Inducible knockout of Clec16a in mice results in sensory neurodegeneration

CLEC16A has been shown to play a role in autophagy/mitophagy processes. Additionally, genetic variants in CLEC16A have been implicated in multiple autoimmune diseases. We generated an inducible whole-body knockout, Clec16aΔUBC mice, to investigate the loss of function of CLEC16A. The mice exhibited a neuronal phenotype including tremors and impaired gait that rapidly progressed to dystonic postures. Nerve conduction studies and pathological analysis revealed loss of sensory axons that are associated with this phenotype. Activated microglia and astrocytes were found in regions of the CNS. Several mitochondrial-related proteins were up- or down-regulated. Upregulation of interferon stimulated gene 15 (IGS15) were observed in neuronal tissues. CLEC16A expression inversely related to IGS15 expression. ISG15 may be the link between CLEC16A and downstream autoimmune, inflammatory processes. Our results demonstrate that a whole-body, inducible knockout of Clec16a in mice results in an inflammatory neurodegenerative phenotype resembling spinocerebellar ataxia.

The role of MIZ-1 in MYC-dependent tumorigenesis

A hallmark of MYC-transformed cells is their aberrant response to antimitogenic signals. Key examples include the inability of MYC-transformed cells to arrest proliferation in response to antimitogenic signals such as TGF-β or DNA damage and their inability to differentiate into adipocytes in response to hormonal stimuli. Given the plethora of antimitogenic signals to which a tumor cell is exposed, it is likely that the ability to confer resistance to these signals is central to the transforming properties of MYC in vivo. At the same time, the inability of MYC-transformed cells to halt cell-cycle progression on stress may establish a dependence on mutations that impair or disable apoptosis. We propose that the interaction of MYC with the zinc finger protein MIZ-1 mediates resistance to antimitogenic signals. In contrast to other interactions of MYC, there is currently little evidence that MIZ-1 associates with MYC in normal, unperturbed cells. The functional interaction of both proteins becomes apparent at oncogenic expression levels of MYC and association with MIZ-1 mediates both oncogenic functions of MYC as well as tumor-suppressive responses to oncogenic levels of MYC.

[Establishment of human cardiac C protein induced experimental autoimmune myocarditis model in rat]

OBJECTIVE

To construct the recombinant plasmid of human cardiac C protein (CCP) peptide with immunogenicity and to express, purification and renature fusion protein. The fusion protein was injected to Lewis rats to establish experimental autoimmune myocarditis (EAM) model.

METHODS

Total RNA was extracted from human heart and used as the template for reverse transcriptase-directed cDNA synthesis. The cDNA was then amplified by polymerase chain reaction (PCR) using oligonucleotide primers specific for CCP peptide with immunogenicity. Subsequently, the purified CCP peptide gene was cloned into PEASY-T1 vector and the ligated product was identified by PCR and DNA sequence analysis. Then the CCP target gene of positive clone was inserted into the pQE30, a prokaryotic expression vector, and the inserting plasmid was transformed into Escherichia coli. host M15. The positive clone extracted from the bacterium liquid was sieved by insertional inactivation sieve method and identified by PCR of bacterium liquid, CCP immunological peptide was purified and renatured in semipermeable membrane. EAM model in Lewis rats was induced by injection of mixture of 100 µg CCP fusion protein immunological peptide and 2.5 g/L completed Freund adjuvant from two double foot pad and subsequent abdominal injection of 0.5 µg pertussis toxin. Two, four, six, and eight weeks after immunization, hemodynamic evaluation was made and hearts underwent histological examination.

RESULTS

The DNA sequence analysis for cloning vector extraction revealed that the CCP target gene was cloned into pQE30 exactly. The DNA of 1000 bp length was obtained by PCR examination of bacterium liquid with transformation of express recombinants which were consistent with the expected size. Purified fusion protein in vertical slab gel electrophoresis showed 35 000 as expected. The recombinant CCP fusion protein existed in inclusion bodies of E. coli and amounted to 80% - 90% of the total protein. Hemodynamic and histological evaluations showed typical acute inflammatory responses at 2 weeks, subacute inflammatory and fibrosis changes at 4 weeks after injection, and signs of chronic dilated cardiomyopathy at 6 weeks post injection.

CONCLUSION

Combination of gene clone technique and histidine tag protein purification technique can be used to synthesize human cardiac C protein to induce EAM model in Lewis rat.

Tea catechins improve left ventricular dysfunction, suppress myocardial inflammation and fibrosis, and alter cytokine expression in rat autoimmune myocarditis

BACKGROUND

Myocarditis is a clinically serious disease. Tea catechins have been shown to reduce inflammation; however the effects of catechins on the development of myocarditis have not been well studied.

