Causal Relationship Between Cystatin C and Herpes zoster: A Mendelian Randomization Analysis

doi:10.21203/rs.3.rs-3103326/v1

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Causal Relationship Between Cystatin C and Herpes zoster: A Mendelian Randomization Analysis

https://doi.org/10.21203/rs.3.rs-3103326/v1

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Objective

This study aimed to examine the association between cysteine C and Herpes zoster (HZ).

Method

We acquired data from the MR Base database and used Mendelian randomization (MR) to evaluate the causal association between cysteine C and HZ.

Results

We selected five single nucleotide polymorphisms from genome-wide association studies that were significantly associated with both cysteine C and HZ. Inverse weighted variance (IVW) and weighted median methods showed that MCI had a protective effect on CP (IVW: β=-1.229, P = 0.010, odds ratio [OR] = 0.293, 95% confidence interval [CI] = 0.114–0.749; Weighted median: β=-1.328, P = 0.008, OR = 0.265, 95%CI = 0.100-0.705). However, MR-Egger analysis suggested no causal association (β=-1.642, P = 0.103, OR = 0.194, 95%CI = 0.048–0.774). The greater precision of weighted median estimator and IVW suggest our results may support a potential causal association between cysteine C and HZ .

Conclusion

The MR analysis demonstrated that cysteine C has a protective effect on HZ.

Mendelian randomization

cysteine C

Herpes zoster

PHN

Herpes zoster (HZ) is a condition resulting from the reactivation of latent varicella-zoster virus (VZV), primarily affecting the elderly population, the manifestation of HZ often leads to postherpetic neuralgia (PHN), which significantly impacts the quality of life of older adults ¹. Research indicates that HZ is linked to compromised immunity². Some studies propose that cystatin C supplementation may alleviate the discomfort associated with HZ by enhancing immune function, reducing pain, and expediting wound healing³. Cystatin C is a cysteine protease inhibitor, which is a high-sensitivity biomarker that predicts kidney function⁴. But There is currently no clear evidence indicating a direct relationship between cysteine C and HZ.

Mendelian randomization (MR) is a method used to evaluate causality in observational studies. It is based on the Mendelian principle of inheritance, which states that genetic variations are randomly inherited. Thus, genetic variations associated with other diseases may also affect the variable of interest. MR evaluates the association between exposure and outcome by comparing populations with different genetic variations and allows for better control of potential confounders compared with traditional observational studies, improving the reliability of the conclusion⁵. Therefore, our study aimed to examine the association between Cystatin C and HZ using two-sample MR analysis.

2.1 Acquired genetic variant data

We acquired data from MR Base (http://app.mrbase. org), a platform for MR research that compiles and summarizes data from genome-wide association studies (GWASs)^{6, 7}.

We used publicly available summary statistics datasets from GWAS meta-analyses for in European (ID: ebi-a-GCST003375, n = 32834, variants = 2153636) as the exposure. We set the threshold of statistical significance as “P < 5.00E − 8; LD Rsq < 0.1” to identify single nucleotide polymorphisms (SNPs). A total of 8 single SNPs associated with cystatin C were obtained. We used the same method to obtain data regarding HZ in European (ID: finn-b-AB1_ZOSTER, n = 2080, variants = 16380433) as the outcome, please see Table 1 for additional details.

Table 1

details of exposure and outcome.
	ID			Trait	First author		Sample size	Number of variants	Year			sex	Population	Build
exposure		ebi-a-GCST003375	cystatin C		Pattaro C	32834		2153636	2016		NA		European	HG19/GRCh37
outcome	finn-b-AB1_ZOSTER			herpes zoster	NA	2080		16380433	2021			Males and Females	European	HG19/GRCh37

