Chloroquine inhibits arginine vasopressin production in isolated rat inner medullary segments induced cAMP collecting duct

Systemic toxicity of chloroquine and hydroxychloroquine: prevalence, mechanisms, risk factors, prognostic and screening possibilities

Chloroquine (CQ) and its hydroxylated analog, hydroxychloroquine (HCQ), are 4-aminoquinoline initially used as an antimalarial treatment. CQ and HCQ (4-aminoquinoline, 4-AQ) are today used in rheumatology, especially to treat rheumatoid arthritis and systemic lupus erythematosus. Their mechanism of action revolves around a singular triptych: 4-AQ acts as alkalizing agents, ionized amphiphilic molecules, and by binding to numerous targets. 4-AQ have so pleiotropic and original mechanisms of action, providing them an effect at the heart of the regulation of several physiological functions. However, this broad spectrum of action is also at the origin of various and original side effects, notably a remarkable chronic systemic toxicity. We describe here the 4-AQ-induced lesions on the eye, the heart, muscle, the nerves, the inner ear, and the kidney. We also describe their prevalence, their pathophysiological mechanisms, their risk factors, their potential severity, and the means to detect them early. Most of these side effects are reversible if treatment is stopped promptly. This 4-AQ-induced toxicity must be known to prescribing physicians, to closely monitor its appearance and stop treatment in time if necessary.

Cholangiocyte autophagy contributes to hepatic cystogenesis in polycystic liver disease and represents a potential therapeutic target

Polycystic liver disease (PLD) is a group of genetic disorders with limited treatment options and significant morbidity. Hepatic cysts arise from cholangiocytes exhibiting a hyperproliferative phenotype. Considering that hyperproliferation of many cell types is associated with alterations in autophagy, we hypothesized that autophagy is altered in PLD cholangiocytes, contributes to hepatic cystogenesis, and might represent a potential therapeutic target. We employed functional pathway cluster analysis and next-generation sequencing, transmission electron microscopy, immunofluorescence confocal microscopy, and western blotting to assess autophagy in human and rodent PLD cholangiocytes. A three-dimensional culture model was used to study the effects of molecular and pharmacologic inhibition of autophagy on hepatic cystogenesis in vitro, and the polycystic kidney disease-specific rat, an animal model of PLD, to study the effects of hydroxychloroquine, a drug that interferes with the autophagy pathway, on disease progression in vivo. Assessment of the transcriptome of PLD cholangiocytes followed by functional pathway cluster analysis revealed that the autophagy-lysosomal pathway is one of the most altered pathways in PLD. Direct evaluation of autophagy in PLD cholangiocytes both in vitro and in vivo showed increased number and size of autophagosomes, lysosomes, and autolysosomes; overexpression of autophagy-related proteins (Atg5, Beclin1, Atg7, and LC3); and enhanced autophagic flux associated with activation of the cAMP-protein kinase A-cAMP response element-binding protein signaling pathway. Molecular and pharmacologic intervention in autophagy with ATG7 small interfering RNA, bafilomycin A₁ , and hydroxychloroquine reduced proliferation of PLD cholangiocytes in vitro and growth of hepatic cysts in three-dimensional cultures. Hydroxychloroquine also efficiently inhibited hepatic cystogenesis in the polycystic kidney disease-specific rat.

CONCLUSION

Autophagy is increased in PLD cholangiocytes, contributes to hepatic cystogenesis, and represents a potential therapeutic target for disease treatment. (Hepatology 2018;67:1088-1108).

