Inhibition of interferon gamma production by peripheral blood mononuclear leukocytes of patients with sarcoidosis. Pathogenic implications

Sarcoidosis Increases Risk of Hospitalized Infection. A Population-based Study, 1976-2013

RATIONALE

Patients with sarcoidosis may have an increased risk of infection similar to other immune-mediated disorders. However, the data are still limited.

OBJECTIVES

To investigate the risk of hospitalized infection among patients with sarcoidosis, using a population-based cohort.

METHODS

Using the Rochester Epidemiology Project record-linkage system, a cohort of incident cases of sarcoidosis in Olmsted County, Minnesota from 1976 to 2013 was identified. Diagnosis was confirmed by individual medical record review. For each patient with sarcoidosis, a sex- and age-matched comparator without sarcoidosis was randomly selected from the same population. Medical records of cases and comparators were individually reviewed for hospitalized infection that occurred after the index date. The cumulative incidence of hospitalized infection overall and by type of infection, adjusted for the competing risk of death, was estimated. Cox models were used to compare the rate of first hospitalized infection between cases and comparators and to evaluate the association between use of immunosuppressive agents and hospitalized infection among cases.

RESULTS

Three hundred and forty-five cases and 345 comparators were identified. Patients with sarcoidosis had a higher risk of a hospitalized infection with a hazard ratio (HR) of 2.00 (95% confidence interval [CI], 1.41-2.84), adjusted for age, sex, and calendar year of index date. Use of oral glucocorticoids was a significant predictor of hospitalized infection with an HR of 3.03 (95% CI, 1.33-6.90) for oral glucocorticoids not exceeding 10 mg/day and an HR of 4.48 (95% CI, 1.54-13.03) for oral glucocorticoids greater than 10 mg/day.

CONCLUSIONS

Patients with sarcoidosis are at increased risk of hospitalized infection. Glucocorticoid therapy is strongly associated with this increased risk.

Toll-like receptor (TLR)-9 genetics and function in sarcoidosis

Sarcoidosis is a systemic disorder characterized by the formation of non-caseating granulomas in variable organs. Toll-like receptor (TLR)-9 is important in the innate immune response against both Mycobacterium tuberculosis and Propionibacterium acnes, candidate causative agents in sarcoidosis. The aim of our study was to investigate possible genetic and functional differences in TLR-9 between patients and controls. TLR-9 single nucleotide polymorphisms were genotyped in 533 patients and divided into a study cohort and validation cohort and 185 healthy controls. Furthermore, part of the promotor as well as the entire coding region of the TLR-9 gene were sequenced in 20 patients in order to detect new mutations. No genetic differences were found between patients and controls. In order to test TLR-9 function, peripheral blood mononuclear cells (PBMCs) of 12 healthy controls and 12 sarcoidosis patients were stimulated with a TLR-9 agonist and the induction of interleukin (IL)-6, interferon (IFN)-γ and IL-23 was measured. Sarcoidosis patients produce significantly less IFN-γ upon stimulation with different stimuli. Regarding IL-23 production, a significant difference between patients and controls was found only after stimulation with the TLR-9 agonist. In conclusion, we did not find genetic differences in the TLR-9 gene between sarcoidosis patients and controls. Sarcoidosis patients produce less IFN-γ regardless of the stimulating agent, probably reflecting the anergic state often seen in their peripheral blood T lymphocytes. The differences in TLR-9-induced IL-23 production could indicate that functional defects in the TLR-9 pathway of sarcoidosis patients play a role in disease susceptibility or evolution.

The anergic state in sarcoidosis is associated with diminished dendritic cell function

Sarcoidosis is a chronic inflammatory disease of unknown cause, characterized by granuloma formation similar to tuberculosis, but without clear evidence of a microbial infection. Because sarcoidosis is linked with clinical anergy and other evidence of diminished cellular immunity, we hypothesized that decreased skin delayed-type hypersensitivity (DTH) responses to recall Ags in affected individuals would be associated with decreased function of their blood dendritic cells (DCs). Our study involved ex vivo isolation, phenotyping, and functional testing of myeloid DCs (mDCs), plasmacytoid DCs, and T lymphocytes from blood of normal healthy volunteers and sarcoidosis subjects with active, untreated pulmonary disease. We found mDC function in the allogeneic MLR directly corresponded to the magnitude of skin DTH reactions to recall Ags in both sarcoidosis subjects and normal volunteers. However, both of these outcomes were significantly decreased in the sarcoidosis group. Diminished mDC function occurred despite up-regulated costimulatory and maturation markers. Clinical relevance is suggested by the inverse relationship between both mDC allogeneic responses and skin DTH responses with clinical disease severity as measured by chest radiograms. Because granulomas form when cellular immunity fails to clear antigenic stimuli, attenuated mDC function in sarcoidosis may contribute to susceptibility and persistence of the chronic inflammation characteristic of this disease.

