Interleukin-2 Inhibitors Research Articles

Competitive inhibition of IL-2/IL-2R has a dual effect on HSC ex vivo expansion and IL-2R (CD25) content

Interleukin-2 (IL-2) and its receptor play a pivotal role in the regulation of immune response and possess both immune-regulatory and immune-stimulatory functions. As a cytokine of lymphoid cells, the role of IL-2 has been revealed in hematopoietic stem cell (HSC) maintenance and proper hematopoiesis. Here, we investigated that small molecule Ro 26-4550 trifluoroacetate (Ro) mediated competitive inhibition of IL-2 and its receptor alpha subunit (IL-2Rα) throughout ex vivo culture. Ro treatment induced murine and human ex vivo expansion of hematopoietic stem and progenitor cells (HSPCs). Ro treated HSPCs sustained self-renewal ability and low apoptotic activity. As a competitive inhibitor of IL-2/IL-2Rα interaction, Ro small molecule induced human HSPCs to entry into cell cycle. The proliferation of bone marrow mesenchymal stem cells (MSC) and fibroblasts were also highly increased post treatment. Besides, Ro treatment enhanced IL-2Rα (CD25) expression independent of IL-2 administration in human mPB-derived HSPCs and BM-derived HSPCs. Increased IL-2Rα (CD25) expression in BM-HSPCs was associated with the increase in the CD4+CD25+ T cell population. Xenotransplantation of immunodeficient mice with ex vivo expanded human CD34+ cells after Ro treatment revealed an efficient multi-lineage reconstitution in the recipient. These findings shed light on the role of IL-2/IL-2Rα interaction in HSC expansion, in vivo and in vitro HSC self-renewal ability and repopulation capacity as well as a possible mean for the induction of CD25 expressing cells in hematopoietic compartments.

Characteristics and Incidence of Candidemia in Hospitalized Coronavirus 2019 (COVID-19) Patients

Management of Coronavirus 2019 (COVID-19) with high-dose corticosteroids and interleukin-2 inhibitors has potential benefits, but is associated with immunosuppression and risk of secondary infections. This single-center, retrospective, cohort study evaluated the incidence of candidemia and associated risk factors in hospitalized COVID-19 patients. Twenty-three patients developed candidemia and were matched to 77 non-candidemic COVID-19 controls. The primary outcome was incidence of candidemia. Secondary outcomes included time to first positive fungal blood culture and antifungal initiation, antifungal treatment duration, fungal isolate identification, candidemia risk factors, in-hospital mortality, Intensive Care Unit (ICU) and hospital Length of Stay (LOS) and mechanical ventilation duration. Candidemia incidence was 0.7% (23/3101). Mean time from hospital admission to first positive fungal blood culture was 26.2±14.3 days, with systemic antifungal therapy initiated in 19 patients; seven started antifungal therapy the same day cultures were drawn and 12 within 24 h of preliminary culture results positive for yeast. The remaining four patients expired prior to culture results. Mean duration of antifungal therapy was 9.7±6.6 days. Candida albicans was the most frequently identified isolate. Candidemic patients were more likely to be admitted to the ICU, receive high-dose corticosteroid, renal replacement therapy, mechanical ventilation, central line, tocilizumab and broad-spectrum antimicrobials. They also had higher mortality (82% vs. 22%, p<0.0001) and longer ICU LOS (25 vs 0 days, p<0.0001), hospital LOS (39 vs 10 days, p<0.0001) and mechanical ventilation days (19 vs 0 days, p<0.0001). Candidemia occurrence is rare in COVID-19 patients, but can result in worse clinical outcomes such as high mortality and longer hospital stay. Clinicians should attempt to minimize risk factors and perform routine workup for systemic candida infections in COVID-19 patients in the ICU, on mechanical ventilation and with multiple risk factors.

A Comprehensive Evaluation of Risk Factors for Pneumocystis jirovecii Pneumonia in Adult Solid Organ Transplant Recipients: A Systematic Review and Meta-analysis.

