Serum fibroblastic growth factor 23 in acute Sarcoidosis and normal kidney function.

BACKGROUND: Serum fibroblastic growth factor (FGF) 23 has recently been established as a major physiological regulator of phosphate homeostasis and may have a causal role in adverse cardiovascular and bone outcomes. However its role in states of disordered phosphate homeostasis and normal kidney function is as yet under characterised. AIMS: To investigate whether this biomarker of vascular calcification and adverse bone outcomes is detectable in patients with sarcoidosis. DESIGN: We conducted a cross sectional study on a convenience sample of patients presenting with acute sarcoidosis to a respiratory tertiary referral unit. METHODS: We set out to systematically examine the characteristics and determinants of serum FGF-23 in patients presenting with acute sarcoidosis. RESULTS: We studied 39 patients, 26 were male. Mean (SD) age was 33 (9.6) years. 15.4% of patients had a serum level of FGF-23 ≥ 9.9 pg/mL. The remaining 84.6% of patients had a serum FGF-23 < 9.9 pg/mL. Those with a detectable serum FGF-23 had a significantly higher serum calcium (P = 0.007), and lower serum iPTH (P<0.001). Serum phosphate and 25-hydroxyvitamin D were not statistically significantly different between groups (P=0.25 and P=0.83). The proportion of patients with stage II disease on CXR was higher in those with a detectable FGF-23 (P<0.001). CONCLUSIONS: Serum FGF-23 was below the level of detection in the majority of this cohort of patients presenting with acute sarcoidosis. A detectable serum FGF-23 was associated with a higher serum calcium and lower serum iPTH.

Radiological remission and recovery of thirst appreciation after infliximab therapy in adipsic diabetes insipidus secondary to neurosarcoidosis.

BACKGROUND: Neurosarcoidosis is a rare and aggressive variant of systemic sarcoidosis which may result in hypothalamic-pituitary dysfunction. We report a case of hypothalamic hypopituitarism secondary to neurosarcoidosis complicated by adipsic diabetes insipidus (ADI). Initiation of anti-tumour necrosis factor-α (TNF-α) therapy resulted in both radiological disease remission and recovery of osmoregulated thirst appreciation after 3 months. CASE SUMMARY: A 22-year-old man was referred to the endocrinology service with profound weight gain, polyuria and lethargy. Biochemical testing confirmed anterior hypopituitarism while posterior pituitary failure was confirmed by hypotonic polyuria responding to desmopressin. Magnetic resonance imaging (MRI) demonstrated extensive hypothalamic infiltration; neurosarcoidosis was confirmed histologically after excisional cervical lymph node biopsy. Osmoregulated thirst appreciation was normal early in the disease course despite severe hypotonic polyuria. However, subsequent subjective loss of thirst appreciation and development of severe hypernatraemia in the setting of normal cognitive function indicated onset of ADI. MANAGEMENT: Clinical management involved daily weighing, regular plasma sodium measurement, fixed daily fluid intake and oral desmopressin. We initiated immunosuppressive therapy with pulsed intravenous anti-TNF-α therapy (infliximab) after multidisciplinary team consultation. OUTCOME: Infliximab therapy resulted in successful radiological disease remission and complete recovery of osmoregulated thirst appreciation. This was confirmed by subjective return of thirst response and maintenance of plasma sodium in the normal range in the absence of close biochemical monitoring.

Barking up the wrong tree? Use of polymerase chain reaction to diagnose syphilitic aortitis.

The presentation of syphilitic aortitis is often atypical and available serological tests are non-specific. The diagnostic gold standard remains direct identification of microorganisms in tissue. We present a case of syphilitic aortitis that presented as a mediastinal mass and report the use of polymerase chain reaction for Treponema pallidum to diagnose syphilitic aortic disease.

Abnormal pulmonary granuloma formation in osteopontin-deficient mice.

Osteopontin is a novel cytokine that is expressed in pulmonary granulomatous disease such as sarcoidosis and tuberculosis. It can regulate macrophage and T cell migration, activation, and cytokine expression, yet its role in granuloma formation and evolution is unknown. We induced hypersensitivity pulmonary granulomas by embolizing Schistosoma mansoni eggs to the lungs of osteopontin-deficient (null mutant) mice and osteopontin-sufficient (wild-type control) mice. Granulomas from osteopontin-null animals were smaller at early time points and contained remarkably few macrophages and macrophage-derived epithelioid cells and giant cells. T cell accumulation was unaffected by osteopontin deficiency. These results demonstrate that osteopontin regulates macrophage accumulation during pulmonary granuloma formation, and may explain the impaired ability of osteopontin-deficient hosts to control mycobacterial disease.

Osteopontin augments CD3-mediated interferon-gamma and CD40 ligand expression by T cells, which results in IL-12 production from peripheral blood mononuclear cells.

Osteopontin is an RGD-containing bone matrix protein with cytokine-like functions that is associated with early stages of Th1-mediated diseases. Although the function of osteopontin in these responses is unknown, it is expressed by activated T cells and macrophages and can costimulate T cell proliferation. Studies have demonstrated that early IL-12 and IFN-gamma expression is required to induce a protective response to many intracellular pathogens. Herein, we demonstrate that osteopontin stimulation augments the ability of anti-CD3 monoclonal antibody to induce CD40 ligand (CD40L) and IFN-gamma expression on human T cells, resulting in CD40L- and IFN-gamma-dependent IL-12 production in vitro. These findings suggest a functional role for osteopontin in early Th1 responses, namely regulation of T cell-dependent IL-12 production. Further, osteopontin up-regulation of CD40L provides mechanistic support for the association of osteopontin with polyclonal B cell proliferation and humoral autoimmune disease.

Osteopontin is associated with T cells in sarcoid granulomas and has T cell adhesive and cytokine-like properties in vitro.

Sarcoidosis is a systemic disease characterized by the accumulation of activated T cells and widespread granuloma formation. In addition, individual genetic predisposition appears to be important in this disease. Osteopontin, a noncollagenous matrix protein produced by macrophages and T lymphocytes, is expressed in the granulomas of tuberculosis, and is associated with genetic susceptibility to intracellular infection. The function of osteopontin in these T cell-mediated responses is unknown. We sought to elucidate the role of osteopontin in granulomatous inflammation by characterizing its expression in different stages of sarcoidosis and its effector function on T cells in vitro. Lymphocyte-associated expression of osteopontin in sarcoidosis was demonstrated by immunohistochemistry, and its expression correlated with granuloma maturity. In addition, osteopontin induced T cell chemotaxis, supported T cell adhesion (an effect enhanced by thrombin cleavage of osteopontin), and costimulated T cell proliferation. These results suggest a novel mechanism by which osteopontin and thrombin modulate T cell recruitment and activation in granulomatous inflammation.