Ellen C. Riemer

Pulmonary Involvement in Sjögren Syndrome

Sjögren syndrome is a slowly progressing autoimmune disease. Pulmonary manifestations are frequent in primary Sjögren syndrome but often not clinically significant; the most common are xerotrachea, interstitial lung diseases, and small airway obstruction. Pulmonary manifestations in Sjögren syndrome have a slow progression and favorable prognosis, with the exception of primary pulmonary lymphoma and pulmonary hypertension.

Anti-mitogenic effects of β-agonists and PGE2 on airway smooth muscle are PKA dependent

Inhaled β‐agonists are effective airway smooth muscle (ASM)‐relaxing agents that help reverse bronchoconstriction in asthma, but their ability to affect the aberrant ASM growth that also occurs with asthma is poorly understood. β‐Agonists exhibit PKA‐dependent antimitogenic effects in several cell types. However, recent studies suggest that Epac, and not PKA, mediates the antimitogenic effect of cAMP in both ASM and fibroblasts. This study aims to clarify the roleof PKA in mediating the effect of GS‐coupled receptors on human ASM growth. Pretreatmentof ASM cultures with β‐agonists albuterol, isoproterenol, or salmeterol (100 nM to 10 µM) caused a significant (‐25–30%) inhibition of EGF‐stimulated ASM thymi‐dine incorporation and cell proliferation, whereas a much greater inhibition was observed from pretreatment with PGE2 (75–80%). However, all agents were ineffective in cells expressing GFP chimeras of either PKI (a PKA inhibitor) or a mutant PKA regulatory subunit relative to the control cells expressing GFP. The antimitogenic efficacy of PGE2 in inhibiting control cultures was associated with greater ability to stimulate sustained PKA activation and greater inhibition of late‐phase promitogenic p42/p44 and PI3K activities. These findings suggest that therapeutic approaches enabling superior PKA activation in ASM will be most efficacious in deterring ASM growth.—Yan, H., Deshpande, D. A., Misior, A. M., Miles, M. C., Saxena, H., Riemer, E. C., Pascual, R. M., Panettieri, R. A., Penn. R. B. Anti‐mitogenic effects of β‐agonists and PGE2 on airway smooth muscle are PKA dependent. FASEB J. 25, 389–397 (2011). www.fasebj.org

Bleomycin delivery by osmotic minipump: similarity to human scleroderma interstitial lung disease

The interstitial lung diseases (ILD) include a large number of chronic, progressive, irreversible respiratory disorders involving pulmonary fibrosis, the most common of which are idiopathic pulmonary fibrosis and scleroderma lung disease (SSc ILD). Because bleomycin causes lung fibrosis when used in cancer chemotherapy, it is used to model human ILD in rodents. In most studies, bleomycin has been delivered directly into the lung by intratracheal or intraoral administration. Here we have compared the effects in mice of bleomycin delivered directly into the lungs (direct model) or systemically using osmotic minipumps (pump model) to determine which more closely resembles human ILD. The pump model is more similar to human SSc ILD in that: 1) lung injury/fibrosis is limited to the subpleural portion of the lung in the pump model and in SSc ILD, whereas the entire lung is affected in the direct model; 2) conversely, there is massive inflammation throughout the lung in the direct model, whereas inflammation is limited in the pump model and in SSc ILD; 3) hypertrophic type II alveolar epithelial cells are present at high levels in SSc ILD and in the pump model but not in the direct model; and 4) lung fibrosis is accompanied by dermal fibrosis. The pump model is also move convenient and humane than the direct model because there is less weight loss and mortality.

PKC-dependent regulation of the receptor locus dominates functional consequences of cysteinyl leukotriene type 1 receptor activation

Leukotrienes are important lipid mediators of asthma that contribute to airway inflammation and bronchoconstriction. Critical mechanisms for physiological regulation of the main G protein‐coupled receptor (GPCR) mediating the leukotriene responses in asthma, cysteinyl leukotriene type 1 receptor (CysLT1R), have not been delineated. Although desen‐sitization of GPCRs is a well‐established phenomenon, studies demonstrating its physiological relevance are lacking. Here, we demonstrate that relief of PKC‐mediated desensitization of endogenous CysLT1Rs augments multiple LTD4‐stimulated cellular functions, with associated increases in intracellular signaling events. In analyses of airway smooth muscle contraction ex vivo, PKC inhibition augmented LTD4‐stimulated contraction, and increased phosphoinositide hydrolysis and calcium flux in both murine and human airway smooth muscle cells. Similarly, for human monocytes, PKC inhibition augmented LTD4‐stimulated calcium flux and cell migration assessed in transwell chamber experiments and also augmented LTD4‐induced production of monocyte chemotactic protein assessed by ELISA. In contrast, PKC inhibition had no effect or slightly attenuated these cell functions and signaling events promoted by other receptor agonists, suggesting that despite antithetical effects on downstream events, desensitization of the CysLT1R is the principal mechanism by which PKC regulates the functional consequences of CysLTIR activation.—Deshpande, D. A., Pascual, R. M., Wang, S.‐W., Eckman, D. M., Riemer, E. C., Funk, C. D., Penn, R. B. PKC‐dependent regulation of the receptor locus dominates functional consequences of cysteinyl leukotriene type 1 receptor activation. FASEB J. 21, 2335–2342 (2007)

Hemophagocytic Lymphohistiocytosis Complicating Influenza A Infection

During the influenza A (H3N2) season of 2003–2004, several influenza-related complications and deaths were reported in children. Hemophagocytic lymphohistiocytosis complicating influenza A infection is very rare. We report a 3-year-old girl who presented with severe pneumonia and hemophagocytic lymphohistiocytosis associated with influenza A infection. Clinicians should be aware of hemophagocytic syndrome as a serious complication of influenza A infection.

