The Oral Microbiome in Health and Its Implication in Oral and Systemic Diseases.

The oral microbiome can alter the balance between health and disease, locally and systemically. Within the oral cavity, bacteria, archaea, fungi, protozoa, and viruses may all be found, each having a particular role, but strongly interacting with each other and with the host, in sickness or in health. A description on how colonization occurs and how the oral microbiome dynamically evolves throughout the host's life is given. In this chapter the authors also address oral and nonoral conditions in which oral microorganisms may play a role in the etiology and progression, presenting the up-to-date knowledge on oral dysbiosis as well as the known underlying pathophysiologic mechanisms involving oral microorganisms in each condition. In oral pathology, oral microorganisms are associated with several diseases, namely dental caries, periodontal diseases, endodontic infections, and also oral cancer. In systemic diseases, nonoral infections, adverse pregnancy outcomes, cardiovascular diseases, and diabetes are among the most prevalent pathologies linked with oral cavity microorganisms. The knowledge on how colonization occurs, how oral microbiome coevolves with the host, and how oral microorganisms interact with each other may be a key factor to understand diseases etiology and progression.

Periodontal inflammation in renal transplant recipients receiving everolimus or tacrolimus - preliminary results.

OBJECTIVE: To compare oral health status between renal transplant recipients (RTRs) receiving tacrolimus (Tac) or everolimus (ERL) as immunosuppressive therapy. DESIGN: This study is a cross-sectional study. METHODS: Thirty-six RTRs receiving Tac and 22 RTRs receiving ERL were included in the study. Age, gender, time since transplant and pharmacological data were recorded for both groups. Oral health status was assessed through the evaluation of teeth, periodontal parameters as well as saliva flow rate and pH. RESULTS: RTRs receiving ERL were older than those receiving Tac. No differences were found between groups concerning oral hygiene habits, oral symptoms, smoking habits, unstimulated and stimulated saliva flow rate and pH, clinical attachment level or the number of decayed, missing and filled teeth. However, RTRs receiving ERL presented lower visible plaque index and lower values for bleeding on probing when compared to RTRs receiving Tac. In addition, RTRs receiving ERL presented a gingival index varying from normal to moderate inflammation whereas RTRs receiving Tac presented a gingival index varying from mild to severe inflammation. CONCLUSIONS: RTRs receiving ERL have lower periodontal inflammation when compared to RTRs receiving Tac.

Renal dopaminergic system activity in rat remnant kidney up to twenty-six weeks after surgery.

AIMS: In 3/4 nephrectomized (3/4nx) rats the renal dopaminergic system was suggested to be involved in the adaptive increase of sodium excretion two weeks after renal mass ablation. The aim of the present study was to evaluate the renal adaptations in sodium handling and renal dopaminergic system activity in 3/4nx rats up to twenty-six weeks after surgery. MAIN METHODS: The rats were placed in metabolic cages for the collection of 24 h urine for evaluation of sodium, dopamine, dopamine precursor and metabolites. Blood pressure, aromatic L-amino acid decarboxylase (AADC) activity in proximal tubules and the effect of dopamine D(1) receptor selective antagonist (Sch-23390) on natriuresis was evaluated. KEY FINDINGS: A time-dependent increase in both systolic and diastolic blood pressure was observed in 3/4nx rats, and this was accompanied by a decrease in urinary levels of dopamine and in renal AADC activity at twenty-six weeks after renal mass ablation. In contrast to what has been found two weeks after renal mass ablation, the natriuretic response to volume expansion was progressively reduced in 3/4nx rats at ten and twenty-six weeks after surgery and this was accompanied by insensitivity of natriuresis to Sch-23390. SIGNIFICANCE: In conclusion the renal dopaminergic system activity is compromised in 3/4nx rats in a time-dependent manner after renal mass ablation. It is suggested that this may contribute to compromise sodium excretion and increase blood pressure, in chronic renal insufficiency.

Cardiac remodeling and dysfunction in nephrotic syndrome.

There is an increased incidence of heart disease in patients with chronic nephrotic syndrome (NS), which may be attributable to the malnutrition and activated inflammatory state accompanying the sustained proteinuria. In this study, we evaluated renal function, cardiac morphometry, contractile function, and myocardial gene expression in the established puromycin aminonucleoside nephrosis rat model of NS. Two weeks after aminonucleoside injection, there was massive proteinuria, decreased creatinine clearance, and a negative sodium balance. Skeletal and cardiac muscle atrophy was present and was accompanied by impaired left ventricular (LV) hemodynamic function along with decreased contractile properties of isolated LV muscle strips. The expression of selected cytokines and proteins involved in calcium handling in myocardial tissue was evaluated by real time polymerase chain reaction. This revealed that the expression of interleukin-1beta, tumor necrosis factor-alpha, and phospholamban were elevated, whereas that of cardiac sarco(endo)plasmic reticulum calcium pump protein was decreased. We suggest that protein wasting and systemic inflammatory activation during NS contribute to cardiac remodeling and dysfunction.

