Pressure overload regulates expression of cytokines, γH2AX, and growth arrest- and DNA-damage inducible protein 153 via glycogen synthase kinase-3β in ischemic-reperfused hearts

DNA damage and arterial hypertension. A systematic review and meta-analysis

Oxidative DNA damage markers (8OHdG, comet assay, gammaH2AX) are becoming widely used in clinical cardiology research. To conduct this review of DNA damage in relation to hypertension in humans, we used databases (e.g. PubMed, Web of Science) to search for English-language publications up to June 30, 2022 and the terms: DNA damage, comet assay, gammaH2AX, 8OHdG, strand breaks, and arterial hypertension. Exclusion criteria were: children, absence of relevant controls, extra-arterial hypertensive issues, animal, cell lines. From a total of 79526, 15 human studies were selected. A total of 902 hypertensive patients (pts): (comet: N=418 pts; 8OHdG: N=484 pts) and 587 controls (comet: N=203; 8OHdG: N=384) were included. DNA damage was significantly higher in hypertensive pts than healthy controls (comet 26.6±11.0 vs 11.7±4.07 arbitrary units /A.U./; P<0.05 and="" 8ohdg="" 13="" 1="" 4="" 12="" vs="" 6="" 97="" 2="" 67="" ng="" mg="" creatinine="" i=""> P<0.05) confirmed with meta-analysis for both. Greater DNA damage was observed in more adverse cases (concentric cardiac hypertrophy 43.4±15.4 vs 15.6±5.5; sustained/untreated hypertension 31.4±12.1 vs 14.2±5/35.0±5.0 vs 25.0 ±5.0; non-dippers 39.2±15.5 vs 29.4±11.1 A.U.; elderly 14.9±4.5 vs 9.3±4.1 ng/mg creatinine; without carvedilol 9.1±4.2 vs 5.7±3.9; with coronary heart disease 0.5±0.1 vs 0.2±0.1 ng/mL) (P<0.05) confirmed with meta-analysis. DNA damage correlated strongly positively with serum glycosylated haemoglobin (r=0.670; P<0.05) and negatively with total antioxidant status (r=-0.670 to -0.933; P<0.05). This is the first systematic review with meta-analysis showing that oxidative DNA damage was increased in humans with arterial hypertension compared to controls.

Mechanism and significance of apoptosis of the immortalized human oral mucosal epithelial cells established by Lentivirus-mediated hTERT

During the transition from human oral mucosal epithelial cells (HOMEC) to oral squamous cell carcinoma cells (Cal27), the cells must have undergone a precancerous state. To explore the malignant rule of HOMEC, plv-HOMEC was used as a model cell for the precancerous state to investigate plv-HOMEC's apoptosis by comparing human oral mucosal epithelial cells established by Lentivirus-mediated hTERT (plv-HOMEC) with HOMEC and human Cal27. The lentiviral particles overexpressing hTERT were packaged and transfected into primary HOMEC to obtain plv-HOMEC. Expression levels of NF-κB were detected in the cytoplasm and nucleus of Cal27, plv-HOMEC and HOMEC. The level of intracellular reactive oxygen species was measured to verify the endoplasmic reticulum pathway, cytochrome C expression was detected to verify the mitochondrial pathway, and FasL gene expression was detected to verify the death receptor apoptosis pathway. The total expression of NF-κB in plv-HOMEC increased, mainly due to the greater nuclear import of NF-κB, but it was still much lower than Cal27. The endoplasmic reticulum apoptosis pathway of plv-HOMEC was not significantly affected, and there were no significant differences between them and the HOMEC cells; the mitochondrial apoptosis pathway of plv-HOMEC was inhibited, and the expression of Cyt C was very close to that of Cal27, indicating that the characteristics of plv-HOMEC are so familiar with cancer cells; the death receptor apoptosis pathway of plv-HOMEC was also inhibited, and in this apoptotic pathway, plv-HOMEC were more similar to cancer cells than to HOMEC cells. The present data suggest that NF-κB nucleation may increase in the early stage of healthy cells' carcinogenesis, followed by inhibition of the mitochondrial pathway and the death receptor apoptotic pathway.