2.2. Mendelian randomization analysis

After data acquisition, we evaluated the association between the SNPs and cystatin C. We examined the association between each SNP and HZ: separately. Finally, combined with the results, we used MR analysis to evaluate the causal association between cystatin C and HZ. Three statistical methods were used to investigate the relationship between cystatin C and HZ: MR-Egger regression, weighted median estimator, and inverse variance weighting (IVW). MR-Egger regression is a statistical technique applied in MR studies to examine causal associations between exposure and outcome. This method is commonly used to identify and adjust for pleiotropic effects in which a genetic variant influences outcomes through various paths. The MR-Egger approach utilizes instrumental variables to estimate the causal effect of the exposure on the outcome, taking into account any potential effects resulting from pleiotropy⁸. The weighted median estimator is a statistical method that is used to estimate the typical value of a population by computing the median score of a weighted sample. In this technique, each data point in the sample is assigned a weight that denotes its relative significance or impact on the overall estimation of the population parameters. The weighted median estimator is particularly useful when outliers are present in the data distribution as it provides a more robust measure of central tendency than traditional techniques such as the arithmetic mean⁹. IVW is a statistical analysis technique commonly employed in meta-analyses to integrate the effect size estimates derived from numerous studies. In the IVW, the weight assigned to each study is proportional to its inverse variance, which signifies the accuracy of its effect estimate. By considering both the sample size and the variation in effect sizes across studies, the IVW approach constructs a pooled effect size¹⁰.

2.3. Heterogeneity test and sensitivity analysis

We tested the heterogeneity between SNPS by calculating Q value¹¹ and Ι² value¹². We also conducted a "leave-one-out" analysis to explore the potential influence of an individual SNP on the causal association.

2.4. Statistical analysis

MR analysis was completed using the “TwoSampleMR” package of the R-project (V4.2.3)¹³. Calculation of the causal association between cystatin C and HZ was reported as an odds ratio (OR) with a corresponding 95% confidence interval (CI). Significance was evaluated based on a p-value less than 0.05, indicating the statistical significance of the observed difference.

3.1 Detail of SNPs

We selected 5 independent SNPs from GWASs that were significantly associated with both cystatin C and HZ. For details about each of the SNPs, refer to Table 2 and Fig. 1.

Table 2

details of each SNP.
SNP	effect_allele.exposure	β.exposure	pval.exposure
rs3827143	G	0.072	1.00e-15
rs4293393	G	0.019	3.20e-15
rs4714704	A	0.013	1.30e-08
rs4859682	A	-0.013	4.90e-12
rs653178	T	0.012	1.70e-10

3.2 Mendelian randomization

MR-Egger regression, weighted median estimator, and IVW results are presented in Table 3 and Fig. 2. IVW and weighted median methods showed that cystatin C had a protective effect on HZ (IVW : β=-1.229, P = 0.010,OR = 0.293, 95% CI = 0.114–0.749. with the weighted median estimator, these values were: β=-1.328, P = 0.008 OR = 0.265, 95% CI = 0.100-0.705). On the other hand, MR-Egger analysis suggested no causal association between cystatin C and HZ (β=-1.642 P = 0.103 OR = 0.194, 95%CI = 0.048–0.774). However, the weighted median estimator and IVW allow for greater precision in estimates than MR-Egger analysis¹⁴. Therefore, our results may support a potential causal association between cystatin C and HZ.

Table 3

Causal Associations Between cysteine C and HZ
method	nsnp	b	se	pval		OR(95%CI)
MR Egger	5	-1.642	0.707	0.102	0.194(0.048–0.774)
Weighted median	5	-1.328	0.008	0.008		0.265(0.100-0.705)
IVW	5	-1.229	0.479	0.010		0.293 (0.114–0.749)

3.3 Heterogeneity test and sensitivity analysis

Cochran's Q test and Ι² results suggested no heterogeneity (Table 3). Low heterogeneity indicates the reliability of MR results¹⁵. The horizontal pleiotropy test showed no pleiotropy in our MR analysis (MR-Egger regression intercept=-0.018, standard error = 0.022, P = 0.485; P > 0.05 represents no pleiotropy and conforms to MR), The "leave-one-out" analysis showed that no individual SNP had a significant impact on the causal inference (Fig. 3).

