Efficacy and safety of manuka honey for dry eye

Effect of low dose honey on the apoptosis and inflammation gene expression in corneal limbal stem cells and keratocytes and its efficacy as an ophthalmic formulation in the treatment of dry eye: in-vitro and clinical study

Background

The use of honey as an eye treatment encounters challenges due to its high osmolarity, low pH, and difficulties in sterilization. This study addresses these issues by employing a low concentration of honey, focusing on both in-vitro experiments and clinical trials for treating dry eye disease in corneal cells.

Methods

In the in-vitro experiment, we investigated the impact of a 1% honey-supplemented medium (HSM) on limbal stem cells (LSCs) and keratocytes using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay and real-time polymerase chain reaction (PCR) for BCL-2, BAX, and IL-1β gene expression. Simultaneously, in the clinical trial, 80 participants were divided into two groups, receiving either a 1% w/v honey ophthalmic formulation or a placebo for 3 months. Study outcomes included subjective improvement in dry eye symptoms, tear break-up time (TBUT), and Schirmer's test results.

Results

MTT results indicated that 1% HSM did not compromise the survival of corneal cells and significantly reduced the expression of the IL-1β gene. Additionally, participants in the honey group demonstrated a higher rate of improvement in dry eye symptoms and a significant enhancement in TBUT values at the three-month follow-up. However, there was no significant difference between the study groups in terms of Schirmer's test values. No adverse events were observed or reported.

Conclusion

In conclusion, 1% honey exhibits anti-inflammatory and anti-infective properties, proving effective in ameliorating dry eye symptoms and enhancing tear film stability in patients with dry eye disease.Clinical Trial Registration: https://irct.behdasht.gov.ir/trial/63800.

An updated review of functional ingredients of Manuka honey and their value-added innovations

Manuka honey (MH) is a highly prized natural product from the nectar of Leptospermum scoparium flowers. Increased competition on the global market drives MH product innovations. This review updates comparative and non-comparative studies to highlight nutritional, therapeutic, bioengineering, and cosmetic values of MH. MH is a good source of phenolics and unique chemical compounds, such as methylglyoxal, dihydroxyacetone, leptosperin glyoxal, methylsyringate and leptosin. Based on the evidence from in vitro, in vivo and clinical studies, multifunctional bioactive compounds of MH have exhibited anti-oxidative, anti-inflammatory, immunomodulatory, anti-microbial, and anti-cancer activities. There are controversial topics related to MH, such as MH grading, safety/efficacy, implied benefits, and maximum levels of contaminants concerned. Artificial intelligence can optimize MH studies related to chemical analysis, toxicity prediction, multi-functional mechanism exploration and product innovation.

Inflammation mechanism and anti-inflammatory therapy of dry eye

Dry eye is a widespread chronic inflammatory disease that causes fatigue, tingling, burning, and other symptoms. Dry eye is attributed to rheumatic diseases, diabetes, hormone disorders, and contact lenses, which activate inflammatory pathways: mitogen-activated protein kinases (MAPK) and nuclear factor-B (NF-κB), promote macrophage inflammatory cell and T cell activation, and inflammation factors. Clinicians use a combination of anti-inflammatory drugs to manage different symptoms of dry eye; some of these anti-inflammatory drugs are being developed. This review introduces the dry eye inflammation mechanisms and the involved inflammatory factors. We also elucidate the anti-inflammatory drug mechanism and the detection limits.

Combinatorial efficacy of Manuka honey and antibiotics in the in vitro control of staphylococci and their small colony variants

Introduction

Staphylococci are among the list of problematic bacteria contributing to the global antibiotic resistance (ABR) crisis. Their ability to adopt the small colony variant (SCV) phenotype, induced by prolonged antibiotic chemotherapy, complicates staphylococcal infection control options. Novel and alternative approaches are needed to tackle staphylococcal infections and curb ABR. Manuka honey (MH), a non-antibiotic alternative is recognized for its unique antibacterial activity based on its methylglyoxal (MGO) component.

Methods

In this study, MH (MGO 830+) was tested in combination with gentamicin (GEN), rifampicin (RIF), or vancomycin (VA) against staphylococcal wildtype (WT) and SCVs. To our knowledge, there are no current studies in the literature documenting the effects of MH on staphylococcal SCVs. While Staphylococcus aureus is well-studied for its international ABR burden, limited data exists demonstrating the effects of MH on S. epidermidis and S. lugdunensis whose pathogenic relevance and contribution to ABR is also rising.

Results & discussion

The three staphylococci were most susceptible to RIF (0.06-0.24 μg/ml), then GEN (0.12-0.49 μg/ml), and lastly VA (0.49-0.96 μg/ml). The MICs of MH were 7%, 7-8%, and 6-7% (w/v), respectively. Fractional inhibitory concentration (FIC) evaluations showed that the combined MH + antibiotic effect was either additive (FICI 1-2), or partially synergistic (FICI >0.5-1). While all three antibiotics induced SCVs in vitro, stable SCVs were observed in GEN treatments only. The addition of MH to these GEN-SCV-induction analyses resulted in complete suppression of SCVs (p<0.001) in all three staphylococci, suggesting that MH's antibacterial properties interfered with GEN's SCV induction mechanisms. Moreover, the addition of MH to growth cultures of recovered stable SCVs resulted in the inhibition of SCV growth by at least 99%, indicating MH's ability to prevent subsequent SCV growth. These in vitro analyses demonstrated MH's broad-spectrum capabilities not only in improving WT staphylococci susceptibility to the three antibiotics, but also mitigated the development and subsequent growth of their SCV phenotypes. MH in combination with antibiotics has the potential to not only resensitize staphylococci to antibiotics and consequently require less antibiotic usage, but in instances where prolonged chemotherapy is employed, the development and growth of SCVs would be hampered, providing a better clinical outcome, all of which mitigate ABR.