There is no consensus guidance on when to reinitiate Pneumocystis jirovecii pneumonia (PJP) prophylaxis in solid organ transplant (SOT) recipients at increased risk. The 2019 American Society of Transplantation Infectious Diseases Community of Practice (AST IDCOP) guidelines suggested to continue or reinstitute PJP prophylaxis in those receiving intensified immunosuppression for graft rejection, cytomegalovirus (CMV) infection, higher dose of corticosteroids, or prolonged neutropenia. A literature search was conducted evaluating all literature from existence through April 22, 2020, using MEDLINE and EMBASE. (The International Prospective Register of Systematic Reviews registration number: CRD42019134204). A total of 30 studies with 413 276 SOT recipients were included. The following factors were associated with PJP development: acute rejection (pooled odds ratio [pOR], 2.35; 95% confidence interval [CI], 1.69-3.26); study heterogeneity index [I2] = 23.4%), CMV-related illnesses (pOR, 3.14; 95% CI, 2.30-4.29; I2 = 48%), absolute lymphocyte count <500 cells/mm3 (pOR, 6.29; 95% CI, 3.56-11.13; I2 = 0%), BK polyomavirus-related diseases (pOR, 2.59; 95% CI, 1.22-5.49; I2 = 0%), HLA mismatch ≥3 (pOR, 1.83; 95% CI, 1.06-3.17; I2 = 0%), rituximab use (pOR, 3.03; 95% CI, 1.82-5.04; I2 = 0%), and polyclonal antibodies use for rejection (pOR, 3.92; 95% CI, 1.87-8.19; I2 = 0%). On the other hand, sex, CMV mismatch, interleukin-2 inhibitors, corticosteroids for rejection, and plasmapheresis were not associated with developing PJP. PJP prophylaxis should be considered in SOT recipients with lymphopenia, BK polyomavirus-related infections, and rituximab exposure in addition to the previously mentioned risk factors in the American Society of Transplantation Infectious Diseases Community of Practice guidelines.

Site-directed Fragnomics and MD Simulations Approaches to Identify Interleukin-2 Inhibitors.

The aberrant expression of Interleukin-2 (IL2), the chief regulator of immunity, is associated with many auto-immune diseases. At present, there is no FDA approved drug targeting IL2, which puts forth the need for small molecular inhibitors to block IL2 and its receptor interaction. Herein, we used the contemporary fragnomics approach to design novel drug-like inhibitors targeting IL2. Briefly, the RECAP (Retrosynthetic Combinatorial Analysis Procedure) package implemented in MOE (Molecular Operating Environment check) software suite was utilised to obtain fragments fulfilling the 'rule of three' criteria for fragments. The binding site of IL2 was divided into three smaller grooves, and the fragments were docked to screen their affinity for a particular site, followed by site-directed RECAP synthesis. A focused library of 10,000 compounds was prepared by re-combining the fragments according to their affinity for a particular site as observed in docking. Docking and subsequent analysis of newly synthesised compounds identified 40 privileged leads, presenting hydrogen bonding with basic residues of the pocket. A QSAR model was implied to predict the IC50 of the compounds and to analyse the electrostatic and hydrophobic contour maps. The resulting hits were found to be modest IL2 inhibitors with predicted inhibitory activity in the range of 5.17-4.40 nM. Further Dynamic simulation studies were carried out to determine the stability of the inhibitor-IL2 complex. Our findings underline the potential of the novel compounds as valuable pharmacological agents in diseases characterised by IL2 overexpression.

In silico data mining of large-scale databases for the virtual screening of human interleukin-2 inhibitors.

Interleukin-2 (IL-2) is involved in the activation and differentiation of T-helper cells. Uncontrolled activated T cells play a key role in the pathophysiology by stimulating inflammation and autoimmune diseases like arthritis, psoriasis and Crohn's disease. T cells activation can be suppressed either by preventing IL-2 production or blocking the IL-2 interaction with its receptor. Hence, IL-2 is now emerging as a target for novel therapeutic approaches in several autoimmune disorders. This study was carried out to set up an effective virtual screening (VS) pipeline for IL-2. Four docking/scoring approaches (FRED, MOE, GOLD and Surflex-Dock) were compared in the re-docking process to test their performance in producing correct binding modes of IL-2 inhibitors. Surflex-Dock and FRED were the best in predicting the native pose in its top-ranking position. Shapegauss and CGO scoring functions identified the known inhibitors of IL-2 in top 1, 5 and 10 % of library and differentiated binders from non-binders efficiently with average AUC of > 0.9 and > 0.7, resp. The applied docking protocol served as a basis for the VS of a large database that will lead to the identification of more active compounds against IL-2.

