Low Serum Zinc Concentration Is Associated With Infection Particularly in Patients With Stage 5 Chronic Kidney Disease Medicated with Proton Pump Inhibitors

Elevated luminal inorganic phosphate suppresses intestinal Zn absorption in 5/6 nephrectomized rats

Zinc (Zn) is an essential trace element in various biological processes. Chronic kidney disease (CKD) often leads to hypozincemia, resulting in further progression of CKD. In CKD, intestinal Zn absorption, the main regulator of systemic Zn metabolism, is often impaired; however, the mechanism underlying Zn malabsorption remains unclear. Here, we evaluated intestinal Zn absorption capacity in a rat model of CKD induced by 5/6 nephrectomy (5/6 Nx). Rats were given Zn and the incremental area under the plasma Zn concentration-time curve (iAUC) was measured as well as the expression of ZIP4, an intestinal Zn transporter. We found that 5/6 Nx rats showed lower iAUC than sham-operated rats, but expression of ZIP4 protein was upregulated. We therefore focused on other Zn absorption regulators to explore the mechanism by which Zn absorption was substantially decreased. Because some phosphate compounds inhibit Zn absorption by coprecipitation and hyperphosphatemia is a common symptom in advanced CKD, we measured inorganic phosphate (Pi) levels. Pi was elevated in not only serum but also the intestinal lumen of 5/6 Nx rats. Furthermore, intestinal intraluminal Pi administration decreased the iAUC in a dose-dependent manner in normal rats. In vitro, increased Pi concentration decreased Zn solubility under physiological conditions. Furthermore, dietary Pi restriction ameliorated hypozincemia in 5/6 Nx rats. We conclude that hyperphosphatemia or excess Pi intake is a factor in Zn malabsorption and hypozincemia in CKD. Appropriate management of hyperphosphatemia will be useful for prevention and treatment of hypozincemia in patients with CKD.NEW & NOTEWORTHY We demonstrated that elevated intestinal luminal Pi concentration can suppress intestinal Zn absorption activity without decreasing the expression of the associated Zn transporter. Increased intestinal luminal Pi led to the formation of an insoluble complex with Zn while dietary Pi restriction or administration of a Pi binder ameliorated hypozincemia in chronic kidney disease model rats. Therefore, modulation of dietary Pi by Pi restriction or a Pi binder might be useful for the treatment of hypozincemia and hyperphosphatemia.

Long-Term Proton Pump Inhibitor Therapy Increases the Risk of Infection in Patients with Incident Hemodialysis

BACKGROUND

Infection is one of the most common causes of death in patients with chronic kidney disease (CKD). Proton pump inhibitors (PPIs) are not only widely used in patients with CKD but also represent a known risk factor for infection in the general population. Here, we investigated associations between PPIs and infection events in patients with incident hemodialysis.

METHODS

We analyzed data from 485 consecutive patients with CKD who started hemodialysis at our hospital between January 2013 and December 2019. We analyzed associations between infection events and long-term (≥6 months) PPI use before and after propensity score-matched analysis.

RESULTS

Of the 485 patients, PPIs were administered to 177 patients (36.5%). During 24 months of follow-up, infection events occurred in 53 patients (29.9%) with PPIs and 40 patients (13.0%) without PPIs (p < 0.001). Patients with PPIs had a significantly higher cumulative incidence rate of infection events than those without PPIs (hazard ratio [HR] 2.13, 95% confidence interval [CI]: 1.36-3.32; p < 0.001). Even after propensity score-matched analysis (132 patients matched in each), the rate of infection events was higher for patients with PPIs (28.8% vs. 12.1%, HR 2.88, 95% CI: 1.61-5.16; p < 0.001). Similar results were obtained for severe infection events in both unmatched (14.1% vs. 4.5%, HR 2.97, 95% CI: 1.47-6.00; p = 0.002) and propensity score-matched analyses (14.4% vs. 3.8%, HR 4.54, 95% CI: 1.85-11.13; p < 0.001).

CONCLUSIONS

In patients with incident hemodialysis, long-term PPI use increases the risk of infection. Clinicians should be wary of unnecessarily prolonging PPI therapy.

Incidence, Pathogenesis, and Management of Proton Pump Inhibitor-Induced Nephrotoxicity

Proton pump inhibitors are widely used in the treatment of various acid-related diseases and are among the most commonly used drugs. Studies estimate that 25-70% of proton pump inhibitors are prescribed for inappropriate treatments, doses, and indications, where the benefits of proton pump inhibitor use may be less than the risk of adverse drug reactions for many patients. Acute interstitial nephritis is an immune-mediated atypical kidney injury in the long-term use of proton pump inhibitors that causes problems for clinicians and patients. In this review, we summarize the current knowledge of proton pump inhibitors inducing acute interstitial nephritis, chronic kidney disease, and even end-stage renal disease in terms of incidence, pathogenesis, factors, clinical features, and diagnosis. We discuss how these factors change under conditions of acute interstitial nephritis, chronic kidney disease, and end-stage renal disease. The purpose of this review is to assess the current evidence to help clinicians and patients interpret the potential causal relationship between proton pump inhibitor intake and nephrotoxicity. This prompts clinicians to consider the appropriate dose and duration of proton pump inhibitor therapy to avoid inappropriate use.

Micronutrient Improvement of Epithelial Barrier Function in Various Disease States: A Case for Adjuvant Therapy

The published literature makes a very strong case that a wide range of disease morbidity associates with and may in part be due to epithelial barrier leak. An equally large body of published literature substantiates that a diverse group of micronutrients can reduce barrier leak across a wide array of epithelial tissue types, stemming from both cell culture as well as animal and human tissue models. Conversely, micronutrient deficiencies can exacerbate both barrier leak and morbidity. Focusing on zinc, Vitamin A and Vitamin D, this review shows that at concentrations above RDA levels but well below toxicity limits, these micronutrients can induce cell- and tissue-specific molecular-level changes in tight junctional complexes (and by other mechanisms) that reduce barrier leak. An opportunity now exists in critical care—but also medical prophylactic and therapeutic care in general—to consider implementation of select micronutrients at elevated dosages as adjuvant therapeutics in a variety of disease management. This consideration is particularly pointed amidst the COVID-19 pandemic.