Activation of p53 with Nutlin-3a radiosensitizes lung cancer cells via enhancing radiation-induced premature senescence

Radiotherapy is routinely used for the treatment of lung cancer. However, the mechanisms underlying ionizing radiation (IR)-induced senescence and its role in lung cancer treatment are poorly understood. Here, we show that IR suppresses the proliferation of human non-small cell lung cancer (NSCLC) cells via an apoptosis-independent mechanism. Further investigations reveal that the anticancer effect of irradiation correlates well with IR-induced premature senescence, as evidenced by increased senescence-associated β-glactosidase (SA-β-gal) staining, decreased BrdU incorporation and elevated expression of p16(INK4a) (p16) in irradiated NSCLC cells. Mechanistic studies indicate that the induction of senescence is associated with activation of the p53-p21 pathway, and that inhibition of p53 transcriptional activity by PFT-α attenuates IR-induced tumor cell killing and senescence. Gain-of-function assays demonstrate that restoration of p53 expression sensitizes H1299 cells to irradiation, whereas knockdown of p53 expression by siRNA inhibits IR-induced senescence in H460 cells. Furthermore, treatment with Nutlin-3a, a small molecule inhibitor of MDM2, enhances IR-induced tumor cell killing and senescence by stabilizing the activation of the p53-p21 signaling pathway. Taken together, these findings demonstrate for the first time that pharmacological activation of p53 by Nutlin-3a can sensitize lung cancer cells to radiation therapy via promoting IR-induced premature senescence.

Astrocyte pathology in Alexander disease causes a marked inflammatory environment

Astrocytes and microglia are commonly involved in a wide variety of CNS pathologies. However, they are typically involved in a secondary response in which many cell types are affected simultaneously and therefore it is difficult to know their contributions to the pathology. Here, we show that pathological astrocytes in a mouse model of Alexander disease (AxD; GFAPTg;Gfap+/R236H) cause a pronounced immune response. We have studied the inflammatory response in the hippocampus and spinal cord of these mice and have found marked microglial activation, which follows that of astrocytes in a spatial pathological progression, as shown by increased levels of Iba1 and microglial cell (Iba1+) density. RNA sequencing and subsequent gene ontology (GO) analysis revealed that a majority of the most upregulated genes in GFAPTg;Gfap+/R236H mice are directly associated with immune function and that cytokine and chemokine GO attributes represent nearly a third of the total immune attributes. Cytokine and chemokine analysis showed CXCL10 and CCL2 to be the most and earliest increased molecules, showing concentrations as high as EAE or stroke models. CXCL10 was localized exclusively to astrocytes while CCL2 was also present in microglia. Despite the high levels of CXCL10 and CCL2, T cell infiltration was mild and no B cells were found. Thus, mutations in GFAP are sufficient to trigger a profound inflammatory response. The cellular stress caused by the accumulation of GFAP likely leads to the production of inflammatory molecules and microglial activation. Examination of human AxD CNS tissues also revealed microglial activation and T cell infiltrates. Therefore, the inflammatory environment may play an important role in producing the neuronal dysfunction and seizures of AxD.

Loss of caveolin-1 from bronchial epithelial cells and monocytes in human subjects with asthma.

Caveolin‐1 has emerged as a critical regulator of signaling pathways involved in lung fibrosis and inflammation.

Lack of nitric oxide synthases increases lipoprotein immune complex deposition in the aorta and elevates plasma sphingolipid levels in lupus

Systemic lupus erythematosus (SLE) patients display impaired endothelial nitric oxide synthase (eNOS) function required for normal vasodilatation. SLE patients express increased compensatory activity of inducible nitric oxide synthase (iNOS) generating excess nitric oxide that may result in inflammation. We examined the effects of genetic deletion of NOS2 and NOS3, encoding iNOS and eNOS respectively, on accelerated vascular disease in MRL/lpr lupus mouse model. NOS2 and NOS3 knockout (KO) MRL/lpr mice had higher plasma levels of triglycerides (23% and 35%, respectively), ceramide (45% and 21%, respectively), and sphingosine 1-phosphate (S1P) (21%) compared to counterpart MRL/lpr controls. Plasma levels of the anti-inflammatory cytokine interleukin 10 (IL-10) in NOS2 and NOS3 KO MRL/lpr mice were lower (53% and 80%, respectively) than counterpart controls. Nodule-like lesions in the adventitia were detected in aortas from both NOS2 and NOS3 KO MRL/lpr mice. Immunohistochemical evaluation of the lesions revealed activated endothelial cells and lipid-laden macrophages (foam cells), elevated sphingosine kinase 1 expression, and oxidized low-density lipoprotein immune complexes (oxLDL-IC). The findings suggest that advanced vascular disease in NOS2 and NOS3 KO MRL/lpr mice maybe mediated by increased plasma triglycerides, ceramide and S1P; decreased plasma IL-10; and accumulation of oxLDL-IC in the vessel wall. The results expose possible new targets to mitigate lupus-associated complications.

Rapid development of sarcoid tenosynovitis.

We report a case of acute tenosynovitis from sarcoidosis and review previously reported cases of this entity. A woman with known pulmonary sarcoidosis rapidly developed painless nodules in the tendon sheaths of the dorsum of both hands and wrists. Sarcoid tenosynovitis is almost exclusively found in the upper extremity. The flexor and extensor tendons are equally affected. The condition may respond to medical therapy including corticosteroids and other immunomodulating medications. Surgical debulking and tendon sheathectomy have also been curative. The disease has also been reported to spontaneously resolve. Our patient dramatically improved while on methotrexate.