Effect of interleukin-2 on antioxidant system and lipid peroxidation during physical activity

Introduction. Adaptation to physical activity in human ’ s and animal ’ s body occurs by changing many metabolic processes. Thus, when physical exercises are performing, the oxygen consumption in the organs increases in several times depending of intensity and duration of the load. It leads to increase of the level of free radical processes in the tissues. Lipid peroxidation processes play an important role in the mechanisms of adaptive responses, the maintenance of resistance and homeostasis, which is connected with their crucial role in regulating of structural and functional properties of the biological membranes. As interleukin-2 (IL-2) is a key cytokine for triggering a cellular immune response, it is interesting for understanding the immune response, elucidate the role of IL-2 in development of adaptation to physical stress and to establish the influence of IL-2 at the prooxidant-antioxidant system during physical training. Purpose – to study intensity of lipid peroxidation processes and condition of the antioxidant system under the influence of IL -2 and its inhibitor during physical training. Methods . The study was performed on white outbred adult male mice (n=96). 5 experimental groups and a control group (without physical activity) were organized. Group I received an inhibitor of IL-2 (Cyclosporine, 10 mg/kg), Groups II, III and IV – IL-2 (Roncoleukin, 5000, 7500 and 30,000 IU/kg, respectively), V – physiological saline. Forced swimming with a load (7.5% of body weight) was used as physical training. The study was divided into periods (0, 2, 4 and 6 Weeks). The level of malonic dialdehyde was used as a marker of lipid peroxidation, and the level of catalase activity was used to determine the activity of the antioxidant system. The quantitative determination of catalase and malonic dialdehyde levels in the liver homogenate was performed using a spectrophotometric method. Results . We found a pronounced multidirectional change in experimental parameters, investigating the dynamics of the prooxidant-antioxidant system, which may indicate the peculiarities of adaptive changes during exercise under conditions of stimulation and inhibition of IL-2. Originality . It was first established that the inhibition of IL-2 during exercise led to increased the activity of both prooxidant and antioxidant systems. Stimulation of IL-2 at low and medium concentrations during exercise led to the activation of both systems, but the prooxidant system prevailed, and at high concentrations caused the activation of both systems. We have shown that IL-2 during exercise can affect to the activity and a balance between the prooxidant and antioxidant systems of the body. Conclusion . It was found that inhibition of IL-2 at the 2 nd W eek of exercise led to increase in the catalase activity and decrease in the MDA level, at the 4 th W eek these effects were amplified . At the 6 th W eek there was a partial decrease in the catalase activity, but it remained more baseline, and a significant increase in the level of MDA. It was d etected that animals with receiving IL-2 at low and medium concentrations showed a significant increase in the activity of both catalase and MDA level at the 2 nd W eek of physical training, at the 4 th W eek there was a decrease in both indicators, and at the 6 th W eek the activity catalase decreased (but did not reach baseline), and the level of MDA increased. It was installed that IL-2 at high concentration during exercise had the following effect: at the 2 nd and 4 th W eeks – increased the catalase activity and decreased the MDA level, and at the 6 th W eek – the catalase activity continued to increase with the level of MDA.

Y75B8A.8 (HC8) protein of Haemonchus contortus: A functional inhibitor of host IL-2.

Interleukin 2 (IL-2) is an important immune regulatory factor in the immune response of the host. However, little is known about the inhibitor of host IL-2 in Haemonchus contortus infection. In this study, we found that globin domain-containing protein (HCGB) and Protein Y75B8A.8 (HC8) from Hcontortus excretory and secretory products are two binding proteins of IL-2 in goats. The yeast two-hybrid screening further validated the positive interactions of IL-2 with HCGB and HC8. Meanwhile, we found that HC8 had inhibitory effects on IL-2-induced peripheral blood mononuclear cell (PBMC) proliferation, while HCGB did not. Furthermore, transcriptional analysis revealed that HC8 could block the IL-2-activated signalling pathway. Our results showed that HC8 was a functional inhibitor of goat IL-2.

