Association of vitamin D with macrophage migration inhibitory factor and interleukin-8 in diabetic foot infection

Shalbha Tiwari; Daliparthy D Pratyush; Sanjeev K Gupta; Surya K Singh

doi:10.4103/cdrp.cdrp_6_21

ORIGINAL ARTICLE

Year : 2022 | Volume : 1 | Issue : 1 | Page : 9-12

Association of vitamin D with macrophage migration inhibitory factor and interleukin-8 in diabetic foot infection

Shalbha Tiwari¹, Daliparthy D Pratyush², Sanjeev K Gupta³, Surya K Singh⁴
¹ Department of Endocrinology and Metabolism, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh; Department of Research, Chellaram Diabetes Institute, Pune, Maharashtra, India
² Department of Endocrinology and Metabolism, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh; Division of ECD, Indian Council of Medical Research DHR, New Delhi, India
³ Department of General Surgery, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India
⁴ Department of Endocrinology and Metabolism, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India

Date of Submission	20-Oct-2021
Date of Decision	01-Nov-2021
Date of Acceptance	02-Nov-2021
Date of Web Publication	07-Jan-2022

Correspondence Address:
Surya K Singh
Department of Endocrinology and Metabolism, Institute of Medical Sciences, Banaras Hindu University, Varanasi - 221 005, Uttar Pradesh
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/cdrp.cdrp_6_21

Abstract

Background: Diabetic foot wound is an important health challenge throughout the world. Interleukin 8 (IL8) and macrophage-migration inhibitory factor (MIF) play a significant role in host defense and in wound healing. Immune perturbation and Vitamin D deficiency also contribute to nonhealing of diabetic foot wounds. We aimed to evaluate the serum concentration of IL8 and MIF in diabetic patients with and without foot infection and its association with Vitamin D status. Material and Methods: Serum concentrations of 25 dihydroxyvitamin Vitamin D and cytokines (IL8 and MIF) were measured by radioimmunoassay and enzyme-linked immunosorbent assay, respectively, from 100 subjects with diabetes and foot infection as cases and 73 subjects with diabetes without foot infection as controls. Data were presented as mean (± standard error of mean [SE]) unless otherwise indicated and were analyzed by SPSS 16.0. Results: There was no significant difference in the mean (±SE) of age, duration of diabetes, hemoglobin A1C, and body mass index between the two groups. The mean (±SE) concentration of IL8 was significantly higher and MIF was significantly lower in cases than controls. Vitamin D correlated negatively with IL8 (r = −0.191) and positively (r = 0.1) with MIF. However, only the former correlation was statistically significant (P = 0.01). IL8 was also significantly high in patients with severe Vitamin D deficiency (<10 ng/ml) compared to patients with Vitamin D more than 10 ng/ml. Conclusion: Serum concentration of IL8 is significantly higher in diabetic foot infections compared to controls. Severe Vitamin D deficiency was associated with IL8 concentration in patients with diabetes.

Keywords: Cytokines, diabetic foot, interleukin 8, macrophage-migration inhibitory factor, Vitamin D

How to cite this article:
Tiwari S, Pratyush DD, Gupta SK, Singh SK. Association of vitamin D with macrophage migration inhibitory factor and interleukin-8 in diabetic foot infection. Chron Diabetes Res Pract 2022;1:9-12

How to cite this URL:
Tiwari S, Pratyush DD, Gupta SK, Singh SK. Association of vitamin D with macrophage migration inhibitory factor and interleukin-8 in diabetic foot infection. Chron Diabetes Res Pract [serial online] 2022 [cited 2023 Mar 29];1:9-12. Available from: https://cdrpj.org//text.asp?2022/1/1/9/335258

Introduction

Diabetic foot problems pose a huge economic burden on individuals.^[1],[2] Complexity of diabetic foot wounds makes the treatment difficult and expensive. Although several studies have shown risk factors associated with it, still there is limited understanding about diabetic foot wound. In addition to several endogenous factors leading to causation and progression of diabetic foot wounds, “infection” is one of the exogenous factors that lead to the worsening of diabetic foot wounds. Nonhealing diabetic foot wounds symbolize hyper-inflammatory state^[3] and restoration of immune homeostasis in wound microenvironment is essential for effective wound healing.

