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Infection with the SARS (Severe Acute Respiratory Syndrome)-associated coronavirus results in respiratory failure probably by immunological mechanisms in 10% of patients. Laboratory markers that predict subsequent respiratory failure would therefore be useful in patient management.
We describe the clinical course, hematologic parameters, lymphocyte subpopulations and markers of inflammation in two patients with SARS, i.e., one man with diabetes mellitus and one pregnant woman, infected by the same viral isolate.
The patient with underlying diabetes mellitus developed respiratory failure after admission in the second week of the illness while the second patient developed only a mild disease without respiratory failure. Subsequent respiratory dysfunction was associated with lown umbers of Natural Killer (NK) cells at presentation and elevated CRP levels during the illness.
NK cells and CRP levels at the end of the first week of the disease might be related to subsequent respiratory dysfunction and may link underlying conditions to disease severity.
Immunomodulatory properties and molecular effects in inflammatory diseases of low-dose X-irradiation
(2012)
Inflammatory diseases are the result of complex and pathologically unbalanced multicellular interactions. For decades, low-dose X-irradiation therapy (LD-RT) has been clinically documented to exert an anti-inflammatory effect on benign diseases and chronic degenerative disorders. By contrast, experimental studies to confirm the effectiveness and to reveal underlying cellular and molecular mechanisms are still at their early stages. During the last decade, however, the modulation of a multitude of immunological processes by LD-RT has been explored in vitro and in vivo. These include leukocyte/endothelial cell adhesion, adhesion molecule and cytokine/chemokine expression, apoptosis induction, and mononuclear/polymorphonuclear cell metabolism and activity. Interestingly, these mechanisms display comparable dose dependences and dose-effect relationships with a maximum effect in the range between 0.3 and 0.7 Gy, already empirically identified to be most effective in the clinical routine. This review summarizes data and models exploring the mechanisms underlying the immunomodulatory properties of LD-RT that may serve as a prerequisite for further systematic analyses to optimize low-dose irradiation procedures in future clinical practice.
Ubiquitylation in immune disorders and cancer: from molecular mechanisms to therapeutic implications
(2012)
Conjugation of ubiquitin to proteins (ubiquitylation) has emerged to be one of the most crucial post-translational modifications controlling virtually all cellular processes. What was once regarded as a mere signal for protein degradation has turned out to be a major regulator of molecular signalling networks. Deregulation of ubiquitin signalling is closely associated with various human pathologies. Here, we summarize the current knowledge of ubiquitin signalling in immune deficiencies and cancer as well as the available therapeutic strategies targeting the ubiquitin system in combating these pathogenic conditions.
Research over the past few years has provided fascinating results indicating that biglycan, besides being a ubiquitous structural component of the extracellular matrix (ECM), may act as a signaling molecule. Proteolytically released from the ECM, biglycan acts as a danger signal signifying tissue stress or injury. As a ligand of innate immunity receptors and activator of the inflammasome, biglycan stimulates multifunctional proinflammatory signaling linking the innate to the adaptive immune response. By clustering several types of receptors on the cell surface and orchestrating their downstream signaling events, biglycan is capable to autonomously trigger sterile inflammation and to potentiate the inflammatory response to microbial invasion. Besides operating in a broad biological context, biglycan also displays tissue-specific affinities to certain receptors and structural components, thereby playing a crucial role in bone formation, muscle integrity, and synapse stability at the neuromuscular junction. This review attempts to provide a concise summary of recent data regarding the involvement of biglycan in the regulation of inflammation and the musculoskeletal system, pointing out both a signaling and a structural role for this proteoglycan. The potential of biglycan as a novel therapeutic target or agent for the treatment of inflammatory diseases and skeletal muscular dystrophies is also addressed.