AIMS

To clarify the role of catechins, using an experimental autoimmune myocarditis (EAM) model.

METHODS AND RESULTS

Lewis rats were immunized with porcine cardiac myosin to establish EAM. Tea catechins were administered orally from day 0 to day 21 (Group A, n=12), from day 14 to day 21 (Group B, n=8), or saline (Group C, n=9) daily. Rats were killed on day 21. Echocardiograms indicated that Group A showed significantly improved cardiac function compared to Group C. Pathologically, non-treated EAM hearts showed severe myocardial cell infiltration and fibrosis; however Group A showed significantly less area. Immunohistochemistry revealed enhanced expression of NF-kappaB and ICAM-1 in non-treated EAM hearts, which was suppressed by catechin administration in Group A. mRNA levels of TNF-alpha were decreased and Th2 cytokines were markedly enhanced in Group A compared with the control group. Late catechin administration (Group B) showed limited effects on EAM.

CONCLUSION

The catechins suppressed ventricular remodelling in EAM; thus catechin treatment might be a promising option for the prevention of EAM myocarditis.

Activation of the endoplasmic reticulum stress response in autoimmune myositis: potential role in muscle fiber damage and dysfunction

OBJECTIVE

The etiology and pathogenesis of human inflammatory myopathies remain unclear. Findings of several studies suggest that the degree of inflammation does not correlate consistently with the severity of clinical disease or of structural changes in the muscle fibers, indicating that nonimmune pathways may contribute to the pathogenesis of myositis. This study was undertaken to investigate these pathways in myositis patients and in a class I major histocompatibility complex (MHC)-transgenic mouse model of myositis.

METHODS

We examined muscle tissue from human myositis patients and from class I MHC-transgenic mice for nonimmune pathways, using biochemical, immunohistochemical, and gene expression profiling assays.

RESULTS

Up-regulation of class I MHC in skeletal muscle fibers was an early and consistent feature of human inflammatory myopathies. Class I MHC staining in muscle fibers of myositis patients showed both cell surface and a reticular pattern of internal reactivity. The pathways of endoplasmic reticulum (ER) stress response, the unfolded protein response (glucose-regulated protein 78 pathway), and the ER overload response (NF-kappaB pathway) were significantly activated in muscle tissue of human myositis patients and in the mouse model. Ectopic expression of wild-type mouse class I MHC (H-2K(b)) but not degradable glycosylation mutants of H-2K(b) induced ER stress response in C(2)C(12) skeletal muscle cells.

CONCLUSION

These results indicate that the ER stress response may be a major nonimmune mechanism responsible for skeletal muscle damage and dysfunction in autoimmune myositis. Strategies to interfere with this pathway may have therapeutic value in patients with this disease.

New immunopathologic insights into multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory and demyelinating disease of the central nervous system. Although the immune system seems to play an important role in the pathogenesis of disease, target antigens are still uncertain and pathways leading to tissue destruction have not been fully elucidated. Recent studies have significantly contributed to a better understanding of the disease process and broadened our view on possible scenarios of disease initiation and progression. We review the role of the immune system for the manifestation and evolution of MS and discuss different pathogenetic concepts. We conclude with an outlook on future strategies to identify the cause of MS.

Alpha4-integrin-VCAM-1 binding mediates G protein-independent capture of encephalitogenic T cell blasts to CNS white matter microvessels

Direct in vivo evidence is still lacking for alpha4-integrin-mediated T cell interaction with VCAM-1 on blood-brain barrier-endothelium in experimental autoimmune encephalomyelitis (EAE). To investigate a possible alpha4-integrin-mediated interaction of encephalitogenic T cell blasts with VCAM-1 on the blood-brain barrier white matter endothelium in vivo, we have developed a novel spinal cord window preparation that enabled us to directly visualize CNS white matter microcirculation by intravital fluorescence videomicroscopy. Our study provides the first in vivo evidence that encephalitogenic T cell blasts interact with the spinal cord white matter microvasculature without rolling and that alpha4-integrin mediates the G protein-independent capture and subsequently the G protein-dependent adhesion strengthening of T cell blasts to microvascular VCAM-1.

Infection and the etiology and pathogenesis of multiple sclerosis

Multiple sclerosis (MS) currently defies clinical and scientific definitions, and carries a prognosis that remains practically unchanged despite many years of intensive research. Although the prevailing dogma is that MS is an immune-mediated condition, it fulfills none of the criteria of an autoimmune disease. On the other hand, there is enough significant data to suggest that infectious agents(s) could be involved in either direct damage to the white matter or induce inflammatory responses that secondarily affect the brain. Our goal here is to review the data supporting the possibility that infection has a critical role in the disease, examine the list of potential candidates that have been suggested, and outline an approach regarding the potential role of infectious agents in the etiology and pathogenesis of MS.