Recurrent sarcoidosis in lung transplant allografts: granulomas are of recipient origin

INTRODUCTION

Sarcoidosis accounts for only 2.8% of lung transplants in the United States. It is, however, the most commonly reported disease to recur after lung transplantation. In most cases, recurrence is diagnosed as an incidental finding in transbronchial lung allograft biopsy (TBLAB) and is unrelated to clinical or radiologic abnormalities. The origin of the histiocytes composing the noncaseating granulomas in the allograft lung in patients with recurrent sarcoidosis (RS) was analyzed using DNA identity testing in 4 cases.

MATERIAL AND METHODS

Native lung resections and corresponding transbronchial biopsies from patients who underwent lung transplantation for sarcoidosis between 1990 and 2004 and who developed RS were gathered from the paraffin block archives of University of Pittsburgh Medical Center. Clinical parameters including age, sex, grade of rejection, number of episodes of RS, and follow-up were recorded. Native lungs and corresponding TBLAB showing granulomas consistent with RS were microdissected in cases where adequate material was available. DNA was extracted, and an ABI AmpflSTR commercial kit was used to simultaneously amplify 15 short tandem repeat (STR) loci as well as 1 marker for the XY chromosomes. The informative STR loci in native lung (pure recipient), nongranulomatous donor lung, and granulomas in donor lung were analyzed in 4 patients. The relative proportion of donor and recipient cells in the chimera was quantified using the fluorescence intensity of each peak on an electropherogram. FISH analysis using probes targeted to X and Y chromosomes was performed in a case of sex-mismatched lung transplantation.

RESULTS

Eight patients with RS were identified. Two had bilateral lung transplantation, and the remaining 6 had single-lung transplantation. The age at transplantation ranged between 39 and 53. Five were females and 3 were men. Recurrent disease was diagnosed in 1 to 11 biopsies per patient and occurred first in the first 6 months following transplantation in 2 cases (25%), between 6 months and 1 year in 2 other cases (25%), and between 1 and 2 years in 4 cases (50%). In 4 patients, sufficient material allowed for DNA analysis. Amplification failed in 1 of the 4 cases, while the other 3 were successful. Patient 1 showed no ACR and granulomatous inflammation of RS in TBLAB. Donor (D) to recipient (R) profile changed from "normal" donor lung (37% D, 63% R) to 15% D and 85% R DNA in the granuloma. In patient 2, the TBLAB showed minimal ACR and granulomatous inflammation. D to R profile changed from 75% D and 25% R in the "normal" D lung to 54% D and 46% R in the granuloma. Patient 3 showed no ACR and RS in TBLAB. D to R profile changed from 85% D and 15% R in the "normal" D lung to 71% D and 29% R in the granuloma. FISH analysis showed a predominance of male cells of recipient origin.

CONCLUSIONS

DNA analysis of 3 cases of RS suggests that the presence of recurrent granulomas in the graft is associated with an increase in the percentage of recipient DNA in the epithelioid cell clusters, as confirmed by the FISH analysis of 1 case.

The immune system in eating disorders: an overview

Eating disorders, such as anorexia nervosa and bulimia nervosa, are becoming more and more common in our society. Although they are psychiatric illnesses, there are many factors involved, including abnormal food behavior. Nutrients play an important role in the development and functionality of immunocompetent cells. An impaired immunocompetence has been shown to be an important causal factor in the increased susceptibility of malnourished individuals to infectious disease. Therefore, studies on the immune system are of great interest when assessing the extent to which the nutritional status of these patients could be affected. However, the literature in this field is controversial, and the mechanisms are not yet completely defined, although some hypotheses try to clarify the disturbances caused in the organism under these bizarre circumstances. In spite of the fact that the immune system is altered by distorted food behaviors, such as in eating disorders, the awareness of characteristics of other systems involved, and therefore altered, by these pathologies would be very helpful for understanding the mechanisms triggered in these syndromes. In fact, the interactions among the immune and other systems in eating disorders are beginning to be studied. Finally, the main goals are to limit the evolution of these illnesses through early diagnosis, and to devise a long-lasting, definitive cure for these patients through appropriate therapy.

Low lymphocyte interferon-gamma production and variable proliferative response in anorexia nervosa patients

Interferon-gamma (IFN-gamma) production by peripheral blood mononuclear cells (PBMC) in 14 patients with anorexia nervosa (AN) was significantly lower than in 14 age-matched healthy controls. Follow-up samples in four patients displayed low levels, except in two when they recovered the IFN-gamma production as the hormonal cycles were restored. A large interindividual variation for the lymphocyte proliferative response was observed in 30 AN patients. DNA synthesis of PBMC was normal in 8 patients (27%), significantly increased in 6 (20%) (P < 0.001), and significantly decreased in 16 (53%) (P < 0.001). IFN-gamma inhibition was reversed by culturing a control lymphocyte population with monocytes from patients with AN. This was not observed in cultures of control monocytes and AN lymphocytes. IL-2 receptor (TAC subunit) was assessed and no difference was found in the number of TAC-positive cells between patients and controls. These results point out impaired production of the immunomodulator cytokine IFN-gamma as a major functional defect of AN peripheral lymphocytes.