Interleukin (IL)-10 and IL-22 are key members of the IL-10 cytokine family that share characteristic properties such as defined structural features, usage of IL-10R2 as one receptor chain, and activation of signal transducer and activator of transcription (STAT)-3 as dominant signaling mode. IL-10, formerly known as cytokine synthesis inhibitory factor, is key to deactivation of monocytes/macrophages and dendritic cells. Accordingly, pre-clinical studies document its anti-inflammatory capacity. However, the outcome of clinical trials assessing the therapeutic potential of IL-10 in prototypic inflammatory disorders has been disappointing. In contrast to IL-10, IL-22 acts primarily on non-leukocytic cells, in particular epithelial cells of intestine, skin, liver, and lung. STAT3-driven proliferation, anti-apoptosis, and anti-microbial tissue protection is regarded a principal function of IL-22 at host/environment interfaces. In this hypothesis article, hidden/underappreciated pro-inflammatory characteristics of IL-10 and IL-22 are outlined and related to cellular priming by type I interferon. It is tempting to speculate that an inherent inflammatory potential of IL-10 and IL-22 confines their usage in tissue protective therapy and beyond that determines in some patients efficacy of type I interferon treatment.
Altered mucosal immune response after acute lung injury in a murine model of Ataxia Telangiectasia
(2014)
Background: Ataxia telangiectasia (A-T) is a rare but devastating and progressive disorder characterized by cerebellar dysfunction, lymphoreticular malignancies and recurrent sinopulmonary infections. In A-T, disease of the respiratory system causes significant morbidity and is a frequent cause of death.
Methods: We used a self-limited murine model of hydrochloric acid-induced acute lung injury (ALI) to determine the inflammatory answer due to mucosal injury in Atm (A-T mutated)- deficient mice (Atm−/−).
Results: ATM deficiency increased peak lung inflammation as demonstrated by bronchoalveolar lavage fluid (BALF) neutrophils and lymphocytes and increased levels of BALF pro-inflammatory cytokines (e.g. IL-6, TNF). Furthermore, bronchial epithelial damage after ALI was increased in Atm−/− mice. ATM deficiency increased airway resistance and tissue compliance before ALI was performed.
Conclusions: Together, these findings indicate that ATM plays a key role in inflammatory response after airway mucosal injury.
Chronic inflammation as an important epigenetic and environmental factor for putative tumorigenesis and tumor progression may be associated with specific activation of Toll-like receptors (TLR). Recently, carcinogenesis has been suggested to be dependent on TLR7 signaling. In the present study, we determined the role of both TLR7 and TLR8 expression and signaling in tumor cell proliferation and chemoresistance in pancreatic cancer. Expression of TLR7/TLR8 in UICC stage I-IV pancreatic cancer, chronic pancreatitis, normal pancreatic tissue and human pancreatic (PANC1) cancer cell line was examined. For in vitro/in vivo studies TLR7/TLR8 overexpressing PANC1 cell lines were generated and analyzed for effects of (un-)stimulated TLR expression on tumor cell proliferation and chemoresistance. TLR expression was increased in pancreatic cancer, with stage-dependent upregulation in advanced tumors, compared to earlier stages and chronic pancreatitis. Stimulation of TLR7/TLR8 overexpressing PANC1 cells resulted in elevated NF-κB and COX-2 expression, increased cancer cell proliferation and reduced chemosensitivity. More importantly, TLR7/TLR8 expression increased tumor growth in vivo. Our data demonstrate a stage-dependent upregulation of both TLR7 and TLR8 expression in pancreatic cancer. Functional analysis in human pancreatic cancer cells point to a significant role of both TLRs in chronic inflammation-mediated TLR7/TLR8 signaling leading to tumor cell proliferation and chemoresistance.
The processing of pain undergoes several changes in aging that affect sensory nociceptive fibers and the endogenous neuronal inhibitory systems. So far, it is not completely clear whether age-induced modifications are associated with an increase or decrease in pain perception. In this study, we assessed the impact of age on inflammatory nociception in mice and the role of the hormonal inhibitory systems in this context. We investigated the nociceptive behavior of 12-month-old versus 6–8-week-old mice in two behavioral models of inflammatory nociception. Levels of TRP channels, and cortisol as well as cortisol targets, were measured by qPCR, ELISA, and Western blot in the differently aged mice. We observed an age-related reduction in nociceptive behavior during inflammation as well as a higher level of cortisol in the spinal cord of aged mice compared to young mice, while TRP channels were not reduced. Among potential cortisol targets, the NF-κB inhibitor protein alpha (IκBα) was increased, which might contribute to inhibition of NF-κB and a decreased expression and activity of the inducible nitric oxide synthase (iNOS). In conclusion, our results reveal a reduced nociceptive response in aged mice, which might be at least partially mediated by an augmented inflammation-induced increase in the hormonal inhibitory system involving cortisol.