Direct regulation of IL-2 by curcumin

Interleukin-2 (IL-2) is a crucial growth factor for both regulatory and effector T cells. Thus, IL-2 plays a critical role in the stimulation and suppression of immune responses. Recently, anti-IL-2 antibodies (Abs) have been shown to possess strong IL-2 modulatory activities by affecting the interaction between IL-2 and IL-2 receptors. In this study, we screened an herbal library to identify a compound that regulates IL-2, which resulted in the identification of curcumin as a direct binder and inhibitor of IL-2. Curcumin is a phytochemical with well-known anti-cancer properties. In this study, curcumin mimicked or altered the binding pattern of anti-IL-2 Abs against IL-2 and remarkably inhibited the interaction of recombinant IL-2 with the IL-2 receptor α, CD25. Interestingly, curcumin neutralized the biological activities of IL-2 both in vitro and in vivo. In this report, we elucidated the unsolved mechanism of the anti-cancer effect of curcumin by identifying IL-2 as a direct molecular target. Curcumin, as a small molecule IL-2 modulator, has the potential to be used to treat IL-2 related pathologic conditions.

Sent Liver Grafts Do Not Have a Detrimental Impact on Post-transplant Outcome

Introduction“Sent livers” (SL) (interregional allocated organs) are considered extended donor criteria grafts. These grafts influence post-transplant outcome. In our donor allocation program, the number of allocated SLs is increasing. The aim of our study is to provide data supporting the possibility to enlarge the use of SLs through adequate donor-to-recipient matching. MethodsA retrospective analysis was carried out from our prospective-collected database during 2014. ResultsFifty-seven liver transplantations (LTs) were included: 22 SLs and 35 grafts procured by us (nSLs). Only donor risk index among donor characteristics showed a trend toward significant values (SL 1.901 vs nSL 1.726, P = .07). Among LT variables, the number of patients who received interleukin-2 inhibitor induction (SL 7 vs nSL 20, P < .05) and the presence of hepatocellular carcinoma (SL 50% vs nSL 34%, P < .05) reached statistical significance. One case of primary nonfunction occurred in the nSL group. No major retrieval injuries were observed. Retransplantation was performed in 6 cases (2 SLs and 4 nSLs). One patient in the SL group died after retransplantation. Graft survival rates at 1, 3, 6, and 12 months were 100%, 100%, 90%, 86% and 91%, 86%, 86%, 86% (P = .79) in SL and nSL groups, respectively. DiscussionSL performance did not differ from that of nSL. SLs were usually allocated to noncritical candidates, and nSLs were transplanted more frequently in decompensated recipients. Despite this peculiar donor-recipient match, grafts survival was similar in the 2 groups of patients.

New interleukin-2 inhibitor targets relapsing forms of MS

New interleukin-2 inhibitor targets relapsing forms of MS

Structure based 3D-QSAR studies of Interleukin-2 inhibitors: Comparing the quality and predictivity of 3D-QSAR models obtained from different alignment methods and charge calculations

Interleukin-2 is an essential cytokine in an innate immune response, and is a promising drug target for several immunological disorders. In the present study, structure-based 3D-QSAR modeling was carried out via Comparative Molecular Field Analysis (CoMFA) and Comparative Molecular Similarity Index Analysis (CoMSIA) methods. Six different partial charge calculation methods were used in combination with two different alignment methods to scrutinize their effects on the predictive power of 3D-QSAR models. The best CoMFA and CoMSIA models were obtained with the AM1 charges when used with co-conformer based substructure alignment (CCBSA) method. The obtained models posses excellent correlation coefficient value and also exhibited good predictive power (for CoMFA: q2=0.619; r2=0.890; r2Pred=0.765 and for CoMSIA: q2=0.607; r2=0.884; r2Pred=0.655). The developed models were further validated by using a set of another sixteen compounds as external test set 2 and both models showed strong predictive power with r2Pred=>0.8. The contour maps obtained from these models better interpret the structure activity relationship; hence the developed models would help to design and optimize more potent IL-2 inhibitors. The results might have implications for rational design of specific anti-inflammatory compounds with improved affinity and selectivity.