Macrophages and related cytokines are one of the key components of host defense that not only help in infection control but also promote wound healing.^[4] Expression of macrophage migration inhibitory factor (MIF) at sites of inflammation^[5],[6] suggests its role in regulating the functions of macrophages in host defense. Interleukin 8 is a chemokine produced by stimulated monocytes/macrophages^[7] which primarily mediate activation and migration of neutrophils from peripheral blood to tissue site, a crucial step for infection control.^[8] Thus, it is important to understand the profile of these two important immune parameters in relation to diabetic foot infections.

The inflammatory cytokine concentrations in diabetic foot wounds are also found to be associated with Vitamin D deficiency.^[9] In the present study, we aimed to evaluate the serum level of MIF and interleukin 8 (IL8) in type 2 diabetes subjects with foot infection and without foot infection. and its correlation with Vitamin D status of the host.

Material and Methods

The study was conducted at endocrine and general surgery department of a medical college and university hospital in North India. Written informed consent was obtained. The study was approved by Institutional Ethics Committee.

Selection of subjects

Type 2 diabetes subjects with foot infection admitted to the endocrine and surgery unit wards of the university hospital were recruited in the study as cases and subjects with diabetes without foot infection were recruited as study controls. Subjects on immunosuppressants and having a compromised blood supply of the limbs were excluded from the study.

Blood samples were collected after an overnight fast in a plain vial and in ethylenediamine tetraacetic acid vial for serum biomolecular profiles (biochemical and immunological) and hemoglobin A1C (HbA1c), respectively. Aliquoted serum samples were stored at −80° C till the assay period.

Biochemical and immunological analysis

HbA1c was measured routinely in the endocrine laboratory using Drew Scientific DS5 HbA1c analyzer. Serum 25 hydroxy Vitamin D concentration was measured by radioimmunoassay (RIA) using commercially available kit (Diasorin, Italy). The intra and inter-assay variations coefficients of variation (% CV) were 11.7 and 12.5, respectively. MIF (RayBiotech, Inc. Norcross GA) and IL8 (Diaclone, France) concentrations were measured by enzyme-linked immunosorbent assay as per manufacturer's protocol. The minimum detectable dose (sensitivity) of MIF was <6 pg/ml. The intra and interassay CV were <10 and <12, respectively. The minimum detectable dose (sensitivity) of IL8 was 29 pg/ml. Intra and interassay %CV were 3.1 and 9.7, respectively.

Statistical analysis

Data were analyzed by using SPSS 16.0 (SPSS Inc., Chicago, US) and Graph Pad 3.0 (GraphPad Software, Inc. San Diego, US) software. Unpaired t-test was used to compare the clinical characteristics and the cytokine levels of cases and controls. Correlation analysis was used to assess the association between Vitamin D and cytokine level in the study population. Independent “t”-test was used to compare the cytokine level in subjects with severe Vitamin D deficiency from that of remaining subjects.

Results

Cytokine concentrations in cases and controls

The age, duration of diabetes, HbA1c, Vitamin D, and body mass index (BMI) of study participants of the two groups are summarized in [Table 1]. There was no significant difference in the mean (±Standard Error of Mean [SE]) age, duration of diabetes, HbA1c, and BMI between the two groups on statistical analysis. Although Vitamin D level was comparatively lower in cases than controls, the difference did not reach statistical significance. The mean (±SE) concentration of inflammatory cytokines IL8 was significantly (P = 0.009) higher and of MIF was significantly (P < 0.0001) lower in cases than controls.

Table 1: Comparison of clinical parameters and cytokine profile of diabetic foot infection cases and controls with diabetes

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Vitamin D and cytokines-correlations analysis

There was a significant negative correlation of Vitamin D with IL8 [Figure 1]. No significant correlation of Vitamin D with MIF [Figure 2] was observed. The correlation coefficient and P value for IL8 were r = −0.191; P = 0.01 and MIF were r = 0.1; P = 0.3.

Figure 1: Correlation between Vitamin D and interleukin 8

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Figure 2: Correlation between Vitamin D and macrophage-migration inhibitory factor

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Cytokine level in severe Vitamin D deficiency

Subjects with severe Vitamin D deficiency (25 dihydroxyvitamin [OH] Vitamin D <10 ng/ml) have significantly higher level of IL8 compared to those having 25 (OH) Vitamin D ≥10 ng/ml. There was no difference observed in MIF concentration between the two sub groups [Table 2]. The analysis did not show statistical difference in cytokine levels with Vitamin D concentration cutoff of 20 ng/ml.