Renal dopaminergic system activity in uninephrectomized rats up to 26 weeks after surgery.

BACKGROUND: Dopamine of renal origin exerts natriuretic and diuretic effects by activating D1-like receptors located at various regions in the nephron. Two weeks after uninephrectomy the renal dopaminergic system was suggested to be involved in the adaptative increase of sodium excretion. AIM: The aim of the present study was to evaluate the renal adaptations in sodium handling and renal dopaminergic system activity in uninephrectomized (Unx) rats up to 26 weeks after the surgery. RESULTS: A time-dependent increase in both systolic and diastolic blood pressure was observed in Unx rats up to 26 weeks after uninephrectomy. This was accompanied by a compensatory increase in aromatic L-amino acid decarboxylase at 2 weeks but not 10 and 26 weeks after uninephrectomy. In contrast to what has been found 2 weeks after uninephrectomy, at 10 and 26 weeks after surgery the natriuretic response to volume expansion was reduced in Unx rats and this was accompanied by insensitivity of natriuresis to dopamine D1 receptor selective antagonist (Sch23390). CONCLUSION: A time-dependent decrease in dopamine sensitive natriuresis is observed in Unx rats throughout the 26 weeks after uninephectomy. It is suggested that this may contribute to compromise sodium excretion and increase blood pressure.

Blunted renal dopaminergic system activity in HgCl2-induced membranous nephropathy.

The present study evaluated the possible role of the renal dopaminergic system in the sodium retention of HgCl2-induced nephrotic syndrome. The time courses of urinary excretion of sodium, protein, dopamine and the precursor l-3,4-dihydroxyphenylalanine (L-Dopa) were evaluated in HgCl2-treated and control rats up to day 21. The renal aromatic l-amino acid decarboxylase (AADC) activity, the enzyme responsible for the synthesis of renal dopamine, was evaluated during negligible proteinuria accompanied with enhanced sodium retention (day 7), increased proteinuria accompanied with greatest sodium retention (day 14) as well as during increased proteinuria accompanied with negative sodium balance (day 21). Also, the influence of volume expansion (VE, 5% bw) and the effects of the D1-like agonist fenoldopam (10 microg kg bw(-1) min(-1)) on natriuresis and on proximal tubular Na+,K+-ATPase activity were examined on day 14. The daily urinary dopamine output and urinary dopamine/L-Dopa ratios were reduced in HgCl2-treated rats from day 2 and beyond. This was accompanied by a marked decrease in renal AADC throughout the study. During VE, the fenoldopam-induced inhibition of proximal tubular Na+,K+-ATPase activity was similar between HgCl2-treated and control rats. However, the urinary sodium excretion during fenoldopam infusion was markedly increased by 60% to 120% in control rats but was not altered in HgCl2-treated rats. It is concluded that HgCl2 nephrosis is associated with a blunted renal dopaminergic system activity. However, the lack of renal dopamine in HgCl2 nephrosis does not appear to be related with the overall renal sodium retention in a state of proteinuria.

Jejunal dopamine and Na,K+-ATPase activity in nephrotic syndrome.

BACKGROUND: The occurrence of complementary functions in sodium transport between the intestine and the kidney was suggested to occur when the renal function is immature or compromised and jejunal dopamine has been implicated in this renal-intestinal cross-talk. The jejunal sodium transport was not previously evaluated in the nephrotic syndrome. METHODS: We examined the jejunal Na(+),K(+)-ATPase activity and the role of dopamine in puromycin aminonucleoside (PAN) and HgCl(2)-induced nephrotic syndrome rat models. RESULTS: In both nephrotic syndrome rat models, the jejunal Na(+),K(+)-ATPase activity was reduced during greatest sodium retention and ascites accumulation (PAN nephrosis, day 7; HgCl(2) nephrosis, day 14), whereas during enhanced sodium excretion and ascites mobilization the jejunal Na(+),K(+)-ATPase activity was increased in HgCl(2) nephrosis (day 21) and was similar to controls in PAN nephrosis (day 14). In both PAN- and HgCl(2)-induced nephrosis, the jejunal aromatic L-amino acid decarboxylase (AADC) activity, the enzyme responsible for the synthesis of jejunal dopamine, did not differ from controls. In addition, the jejunal Na(+),K(+)-ATPase activity was not sensitive to inhibition by dopamine (1 microM) in both experimental groups throughout the study. CONCLUSIONS: In the nephrotic syndrome the jejunal Na(+),K(+)-ATPase activity may respond in a compensatory way to changes in extracellular volume, through dopamine-independent mechanisms.