Macrophages respond to the Th2 cytokine IL-4 with elevated expression of arachidonate 15-lipoxygenase (ALOX15). Although IL-4 signaling elicits anti-inflammatory responses, 15-lipoxygenase may either support or inhibit inflammatory processes in a context-dependent manner. AMP-activated protein kinase (AMPK) is a metabolic sensor/regulator that supports an anti-inflammatory macrophage phenotype. How AMPK activation is linked to IL-4-elicited gene signatures remains unexplored. Using primary human macrophages stimulated with IL-4, we observed elevated ALOX15 mRNA and protein expression, which was attenuated by AMPK activation. AMPK activators, e.g. phenformin and aminoimidazole-4-carboxamide 1-β-d-ribofuranoside inhibited IL-4-evoked activation of STAT3 while leaving activation of STAT6 and induction of typical IL-4-responsive genes intact. In addition, phenformin prevented IL-4-induced association of STAT6 and Lys-9 acetylation of histone H3 at the ALOX15 promoter. Activating AMPK abolished cellular production of 15-lipoxygenase arachidonic acid metabolites in IL-4-stimulated macrophages, which was mimicked by ALOX15 knockdown. Finally, pretreatment of macrophages with IL-4 for 48 h increased the mRNA expression of the proinflammatory cytokines IL-6, IL-12, CXCL9, and CXCL10 induced by subsequent stimulation with lipopolysaccharide. This response was attenuated by inhibition of ALOX15 or activation of AMPK during incubation with IL-4. In conclusion, limiting ALOX15 expression by AMPK may promote an anti-inflammatory phenotype of IL-4-stimulated human macrophages.
Hypoxia potentiates palmitate-induced pro-inflammatory activation of primary human macrophages
(2015)
Pro-inflammatory cytokines secreted by adipose tissue macrophages (ATMs) contribute to chronic low-grade inflammation and obesity-induced insulin resistance. Recent studies have shown that adipose tissue hypoxia promotes an inflammatory phenotype in ATMs. However, our understanding of how hypoxia modulates the response of ATMs to free fatty acids within obese adipose tissue is limited. We examined the effects of hypoxia (1% O2) on the pro-inflammatory responses of human monocyte-derived macrophages to the saturated fatty acid palmitate. Compared with normoxia, hypoxia significantly increased palmitate-induced mRNA expression and protein secretion of IL-6 and IL-1β. Although palmitate-induced endoplasmic reticulum stress and nuclear factor κB pathway activation were not enhanced by hypoxia, hypoxia increased the activation of JNK and p38 mitogen-activated protein kinase signaling in palmitate-treated cells. Inhibition of JNK blocked the hypoxic induction of pro-inflammatory cytokine expression, whereas knockdown of hypoxia-induced transcription factors HIF-1α and HIF-2α alone or in combination failed to reduce IL-6 and only modestly reduced IL-1β gene expression in palmitate-treated hypoxic macrophages. Enhanced pro-inflammatory cytokine production and JNK activity under hypoxia were prevented by inhibiting reactive oxygen species generation. In addition, silencing of dual-specificity phosphatase 16 increased normoxic levels of IL-6 and IL-1β and reduced the hypoxic potentiation in palmitate-treated macrophages. The secretome of hypoxic palmitate-treated macrophages promoted IL-6 and macrophage chemoattractant protein 1 expression in primary human adipocytes, which was sensitive to macrophage JNK inhibition. Our results reveal that the coexistence of hypoxia along with free fatty acids exacerbates macrophage-mediated inflammation.