Cardiac morbidity in HIV infection is associated with checkpoint inhibitor LAG-3 on CD4 T cells

Recent findings point to a role of Checkpoint Inhibitor (CPI) receptors at the tissue level in immune homeostasis. Here we investigated the role of CPI molecules on immune cells in relation to cardiac function. Participants recruited in Chennai, India consisted of HIV+ ART naive viremic (Gp1 n = 102), HIV+ on ART, virologically suppressed (Gp2, n = 172) and HIV negative healthy controls (Gp3, n = 64). A cross-sectional analysis of cardiac function, arterial resistance and immunologic assessment of CPI expressing T cells was performed. Data indicate that ART naive exhibited cardiac function impairment and greater arterial stiffness than the other groups. Frequencies of CD4+ T cells expressing LAG-3 and PD1 were higher in ART naïve while TIGIT and TIM3 were similar among the patient groups. LAG-3+, PD1+ and dual LAG-3+PD1+ CD4 T cells were inversely correlated with cardiac function and arterial elasticity and directly with arterial stiffness in ART naïve participants and with arterial elasticity in virally suppressed group on ART. We conclude that HIV induced upregulation of LAG-3 singly or in combination with PD1 in immune cells may regulate cardiac health and warrant mechanistic investigations. The implications of these findings have bearing for the potential utility of anti-LAG-3 immunotherapy for cardiac dysfunction in chronic HIV infection.

AT1-receptor blockade: Protective effects of irbesartan in cardiomyocytes under hypoxic stress

Hypoxia induces myocardial injury through the activation of inflammatory and oxidative processes. The pivotal role of the renin angiotensin system (RAS) in the pathogenesis of cardiovascular diseases has been firmly established in clinical trials and practice; in fact many experimental and clinical data have highlighted that its inhibition has a cardioprotective role. Activated RAS also stimulates inflammation directly inducing proinflammatory and oxidative gene expression. This study aimed to investigate the protective role of a pre-treatment (10 and 100 μM) with irbesartan on injury induced by 24 h of hypoxia in HL-1 cardiomyocytes; in particular, we have analyzed the natriuretic peptide (BNP) expression, a biomarker able to modulate inflammatory reaction to cardiac injury and some markers involved in oxidative stress and inflammation. Our results demonstrated that a pre-treatment with 100 μM irbesartan significantly increased SOD activity and catalase expression of 15 and 25%, respectively, compared to hypoxic cells (P<0.05). On the other hand, it was able to reduce the release of peroxynitrite and iNOS protein expression of 20 and 50% respectively (P<0.05). In addition irbesartan exerts an anti-inflammatory activity reducing Toll-like receptors (TLRs)-2 and -4 mRNA expression, TNF-alpha expression and activity (20%) and increasing the expression of the cytokine IL-17 (40%) (P<0.05 vs hypoxia). Our findings also showed that BNP induced by ischemia was significantly and in a concentration-dependent manner reduced by irbesartan. The findings of our study demonstrated that the AT1 receptor antagonist irbesartan exerts a protective role in an in vitro hypoxic condition reducing oxidative stress and inflammation.

[Role of poly(ADP-ribose) polymerases-1-mediated blockade of autophagy in ischemia/reperfusion injury of rat cardiomyocytes]

OBJECTIVE

To investigate the role of poly(ADP-ribose) polymerases-1 (PARP-1)-mediated blockade of autophagic flow in myocardial ischemia-reperfusion injury.

METHODS

H9c2 cells, a rat cardiac myocyte line, were divided into control group, hypoxia/ reoxygenation model group (H/R group), PARP-1 inhibitor (PJ34) group, and PJ34 + H/R group. The total protein was extracted from the cells in each group to detect the expressions of pADPr, Bax, the DNA damage marker protein p-YH2ax, and autophagic flow-associated proteins LC3BⅡ/LC3Ⅰ, Beclin-1, and P62 using Western blotting.