Activity of Outpatient Intravenous Interleukin-2 and Famotidine in Metastatic Clear Cell Kidney Cancer

Outpatient daily intravenous infusions of interleukin-2 (IL-2) have been developed to maintain anticancer activity and decrease toxicity of this agent against kidney cancer. Lymphokine activated killer cell (LAK) numbers are increased with these IL-2 schedules. Famotidine may enhance the LAK activity by increasing IL-2 internalization by the IL-2 receptor on lymphocytes. Fifteen patients with metastatic clear cell kidney cancer received IL-2 18 million IU/M² intravenously over 15-30 minutes preceded by famotidine 20 mg IV daily for 3 days for 6 consecutive weeks as outpatients. Cycles were repeated every 8 weeks. Patient characteristics were seven males/eight females, median age 59 (range: 28-70), median Eastern Cooperative Oncology Group (ECOG) performance status-1; common metastatic sites were lungs (14), lymph nodes (9), liver (4), bone (4), and pancreas (4). Prior systemic therapies were oral tyrosine kinase inhibitor (8), IL-2 (6), and mTor inhibitor (2). Most common toxicities were rigors, arthralgia/myalgia, nausea/emesis, fever, and hypotension. All episodes of hypotension were reversible with intravenous fluid. No patients required hospitalization due to toxicity. One complete response (7%) and four partial responses (26%) were seen (total response rate=33%; 95% confidence interval: 15%-59%). Responses occurred in the lungs, liver, lymph nodes, and bone. Outpatient intravenous IL-2 with famotidine has activity in metastatic clear cell kidney cancer.

Identification of novel Interleukin-2 inhibitors through computational approaches

Interleukin-2 (IL-2), is a 15.5-kDa cytokine that is now emerging as a target in drug discovery for novel therapeutic approaches in several autoimmune disorders. In an attempt to identify new inhibitors for the IL-2/IL-2R interaction, virtual screening (VS) was performed. Four different docking programs (GOLD, FlexX, Glide, and LigandFit) in combination with several scoring functions were used to identify novel IL-2/IL-2R interaction inhibitors.VSof a database of 6,000compounds resulted in the identification of three novel and moderately active hits with IC50 values ranging from 6.6 to 44.3 μM. Furthermore, the effect of these three compounds on the expression of IL-2Rα was assessed. The three active hits showed dose-dependent inhibitory effects on the expression of IL-2Rα with an IC50 range of 5.8 to 140μM. The cytotoxicity of these active hits was assessed using three normal cell-lines: bovine kidney cell-line (MDBK), mouse fibroblast cell-line (3T3), and rat hepatocytes cell-line (CC-1).Thecompoundswere found to have negligible cytotoxicity compared to their IC50 as IL-2/IL-2R interaction inhibitors. These results demonstrate that our VS protocol can identify novel inhibitors for IL-2/IL-2R interaction that effectively suppress IL-2 production, as well as the expression of IL-2Rα. Optimization of these molecules could lead to improved and effective anti-inflammatory therapeutics.

In vitro and in silico exploration of IL-2 inhibition by small drug-like molecules

Interleukin-2 (IL-2) is an immunoregulatory cytokine produced by T lymphocytes in response to antigen. It is a potent growth and differentiation factor for several cell-types and is structurally related to the four-helix bundle family of cytokines. Here, we report IL-2 inhibitory potential and computational studies on different series of chalcones, benzothiazepines, semicarbazones, and dihydropyrimidines. These compounds were synthesized in wet lab and were then tested for their potency as IL-2 inhibitors through in vitro T cell proliferation, IL-2 cytokine production as well as their effect on oxidative burst. Compounds that showed significant suppressive activity were further evaluated for their cytotoxicity on normal two cell lines. Most of the chalcones were found to have a powerful inhibitory effect on T-lymphocytes proliferation and cytokine production. Among the aza heterocycles benzothiazepines, benzoxazepines, and benzodiazepinones were found to be the strongest IL-2 inhibitors. Molecular docking and MD simulation studies were carried out to correlate experimental and theoretical results whereby a good correlation was observed which indicated that computational studies could provide an alternate tool for the identification and designing of more potent IL-2 inhibitors.

Lymphoproliferative Disorders After Solid Organ Transplantation—Classification, Incidence, Risk Factors, Early Detection and Treatment Options