Cystatin C is an inhibitor of cysteine protease that is secreted and expressed in significant amounts in bodily fluids. Its molecular weight is relatively small, making it a convenient marker for measuring glomerular filtration rate in clinical settings as an indicator of renal function. Recent research has demonstrated that Cystatin C is intricately linked to numerous pathological processes via diverse mechanisms. Consequently, variations in Cystatin C concentrations not only serve as an indicator of renal function, but also possess noteworthy clinical implications for other ailments ¹⁶. Specifically, investigations have revealed that the up-regulation of Cystatin C is associated with oxidative stress-induced apoptosis of rat neurons¹⁷, while other studies have observed a marked reduction in Cystatin C expression within both atherosclerosis and aneurysm lesions¹⁷.

Well known HZ is closely associated with low immunity². There is increasing evidence suggested that cystatin C is involved in many immune processes¹⁷. Recent studies have shown that cystatin C may play a role in regulating the activity of white blood cells. Specifically, it has been shown to inhibit the activity NK cell. By inhibiting their activity, cystatin C may be able to prevent the immune system from attacking healthy cells and tissues¹⁸. In addition to its effects on NK cells, cystatin C has also been shown to regulate the activity of other immune cells, including T cells and B cells¹⁶. The mechanism of cystatin C regulating immune cells may be that it is absorbed by immune cells in various tissues to regulate the intracellular and extracellular cysteine protease activity¹⁹. The immunoregulatory effect of cystatin C may be one of the mechanisms of its association with HZ.

The association between cystatin C and HZ may be further elucidated by its properties as a pain marker. Previous research has demonstrated a significant increase in cystatin C levels in the cerebrospinal fluid of individuals experiencing severe pain ²⁰. PHN, a frequent neurological complication of HZ, is characterized by intense burning or electric shock sensations resulting from nerve damage caused by viral replication-induced inflammation ²¹. As such, researchers have hypothesized that cystatin C may serve as a predictive biomarker for PHN ³, and the results of our study provide evidence for this point.

Mendelian randomization is a randomization technique that mitigates experimental bias by randomizing groups, thereby ensuring repeatability and comparability, and promoting rigor and precision in scientific experiments²². This study is the first to use Mendelian randomization to analyze the relationship between cystatin C and HZ, and found that cystatin C has a certain protective effect on HZ. The results are highly reliable, which is also a highlight of this study. However, our study has some limitations. First, the sample size used in this study was relatively small. Second, the study population was European only.

In this study, MR analysis was used to prove that cystatin C has a protective effect on HZ; therefore, cystatin C has a certain protective effect on HZ. Cystatin C may be a potential biomarker for evaluating HZ and PHN, the specific dose-effect relationship needs further clinical study.

CI, confidence interval; HZ, Herpes zoster; GWAS, genome-wide association study; IVW, inverse weighted variance, Mendelian randomization; OR, odds ratio; SNP, single nucleotide polymorphism.

Ethical Approval

This study not need ethical approval

Funding

Guangxi Medical and heal key discipline construction project.

Declaration of interest

Data availability

Author contributions

Hongtao Liu writes the manuscript, and Fengkun Zhou reviews and finalizes the manuscript

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No competing interests reported.

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Version 1

posted

You are reading this latest preprint version

Causal Relationship Between Cystatin C and Herpes zoster: A Mendelian Randomization Analysis

Status:

Version 1

Abstract

Objective

Method

Results

Conclusion

Figures

1. INTRODUCTION

2. MATERIALS AND METHODS

2.1 Acquired genetic variant data

2.2. Mendelian randomization analysis

2.3. Heterogeneity test and sensitivity analysis

2.4. Statistical analysis

3. RESULTS

3.1 Detail of SNPs

3.2 Mendelian randomization

3.3 Heterogeneity test and sensitivity analysis

4. DISCUSSION

5. CONCLUSION

Abbreviations

Declarations

References

Additional Declarations

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