RESULTS

Compared with the control cells, the cells with H/R exhibited significantly increased expressions of pADPr, Bax and p-YH2ax (P < 0.05). The expressions of LC3B Ⅱ, beclin-1 and p62 were also increased significantly in the cells with H/R (P < 0.05), indicating the block of the autophagic flow. The application of PARP-1 inhibitor PJ34 in the cells with H/R significantly inhibited the expressions of pADPr (P < 0.05) and Bax (P < 0.01), and alleviated DNA damage in the cells. PJ34 treatment did not cause significant changes in the expressions of LC3B Ⅱ and beclin-1 but significantly decreased the expression of p62 (P < 0.05) in the cells with H/R.

CONCLUSIONS

Block of autophagic flow mediated by PARP-1 activation plays a role in myocardial ischemiareperfusion injury, and inhibition of PARP-1 activity can reverse autophagic flow block to reduce the injury.

Sodium bicarbonate loading limits tubular cast formation independent of glomerular injury and proteinuria in Dahl salt-sensitive rats

Sodium bicarbonate (NaHCO₃) slows the decline in kidney function in patients with chronic kidney disease (CKD), yet the mechanisms mediating this effect remain unclear. The Dahl salt-sensitive (SS) rat develops hypertension and progressive renal injury when fed a high salt diet; however, the effect of alkali loading on kidney injury has never been investigated in this model. We hypothesized that NaHCO₃ protects from the development of renal injury in Dahl salt-sensitive rats via luminal alkalization which limits the formation of tubular casts, which are a prominent pathological feature in this model. To examine this hypothesis, we determined blood pressure and renal injury responses in Dahl SS rats drinking vehicle (0.1 M NaCl) or NaHCO₃ (0.1 M) solutions as well as in Dahl SS rats lacking the voltage-gated proton channel (Hv1). We found that oral NaHCO₃ reduced tubular NH₄⁺ production, tubular cast formation, and interstitial fibrosis in rats fed a high salt diet for 2 weeks. This effect was independent of changes in blood pressure, glomerular injury, or proteinuria and did not associate with changes in renal inflammatory status. We found that null mutation of Hv1 also limited cast formation in Dahl SS rats independent of proteinuria or glomerular injury. As Hv1 is localized to the luminal membrane of TAL, our data suggest that alkalization of the luminal fluid within this segment limits cast formation in this model. Reduced cast formation, secondary to luminal alkalization within TAL segments may mediate some of the protective effects of alkali loading observed in CKD patients.

Chronic Remote Ischemic Conditioning Is Cerebroprotective and Induces Vascular Remodeling in a VCID Model

Vascular contributions to cognitive impairment and dementia (VCID) make up 50% of the cases of dementia. The purpose of this study was to determine the effect of chronic remote ischemic conditioning (C-RIC) on improving long-term (6 months) outcomes and cerebral blood flow (CBF) and collateral formation in a mouse model of VCID. Adult C57BL/6J male mice (10 weeks) were randomly assigned to four different groups: (1) sham-bilateral carotid artery stenosis (BCAS), (2) BCAS + sham RIC, (3) BCAS+C-RIC for 1 month (1MO), and (4) BCAS+C-RIC-4 months (4MO). CBF, cognitive impairment, and functional outcomes were performed up for 6 months after BCAS surgery. The expression of CD31, α-SMA, and myelin basic protein (MBP) was assessed by immunohistochemistry (IHC). Additional set of mice were randomized to sham, BCAS, and BCAS+C-RIC. The cerebrovascular angioarchitecture was studied with micro-CT. RIC therapy for either 1 or 4 months significantly improved CBF, new collateral formation, functional and cognitive outcomes, and prevented white matter damage. There was no difference between C-RIC for 1 or 4 months; IHC studies at 6 months showed an increase in brain CD31 and α-SMA expression indicating increased angiogenesis and MBP indicating preservation of white matter in animals receiving RIC. One month of daily RIC is as effective as 4 months of daily RIC in improving CBF, angiogenesis, and long-term functional outcomes (6 months) in a VCID model. This suggests that 1 month of RIC is sufficient to reduce cognitive impairment and induce beneficial cerebrovascular remodeling.

