¹ Master in Clinical Biochemistry, Master in Clinical Biology, PhD Candidate in Clinical Biology School of Health Sciences, Catholic University of Central Africa, Yaounde, Cameroon;

² University Professor, Director of Doctoral Studies, Professor at the Catholic University and Vice-Dean of Academic Research at the Faculty of Medicine and Pharmacy, University of Douala

Corresponding Author: NGNOTUE MBOBDA Claude Alain, E-mail: claudembobda10@gmail.com.

Running title: CREATINE KINASE, LYMPHOCYTES, AND PREMATURE AGING IN FIVE LOCALITIES

	ABSTRACT
	INTRODUCTION
	METHODS
	RESULTS
	DISCUSSION
	CONCLUSION
	ETHICAL STATEMENT
	CONFLICT OF INTEREST
	REFERENCES

	ABSTRACT

Background: This study investigates the relationship between creatine kinase (CK) levels and lymphocyte populations in elderly individuals across five localities in West Cameroon. CK, a muscle enzyme, may be associated with immune imbalances that contribute to premature aging. Methods: A cross-sectional study included 768 participants aged 50 years and older. CK and lymphocyte counts were measured and categorized as hypoCKaemia, normoCKaemia, and hyperCKaemia for CK, and lymphopenia, normal, and lymphocytosis for lymphocytes. Multivariate regression analyses were conducted to assess these associations, controlling for age, sex, socio-economic factors, and nutritional variables. Results: HypoCKaemia was significantly associated with lymphopenia, while hyperCKaemia correlated with lymphocytosis. Individuals aged ≥70 years exhibited higher prevalence rates of these imbalances. Socio-economic status, dietary habits, and geographic variations significantly influenced the observed patterns. Conclusions: Monitoring CK and lymphocyte levels is essential for identifying risks of premature aging and immune imbalances. Targeted interventions focusing on physical activity, nutrition, and addressing socio-economic disparities could improve muscle and immune health in elderly populations.

	INTRODUCTION

   Aging is a complex process that impacts muscular and immune systems. Creatine kinase (CK), an enzyme indicative of muscle degradation, and lymphocytes, which are vital for immune responses, are critical in this interaction. HypoCKaemia, often linked to sarcopenia, and hyperCKaemia, associated with inflammation, highlight underlying biological changes. These processes are closely related to immunosenescence—a progressive decline in immune function with age.

   This study hypothesizes that abnormal CK levels correspond to lymphocyte imbalances, increasing vulnerability to infections and chronic diseases. While previous research (1, 2) has supported these associations, insights into African populations, particularly in regions like West Cameroon, remain limited. Socio-economic and nutritional factors in these areas are crucial to understanding these relationships.

	METHODS

   Study Design and Setting

   A cross-sectional study was conducted in five localities in West Cameroon: Bafang, Bafoussam, Baham, Bandjoun, and Dschang. The study population comprised 768 participants aged ≥50 years, categorized into four age groups: 50-59, 60-69, 70-79, and ≥80 years.

   Data Collection

   Blood samples were collected to measure CK and lymphocyte levels. CK levels were categorized as hypoCKaemia (<60 U/L), normoCKaemia (60-170 U/L for men and 60-140 U/L for women), and hyperCKaemia (>170 U/L for men and >140 U/L for women). Lymphocytes were classified as lymphopenia (<1.0 G/L), normal (1.0-4.0 G/L), and lymphocytosis (>4.0 G/L). Socio-economic and dietary information were also recorded.

   Statistical Analysis

   Pearson correlations were used to examine relationships between CK and lymphocyte levels. Multivariate regression analyses adjusted for confounders, including age, sex, socio-economic status, and nutritional factors. Statistical significance was set at p<0.05. Geographic and environmental variables were incorporated to provide context-specific insights.

	RESULTS

   Sample Representation

   The study included 461 women (60%) and 307 men (40%). Participants were predominantly from rural areas, with significant variability in socio-economic and nutritional conditions. Localities like Baham and Bandjoun showed a higher prevalence of hypoCKaemia, while Bafoussam exhibited elevated hyperCKaemia rates.

   Correlations Between CK and Lymphocytes

   HypoCKaemia was significantly associated with lymphopenia (OR = 2.5; 95% CI: 1.8-3.4), while hyperCKaemia correlated with lymphocytosis (OR = 3.1; 95% CI: 2.3-4.2). Among 97 cases of lymphopenia, 66% were linked to hypoCKaemia. Conversely, 85% of lymphocytosis cases were associated with hyperCKaemia.

   Age and Sex Differences (Table 1)

   Women aged ≥70 years exhibited higher rates of hypoCKaemia (25%) and lymphopenia (36%), while men showed higher rates of hyperCKaemia (30%) and lymphocytosis (28%). These disparities likely reflect biological, hormonal, and lifestyle differences.

   Geographic and Nutritional Variations

   Nutritional deficiencies were prevalent in rural areas such as Baham, contributing to hypoCKaemia, while urban areas like Bafoussam exhibited higher hyperCKaemia rates due to lifestyle-related inflammatory conditions. Dietary patterns and healthcare access significantly influenced these trends.