Renal dopaminergic system activity in the rat remnant kidney.

BACKGROUND: Renal dopamine exerts natriuretic and diuretic effects by activating D1-like receptors. Uninephrectomy results in increased renal dopaminergic activity and dopamine-sensitive enhanced natriuresis. METHODS: The present study evaluated renal adaptations in sodium handling and the role of dopamine in rats submitted to (3/4) nephrectomy: right nephrectomy and excision of both poles of the left kidney ((3/4)nx rats). RESULTS: Two weeks after surgery the absolute urinary levels of dopamine were markedly reduced in (3/4)nx rats whereas the urinary dopamine excretion per % of residual nephrons was significantly increased in the remnant kidney of (3/4)nx rats. The V(max) values for renal aromatic L-amino acid decarboxylase, the enzyme responsible for the synthesis of renal dopamine, were decreased in (3/4)nx rats. Renal catechol-O-methyltransferase activity, the enzyme responsible for the methylation of dopamine, was increased in (3/4)nx rats whereas the renal activities of monoamine oxidases A and B did not differ between (3/4)nx and Sham animals. Volume expansion (5% body weight) resulted in similar natriuretic responses in (3/4)nx and Sham rats. During D1 antagonist administration (Sch-23390, 30 microg x h(-1) x kg(-1)) the natriuretic response to volume expansion was reduced in (3/4)nx rats more pronouncedly than in Sham animals. CONCLUSION: The decrease in absolute renal dopamine output in (3/4)nx rats is related with reduced renal synthesis and enhanced O-methylation of the amine. However, this is accompanied in (3/4)nx rats by increased renal dopamine excretion per residual nephrons and dopamine-sensitive enhanced natriuresis.

Regulation of apical transporter of L-DOPA in human intestinal Caco-2 cells.

The present study examined the nature of the apical inward L-3,4-dihydroxyphenylalanine (L-DOPA) transporter in human intestinal epithelial Caco-2 cells, and whether protein kinases modulate the activity of this transporter. The apical inward transfer of L-DOPA was promoted through an energy-dependent and sodium-insensitive transporter (Km=33 microM; Vmax=2932 pmol/mg protein/6 min). This transporter was insensitive to N-(methylamino)-isobutyric acid, but competitively inhibited by 2-aminobicyclo(2,2,1)-heptane-2-carboxylic acid (BCH; IC50=83 microM). The organic cation inhibitor decynium 24 failed to affect the accumulation of L-DOPA, whereas the organic anion inhibitor 4,4'-diisothiocynatostilbene-2,2'-disulphonic acid (DIDS) competitively inhibited L-DOPA uptake (IC50=83 microM). However, the apical-to-basal and basal-to-apical transepithelial transport and the cell accumulation of [3H]-PAH was close to that of [14C]-sorbitol and insensitive to DIDS (300 microM). Modulators of protein kinase A (PKA) [cyclic adenosine monophosphate (cAMP), forskolin, H-89 and cholera toxin], protein kinase G (PKG) [cyclic guanosine monophosphate (GMP), zaprinast, LY 83583 and sodium nitroprusside] and protein kinase C (PKC) (phorbol 12,13-dibutirate and chelerythrine) failed to affect the accumulation of L-DOPA. The Ca2+/calmodulin inhibitors calmidazolium and trifluoperazine inhibited L-DOPA uptake (IC50s of 53 and 252 microM, respectively), but the rise of intracellular Ca2+ by A23187 (1 microM) and thapsigargin (1 microM) played no role on L-DOPA uptake. It is concluded that Caco-2 cells take up L-DOPA over the apical cell border through the sodium-independent and pH-sensitive L-type amino acid transporter.

Inhibition of calcium-independent luminal uptake of L-dopa by calmodulin antagonists in immortalized rat capillary cerebral endothelial cells.