MiR-486 regulates cardiomyocyte apoptosis by p53-mediated BCL-2 associated mitochondrial apoptotic pathway

BACKGROUND

Cardiomyocyte apoptosis is a common pathological manifestation that occurs in several heart diseases. This study aimed to explore the mechanism of microRNA-486 (miR-486) in cardiomyocyte apoptosis by interfering with the p53-activated BCL-2 associated mitochondrial pathway.

METHODS

miR-486 mimics and inhibitors were transfected into the primary cardiomyocytes of suckling Sprague-Dawley rat pups, and H₂O₂ was used to induce apoptosis. Flow cytometry and TUNEL were both used to detect cardiomyocyte apoptosis, while the relative mRNA transcript and protein levels of miR-486, p53, Bbc3, BCL-2, and cleaved caspase-3 were detected using RT-PCR and western blot analysis, respectively.

RESULTS

miR-486 overexpression significantly decreased the expressions of p53, Bbc3 and cleaved caspase-3 (P < 0.05), and BCL-2 expression was significantly increased (P < 0.05), which in turn caused a significant decrease in the rate of cardiomyocyte apoptosis (P < 0.05). In contrast, miR-486 silencing resulted in an elevated rate of cardiomyocyte apoptosis (P < 0.05).

CONCLUSION

miR-486 may regulate cardiomyocyte apoptosis via p53-mediated BCL-2 associated mitochondrial apoptotic pathway. Therefore, up-regulating miR-486 expression in cardiomyocytes can effectively reduce the activation of the BCL-2 associated mitochondrial apoptotic pathway, consequently protecting cardiomyocytes.

Status of stem cells in diabetic nephropathy: predictive and preventive potentials

BACKGROUND

Recruitment of stem cells to sites of tissue injury constitutes an important mechanism aimed at tissue repair and regeneration. However, it is not clear how the diabetic milieu affects the viability of endogenous stem cells. Thus, we tested the hypothesis that diabetes mellitus is associated with increased apoptosis which, in turn, contributes to reduction in stem cells and the manifestation of type 2 diabetic nephropathy.

METHODS

Sixteen-week-old male obese type 2 diabetic db/db mice, and their appropriate controls, were used for assessment of the status of endothelial progenitor cells (EPCs), mesenchymal stem cells (MSCs), and hematopoetic stem cells (HSCs) in the peripheral blood and renal tissue using specific cell markers. Further, we explored whether diabetic animals display greater apoptosis of stem cell subsets.

RESULTS

The peripheral blood cells of db/db mice displayed reduction in EPCs (p < 0.05) compared to those of db/m controls. Further, kidney cells prepared from experimental groups also showed reductions in EPCs, MSCs, and HSCs. We also observed increased apoptosis of stem cell subsets in cells prepared from kidneys of db/db than those of db/m mice.

CONCLUSIONS

The present study shows a similar pattern of decline in stem cell subsets in peripheral blood and kidneys of db/db mice, an effect likely related to increased apoptosis. Collectively, the results suggest that apoptosis of stem cells likely contributes to eventual manifestation of renal failure in diabetes mellitus. Monitoring of blood levels of stem cell subsets could predict failure of their reparative and protective effects and eventual manifestations of diabetic complications.

The status of glucocorticoid-induced leucine zipper protein in the salivary glands in Sjögren's syndrome: predictive and prognostic potentials

Background

We recently showed that an imbalance between the pro-inflammatory cytokine, interleukin (IL)-17, and the developmental endothelial locus-1 (Del-1) likely contributes to inflammation and salivary gland abnormalities in Sjögren’s syndrome (SS). The glucocorticoid-induced leucine zipper (GILZ) protein is a pivotal player in mediating the anti-inflammatory effects of glucocorticoids. However, its status and role in salivary gland inflammation and dysfunction in SS are not established. Thus, we tested the hypothesis that SS is associated with reduced GILZ expression, thereby contributing to Del-1/Il-17 imbalance and inflammation in salivary glands.