Table 2: Comparison of cytokines levels in diabetes with and without severe Vitamin D deficiency

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Discussion

Increased IL-8 concentration in patients with diabetic foot infection in our study substantiated the findings of Hirao et al., who also found significantly higher level of IL-8 in patients with septic syndrome than healthy controls and suggested IL-8 as a valuable early indicator of bacterial infection.^[8] It has also been proposed that IL-8 in addition to tumor necrosis factor-alpha (TNF-α) and transforming growth factor beta 1 (TGF-β1) may participate in development and progression of the diabetic complications.^[10]

MIF is a pleiotropic cytokine that functions as a critical mediator of innate immunity and promotes several pathophysiological processes including autoimmune diabetes^[11] and type 2 diabetes.^[12] We observed low circulating level of MIF in subjects with diabetic foot infection compared to subjects with diabetes without foot infection. Our findings were contrary to the previous study where a blood level of MIF was markedly elevated in association with fatal outcome in sepsis.^{[6],[13],[14]}

Our findings indicated dysregulation in the inflammatory cytokine milieu in subjects with diabetes similar to the earlier reports. Researchers have shown that subjects with diabetic foot ulcers exhibit specific and nonrandom upregulation of several acute-phase proteins, cytokines, and chemokines but their study has limitation of confounding variables including age and HbA1c that vary significantly in the subjects with diabetes with and without foot ulcer.^[15]

A potential physiological role for Vitamin D in regulating innate and adaptive component of immunity was documented previously.^[16] A negative correlation of Vitamin D with IL8 in the study participants strongly supported its anti-inflammatory role. Similar were the findings from another study where it was shown that 1α, 25 OH D3 downregulated the expression of inflammatory cytokines TNF-α, IL-6, and IL-1 β and suppressed interferon gamma “mediated macrophage activation.^[17],[18] Zhang et al. have shown that Vitamin D inhibits monocyte/macrophage pro-inflammatory cytokine production.^[19]

Our observation was further strengthened by another important finding of this study. A significant difference in the level of IL-8 was present in subjects with severe vitamin D deficiency, i.e., serum level <10 ng/ml in comparison to subjects with Vitamin D ≥10 ng/ml. This substantiated the previous observation^[9] where Vitamin D <10 ng/ml was proposed as a risk factor for unfavorable immune alteration in diabetic foot infection. Preliminary study showed elevated cytokine response in diabetic foot infection consequent upon Vitamin D deficiency. Previously, Khoo et al. had also shown that elevated Vitamin D3 level in vivo was associated with downregulation of cytokine response in healthy subjects.^[20]

Studies have also shown the effect of Vitamin D on glucose homeostasis, insulin resistance, and β cell dysfunction in subjects at risk of type 2 diabetes^[21] and on markers of inflammation in nondiabetic adults.^[22] Experimental studies support the involvement of Vitamin D in modulating the inflammatory response but human studies are scarce investigating inflammatory biomarkers specifically in subjects with or at high risk of type 2 diabetes and its complications.^[23],[24] Our study reported the influence of Vitamin D status on markers of inflammation in subjects with diabetes and diabetic foot infection. This could possibly have a clinical implication on the use of Vitamin D supplementation in diabetic foot.

The underlying complications and insulin status of the two groups were not evaluated before comparing the cytokine data which is a limitation of the present study. Furthermore, the cytokine status of nondiabetic subjects with soft tissue infection was not included in this study as our intention was to identify the immune changes in subjects with diabetes in presence and absence of foot infection.

Conclusion

IL 8 was higher in patients with diabetic foot infection than in patients with diabetes. IL 8 was negatively correlated with serum vitamin D level in the study subjects of both the groups. Thus, the present study provides a valuable information about the role of vitamin D and its serum level to influence the marker of inflammation in patients with diabetes and diabetic foot infection.

Acknowledgment

The authors wish to thank Dr T. B Singh, Professor-Biostatistics at Institute of Medical Sciences, Banaras Hindu University for providing support in the statistical analysis. The work was funded by the Indian Council of Medical Research, New Delhi, India, in the form of a grant (IRIS ID no. ICMR/RHN/2008-04670) to SKS. ST and DDP thank the University Grant Commission, New Delhi, India, for financial assistance as research fellowships. Part of the study has been presented in Desert Foot 2011 conference at, Phoenix, Arizona, USA by S. T and been awarded with third prize.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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