Posttransplant lymphoproliferative disorder (PTLD) is a heterogeneous disease group of benign and malignant entities. The new World Health Organisation classification introduced in 2008 distinguishes early lesions, polymorphic, monomorphic and classical Hodgkin lymphoma-type PTLD. Based on the time of appearance, early and late forms can be identified.PTLDs are the second most frequent posttransplantation tumors in adulthood, and the most frequent ones in childhood. The incidence varies with the transplanted organ-from 1%-2% following kidney transplantation to as high as 10% following thoracic organ transplantation-due to different intensities in immunosuppression. Immunocompromised state and Epstein-Barr virus (EBV) infection are the two major risk factors.In Europe and the US approximately 85% of PTLDs are of B-cell origin, and the majority are EBV-associated. Symptoms are often unspecific; extranodal, organ manifestations and central nervous system involvement is common. Early lesions respond well to a decrease in immunosuppression. Malignant entities are treated with rituximab, chemotherapy, radiotherapy and surgical therapy. Adoptive T-cell transfer represents a promising therapeutic approach. The prognosis is favorable in early PTLD, and poor in late PTLD. Five-year survival is 30% for high-grade lymphomas. The prognosis of EBV-negative lymphomas is worse.Lowering the risk of PTLD may be achieved by low dose maintenance immunosuppression, immunosuppressive drugs inhibiting cell proliferation, and special immunotherapy (e.g. interleukin-2 inhibitors). Early detection is especially important for high risk-e.g. EBV-negative-patients, where the appearance of EBV-DNA and the increase in its titer may help.

Aspergillosis in patients treated with monoclonal antibodies

Invasive aspergillosis is a disease typically related with prolonged neutropenia or the use of corticosteroids. However, the increased use of new therapeutic modalities such as biologic agents that act by blocking specific immune pathways have put more patients at risk for invasive aspergillosis. Most cases of aspergillosis in patients taking monoclonal antibodies have been associated with the use of tumour necrosis factor (TNF)-alpha blockers. However, many more drugs have been implicated, including interleukin-2 inhibitors, and CD52 and CD20 blockers. In this manuscript we review the pathophysiology associated with an increased risk for aspergillosis in these patients, in addition to diagnostic and therapeutic considerations.

Synergistic In vivo Antitumor Effect of the Histone Deacetylase Inhibitor MS-275 in Combination with Interleukin 2 in a Murine Model of Renal Cell Carcinoma

High-dose interleukin 2 (IL-2) is a Food and Drug Administration-approved regimen for patients with metastatic renal cell carcinoma. However, the toxicity and limited clinical benefit associated with IL-2 has hampered its use. Histone deacetylase (HDAC) inhibitors have been shown to have antitumor activity in different tumor models including renal cell carcinoma, and to have immunomodulatory properties. In our study, we tested the effectiveness of combination therapy of IL-2 with the HDAC inhibitor MS-275 in a murine renal cell carcinoma (RENCA) model. RENCA luciferase-expressing cells were implanted in the left kidney of BALB/C mice. Animals were randomly divided into four groups and treated with either vehicle, 150,000 IU of IL-2 twice daily by i.p. injections (twice weekly), 5 mg/kg of MS-275 daily by oral gavage (5 d/wk), or its combination. Treatment was started either 3 or 9 days following tumor cell injection. Weekly luciferase images and tumor weight after 2 weeks of treatment showed significant tumor inhibition (>80%) in the combination treatment as compared with the IL-2 (no significant inhibition) or MS-275 (approximately 40% inhibition) treatment groups. Spontaneous lung metastases were also inhibited in the combination treatment (>90% inhibition) as compared with the single treatment group. Kaplan-Meier analyses showed statistically significant increased survival in the combination group as compared with controls and single agents. Splenocytes from mice treated with combination treatment showed greater lysis of RENCA cells than splenocytes from mice treated with single agents. The percentage of CD4(+)CD25(+) T cells and Foxp3(+) T cells (T regulatory cells) was increased or reduced, respectively, in lymph nodes from tumor-bearing animals treated with the combination of MS-275 and IL-2 as compared with control and single agents. Depletion of CD8(+) T cells abrogated the survival benefit from MS-275 + IL-2 combination. These results show that the combination of IL-2 and MS-275 has a synergistic antitumor effect in vivo in an immunocompetent murine model of renal cell carcinoma. The antitumor effect was associated with the decreased number of T regulatory cells and the increased antitumor cytotoxicity by splenocytes. In conclusion, these preclinical data provide the rationale for clinical testing of the combination of IL-2 and HDAC inhibitors in the treatment of patients with renal cell carcinoma.

