessarily correlate with the changes seen in migratory responses. In conclusion, our data show for the first time that GH alters lymphocyte migration in the periphery of the immune system. Considering that GH is used as an adjuvant therapeutic agent in immunodeficiencies, including AIDS, the concepts defined herein provide relevant background knowledge for future GH-related immune interventions.

Failure of antibody response to polysaccharide antigen in treated panhypopituitary adults

Although pituitary hormones are known to affect immune function, treated hypopituitarism is not a recognized cause of immune deficiency in humans. We set out to assess integrity of baseline and stimulated immune function in severely hypopituitary adults. Twenty-one panhypopituitary adults (group 1), on stable pituitary replacement including growth hormone, and 12 healthy volunteers (group 2) were studied. Lymphocyte subsets, pneumococcal antibody levels pre- and 1 month after polysaccharide vaccination, T cell numbers and in-vitro interferon (IFN)-gamma response were studied. There were no significant differences in T cell numbers or IFN-gamma secretion. B cell numbers were lower in group 1, especially those with low prolactin levels. Independent of this finding, nine of 21 patients in this group had low antibody response to polysaccharide antigen. This was most striking in those with low insulin-like growth factor 1 levels and appeared to be independent of the use of anti-convulsants or corticosteroid replacement. Significant humoral immune deficiency is seen in panhypopituitarism and may contribute to morbidity.

Sudden death due to aortic rupture in acromegaly

Acromegaly, when left untreated, is associated with premature mortality which is chiefly related to cardiovascular complications. We report on a 50-year-old acromegalic woman, resistant to therapy, who died suddenly because of thoracic aortic rupture and massive bleeding into the left pleural space. The postmortem examination disclosed, nearby the point of rupture, a pulmonary abscess as well as extensive intrinsic alteration of arteries originating from the aortic arch and aorta itself, which featured microscopic cystic medial necrosis. We discussed how these aspects could be related to long-term exposition to growth hormone excess. In particular, this case gives further evidence of vascular system frailty in acromegaly.

GH/IGF-I and bone resorption in vivo and in vitro

IGF-I may act as one of several coupling agents by activating bone formation and bone resorption. In vivo studies in normal subjects, postmenopausal women and patients with excess or diminished GH production (acromegaly and GHD) indicate that both GH and IGF-I activate osteoclasts, but that GH has a more pronounced effect, independently of IGF-I. In vitro, GH and IGF receptors have been demonstrated on osteoclasts and both GH and IGF-I may directly modify osteoclast function and activity. In addition to direct effects on osteoclasts, GH and IGF-I may affect bone resorption indirectly by stimulating release of paracrine mediators that regulate osteoclastic resorption (cytokines). Critical for the bone resorptive process is the balance between OPG and RANKL, which is regulated by many systemic factors. In vivo and in vitro, GH/IGF-I may modulate this balance but these studies are difficult to interpret, reflecting the complexity of this system. Increased OPG expression may possibly protect against GH/IGF-I-induced bone resorption and potentially be important for the long-term beneficial effects of GH replacement. Further studies investigating the OPG/RANKL ratio and system in experimental and transgenic GH/IGF models may clarify these issues.

Growth Hormone/Insulin-Like Growth Factor–I System and Connective Tissues: Basic Aspects and Clinical Implications

This article reviews basic and clinical aspects of the effects of growth hormone and insulin-like growth factor-I on the connective tissues.