The present study examined the involvement of protein kinase A (PKA), protein kinase G (PKG), protein kinase C (PKC), protein tyrosine kinase (PTK) and Ca(2+)/calmodulin mediated pathways on the luminal uptake of L-DOPA through the L-type amino acid transporter in immortalized rat capillary cerebral endothelial (REB-4) cells. Non-linear analysis of the saturation curve for L-DOPA revealed a K(m)value (in microM) of 71+/-9 and a V(max)value of 17+/-1 (in nmol mg protein/6 min). L-DOPA uptake at the luminal cell border was a sodium-independent process and insensitive to N-(methylamino)-isobutyric acid (MeAIB, 1 m m), but sensitive to 2-aminobicyclo(2,2,1)-heptane-2-carboxylic acid (BHC, IC(50)=140 microM). The Ca(2+)/calmodulin inhibitors calmidazolium and trifluoperazine inhibited L-DOPA (2.5 microM) uptake with IC(50)s of 23 and 33 microM, respectively. The inhibitory effect of BHC on the accumulation of L-DOPA was of the competitive type, whereas that of calmidazolium and trifluoperazine was of the non-competitive type. Modulators of PKA (cyclic AMP, forskolin, isobutylmethylxanthine and cholera toxin), PKG (cyclic GMP, zaprinast, LY 83583 and sodium nitroprusside), PKC (phorbol 12,13-dibutyrate, staurosporine and chelerythrine) and PTK (genistein and tyrphostin 25) failed to affect the accumulation of a non-saturating (2.5 microM) concentration of L-DOPA. It is concluded that L-DOPA uptake in RBE-4 cells is promoted through the L-type amino acid transporter and appears to be under the control of calmodulin mediated pathways.

Regulatory pathways and uptake of L-DOPA by capillary cerebral endothelial cells, astrocytes, and neuronal cells.

We examined the nature and regulation of the inward L-3,4-dihydroxyphenylalanine (L-DOPA) transporter in rat capillary cerebral endothelial (RBE4) cells, type 1 astrocytes (DI TNC1), and Neuro-2a neuroblastoma cells. In all three cell types, the inward transfer of L-DOPA was largely promoted through the 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid-sensitive and sodium-independent L-type amino acid transporter. Only in DI TNC1 cells was the effect of maneuvers that increase intracellular cAMP levels accompanied by increases in L-DOPA uptake. Also, only in DI TNC1 cells was the effect of the guanylyl cyclase inhibitor LY-83583 accompanied by a 65% increase in L-DOPA accumulation, whereas the nitric oxide donor sodium nitroprusside produced a 25% decrease in L-DOPA accumulation. In all three cell types, the Ca2+/calmodulin inhibitors calmidazolium and trifluoperazine inhibited L-DOPA uptake in a noncompetitive manner. Thapsigargin (1 and 3 microM) and A-23187 (1 and 3 microM) failed to alter L-DOPA accumulation in RBE4 and Neuro-2a cells but markedly increased L-DOPA uptake in DI TNC1 cells. We concluded that L-DOPA in RBE4, DI TNC1, and Neuro-2a cells is transported through the L-type amino acid transporter and appears to be under the control of Ca2+/calmodulin-mediated pathways. Astrocytes, however, are endowed with other processes that appear to regulate the accumulation of L-DOPA, responding positively to increases in intracellular Ca2+ and cAMP and to decreases in cGMP.

Ca2+/calmodulin mediated pathways regulate the uptake of L-DOPA in mouse neuroblastoma neuro 2A cells.

The present study examined the involvement of protein kinase A (PKA), protein kinase G (PKG), protein kinase C (PKC), protein tyrosine kinase (PTK) and Ca2+/calmodulin mediated pathways on the uptake of L-DOPA through the L-type amino acid transporter in Neuro 2A cells, an in vitro model of neuronal cells. Non-linear analysis of the saturation curve for L-DOPA revealed a Km value (in microM) of 54+/-2 and a Vmax value (in nmol mg protein/6 min) of 34+/-1. L-DOPA uptake was a sodium-independent process and insensitive to N-(methylamino)-isobutyric acid (MeAIB, 1 mM), but sensitive to 2-aminobicyclo(2,2,1)-heptane-2-carboxylic acid (BHC, IC50=82 microM). The Ca2+/calmodulin inhibitors calmidazolium and trifluoperazine inhibited L-DOPA (2.5 microM) uptake with IC50's of 33 and 105 microM, respectively. The inhibitory effect of BHC on the accumulation of L-DOPA was of the competitive type, whereas that of calmidazolium and trifluoperazine was of the non-competitive type. Modulators of PKA (cyclic AMP, forskolin, isobutylmethylxanthine and cholera toxin), PKG (cyclic GMP, zaprinast, LY 83583 and sodium nitroprusside), PKC (phorbol 12,13-dibutirate, phorbol 12-myristate 13-acetate and chelerythrine) and PTK (genistein and tyrphostin 25) failed to affect the accumulation of a non-saturating (2.5 microM) concentration of L-DOPA. It is concluded that L-DOPA uptake in Neuro 2A cells is promoted through the L-type amino acid transporter and appears to be under the control of Ca2+/calmodulin mediated pathways.