Methods

We utilized the nonobese diabetic (NOD) mice, a model of SS-like disease as well as lower-lip biopsy samples of subjects without or with a diagnosis of SS in association with immunostaining studies. These studies were complemented with in vitro and flow-cytometry studies whereby interleukin (IL)-23-treated salivary gland cells were co-cultured with GILZ-expressing cells or control cells; IL-23 is known to increase generation of IL-17.

Results

Salivary glands of NOD mice displayed marked leukocyte infiltration and reduced GILZ expression in association with increased IL-17 but decreased Del-1 expression. A similar pattern was observed for lower-lip biopsy samples of SS than non-SS subjects. Further, IL-23-treated salivary gland cells displayed marked increase in IL-17 but reduced Del-1 positive cells which were reversed with co-culturing with GILZ-expressing cells but not control cells. Collectively, the results are suggestive of dysregulation of GILZ playing a role in inflammation and associated Del-1/Il-17 imbalance in SS.

Conclusions

Complementing our demonstration of Del-1/IL-17 imbalance in salivary glands in SS, the present study has established the relevance and significance of GILZ as a novel predictive and prognostic molecular fingerprint for SS. Thus, assessment of minor salivary gland GILZ expression, in conjunction with Del-1/IL-17 imbalance, could potentially offer a more sensitive approach to help with diagnosis of SS, at early stage of the disease, than that based on leukocyte infiltration. Future studies should establish whether treatment with GILZ ameliorates signs and symptoms of salivary malfunction of SS for which effective treatment options remain elusive.

Whole body vibration therapy: a novel potential treatment for type 2 diabetes mellitus

There is a worsening epidemic of obesity and diabetes in the world. Life style interventions including dietary changes and increase in exercise can improve glucose metabolism and health in general. However, standard exercise programs are strenuous, time-consuming, and thus have low long-term compliance issues. We tested the feasibility of using high frequency, low amplitude whole body vibration (WBV) therapy to improve glucose metabolism in young type 2 diabetic (T2DM) mice. We also aimed to investigate the postulated anti-inflammatory and cytoprotective properties of WBV. Male db/db and db/m mice were exposed to high frequency, low-amplitude WBV. Outcome parameters comprised of body weight, hemoglobin A1c (HbA1c) level, as well as interleukin (IL)-17 (a marker of helper T cells), forkhead box P3 (Foxp3; a marker of regulatory T cells), and gammaH2AX (an index of DNA injury) expression. Furthermore, a 24 h metabolic cage study was carried out immediately after the WBV protocol and fluid intake, urine excretion and urine osmolality were determined. WBV did not affect body weight but improved HbA1c levels in db/db mice. Vibrated db/db mice demonstrated less fluid intake and urine excretion but better urinary concentrating ability than their non-vibrated controls. Pro-inflammatory changes were significantly reduced, as indicated by reduced IL-17 but increased Foxp3 expression. WBV reduced gammaH2AX in db/db mice suggestive of cytoprotective effect. However, WBV was largely without significant effects on assessed parameters in db/m mice. Collectively, our findings suggest that daily, short duration WBV may improve glycemic control, polydipsia, polyuria, and urine osmolality in T2DM in association with reduced inflammation. Thus, WBV may be a viable adjunctive treatment strategy in T2DM.

Upregulation of Programmed Death-1 and Its Ligand in Cardiac Injury Models: Interaction with GADD153

Purpose

Programmed Death-1 (PD-1) and its ligand, PD-L1, are regulators of immune/ inflammatory mechanisms. We explored the potential involvement of PD-1/PD-L1 pathway in the inflammatory response and tissue damage in cardiac injury models.

Experimental Design

Ischemic-reperfused and cryoinjured hearts were processed for flow cytometry and immunohistochemical studies for determination of cardiac PD-1 and PD-L1 in the context of assessment of the growth arrest- and DNA damage-inducible protein 153 (GADD153) which regulates both inflammation and cell death. Further, we explored the potential ability of injured cardiac cells to influence proliferation of T lymphocytes.