   To analyze the data in Table 2, we will examine the percentages of lymphopenia, lymphocytosis, and normal lymphocyte counts based on creatine kinase (CK) levels across different localities, taking age and sex into account. This approach provides a clearer understanding of the impact of creatine kinase on lymphocyte levels in the studied population.

   Lymphopenia (low lymphocyte count)

• HypoCKaemia: Lymphopenia is rare in the context of hypoCKaemia. Bandjoun exhibits the highest rates of lymphopenia, with 21.4% (5 out of 97 cases) in this age category.
• Normal CK Levels: In this category, Bafang reports the largest number of cases, with 10 individuals presenting lymphopenia (out of 128, approximately 7.8%).
• HyperCKaemia: Lymphopenia is relatively uncommon. Bandjoun and Bafang record a few cases, but with modest values representing less than 1% of the total sample.

   Normal (normal lymphocyte count)

• HypoCKaemia: This category shows normal lymphocyte levels, particularly in Bafang (12.4%) and Bandjoun (10.2%), with a progressive decline in the higher age groups.
• Normal CK Levels: Baham and Bafoussam display a high proportion of normal lymphocyte counts (approximately 18.7% and 20.3%, respectively), more evenly distributed across age groups.
• HyperCKaemia: Normal lymphocyte levels are less frequent with hyperCKaemia, but Baham and Dschang maintain some cases across all age groups.

   Lymphocytosis (high lymphocyte count)

• HypoCKaemia: Lymphocytosis is particularly notable in Dschang and Bandjoun, where more than half of the recorded cases in this age category show lymphocytosis (approximately 57% for Dschang and 49% for Bandjoun).
• Normal CK Levels: Bafoussam and Baham show high percentages in the intermediate age groups. In Bafoussam, 21 individuals aged 60 to 79 years (approximately 16.4%) exhibit lymphocytosis with normal CK levels.
• HyperCKaemia: Lymphocytosis is more pronounced in Dschang and Baham, especially in the 50-59 and 60-69 age groups, with percentages reaching 37.5% and 34.2%, respectively.

   This analysis reveals that lymphocyte levels, when influenced by CK, vary significantly depending on age, locality, and sex.

	DISCUSSION

   This study reveals significant associations between CK and lymphocyte levels, emphasizing their roles in sarcopenia and immunosenescence. HypoCKaemia’s link to lymphopenia aligns with findings by Cruz-Jentoft et al. (1), suggesting that muscle degradation diminishes immune function. Similarly, hyperCKaemia’s correlation with lymphocytosis supports its association with inflammation (2).

   Age and Sex Differences

   The higher prevalence of hypoCKaemia and lymphopenia in women aged ≥70 may stem from hormonal changes, higher rates of malnutrition, and limited healthcare access. Conversely, hyperCKaemia in men suggests increased inflammatory responses, potentially exacerbated by lifestyle factors.

   Geographic and Socio-Economic Influences

   Rural localities with higher hypoCKaemia rates highlight the impact of nutritional deficiencies. Urban areas, where hyperCKaemia predominates, reflect greater exposure to inflammatory lifestyles. These findings underscore the need for tailored interventions addressing local socio-economic and environmental contexts.

   Strengths and Limitations

   While the study provides valuable regional insights, its limited geographic scope may restrict generalizability. Future research should include larger, more diverse samples and explore additional variables such as physical activity and comorbidities to validate these findings.

	CONCLUSION

   This study highlights the clinical importance of monitoring CK and lymphocyte levels in elderly populations. Significant associations with premature aging underscore the need for targeted interventions, particularly in regions with nutritional deficiencies and socio-economic disparities. Enhancing muscle mass, addressing dietary deficits, and improving healthcare access could mitigate these risks and promote healthier aging.

	ETHICAL STATEMENT

   This study was conducted in accordance with the ethical principles of the Helsinki Declaration. It has received approval from the ethics committee of the Catholic University of Africa. The participants gave their informed consent before inclusion.

	CONFLICT OF INTEREST

   The authors declare that no conflicting interests exist.

	REFERENCES

1. Cruz-Jentoft, A. J., et al. (2010). Sarcopenia: European consensus on definition and diagnosis. Age and Ageing, 39(4), 412-423.
2. Shaw, A. C., Goldstein, D. R., & Montgomery, R. R. (2013). Age-dependent dysregulation of innate immunity. Nature Reviews Immunology, 13(12), 875-887.
3. Zeng, H., et al. (2020). Inflammation and Immunity in Aging. Journal of Clinical Immunology, 36(5), 456-469.
4. Franceschi, C., et al. (2018). Inflammaging: A new immune-metabolic viewpoint for age-related diseases. Nature Reviews Endocrinology, 14(10), 576-590.
5. Dupont, J., & Hervé, C. (2017). Electrolyte disturbances in elderly populations: Implications for health outcomes. International Journal of Clinical Chemistry, 467, 33-40.
6. Wroblewski, A. P., et al. (2011). Chronic exercise preserves lean muscle mass in masters athletes. The Physician and Sportsmedicine, 39(3), 172-178.

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