Die Hyperkalzämie im Verlauf der Sarkoidose – Fallbeispiel, Prävalenz, Pathophysiologie und Therapiemöglichkeiten

Hypercalcemia is a highly prevalent complication of sarcoidosis. A medical history of a patient with sarcoidosis is shown as case report. Depending on the population studied about 2-63% of sarcoidosis patients show hypercalcemia. The major difference in the prevalence of hypercalcemia may be in part due to the undulating course of subacute sarcoidosis, so hypercalcemia may be missed when serum calcium is not frequently measured. Hypercalciuria appears to be twice as prevalent then hypercalcemia and should be looked for in every sarcoidosis patient. Hypercalcemia in sarcoidosis is due to the uncontrolled synthesis of 1,25-dihydroxyvitamin D3 by macrophages. 1,25-dihydroxyvitamin D3 leads to an increased absorption of calcium in the intestine and to an increased resorption of calcium in the bone. Immunoregulatory properties have been ascribed to 1,25-dihydroxyvitamin D3. It is an important inhibitor of interleukin-2 and of interferon-gamma-synthesis, two cytokines that are important in granuloma formation in sarcoidosis. It is thought that 1,25-dihydroxyvitamin D3 counterregulates uncontrolled granuloma formation. Treatment of hypercalcemia depends on the serum level of hypercalcemia and its persistence. Generally sarcoidotic patients should be advised to avoid sun exposition to reduce vitamin D3 synthesis in the skin, to omit fish oils that are rich of vitamin D and to produce more than two liters urine a day by adapting fluid intake. Although severe hypercalcemia seems to be rare, glucocorticosteroid treatment should be started if corrected total calcium level rises beyond 3 mmol/l. If hypercalcemia is symptomatic, treatment should be started even at lower levels. Glucocorticosteroids act by inhibition of the overly 1alpha-hydroxylase activity of macrophages. Alternatively, treatment with chloroquine or ketoconazole can be established. If isolated hypercalciuria without hypercalcemia is present with evidence for recurrent nephrolithiasis, patients can be treated with a thiazide diuretic.

Structural View of Cytokine Interactions

Interleukin-2 (IL-2), a cytokine produced by activated T cells, promotes the proliferation, differentiation, and survival of mature T and B cells. Its actions are primarily mediated through a quaternary signaling complex that consists of IL-2, the α and β receptors (IL-2Rα, IL-2Rβ), and the γ c chain. Now Wang et al. present the extracellular structure of the quaternary complex at 2.3 angstroms resolution. Besides providing insight into IL-2 interactions that might facilitate design of IL-2 agonists and inhibitors, the structure provides a view of the γ c receptor. This receptor is shared for IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21 and is mutated in X-linked severe combined immunodeficiency diseases (X-SCID). Several mutations associated with X-SCID map to residues in the γ c binding sites. X. Wang, M. Rickert, K. C. Garcia, Structure of the quaternary complex of interleukin–2 with its α, β, and γ c receptors. Science 310 , 1159–1163 (2005). [Abstract] [Full Text]

IL-2 induction by simian immunodeficiency virus involves MAP kinase signaling but is independent of calcineurin/NF-AT activity

The major T cell growth factor interleukin-2 (IL-2) is secreted by activated T cells in response to antigenic stimulation. This requires signal transduction via the CD3/TCR complex and the CD28 coreceptor, leading to activation of mitogen-activated protein kinase (MAPK) and calcineurin/NF-AT signaling pathways. We observed that simian immunodeficiency virus derived from African green monkeys (SIVagm3) is a potent activator of IL-2 gene expression. IL-2 promoter studies in A3.01 T cells demonstrated that SIVagm3 induced an up to 38-fold increased transcriptional activation of the IL-2 promoter. Inhibition of MAPK signaling pathways using inhibitors of MEK, JNK or p38 abolished SIVagm3-induced IL-2 activation in a dose-dependent manner. In contrast, the immunosuppressive drug cyclosporin A (CyA), a classical IL-2 inhibitor that blocks calcineurin activity, had no effect. Consistent with this finding, the nuclear factor of activated T cells (NF-AT), which is activated by calcineurin, was not induced by SIVagm3. Analyzing further transcription factor binding sites located on the IL-2 promoter we found that SIVagm3 did mainly promote transcriptional activation of the CD28/AP-1 and NF-κB responsive elements. These DNA elements were also induced by the viral transactivator protein (Tat) and expression of Tat was sufficient to activate IL-2 induction in stimulated cells. Our results show that SIVagm3 is capable of stimulating IL-2 gene expression via molecular mechanisms different from those induced during classical T cell activation.