Results

The isolated ischemic-reperfused hearts displayed marked increases in expression of PD-1 and PD-L1 in cardiomyocytes; however, immunofluorescent studies indicate that PD-1 and PD-L1 are not primarily co-expressed on the same cardiomyocytes. Upregulation of PD-1/PD-L1 was associated with a) marked increases in GADD153 and interleukin (IL)-17 but a mild increase in IL-10 and b) disruption of mitochondrial membrane potential (ψ_m) as well as apoptotic and necrotic cell death. Importantly, while isotype matching treatment did not affect the aforementioned changes, treatment with the PD-L1 blocking antibody reversed those effects in association with marked cardioprotection. Further, ischemic-reperfused cardiac cells reduced proliferation of T lymphocytes, an effect partially reversed by PD-L1 antibody. Subsequent studies using the cryoinjury model of myocardial infarction revealed significant increases in PD-1, PD-L1, GADD153 and IL-17 positive cells in association with significant apoptosis/necrosis.

Conclusions

The data suggest that upregulation of PD-1/PD-L1 pathway in cardiac injury models mediates tissue damage likely through a paracrine mechanism. Importantly, inhibition of T cell proliferation by ischemic-reperfused cardiac cells is consistent with the negative immunoregulatory role of PD-1/PD-L1 pathway, likely reflecting an endogenous cardiac mechanism to curtail the deleterious impact of infiltrating immune cells to the damaged myocardium. The balance of these countervailing effects determines the extent of cardiac injury.

Targeting serum glucocorticoid-regulated kinase-1 in squamous cell carcinoma of the head and neck: a novel modality of local control

Purpose

The inhibition of serum glucocorticoid-regulated kinase-1 (SGK-1) has been found to decrease growth of colon and prostate cancer cells. The purpose of this study is to evaluate the therapeutic effect of SGK-1 inhibition in head and neck squamous cell carcinoma (SCC).

Experimental Design

Human head and neck tumors (HTB41/43) were established in athymic mice. Growth rates between mice treated with vehicle (PBS) injection (group 1, n = 5), SGK-1 Inhibitor GSK 650394 (group 2, n = 6), systemic cisplatin (group 3, n = 6), and a combination of SGK-1 Inhibitor and cisplatin (group 4, n = 6) were compared using repeated measures one-way ANOVA with Newman-Keuls Multiple Comparison Test. Tumor cells were subsequently submitted to further analyses.

Results

At the end of the experiment mean tumor sizes were 122.33+/−105.86, 76.73+/−36.09, 94.52+/−75.92, and 25.76+/−14.89 mm² (mean +/− SD) for groups 1 to 4. Groups 2 and 3 showed decreased tumor growth compared to controls (p<0.001). Group 4 displayed even greater growth suppression (p<0.0001). Importantly, group 4 fared better than group 3 (p<0.001). CD44 expression was reduced in group 2 (p<0.05), and to an even greater extent in groups 3 and 4 (p<0.0025). A trend towards reduction of HER 2 expression was noted in group 4.

Conclusions

SGK-1 inhibition suppresses tumor growth, and in combination with systemic cisplatin exceeds the effect of cisplatin alone. Decreased expression of CD44 and HER 2 implies depletion of tumor stem cells, and less tumorigenicity. SGK-1 inhibition represents a potential modality of local control for palliation in advanced cases.

Effects of lithium on inflammation

Lithium is an effective medication for the treatment of bipolar affective disorder. Accumulating evidence suggests that inflammation plays a role in the pathogenesis of bipolar disorder and that lithium has anti-inflammatory effects that may contribute to its therapeutic efficacy. This article summarizes the studies which examined the effects of lithium on pro- and anti-inflammatory mediators. Some of the summarized data suggest that lithium exerts anti-inflammatory effects (e.g., suppression of cyclooxygenase-2 expression, inhibition of interleukin (IL)-1β and tumor necrosis factor-α production, and enhancement of IL-2 and IL-10 synthesis). Nevertheless, there is a large body of data which indicates that under certain experimental conditions lithium also exhibits pro-inflammatory properties (e.g., induction of IL-4, IL-6 and other pro-inflammatory cytokines synthesis). The reviewed studies utilized various experimental model systems, and it is thus difficult to draw an unequivocal conclusion regarding the effect of lithium on specific inflammatory mediators.