Chronic use of chloroquine disrupts the urine concentration mechanism by lowering cAMP levels in the inner medulla

Chloroquine, a widely used anti-malaria drug, has gained popularity for the treatment of rheumatoid arthritis, systemic lupus erythematosus (SLE), and human immunodeficiency virus (HIV). Unfortunately, chloroquine may also negatively impact renal function for patients whose fluid and electrolyte homeostasis is already compromised by diseases. Chronic administration of chloroquine also results in polyuria, which may be explained by suppression of the antidiuretic response of vasopressin. Several of the transporters responsible for concentrating urine are vasopressin-sensitive including the urea transporters UT-A1 and UT-A3, the water channel aquaporin-2 (AQP2), and the Na(+)-K(+)-2Cl(-) cotransporter (NKCC2). To examine the effect of chloroquine on these transporters, Sprague-Dawley rats received daily subcutaneous injections of 80 mg·kg(-1)·day(-1) of chloroquine for 4 days. Twenty-four hour urine output was twofold higher, and urine osmolality was decreased by twofold in chloroquine-treated rats compared with controls. Urine analysis of treated rats detected the presence chloroquine as well as decreased urine urea and cAMP levels compared with control rats. Western blot analysis showed a downregulation of AQP2 and NKCC2 transporters; however, UT-A1 and UT-A3 abundances were unaffected by chloroquine treatment. Immunohistochemistry showed a marked reduction of UT-A1 and AQP2 in the apical membrane in inner medullary collecting ducts of chloroquine-treated rats. In conclusion, chloroquine-induced polyuria likely occurs as a result of lowered cAMP production. These findings suggest that chronic chloroquine treatment would exacerbate the already compromised fluid homeostasis observed in diseases like chronic kidney disease.

Why does chloroquine impair renal function?: chloroquine may modulate the renal tubular response to vasopressin either directly by inhibiting cyclic AMP generation, or indirectly via nitric oxide

Chloroquine is one of the antimalaria drugs, also used to treat rheumatoid arthritis and systemic lupus erythematosus (SLE). Although well tolerated in most individuals, it was suggested that chloroquine can exert a profound influence on renal function, especially in individuals with compromised body fluid status. However, epidemiological studies are still lacking. The renal actions of chloroquine are further exacerbated by co-administration of other commonly used drugs such as paracetamol. The following discussion will focus on the evidence that chloroquine is a stimulator of nitric oxide (NO), which mediates many of its renal actions (diuresis, natriuresis and an increase in both glomerular filtration rate (GFR) and plasma vasopressin). Chloroquine appears to modulate the renal tubular response to vasopressin either by directly inhibiting cAMP generation or indirectly via NO.

The effect of chloroquine on renal function and vasopressin secretion: a nitric oxide-dependent effect

We have previously reported that chloroquine administration increases plasma vasopressin concentration and urinary sodium excretion in Sprague-Dawley rats. Because chloroquine has also been shown to stimulate nitric oxide production, the aim of this study was to determine whether nitric oxide mediates chloroquine-induced changes in renal function and secretion of vasopressin. Sprague-Dawley rats (n = 6-8/group) were infused with 2.5% dextrose under Intraval anesthesia (100 mg kg(-1) i.p.). After 3-h equilibration and a control hour, animals received either vehicle, chloroquine (0.04 mg h(-1)), N(omega)-nitro-L-arginine methyl ester (L-NAME) (nitric-oxide synthase inhibitor, 60 microg kg(-1) h(-1)), or combined chloroquine and L-NAME over the next hour. L-NAME or vehicle infusion continued for a further recovery hour. Plasma was collected from a parallel group of animals for vasopressin radioimmunoassay. Chloroquine stimulated a significant increase (p < 0.05) in urine flow rate, glomerular filtration rate, and sodium excretion over the hour of infusion, in comparison with vehicle-infused rats. These effects continued after cessation of chloroquine, reaching maxima in the following recovery hour. Coadministration of L-NAME abolished these effects, returning all parameters to levels comparable with those in vehicle-infused animals. Chloroquine administration was accompanied by a significant increase (p < 0.05) in plasma vasopressin, which was also reversed by L-NAME. The effects of chloroquine on renal function and vasopressin secretion seem to be mediated by pathways involving nitric oxide. These data suggest that chloroquine may stimulate nitric-oxide synthase both centrally, stimulating vasopressin secretion, and within the kidney, where it modulates glomerular hemodynamics and tubular function.