SGK-1 regulates inflammation and cell death in the ischemic-reperfused heart: pressure-related effects

BACKGROUND

Systemic hypertension and the associated increased myocardial load/mechanical stress are common in patients with coronary heart disease. Thus, unraveling of mechanosensitive molecular mechanisms that determine cell fate in the setting of cardiac tissue injury is of scientific and clinical relevance. We tested the hypothesis that the prosurvival, mechanosensitive, serum glucocorticoid-regulated kinase-1 (SGK-1) is a pivotal determinant of pressure-related inflammatory response and cell fate in the ischemic-reperfused heart.

METHODS

Langendorff-perfused rat hearts were subjected to an ischemia reperfusion (IR) insult, at 80 or 160cm water, with perfusate lacking or containing the SGK-1 inhibitor GSK650394A (1 μM); normoxic hearts served as controls. Thereafter, hearts tissues were used for Western blotting or cardiac cells were prepared for flow cytometry and immunofluorescent studies.

RESULTS

An IR insult (i) reduced phosphoSGK-1 (active and protective) in association with disruption of mitochondrial membrane potential (ψm) and increased apoptosis and necrosis and (ii) increased expressions of growth-arrest and DNA damage-associated protein 153 (GADD153; a determinant of inflammation and cell death) and the proinflammatory cytokine interleukin (IL) 17; these effects were greater at high pressure. On the other hand, the anti-inflammatory cytokines IL-10 and IL-27 increased more in ischemic-reperfused hearts subjected to low pressure. SGK-1 inhibition further reduced phosphoSGK-1, increased GADD153 and IL-17, and reduced IL-10 and IL-27 in association with augmented disruption of ψm and exacerbated cell death; these effects were greater at low pressure.

CONCLUSIONS

The results indicate a major pressure-related role for SGK-1 in regulating inflammation and cell fate in the ischemic-reperfused heart.

Reciprocal relation between GADD153 and Del-1 in regulation of salivary gland inflammation in Sjögren syndrome

Endoplasmic reticulum (ER) stress response is a pivotal regulator of inflammation and cell death. An integral component of ER stress-induced apoptosis is expression of growth arrest- and DNA damage-inducible protein 153 (GADD153). Further, ER stress response is implicated in leukocyte adhesion and recent studies have discovered endogenous inhibitors of leukocyte adhesion including the developmental endothelial locus-1 (Del-1). Accordingly, we tested the hypothesis that Sjögren's syndrome (SS) is associated with increased salivary gland expression of GADD153 and increased leukocyte infiltration in association with decreased Del-1 thereby contributing to inflammation and cell death. We utilized the non-obese diabetic (NOD) mice, a model of SS-like disease, in association with immunostaining and flow cytometry-based studies. Salivary glands of 14-week-old NOD mice displayed a) increased GADD153 expression, b) marked reduction in Del-1, c) inflammatory cell infiltrates including CD3+ T and CD19+ B lymphocytes as well as M1 and M2 macrophages and d) increased pro-inflammatory interleukin (IL)-17 but reduced anti-inflammatory cytokine, IL-10. These changes were accompanied with disruption of mitochondrial membrane potential and significant increase in apoptosis and necrosis of salivary gland cells of NOD than control mice. Our collective observations suggested that GADD153 directly and/or indirectly through downregulation of Del-1 contributes importantly to salivary gland inflammation and cell death. To establish the relevance of GADD153 and Del-1 for the human condition, lower lip biopsy samples of non-SS subjects and those with a diagnosis of SS were subjected to immunohistochemistry. The results show intense GADD153 immunostaining but marked reduction in Del-1 expression in biopsy samples of SS compared to non-SS subjects. Collectively, the results indicate that GADD153 regulates inflammation and cell death in salivary gland in SS. Further, Del-1 expression likely provides a mechanistic link between increased GADD153 and leukocyte infiltration and accompanying inflammation of salivary gland tissue in this condition.